Hi everyone,

I plan to "upgrade" a defective vintage audio amplifier with two class D, preferably TPA3255 boards. In order to use the existing heatsinks I would require a board that has the TPA3255 chip mounted on the bottom side, sort of like this one: https://www.diyaudio.com/community/threads/tpa3255-core-pcb.343919/#post-5945395

Do anyone know of such a board?

Thank you and kind regards!

Preamp 12AU7 amplifier stage and a HiFi amplifier stage with a TDA7293 and isolated tone control. What do you think?

Looking for a pair TOKIN TKS45F323 SIT to repair my broken HYUGER HE-SIT-2 amplifier. Any help?

Thanks

​

Stereophile Class A recommended components..

Class A
Best attainable sound for a component of its kind, almost without practical considerations; "the least musical compromise."

Recommended Components 2021 Edition Phono Preamplifiers | Stereophile.com

EQ1616D were nearly old out. The next production will be in July 2021. --> April Production was SOLD OUT.
The Next Production is July 2021.
If you want to reserve a unit of EQ1616D, please let me know.
Thank you for your support!!

Price $985.00 Kit
Assembled Version $1,645 with 2 VCAP ODAM 2.2 (assembled by Sunvalley Japan)


Stereophile Review - November 2020 edition
Gramophone Dreams #42: Sunvalley Audio SV-EQ1616D phono equalizer | Stereophile.com

Sunvalley SV- -EQ1616D 115/230V version (Point to Point Phono amp Kit)
Made in Japan

Price $985 KIT Version
Price $2,050 ASSEMBLED Version ( Assembled by SunValley Japan with tube set (Gold Lion ECC83/B759 X 2 + Brimar ECC82 X 1 + LINLAI/COSSOR WE 274B) + VCAP ODAM 2.2 X 2 (output Cap)
Price $1,585 (assembled version w/o tube set . VCAP ODAM 2.2 X 2 included) + shipping
Assembled Version

This kit does not come with tube set. The following 3 combinations are recommended.

(Plum set)
Gold Lion ECC83 / B759　x 3 + LINLAI 274B
Standard combination. Natural charm

(Bamboo set)
Gold Lion ECC83 / B759 　x 3
WE 274B
Powerful midrange

(Pine set)
Gold Lion ECC83 / 12AX7 　x 2
Brimar 12AU7 x 1
Cossor/Linlai WE274B x 1
Vcap ODAM 2.2uF [2 pieces] x 1
Superb harmonics


● Phono equalizer that emphasizes sound quality
● 2 input systems that are ideal for using 2 turntables
● Output: 1 system (MONO (L) / STEREO switchable) * MONO: L channel Input → L / R dual output
● Compatible with MM / MC cartridges (MC input: head amplifier) * MM: 47kΩ, MC: 20Ω to 50Ω
● Gain: MM35dB, MC + 22dB
* Gain can be selected according to the output voltage of the cartridge ( When HIGH / LOW) or LOW is selected -4dB (MM) /-2.5dB (MC)
● Vacuum tube: Amplification stage (V1 / V2): 12AX7, 2nd stage (V3): 12AX7, 12AU7, 12AT7 can be selected arbitrarily (according to your taste)
* The standard is all 12AX7, and if you want the smooth texture of high frequencies with a high output cartridge, 12AU7 is recommended only for V3 ( I have RCA clear TOP or Brimar to pick)
● Rectifier: Standard / diode module, option / various rectifier tubes (5AR4, 274B, 5R4 etc. can be used) ( I have LinLai 274B, WE274B, ACME 274B or ELROG 274B)
● Turnover frequency adjustment: Switchable
  → Compatible with RIAA, old AES, COLUMBIA / old NAB, LONDON, EU SP , US SP
  * Not only turnover frequency but also low frequency characteristics can be changed simultaneously according to each EQ curve.
● High-frequency roll-off adjustment: ON / OFF selection type
* When ON: Continuously variable (corresponding to all EQ curves), When OFF: No attenuation (for SP LP)
● Detail assembly guide included
● Assembly difficulty: ★★ ★★ ☆ (for intermediate to advanced)


Size mm (including protrusions): W250 x D225 x H135
Weight: 3.8 kg

UPgrade options:
Gold Lion (ECC83/B759 X 2 + Brimar ECC82 X 1) = 215

LinLai/Cossor WE274B $265

VCAP ODAM 2.2 X 2 $85 each


Sunvalley SV-Pre1616D Point to Point Prject

Lundahl MC Transformer will be available Soon... 3 versions with Amorphous core - Standard, OFC, or Silver .
TUBE RECTIFIER











VCAP 2.2uf ODAM

YOU can use sold state RECTIFIER




















VCAP 2.2uf ODAM

Operation Manual 2 & 3

Circuit type: CR type phono equalizer
・ Input: 2 lines
・ Output: 1 system (STEREO / MONO switchable)
・ Corresponding cartridge: MM (47kΩ), MC (50Ω)
MC boost: FET head amplifier
・ Gain: MM36dB ~ 40dB, MC + 25 ~ 32dB (determined by prototype)
・ Vacuum tube: amplification stage: 12AX7 (2), follower stage: 12AX7, 12AU7, 12AT7 can be selected arbitrarily
・ Rectifier: Standard / diode module, option / various rectifiers (5AR4, 274B, 5R4, etc. can be used)
・ Turnover frequency adjustment: Switchable (supports RIAA, EU system SP panel, US system SP panel, AES, NAB, COLUMBIA, etc.)

・ High-frequency roll-off adjustment: ON / OFF selectable (When ON: Continuously variable RIAA and other curves are supported)
(Specifications are subject to change without notice)

Specification :
https://www.kit-ya.jp/user_data/SV-EQ1616D.pdf

Phono + Line stage Amp (Filter - solid state diode or optional 5AR4)

Miles Davis "Someday My Prince Will Come" (Columbia / old NAB curve) 1961


"Art Blakey And The Jazz Messengers" (AES curve) 1958


Miles Davis "Kind Of Blue" (Columbia / old NAB curve) 1959



Sonny Rollins: A Night At The "Village Vanguard" (AES Curve) 1957



Playing LP with the proper curve will make a big difference in the strength of the sound to anyone listening, especially the freshness of the mid-high range,

Since the sound quality of the LP differs depending on the label and recording , the SV-EQ1616D cannot only turn on / off the roll-off (high frequency level attenuation
characteristic) of 1 kHz or more, but also can make fine adjustments when the roll-off is ON. Since it is also possible to control the tone, you can enjoy each LP with the
optimum sound quality.

Reading up on different output stage topologies again, I've had this strange idea coming to my mind. On the EF3-topo, each driver transistor is connected to the opposing rail with a separate resistor, determining the idle current. What if I were to replace each resistor with a simple constant current source?
While the EF3 doesn't seem to be all that popular and widespread, I've never even seen an "EF3.5" anywhere. Is there anything severely wrong with it that didn't occur to me yet? Any thoughts / ideas / sources? I'd like to read up on any previous work, if there happens to be something published anywhere.

Good morning.My name is Alejandro, and I'm a Bang & Olufsen customer.I also regularly repair Bang & Olufsen products.Thank you in advance for letting me participate.

Hello all in the forum
Have reparing Audio power box with 4.1 channel audio processor OT2350. On its output I am getting DC volts no audio passing throu.
Cant find any datasheets online this is link what i get so far
https://oinc-pixnet-net.translate.goog/blog/post/66296896?_x_tr_sl=zh-TW&_x_tr_tl=en&
Pic of the ic is bellow

Any help is wellcome

Lundahl LL2777B for TU-8200​

https://www.diyaudio.com/community/threads/lundahl-for-tu-8200.339756/

• better protection circuit to prevent malfunction when Tube Rolling
• better coupling caps and cathode bypass cap

Price $895.00

• You can adjust the headphone impedance
• better components
• Can use ALPS R27 volume pot

We will offer upgrade kit to upgrade to R version
Lundhal OPT option is coming....



New features
- Active automatic bias adjustment function
Other than 6L6GC that comes with the kit, KT66, KT88, EL34, 6550, etc can also be used.

• UL, Triode and Pentode output mode
• LOW ESR conductive polymer hybrid aluminium cathode Bypass capacitor
• Headphone impedance can be selected by changing the jumper location
• The protective circuit has been improved to avoid malfunction due to tube rolling

My questions are:

Which drivers need the BSC?

How to measure the “z-offset” and which ones need it?
I am working on a set of three way tower speakers using the ScanSpeak Discovery Drivers. I am using the following drivers:

ScanSpeak Discovery D2608/9130 1" Textile Dome HDS Tweeter.
Scanspeak 18W/8434G-00 Discovery, 7" Midwoofer (18 cm).
Scanspeak 22W/8534G00 Discovery 8" Woofer (22 cm).

I am taking inspiration (and some liberty) from Troels Gravesen’s “ScanSpeak Discovery 861.” That is the reason for the drivers I am using and the basis for the cabinets I intend to make. My twist is that I am going to put an “Epique E180HE-44 7" DVC MMAG Extended Range Subwoofer” in each tower in their own enclosures at the base. I have already built a subwoofer using one of these drivers and was impressed with the output. The subwoofers will be ported and run together powered by an external amplifier so the crossover will not need to provide signal for the Epiques.

I have started building a test box as a full scale mockup of the speakers to test the configuration. The woofer will have its own ported chamber (above the sub), and the mid woofer and tweeter will be in an enclosed chamber at the top of the cabinet. I am going to experiment with having the subwoofer forward facing and downward facing (the subwoofer I made using the Epique sub produced the best sound in my room when it was downward firing). The baffle is in two pieces for the test box, that way I can swap out baffles to test subwoofer configuration.

The cabinets will be ¾ inch plywood and the baffle will be one inch thick plywood. The subs get two inch round ports, and the woofer gets a three inch round port.

I am asking for crossover design help. I realize that to really tune the speakers properly, I need to get frd and zma files from the actual drivers and I plan on doing that as soon as I get the baffles made and the holes for the drivers cut out. I will run frequency sweeps in the actual test box. The woofer, mid and tweeter will all be on the same common baffle and I will flush mount them. And counter to what people recommend, I will line them all up on the same axis for symmetry (aesthetics). For now I’m using the frequency responses and impedance from the manufacturer’s datasheet as my test data.

I am looking for advice on the three way crossover. I have done one two-way and now I need help with the three way crossover. Specifically, with “baffle step correction (BSC)” and “z-offset.”

Any input would be greatly appreciated.

Cheers,
George, Tigard Oregon, UDA

Many years ago I bought a BYOB (Build Your Own Buitar) from Hobby Lobby and got it together a few years ago. As a non-musician I have since decided that maybe I could eventually learn to play a frew notes on a bass guitar so I bought a Harley David ... Bentley P-bass kit from the German shop Thomann.
Whilst making work on the body (I will borrow a jig saw for the headstock - my design), I have started looking for a amp/speaker combo. Luckily, with workers replacing the old roofs, and throwing away plywood offcuts, I have enough material for a box to hold that one. It's not furniture grade, but still 15mm pretty acceptable plywood (often referred to as "plyfa" in Swedish). (All dimension in normal units (centigrade).

The guitar is the Harley Benton P-bass as it looks nicer and I just found a heavy coaxial speaker from Master Audio (Italy), an CSX08, an 8", 4.5kg piece with what looks like a small horn tweeter. Stated freqency range 63Hz - 20kHz (could be lower) and recommended crossover frequency of 1.7kHz. 6dB/12dB crossover.
I had an idea to go for a speaker box of approx 400 x 500 x 250mm (16" x 20" x 10") or slightly smaller, using a sort of Onken design or maybe just a single slit, but nothing decided yet.

When it comes to an amp, there's an "issue". I am not going to play at Stockwood ... errr ... Woodstock, but at home and, if I learn more that one note at local events in our old folks club and I think 50W amperage will be enuff.
I've gotten a pair of simple 50W transistor amps built from cheap Chian kits and I guess one of these would be perfect. Else a similar kit from EliExpress is considered: THIS ONE.
For testing I have gotten a D-class chipamp, which had been nice as it doesn't requires a lot of space heatsinks and whatnot. A simple SMPS will do fine (it it works).

I love to fiddle with things and make things a bit diffrunt. I've got 50 shades of pink .. 2 actually for the bass and I will try to mix them in some "odd way". Also gotten a green pickguard that will match the pink body perfectly .
The speaker/amp combo will be covered in vinyl (black-ish) and apart from thinking of power amplifier, I must look up a decent preamp.

This is my plan and I am open for suggestions ... open for REASONABLE suggestions , remember that this is a mid- to lowfi project. For fun. Low cost.

Hi,

I bought a Radford tube amp last week. I ad noticed no humming at the demo of the amp, whyle listening to the music, but at my home it was there. Between the track pauses I can here it 2 metres away. A constant humming coming direct from the coils. The transformer is isolated by rubber gromets and has already be switched to 240V.
What can I do?

Editor's Note: This is the thread for DIY Instruments and Amps - Stuff you or some other non-commercial person made!

For posting photos of your store-bought Instruments and Amps go here:
Post Your Pics of Store-Bought Instruments/Amps Here
End Note

Get a copy of the Grizzly Industrial catalog -- seems that the owner is zonkers for hand/home made guitars -- Grizzly is the source for cutting tools, end mills, boring tools etc., but there is an entire section in the catalog devoted to guitar construction Shop Tools and Machinery at Grizzly.com

good morning everyone.
I've been working on the realization (on paper) of my final speaker for a few months. After doing a lot of research I was able to choose the components, the size of the cabinet, and some drafts of how it should be once completed.
so it will be an active system with dsp minidsp flex htx, hypex and purifi power amps.
I have an 18 subwoofer that covers frequencies from 20 hz to 65 hz.
So I chose the tweeter with double dipole horn beyma tpl 200.
midrange: it will be in a closed box independent from the cabinet for the woofer, the volume will be about 5 liters, and the transducer will be the 18 suoni 6nmb900. woofer: 12 eminence Deltalite 2512 II
or FaitalPRO 12PR 300 4 ohm.
The volume of the box with the Faital transducer would be 55 liters with Q 0.685.
The box with the Eminence transducer would be 65 liters with Q of 0.707.
The uncertainty of the woofer comes from the fact that I don't know how well the Faital can hold the high frequencies without distorting and how qualitatively valid it is up to frequencies of 500/700hz. Or I could keep it up to frequencies of 250/300hz, but then beyond these frequencies I don't know if the midrange would return a big and full-bodied sound as I want. For the cuts I had thought 65/700 48db, 700/2500 48db, 2500/20000. Do you have any advice on this?
regarding the buffle I had thought of a narrow and tapered cabinet, with very rounded edges for the woofer and midrange. I am not sure if the woofer should be far from the midrange and tweeter, or as close as possible. All advice and opinions are welcome.

Have made a TPA3255 board thinking it would be super easy to get working 🙄

But it will not start up, and I'm a bit stuck .....

There is oscillation on OSC_IOM/IOP, see oscilloscope picture.
Had made some stupid mistakes with the reset circuit, but have replaced it with just a blue LED and the 5.6k to 12V which was already there. This means I get 2.6V on reset which should be ok. When I short the LED, bringing RESET to GND and let go again, there is short action on the output surely trying to start up, but it stops right away.
I have put red numbers on the Schematics, for the measured voltages.

Fault is low, and Clip_OTW is high.
This should mean "Overload (OLP) or undervoltage (UVP). Junction temperature lower than 125°C" .... but where is the Under voltage?
Nothing is hot.

When reset is set to GND Fault goes high.

Any suggestions?

Thanks

Hi, I am back on DIY Audio after a few year absence. I have a personal interest in all things audio from turntable rebuilds all the way through to room acoustics. As the owner of both Loud & Clear Edinburgh and Renaissance Audio we are keen to engage with local enthusiasts (in and around Edinburgh) and help where we can with projects and parts supply.

We are also on the look out for service and repair staff with deeper knowledge of both analogue and digital circuits and the fault diagnosis and repair thereof.

I love the interactions and enthusiasm found on this site.

All the best

John

Hi,

I've measured my Quad 306 idle power consumption, which measures 17w. Quad specify that it is 30w. Can someone please confirm what the power consumption is of their 306 at idle? I just want to make sure there isn't a fault. All in circuit measurements check our fine. The sound quality is great in the low end, however, the upper end isn't brilliant.

Hello there,

I'm a young man, with a passion for audio, acoustics and DIY ! I want to get more knowledge, and I think this a one of the best place for it, and I'm looking forward to learn new things.
Greet everyone 🙂
S

A member of this forum sent me a KSS-272a for to try to repair, maybe to replace the laser diode. Well, first of all, I see laser power. It was right, about 120uW. It looks that laser diode was right. So, I replaced the potentiometers, because original potentiometers are very hard to manipulate, and another thing, this potentiometeres are of 2K2, however it measures 1k9, they was out of tolerance. I replaced the electrolitic capacitor, original measures was right, but I don't confide in 90's Nichicon capacitors. Then, I tried to adjust the laser pickup. One, two afternoons trying to adjust, and nothing, it can barely read. What was happening? It looks like it find the right signal shape, but then it get lost. What can I do? I replaced the lens, and now it is ok. Why the original lens is bad? I don't know, it has a good aspect, but it does not work right. It a bit mess to adjust the lens position, but with a 8cm size CD it can be adjusted. Another problem, is that if unscrew the potentiometers board to adjust the potentiometers, the board get board stumble with the motor, and the CD can't read the TOC, a mess...
And yes, it is necesary to adjust the azimuth screws located beneath, yes, a mess...
Well, now it working. The only doubt is how to adjust TB(tracking balance), because following the service manual method don't works.
Needless to say that original laser diode was not replaced.
I still question why the lens is bad, and why it happened.

Moral: Don't blame the laser diode at first sight.

Ciao ragazzi.

Ho una domanda per te.

Ho un amplificatore di potenza in classe A costruito molti anni fa da un mio amico ingegnere elettronico che utilizza una singola coppia di darlington complementari MJ3001 e MJ2501 per una potenza di 32 W per canale, alimentati a 32 V. Funzionava perfettamente e con un bel suono. Purtroppo, un canale non funziona più. Ne approfitterei per aggiornare alcuni componenti come condensatori di filtro e altro. Ho bisogno di sapere quali darlington posso acquistare in sostituzione, dato che gli originali non sono più disponibili, e anche di usare qualcosa di più moderno e di qualità superiore, visto che tutto il lavoro è affidato a una singola coppia.

Avrei pensato alle coppie BDV66D e BDV67D o, ancora meglio, 2SD2449 e 2SB1594, ma ho bisogno del vostro parere autorevole.

Grazie.

Hi
I'm working on a program to simulate loadlines. Here's a link to the first version:

Triode Loadline Simulator v.0.2

The list of tubes is constantly updated. This is a simple javascript, so the program can be run without any installation 🙂 and can be run by most web browsers. To change the parameters (operating point etc.) use triangular indicators that can be dragged using the mouse.

I checked the behavior of the program using different browsers. There is no problem with new versions of browsers. Unfortunately, Internet Explorer version 8.0 and earlier can not cope with it. In a newer version of IE for example. 11.0 this problem does not occur.

Hi I want to build a preamp, I'll post in a different forum I guess. Thanks.

Hi All, I just acquired this very nice unit but unfortunately the tuner section and the display are non functional. Krell had been very helpful in the past but I cant even find their website let alone get any information from them.
Im hoping someone can chime in and point me in the direction of schematics and or a service manual.
Any and all suggestions would be greatly appreciated🙂

Hi, I am creating simple PC app to measure room impulse response measurement using sine sweep sound and then create FIR coefficients from the IR result.
It can be downloaded from here https://sourceforge.net/projects/fircreator/
If you have any thoughts, please let me know.
Thanks.

I am looking for used 6h30 tubes just for testing! I am located in the EU.

Thanks.

Seeking help to find reliable SPICE models for these KTC5200 -KTA1943
For fun I got CoPilot and ChatGTP to make models.....both are vastly different!

Up for sale is an used class A/B power amp of dynacord, model L1800FD.
Very good condition, used for hifi only.

I am willing to trade, the price is 550 EUR + shipping.

By the follow URLs I found only a small amount of books:
http://www.diyaudio.com/forums/everything-else/87-amplifier-design-book.html
http://www.diyaudio.com/forums/everything-else/141923-best-audio-amplifier-book.html
http://www.diyaudio.com/forums/everything-else/142317-electronics-theory-question.html
(ohm's and watt's law)
http://www.diyaudio.com/forums/solid-state/3398-sound-cascodes.html
http://www.diyaudio.com/forums/solid-state/41110-interesting-books.html
http://www.diyaudio.com/forums/everything-else/131079-audio-hi-fi-e-books-web.html

Here my own overview of interesting books for audio power amps, sometimes include preview and read sample, about Google Books

High perfomance audio power amplifiers for music performance and reproduction by B.Duncan
High perfomance audio power ... - Google Books
The Art of Electronics by Paul Horowitz and Winfield Hill
The art of electronics - Google Books
Designing Power Amplifiers - Stephen Kamichik
Designing Power Amplifiers - Google Books
The art of linear electronics by John Linsley Hood
The art of linear electronics - Google Books
Audio electronics by John Linsley Hood
Audio electronics - Google Books
Valve and transistor audio amplifiers by John Linsley Hood
Valve and transistor audio amplifiers - Google Books
Audio Power Amplifier Design Handbook by Douglas Self
Audio power amplifier design handbook - Google Books
Audio Power Transistor Design Handbook - Douglas Self
Audio power amplifier design handbook - Google Books
Douglas Self's "Self On Audio"
Self on Audio - Google Books
"High performance audio amplifier cookbook"
The audiophile's project sourcebook
The audiophile's project sourcebook - Google Books
Valve and Transistor Audio Amplifiers by John Linsley Hood
Valve and transistor audio amplifiers - Google Books
High-Power Audio Amplifier Construction Manual Randy Slone
High-power audio amplifier ... - Google Books
Amazon.com: High-Power Audio Amplifier Construction Manual (9780071341196): G. Randy Slone: Books
"How to Design and Build Audio Amplfiers"
by Mannie Horowitz ISBN 0-8306-1206-8
How to design and build audio ... - Google Books
Structured Electronic Design: Negative-Feedback Amplifiers (Hardcover)
Structured electronic design ... - Google Books
Amazon.com: Structured Electronic Design: Negative-Feedback Amplifiers (9781402075902): Chris J.M. Verhoeven, Arie van Staveren, G.L.E. Monna, M.H.L. Kouwenhoven, E. Yildiz: Books
Feedback Amplifiers: Theory and Design (Hardcover)
Feedback amplifiers: theory and design - Google Books
Amazon.com: Feedback Amplifiers: Theory and Design (9780792376439): Gaetano Palumbo, Salvatore Pennisi: Books
Design of High-Performance Negative-Feedback Amplifiers: Studies in Electrical and Electronic Engineering
Design of high-performance negative ... - Google Books
Amazon.com: Design of High-Performance Negative-Feedback Amplifiers: Studies in Electrical and Electronic Engineering 7 (9780444421401): Ernst H. Nordholt: Books
Trade-offs in analog circuit design: the designer's companion
Trade-offs in analog circuit design ... - Google Books
Designing Analog Chips by Hans Camenzind
Designing Analog Chips by Hans Camenzind
Ultra-Low-Noise Preamplifier for Mooving Coil Phono Cartridges
http://books.google.de/books?id=HdM...a=X&oi=book_result&resnum=6&ct=result#PPA7,M1

I am highly interested on additional books regarded amplifier technologies, also in other languages than English and German. I think, in french, japanese, spain and russian there are also interest books. With today's software (e. g. Finereader) a translate isn't difficult through Googles language tools.

Here interesting books about ground loops (incl. different book read samples)
The Ultimate Live Sound Operator's ... - Google Books
The sound reinforcement handbook - Google Books
Producing great sound for digital video - Google Books
Audio power amplifier design handbook - Google Books
Concert sound and lighting systems - Google Books

I decided to create a desktop system and planned on repurposing a pair of mini monitors from an Energy Take 5.1 home theater setup. I connected the speakers and the sound was thin on one side; a bias to the other side. It turns out that there was no sound coming from the woofer on the thin side.

My first step was to physically switch the speakers, though I felt that if sound was produced by the tweeter that it was unlikely that there was an issue further up the chain. Once switched the thinness moved to the other side, so it was the speaker. I pulled the front baffle off to see if the wires were connected to the woofer and they were. I saw the crossover, but I didn't really investigate further, as I didn't know what I was looking for. The other two mini monitors from the set are dead and gone, otherwise I'd just replace the bad one with one of those.

I have already ordered another pair of speakers, but I would still like to fix the speaker if possible. I think it would be a good learning experience for an electronics newbie. Given that I have narrowed the problem to inside the speaker cabinet, how do I go about troubleshooting the issue?

Thank you.

Life has been rather hectic lately, but it looks like the chances are good that I will be returning to the Dayton Hamvention again this year. This will be my third trip to Dayton, and every year I have met at least two diyAudio forum members there just by chance. People tend to recognize me. I imagine that there were other members that I didn't see. If anyone is going, and there is interest in a bull session or a guided tour of the swap meet junk (oops I mean goodies) we could arange to meet, or at least swap cell phone #'s.

The Dayton hamfest is the largest in the world. Last year attendance for the 3 day event was 22,000 people. The swap meet area holds over 2500 swap spaces. The theme is ham radio, but there are very few restrictions on what can't be sold there, so it is an excellent place to find tubes, transformers, components, complete tube amps, not so complete amps, test equipment, and who knows what else. Sometimes people purchase space just to show off their latest creation, like last years Prius that was covered in solar cells, 11 miles a day without any gas at all.

The swap area is entirely outdoors and is subject to Dayton's finicky weather. It can be cold (35F), warm (75F), sunny or raining, or as with last year all 4 over the 3 days. NOTE! Rain makes the prices drop, a LOT! Last year the weather was cool but nice on Friday. A seller wanted $50 each for some MRI RF amplifiers. Saturday the rain started, and then the rain came down hard. I bought all 6 amplifiers for $100! I got a 0 to 2KV 100 mA Kepco power supply for $20 and an RF spectrum analyzer for free (known to be broken). Both times that I went to Dayton I left with a small SUV full! This year, I have a bigger vehicle.

There are 3 buildings (a hockey arena and support buildings) that house convention style booths that are mostly ham radio related equipment. It's cool to look at all of the ways that you could spend some serious money in ham radio if you are into it. I do have an extra class ham license and a working radio, but not much interest. Being a radio designer, at work for 35+ years, is enough.

I plan to be there when it opens Friday morning, staying until closing, and returning Saturday, staying until I have to set out on the 1100 mile drive home. It really does take more than one day just to cover the swap meet area. The first time I went, I spent two days in the swap area and never did see the ham radio stuff. Last year I was a bit more orgainzed and I covered the swap area in one long day. Saturday I hit the swaps in the morning, and went inside after I got soaked in the rain for the third time (mid afternoon).

Dayton Hamvention 2010 - Amateur Radio Clubs Worldwide: The Lifeline

I've been given a pair of eminence alpha 15a's. Is there a good way to get these configured as a Subwoofer? I've modelled it in Hornresp and come out with a possible dual sealed in series about 80ltrs apprx, but the required power and crossover are pretty insane to get low frequencies. 24db roll off+ and lots of power.
I know the driver isn't designed for this, but I have them sitting around and I need a subwoofer... and I'm on a tight budget.
Would it be a lost cause or is it just a case of finding the right amp to drive them?
Any thoughts?

Howdy all!
I was searching the net for the info of the broken spl dynamics amp, and i stumbled upon this forum.
Lots of usefull stuff!

I also found schematics for the DWM1216FV_V20 power board used in Hifonics and spl dynamics amps. I thought I should share it!

Hey there!

My name is Michael and I'm from Hamburg, Germany. I grew up listening to frequency sweeps (more than music) since my father has been working on loudspeakers and amplifiers for as long as I can remember. He was more an engineer than a music lover, but nevertheless he definitely passed on the love for all things audio to me.
I really got into the hifi hobby around 8 years ago. However up until last year I was only purchasing gear, but then also started building my own stuff. First designing a pair of open baffle speakers (which I never built), then a pair of tiny 4" full-range drivers, afterwards a 2A3 SET tube amp and a pair of high efficiency 80l full range speakers. Currently I am working on an adapter to be able to connect my headphones to the amp. I am not very skilled in woodworking and definitely not very knowledgeable in electrical engineering, but still being able to achieve a sound like that is absolutely amazing. And knowing that no other person in the world has these exact speakers and amp is pretty cool 🙂

My profession is web developer which I have been doing since I was a teenager. I like to combine my hobbies (which web development still is), and while I was still purchasing a lot of gear, always looking for brands that produce certain kinds of products etc., I was missing one website that completely fulfilled my needs. So, I built https://www.hifilog.com. It's meant to be a big (which it is not (yet)) database for hifi products and brands, but also a place where you can collect all the gear you have, keep track of it etc. It's not a business, just my hobby, it's free, no advertisement, no tracking. And open to everyone. Maybe one or the other enjoys it.

While I have been looking into adapter solutions for connecting headphones to a tube amp, I stumbled for example upon https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm. It was a bit too cumbersome for me, so I built http://hifilog.com/calculators/resistors-for-amplifier-to-headphone-adapter. You can choose from multiple circuits and see at one glance which resistor values work best for your specific use case.

So, I'm not only a DIYer for my audio gear, but also like to DIY web stuff that helps with the hobby. Happy about any feedback or ideas!

Here are some photos of the stuff I built:







Cheers,

Michael

Dear Members! I have a Toshiba SC-V50 amplifier, but the right side is very quiet. For the repair I need a repair manual, I find it on the HIFI Engine, but I can't download it. If somebody can download it for me I will very happy. Big thanks for the help!
Have nice day for everyone!

I have a a Hafler DH110 pre amplifier. First, this unit works, but has the following issue. The left channel voltages to the transistors are reading about .3 to .4 volts lower than the right channel. Second, what I have done is verify the left channel voltage drops on all the resistors and against the right channel. These are shown in the attached PDF file. Third, I checked every voltage at each transistor to validate the right channel and left channel voltage discrepancies. Fourth, I have included all my voltage measurements in the PDF file with a schematic. Lastly, my question is this, why is the left channel lower when the power rails are both 23.1V? Each resistor is showing this voltage on the rail side of the resistor. So the rail voltage going to the left or right channel resistors are spot on the 23.1V. Again the unit works, but the amperage draw on the output Q13 and Q14 is 8.1ma on the left channel while the right channel is 13.5ma due to the votage drops on R34 and R35. I did notice that the right channel differential pairs bases run about 12 to 21 mv on the right channel and on the left these volates are 1 to 2 mv. The only thing I can think of is that there is a faulty transisor in the drive path, but I do not know if this thinking is correct. I do have the BC series of transistors to replace everything on the left channel, but do not know if they require matching or if changing them all out is a wise decision. So I am asking for some help from the DIY community to solve this low voltage problem. I am open to all the DIY experts becasue I am at a loss of ideas.

[Moderation edit: This thread split from - https://www.diyaudio.com/community/threads/monsoon-speaker-parts.391848/ ]

Thanks woody for the monsoon planars. Since this is already in the right section, i will post the measurements data here.
Lets start with mh-700.

Up until now, all my custom speaker builds have incorporated active crossovers and multi-channel amplification.

While I am still convinced this is by far the best way to implement a speaker, I am planning a couple builds that (for practicality sake) will use a passive crossover.

I have read a lot of info on the subject but the OCD in me leaves me with some questions yet.

Some of this, I have asked previously.. but I want to be sure I am 100% spot-on regarding the answers.

1) Speaker sensitivity - the electical measurement itself

I understand the basics here: feed a speaker 1 watt at 1k and measure the SPL with a calibrated mic @ 1 meter distance. But details matter.

Question 1.a: Is it not more accurate to measure this AFTER the speaker is actually mounted in the baffle in which it will reside? This affects the final SPL after all, correct?

Question 1.b: In all reality, the TRUE sensitivity (that counts) is when you perform the "what is 1 watt" based on the real driver impedance, correct? In other words - I should do an impedance sweep (using DATS).. take the exact impedance of that driver @ 1k (while mounted in the actual baffle).. then calibrate the signal (measuring voltage) until the product comes out to exactly 1 watt. Is this a more correct way to get a precise measurement of sensitivity? Or should I use the "nominal" impedance (also calculated by DATS) - regardless of the impedance-frequency relation that is "seen" by the amp?

Question 1.c: I imagine the sensitivity of a driver actually fluctuates as frequency changes to some degree since the impedance certainly does, no? Is this taken into account when dealing with a passive xover?

2) Crossover points.

I have asked part of this previously... but will post the one question here along with the others just to be sure everything is answered in one spot for the sake of the algorythms.

Question 2.a: I assume that the calculation for the crossover component values (and frequencies) should be done based on the measured impedance of each driver at the crossover frequency. Correct? This is what seemed to be confirmed to me previously. So for examplle: I plan to crossover a particular driver at 1k.. I should first measure what the exact impedance for that driver is (impedance sweep while mounted in the actual baffle). So if a driver with nominal impedance of 4 ohms is actually 5.5 ohms at 1k, then the 5.5 ohms is what should be used in the calculations for the crossover - correct?

Question 2.b: What is generally the most preferred alignment for typical 3-way passive designs? L-R? Also - provided I use drivers well within their limits (and far enough away from their Fs).. is 1-st order not ideal? I hear this is what my old Vandersteens use (they sound pretty damn good to me). For my own purposes, I will be using these speakers (I will build) for close and near-field listening. I understand 1st order is not ideal for this?

Question 2.c: How much should I worry about time alignment? I hear this is always better to do physically when possible (stepped baffle) - which has its own issues. But how many here are doing this stuff in the passive crossover section?

I have a huge assortment of film caps coming from AliExpress (have had excellent success with over the years). A dozen different values (4 of each value) specifically for crossovers. I also wind my own inductors. So I can certainly "play around" with the crossover as needed here. My assortment of power resistors is a little more limited, but I may get an assortment of those on the way as well (for matching sensitivities where needed).

All the advice is welcome!

-Dean

In the attached diagram, 1/2 and 1/4 watt resistors have the same package size.



I wonder that what are the construction differences of same value resistors with same dimensions but different power ratings? How they managed a higher power rating in the same housing?

Are they differ in spiral turn count? Which one has less spiral turn (which is less inductive), higher wattage or lower wattage?

Are they differ in film material thickness?

Thanks.

For sale, solid walnut enclosures with TB W3-1364sa drivers. Drivers have bamboo cones that have been sitting in the closet for a few years. Cabinets, I just finished, sort of, this week. Amazing sound. The drivers go for silly money right now on Parts Express. I have to many diy speakers/projects.
Any offers?
Peter

I need a schematic diagram of this compact disc player models in top loader version
for attachment 4, 5 and 6 in high resolution open this URL:
Mcintosh MA6400 ????, MicroMega Trio CDP ??? ?????(Wilson Audio),????(Wharfedale),???(MARANTZ),??(JAMO),??(ONKYO),??(TEAC),????(JBL),?????(AUDIOPRO),??(KEF),????,????(Nakamichi),???(Philips),??(ARCAM),

It seems there have been a number of posts lately asking about adding a line stage/preamp to a system so that a tube may be added to the signal chain.

I'm always left asking why a line stage/preamp would even be necessary, since most 'power' amplifiers these days have plenty enough gain to be driven to full power and beyond by any digital source, and even most phono preamps these days provide >40dB gain so can develop 1V peak output from most any MM cartridge.

One place where I've found I'd like just a little bit of gain is for getting the subjective level of my phono setup to match that of my digital sources. Making a line stage with 3X (9dB) gain and low output impedance is not as easy as it sounds. So I've been experimenting...

I came up with a circuit that provides:
- 3X (9dB) gain
- super low THD (0.0003% at 1kHz, 1V rms out)
- low output impedance (about 250 ohms)
- uses a 12AX7 or 6N2P, or with a couple of parts value changes can use 6N1P, 6BQ7, 12AT7.

However, it's not a 'pure tube, zero negative feedback' type of thing. It uses:
- a MOSFET source follower
- local shunt voltage feedback

The triode has its plate load bootstrapped as described by MerlinB in his preamps book.

I simulated the circuit with three different 12AX7 models and a 6N2P model, all with nearly identical results, even for THD.

I wonder if this would end up sounding indistinguishable from an op-amp line stage set for just a few dB of gain.

Does anyone see any fouls, gaffs, mistaken assumptions made, other errors?

for my Centre speaker project I need a SEAS 22TAF/G. If you have one or two pieces for sale in EU, I am happy to take them. Thanks

OK, sorry, I am sure like car forums discussing engine oil, solder has been discussed before. But I would appreciate advice from people who have tried some of the more expensive solders available. I buy parts from Farnell which have several solders with Silver content, but also from HIFi Collective in the UK, which has this lovely selection to choose from: https://www.hificollective.co.uk/components/solder.html

Currently I'm using Oyaide 4.7% silver, simply because it's a good, clean mid-priced solder from a reputable source, with what seems a good specification.

I'm wondering if it's worth using 9.5% silver Mundorf solder, because silver is considerably more conductive than tin ? Has anybody tried these and compared to a more basic solder ? Is there any difference in sound quality.... OK, as I typed that a little part of me did wonder if that's even a sensible question... but I'm interested in other people's experience. I'm not advocating for costly solders, I've no experience of them, hence asking.

This is my first diyAudio post about my recent design and build of quirky loudspeakers. See my recent introduction for brief background about me.
This will need to be an extensive story to give you the full picture of my project. Feel free to jump to the section you're interested in.
I designed and build two versions of this kind of subwoofer, and this post will be about the second version, hence the "version 2" in the title. A post about the smaller "version 1" might come later.



Background
This idea of mine was born out of the last dull, depressing darkness of the Swedish winter. It has been 20+ years since I build a decent loudspeaker on my own, and suddenly this passion came washing over me again. It probably started when my now retired Harman Kardon active speakers started failing, and after trying to repair and revive them simply gave up. Suddenly I was without quality sound in my 88 m² apartment and my restless engineering brain started humming in 200 radians per second to find a solution. 🙃

I just recently found SoundImports EU (apparently the "Parts Express" of Europe!?), which offers an impressive DIY assortment for appealing prices, and ships fast and cheap to my area. I needed a subwoofer, and spontaneously bought the Dayton Audio 6-1/2" Down Firing subwoofer kit, thinking the specs looked to fulfil the needs of my living, fair price, and the box build (well, assembly of pre-cut boards) will be simple and quick. The subwoofer kit was most of that; it makes a lot of low-end noise for being a 6.5" driver. But my ears were not satisfied! So I started researching some more exotic subwoofer builds. I needed a design that would stimulate not only my ears, but also my brain cells during design, and also something different to satisfy my need for novelty.
My prior background in PA-loudspeakers makes my judgement biased; Long time ago I owned setups of 15" bass-reflex, 15" folded horns and 2x18" (pseudo)-horns to cover the low-end of my sound rigs. And those were driven by 19" rack professional amplifiers with power ratings in the kilowatt area. I loved the deep rumbling and physical sensations this setup could produce.
Reality check: I now own and live in an apartment in a multi-tenant house. Even if I would fit a 15-18" subwoofer at home, my skewed audio taste would probably get me evicted or at least throw my reputation among neighbors down the basement. So, I needed to let go of my comfort area: PA-class woofers, but I wanted most of the features they could offer!

Subwoofer requirements
Trying to list what I was aiming for in terms of end results

• Great low-end, sub-woofer response:
  • Flat and loud subwoofer response, say 30-100 Hz ±3 dB.
  • Decent phase response or group delay within the target frequency range.
• Apartment-friendly, semi-portable design (I need to move it in and out of my 3rd floor apartment on my own).
• High acoustic efficiency (avoid the need of another kW amplifier).
• I want to be able to do all engineering design by myself, using free or easily available tools/software.
  • The design needs to be quirky/novel/different to satisfy my restless engineering mind.
• Assembly of the final speaker needs to be relatively clean and un-complicated:
  • I'd like to do all work in my apartment and/or electronics lab.
  • Avoid using wood as building material, as cutting it is too dirty for my facilities.

During my research (well, watching YouTube, visiting many obscure audio pages seemingly designed in the 90's, and scrolling through this excellent forum), I was captivated by two main categories for a custom speaker design, listed here with my conclusions and pros/cons:

• 6th order, dual reflex, triple-chamber parallel bandpass with small (5-8") drivers:
  • Plus (quirky): This is not a very common design!?
  • Using three different tuning frequencies to offer a wide frequency response:
    • Design with all three chambers tuned differently (the default design would have two identical chambers, I assume).
      • Plus (novelty): I never found anyone publishing a 6thr order enclosure with three intentionally different tuning frequencies!
    • Design with two different drivers in the same dual-chamber design to achieve wider frequency response and/or better group delay.
      • Plus (novelty): Also never found this solution online!
  • Using small drivers would allow for a low-height rectangular cuboid that I could possibly hide under a sofa or other furniture.
  • Minus (build): The box will be a regular box that is best built using wooden panels.
  • Inspiration:
    • AudioJudgement: 6th order bandpass box design
• Horn-loaded designs
  
  • Front-loaded folded horn
    • Plus: Ticks most boxes for acoustic performance.
    • Minus (novelty): I owned them before, quite common woofer design.
  • Tapped horn
    • Inspiration: HexiBase: 4" tapped horn with laser-cut wood panels
    • Plus (novelty): Uncommon for being a horn-design!
    • Minus (build): Best built with wooden panels, but I could potentially outsource the cutting in a laminated design
  • 3D-printed horn-hybrid / wave guide
    • Inspiration: HexiBase 3D printed folded wave guide 3" subwoofer
    • Cool stuff, but I don't own a 3D printer, and acquiring one would just throw me into another rabbit hole of endless distractions
  • Quarter-wave transmission line
    • Transmission lines are basically straight-line horn designs, I learned.
    • Minus (novelty): Common layout in some high-end, full-range speakers.
    • Minus (build): Usually built with wood panels as square boxes.
    • Non-rectangular cuboid transmission lines:
      • Inspiration:
        • AudioJudgement: Pipe Speakers with dual 2.5" drivers
          • I actually built a version of these speakers too, more about that in another post.
        • El Pipe-O subwoofers
      • Wait WHAT!? Standard pipe fittings can make a good transmission line enclosure!?
      • What if it scaled up...? Hold my beer... (all boxes ticked)! 🤩

Engineering design
I decided to use a quarter-wave transmission-line enclosure, based entirely on standard pipe fittings! Because in theory it is supposed to work just great, AND just the idea of it sound ridiculous. That's just what I was looking for!
I read numerous guides and theory for transmission line enclosures (hereafter: TL), e.g: quarter-wave, diysubwoofers.
I learned quickly that Hornresp is a great tool to use for evaluating potential designs (my deepest gratitude to the Hornresp team for offering this great piece of software!).
SpicyTL is another very promising software, but haven't come to terms with those libraries quite yet, despite being based on the SPICE software, which I'm previously familiar with.


How big?
The high-level design of a TL subwoofer enclosure starts with two parameters: Lowest resonance frequency and mouth air speed at max intended SPL. The former is easy to approximate: "Quarter wave" means that one-quarter of the longest wave needs to fit inside the line. Deep sub-bass down to 20 Hz would be lovely, but 343 m/s / 20 Hz / 4 = 4.3 m, which would be inconvenient to squeeze into my apartment with 2.5 m ceiling height without folding (complicated build). What about setting the max line length to 2.5 m then, as in using my full height of the ceiling walls? 343 m/s / 2.5 m / 4 = 34.3 Hz. Well, this is not too bad, considering I just saved one 180° fold and 1.8 meters of piping! Regardless of the TL lowest resonance frequency, the selected driver needs to be able to work properly at these levels.
The air speed at the line mouth is important because high air velocities will cause turbulence at high sound levels, which might create huffing, puffing and whining sounds, or just simply "chuffing". Carefully designing the mouth geometry could alleviate much of this problem, but in my case, I will need to accept the shape and geometry of standard pipes! I assumed a guesstimate of 10-15 m/s for maximum air speed at the mouth. Knowing this number makes it easy to calculate a suitable diameter for the TL. I made some simple estimations by calculating the maximum volumetric air flow at the mouth (cross-section area * max air speed), and comparing that to what a suitable driver would be able to generate, given by TS-parameters Xmax * Sd (with care taken to unit conversions).
Off-the-shelf piping comes in highly standardized diameters. I browsed through dozens of product catalogs of both plastic, paper and metal pipes from my local hardware stores, and decided to go with large plastic pipes. The relevant sizes for a sub-woofer that I could easily buy are (outer) diameters 110 mm or 160 mm. This types of plastic pipes are normally used to carry sewage water inside- and between buildings. This makes a great excuse is the designs turns out to sound like ****! 🤪

I decided quickly that I wanted to build a TL without any need for an additional "throat chamber" made as a typical rectangular box (again, no wood, please!). This is a key difference from the inspiration I got from the typical El Pipe-O subwoofers. Basic design rule: Use only standard pipe fittings!

The next challenge I encountered is that a simple straight line made with smooth, hard linings will sound like an echo chamber. Therefore, careful consideration must be put into the type and amount of damping. Thankfully, Hornresp allowed me to evaluate both placing, properties and amount of damping material through simulations. More about the outcome later.

Driver requirements
From the TL-design sources mentioned above, I read that suitable drivers for TL enclosures, in terms of TS-parameters would need a low Fs (quite obvious for a subwoofer design!?), but even more importantly, low Qts (effectively meaning low Qes!?). Attention to the risk of over-excursion is important with low-Qts drivers. This might, or might not, be a problem in a TL design.
I made a list... well many lists, of potential drivers to use in my design. I didn't want to spend a fortune, in case this experiment failed. But I still wanted a great fit in characteristics (TS-parameters) for a TL. As a surprise, the very same driver included in the budget subwoofer kit I first bought from SoundImports (DCS165-4) turned out as the best budget alternative driver for a TL-design, thanks to its reasonably low Qts of 0.34!
Here's a list of my four favorite drive candidates:

• Dayton Audio DCS165-4 - 6.5"
• SEAS CD22RN4X - H1192 - 8"
• Dayton Audio UM8-22 - 8"
• Dayton Audio UMII8-22 - 8"

I did plenty of simulations in Hornresp. Actually I enjoyed this process a bit too much, since my profession is simulation of non-linear mechatronic systems. I found Hornresp to be a very satisfying tool that tickled most of my geeky traits. Long story short, I decided to build two different pipe-sub designs. One based on the 6.5" DCS165-4, and one design based on the 8" UM8-22 (first generation, which seems to be out of production now). The 6.5" version became "version 1", which I will eventually probably write another post on. This post will continue about the 8" version.


The selection of driver is made not only on the TS-parameters, price and availability, but also on geometric details like exact baffle size. Since I am basing my entire enclosure on standard pipes, I really want to maximize the cone area able to fit onto or into a standardized pipe! I would not allow valuable millimeters get wasted by a sloppy mechanical fit! Many driver candidates got rejected on the simple basis that their data sheets did NOT include precise measurements of the baffle, mounting holes or cutout diameter!


The selected "Ultimax UM8-22 Subwoofer" is a pretty sturdy piece of driver at 6.9 kg, dual 2", 2 Ohm voice coils and ±16 mm of linear excursion and specified at 300 W rms power!

As soon as I got my driver delivered, I measured its TS-parameters using a DATS V3. Maybe not surprising, but the TS-parameters were deviating from the datasheet. This would probably mean that the TS system will not behave as simulated. But taking this into account in the design process is one variable to much to handle right now. And in best of cases, the actual TS-parameters will stabilize close to the datasheet values after some "burn-in" of the driver.


Transmission Line Layout
A long straight line at ~2.5 m, and enough diameter to support the maximum air flow of the driver. Sound simple!
But... I learned through simulations that a straight TL design without any tricks will have a quite narrow bandwidth in frequency. For a design reaching just below 30 Hz (±3 dB), a destructive interference pattern would show up at 90 Hz (basically 3 * lowest resonance), and severely reducing the sound pressure output near this upper range.
I found a trick, which is to mount the driver "offset" along the TL. According to theory, and simulations, this will alleviate the first order of destructive interference patterns in the frequency range. I experimented a lot through Hornresp simulations, with the rule of thumb that a good driver offset seem to be 1/3 of the full TL length away from the closed-end.
This trick does not only produce a very appealing frequency response, but it also opens up for a few more positive design options (which "version 1" does not have):

• The driver does not need to be mounted on the closed-end of the TL
  • The TL closed-end can rest directly on the floor
    • No need for protection or vertical offset of the TL to allow the driver cone coming close to the floor
    • This effectively saves about 200 mm of dead vertical space, which can be used for the main TL length instead. Great when the vertical space is the limiting factor for the design!
  • The driver can instead be mounted facing outwards, which is (in my opinion) esthetically preferable.

Hornresp layout:


The UM8-22 driver has a baffle cut-out of 189 mm (according to drawing), which is obviously too large to fit in a 160 mm pipe. Hence, an adaptor is needed. After scrolling through many products of sewage pipes, I found a standar component named "chamber rodding tee", which is available as 160 mm diameter for the main line, and 200 mm for the inspection inlet. The UM8-22 driver fits perfectly into the take-out section with only "minimal" changes to the plastic structure. The rodding tee pipe comes only in the color Obnoxious Orange, so I spent some time learning how to paint Polypropylene plastic.

The main TL is constructed out of "premium" drainage pipes from Geberit: Silent-PP. I picked these pipes mainly because of the aesthetics (available in black), but almost ironically, these pipes are intended for "sound-optimised installation of drainage systems" 😄 What it actually means is that the wall thickness is higher than the pipe standard requires, which increases the stiffness of the pipe, and hence reduces resonances in a typical drainage installation.

Simulation results

Hornresp results are presented assuming eight space radiation. Datasheet TS-params are used for UM8-22.
Acoustic output at 1 W (left graph), and max power 300 W (right graph). Sections of bold red means excursion-limited output.


Group delay (left graph). Mouth air speed at 300 W (right graph).


End results
So far, this unit has been in operation for a few months in my apartment. It plays LOUD and DEEP! Probably generating slight annoyance in my neighbors, but I'm till not evicted 😄.
It is currently hooked up with the dual 2 Ohm voice coils in series and powered by a tiny 100 W class-D amplifier, which is capable of generating more rumbling than I dare to continuously play in a multi-tenant house.
I do realize that my living room most likely has strong constructive resonances around the lower end of the pipe-sub's frequency range, which might make it sound more impressive than it might be in a resonant-free environment. Though, I recently took my "pipe-sub v2" (also known as "Bazooka-sub", or "Super-Mario-Woofer") to a workshop and hooked up to a more capable amplifier to test it's capability in a bigger room, and an environment where people wouldn't mind some loud noises. I can only say it did not fail to surprise me, as it continued to played deep and loud with linear excursion (and surprisingly low amounts of chuffing and/or air leakage) for as long as the amplifier's power supply could support us.


Super-mario-woofer!?


Full-size image of end result:


I'm looking forward to your feedback on this project!

Hi.

I need to buy an inexpensive oscilloscope to measure the output signal/voltage from my turntable cartridge from each channel so I can set Azimuth and be sure that the left and right channel are outputting the same level.

I know nothing about these things but I see prices betwen 40 bucks to thousands. Can I get away with a cheap one for this purpose?

https://www.amazon.com/HANMATEK-HO1...-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Thanks,
Stu

I bought a pair of used E160 a while ago. Their sensitivity was very low, and one of the speakers had a mains hum, even lower sensitivity than the other one and a ragged frequency response. I brought the panels to Silberstatic to have them refurbished with new membranes. Dirk Jesberger told me to swap the electrolytic, and that two segment resistors on the panel had burnt out.

When I received the refurbished panels back, I changed the cap. The old one was not terrible (something like 305 instead of 330 µF and a few 10 mR ESR). I also noticed that the HV trim pot was at max and changed it back to the setting of the other board (about 3/4 of the range). Putting everything together, the speakers played, but the one with that had the board I changed the electrolytic on made a popping sound about every 20 s (it takes a little longer at first, and the interval between pops can be anything from 2 to 40 s).

The pops are like an LP record with a really bad scratch. They don't seem to be an electric discharge in the panel as they are a little too dull for that and I can't localize them, i.e. they are the same loudness at the bottom and top of the panel. They also stop the very second I unplug from mains. The speakers will play on after that (and sound absolutely gorgeous), grow slightly fainter after a few minutes but play for maybe half an hour before they residual HV is completely gone.

I just got off the phone with Dirk Jesberger, and he confirms that it is the board and a common problem. He said it was probably a transistor but wasn't sure.

- Does anyone have an idea or a schematic of the Capaciti board?

- I didn't have this popping sound when the panel was in poor condition and the was HV dialed to max. Any chance going back to max will solve the problem? I haven't really dared to do that with the newly refurbished panel.

- Is the fact that the popping diappears the second the mains are disconnected, but takes about 30 s to reappear when mains is reconnected a hint? My idea was that there is a discharge due to overvoltage or a shady component somewhere on the board, but since it takes about 20 s for the voltage to build, this does not really explain why it stops immediately when mains are disconnected.

- Does anyone know what the original voltage setting was supposed to be? Dirk Jesberger said I could probably dial it down because his membranes are more sensitive.

Thanks

Hi,
Does anyone have the specs of this OB from Papa?
[Report] Burning Amp 2012 [English]


Baffle dimensions and slot details would be great.

Thanks,
C.

Hi all! I got this 50w Fender Hotrod Deville on the bench and I am losing my mind!

Came in for a blown up output section, output transformer was blown, screen resistor absolutely self destructed and it was loaded with crappy IC filter caps.

I replaced the output tubes, output transformer, screen resistor, grid resistor, and flyback diode on one of the output tubes (R61 went nuclear, R64, and CR4) as well as doing a full recap I finally managed to get the amp to kind of function. After many hours I finally figured out that having the speaker jack not connected to the chassis the amp outputs almost perfectly except for a nasty hum. With the speaker out jack connected to the chassis the output is extremely low and sounds like the output is dead shorted. to simplify the issue I have connected only the 8ohm tap, feedback line, and speaker common tap to a single output jack.

What would cause the amp to not function when the common tap on OT is connected to ground (as per schematic)?

I have tested and verified the following:

-All supply voltages on the tubes, ICs, output transformer, and heaters are correct with no AC ripple in the supply
-Bias supply is rock solid with no ripple and the output tubes are biased properly
-All diodes test good
-All ground connections are solid
-When the "shorted" issue is present signal is going all the way to the grid of output tubes as it should
-The new output transformer is a direct replacement for the old one and is connected exactly the same (except for how I simplified the output jack, wich did not affect the issue at all)

I will attach the schematic for this amp. Any help is GREATLY appreciated!

I handed out PCBs for this BJT Simple Matcher jig, during talk#3 at Burning Amp yesterday. For those who couldn't attend, I've attached the Gerber .zip file below. You can send it to a PCB fab and have some boards shipped straight to you.

If you haven't yet ordered PCBs from an online fab, it's fairly easy and painless. Here's a brief explanation: Ordering PCBs online (using Gerber files): A walkthrough -- featuring the fab "JLCPCB"

Unfortunately, some of the figures in my "slide deck" didn't render very sharply on the projection system, so I've included the entire presentation below in .pdf format which features infinite resolution vector graphics. The presentation slides are fairly self-explanatory, so this Forum post includes only a few addenda:

1. There are sockets for four transistors on the board. Two 5-pin sockets for PNP transistors, and two more 5-pin sockets for NPN transistors. These are arranged so that if you happen to own some 10-pin DIP sockets {which are uncommon}, you can fit two 10-pin DIP sockets on the board. Otherwise just fit 5-pin single inline "breakaway" sockets as shown in the picture attached below. I handed these out to BAF24 attendees; they are inexpensive if purchased from eBay. Here are a few eBay product titles:
2. The circuit schematic diagram in .pdf format is attached below. That's the one to print, since .pdf has infinite resolution. Instructions for using the Simple Matcher jig appear right there on the schematic. And of course, also in the presentation slides.

3. To maximize the life of the 9V battery, I'm deliberately running the LED indicator at very low current. Please compensate for this low current by fitting a super bright LED. The LED part number called out in the Parts List attached below, shines at nineteen thousand milli-candelas. That's pretty bright.

4. As promised during the talk, I've included an image of the inexpensive handheld meter I purchased for matching, which has 0.1% basic accuracy and whose DC voltage display goes down to tenths of a millivolt. It's not the only possibility, it's probably not the very best, but it's relatively cheap and relatively easy to buy. However, as emphasized during the discussion, you will get "a lot better than nothing" matching results, even with the cheapest meters that only go down to 1 millivolt resolution.

5. The schematic includes printed instructions which tell you how to use the BJT Simple Matcher PCB. Just print out the (.pdf) schematic and bring it to the measurement lab, on the day when you're doing the matching work.

6. "AIR LOCK BOX"?? During my BAF presentation, an audience member's question (@ timestamp 27:29 in the YouTube video) included a remark that in his own matching efforts with another jig, it was useful to cover the entire test jig with a (removable, 5-sided) box made of insulating foam or foam-core. This minimized air currents around the two transistors being measured, and therefore sped up the thermal equilibration of the transistors. If I'm remembering correctly, his arrangement took about 60-90 seconds to get a stable delta-VBE reading {on a different jig}, whereas my slide deck says 90-120 seconds for this BJT Simple Matcher jig with no box. So it might be a quick and inexpensive experiment that you may wish to try; possibly a box could speed up your hour-and-a-half marathon of matching. Several attendees were also concerned that the human test operator's breathing, might create unwanted air currents which slowed the equilibration process. An insulated box separating human and jig, might mitigate these concerns. I speculate that a box 125 x 125 x 75 mm (5 x 5 x 3 inches) would be a handy size to easily cover the BJT Simple Matcher board and wire leads.

_

Who can upload the schematic diagram ?
some images in the attachment - more images under
https://old-fidelity-forum.de/thread-28138.html

This thread will follow my build of the Halcyon speakers, designed by Curt Campbell. I'm not sure if this is technically a F.A.S.T design, but I think it is. There is a single Alpair 10p and two SB Acoustics SB17 midwoofers. Curt described the design: "The Alpair is housed in a semi open back cylindrical enclosure, while the SB17's perform in individual transmission lines that are merged at the port in a mass loaded configuration"

Curt shared that one of his friends, a professional opera singer, preferred the Halcyon's to any of his other higher-end designs. This raises my already high expectations that this is going to be a fine speaker indeed. Strangely, other than Curt and Jim Holtz, I don't know of anybody who has heard them and I don't know how many pairs have been built. Madisound says they have sold several kits, but I haven't been able to find a build thread or any pictures of completed Halcyons other than the original test mules.

Bob Berner (bob@bigwoodstudio.net) made a terrific flat pack for the Halcyons. Everything fits perfectly and the BB plywood is very high quality. Bob is very helpful and prompt. From idea to delivery for a brand new design with no CAD drawings, Bob completed the whole process in just a few weeks. He is great to work with (he also built a FruglHorn XL kit for me) and I encourage anybody interested in a flat pack to contact him. He has good prices, great service, and a very supportive approach.

Here is Curt's website section on the Halcyons:

Speaker Design Works

This is the the only finished Halcyon I have seen images of:

I'm going to build my own RIAA pre-amp. It will be fitted inside the turntable. My MM cartridge (Ortofon 2M Red) specifies the load capacitance as 150 - 300 pF. Am I better of aiming for the low side (150 pF), the high side (300 pF) or something in the middle? Besides the tone-arm's cable capacitance (some 20 - 30 pF, I presume) I can dial in any capacitive load I want. Which is preferred, or is this a matter of personal (audible) taste?

EDIT 2025-05-15:

My build is almost finished. See post 107 for the details.

EDIT 2025-05-22:

For final schematics and power supply details see post #137 You can ignore most, if not all of the attempts at getting a SNR number.

EDIT 2025-05-25:

The design of the RIAA pre-amp is by MarcelvdG. See Single-stage active RIAA correction with second- or third-order Butterworth high-pass included

I have for sale a number of Dayton Audio drivers:

1. RSS265HF-8 10" x 5, 1 new in box, 4 used and in nice condition. $125 for the new in box driver, $75 each for the used ones. I would prefer local sale for the used ones unless buyer wants to use a pack and ship service to have them shipped. I can ship the driver that is new in the box with buyer paying for shipping.

Dayton Audio RSS265HF-8

2. RSS315HO-4 12" x 1: New in box, $150, local sale or shipped. If latter buyer pays for shipping.

Dayton Audio RSS315HO-4

3. RS270S-8 10" x 4: Shielded version, burned in but never installed, $65 each. Drivers are in original boxes, local sale or shipped. If latter buyer pays for shipping. Below is a link to the non-shielded model.

Dayton Audio RS270S-8

Payment via Zelle of PayPal F&F. All items sold "as is" with no warranty expressed or implied. This is my first time selling here but I have sold on both USAudio Mart (tony4660) and Audiogon (clio09) so feel free to check my feedback there.

One amp died when Main positive and negative power in crossed, and the other failed with a multimeter attached while connected to speaker terminals while loaded. Of these two are the components I have to replace with bd139 & bd140, IRFP064N, IRF640. The first amp I have replaced with bd139 and bd140, new 47ohm resistors & IRFP064N, and repaired a trace under the coils.
I have the other amp all with the same symptoms, but additionally, the pwm/protection board has some failed components I have been scouring the forum for. I found here the schematic to help Identify resistor values but no ID on the transistor in position Q5. I dont know what Q5 is, a pnp transistor or linear voltage regulator? https://www.diyaudio.com/community/...-type-3-protectionmarkedtype3-01-pdf.1270452/
Im also reading a handful of odd resistor values on the pwm board as well.

Where I can get a hold of a replacement board? Tracing Q5 to r10A (top), bottom middle leg to pin 1, left leg to C1898, But What does the right leg lead to seeing as it blown the trace? Probing what little left of the trace shows that its connected to pin1(bottom leg & top). What is the transistor of Q5?

Hello, hoping someone may guide me to the right source for this.

My band just bought a Polyeffects Polyverb convolution reverb pedal to be used for typical mixer send/return duties. It works adequately but we are diming the output level to get a just acceptable level. I'd like to include an interface that would allow a greater output range. I see that most "instrument to line level" seem to assume that the instrument is a high impedance source such as a guitar pickup. I have to assume that the output to this device is active and of a much more lower impedance as found in active devices (50-200 ohms perhaps?).

I'm a senior electronic tech during the day and build my own pedals, mic pre's and guitar tube amps so figured I might be up for the job of building a high quality low distortion "instrument to line level converter" that is compatible with the requirements of what I need this to do.

Would anyone be aware of a schematic or good source for something like this? I'm assuming the use of a very high quality OP amp which I'm fine spending the money on. Or, if there is an off the shelf device I'd take a look at that, too. The Polyverb IR reverbs are very high quality and I'd like to maintain alot of the fidelity that the pedal is capable of.

Thanks for reading and input all,
Best,
Phil D.

I'm working on a sound installation that will use eight of those speakers that will be placed on a floor in a art gallery.

The speakers should be as low as possible. How can I planning the wooden box? is there any rules for that?

I'm using this 4mm plywood for laser cutter for building the boxes.
I care about the esthetic of the speakers (meaning speakers must be low as possible to the floor) but the sound quality is also consideration.

Any tips?

I am writing to ask for specifications and T/S perimeters for RCF L15P06C.

I found only some magazine ad:

¿Quieres hacer un Pre+Amp que funcione con una etapa 12AU7 y una etapa de amplificación HiFi con el TDA7293 y control de tonos aislados?

Hi,

I'm attempting to repair a Tannoy TS12 subwoofer. Audio passthrough works but the amp isn't working, I get no level from the sub. I believe based on the other threads about this sub that it's a question of replacing certain caps/transistors, but I'm stuck at removing the plate amp from the cabinet. I've removed the ten screws, but it will only come out about one inch from the cabinet, so I can't get to the spade connectors to disconnect the driver. Would appreciate help from anyone that has experience removing the amp. Does the driver need to be removed in order to remove the plate amp?

First of all: I didn’t really noticed this forum before. I think I have stumbled across some threads in my research to do this project. Now that I have registered, I think it is nice to share my attempts to recreate a NAD 3020 (or actually 3120). So here it is, hope you like it! I certainly enjoyed creating it (and continue to enjoy it when listening to it)!

Disclaimer: just as I was about to start this thread I noticed that other people have played with the idea to recreate this fantastic amp themselves. So yeah there might indeed be a sect going on right here 😉, I hope this doesn't bother anybody too much then. I did this project as a big learning thing and just for fun. Didn't really study electronics so at times it was a bit of a learning curve and I am still figuring things out. The amp is working perfectly fine though but if there are things that are odd in my attempts and design, please let me know!

The circuit design of the amp is – of course – not mine but from NAD. So credits to them for creating this lovely sounding historic piece of equipment. I recreated the boards myself to fit my needs (see below) and added some features to it (and left some out). I tried to keep it as close to the original as possible but ended up creating a simpler version more like a 3120 (or even more simple with just a volume knob).

Schematics
My attempts started last year when I got the idea to build my own amp. Just to see how far I can get and if I could – in theory – end up with a fully working device. A bonus would be that it sounded half decent and didn’t start a house fire… 😊

Searching for a suitable candidate I found that the design of the NAD 3020 would suit my needs. I wanted a proven concept, not too complicated and not too powerful. Furthermore, it had a nice small form factor and of course had somewhat of a reputation.

First I recreated the schematics in KiCAD. I’ve used the schematics from the 3020B as a reference and worked from there. The main difference is the lack of balance control, mono buttons and muting. I also used more foil based capacitors replacing some of the electrolytic caps in the signal paths.



The lack of a proper input selection switch eventually made me design a digital logic board with LED’s and relay switches. A microchip PIC16F628 does the switching but also acts as a power-on delay and controls the speaker outputs for muting and protection. The protection that has been integrated is DC detection, AC dropout (acts as a soft power-down) and of course the delayed power-on. The soft clipping is of course also integrated into the amp.


I incorporated some extra power supplies for the digital 24V and 5V rails (needed for the relays and PIC). These are all relatively low powered and taken from the main positive power-supply, so the digital signals are separated from the pre-amp and phono stage.


PCB designs
The design of the PCB’s took some time to develop. I wanted to etch these myself and therefore used a maximum PCB size of 100x160mm (most boards are a little smaller in length). All boards are single sided and I have used as little jumpers as possible.

The design resulted in a power-amp PCB per channel, one PCB for the phono and preamp stage and one PCB for the power-supply. The last board I etched was the logic board and input selection board. They fit nicely together onto one 100x160 board. In the end I added a separate fuse-holder board and speaker inductor board.


I’ve taken special care to route all ground planes (if any) and ground wires back to a single point. Took some time to carefully prevent ground-loops when interconnecting the boards. As far as I can tell it all worked out as there are no hums, noises or anything like that. There were some oscillations going on in the phono-stage so I ended up tweaking that somewhat and making it look more like the 3020i version of the amp. I added some extra capacitance around the transistors but I might look into that a bit deeper somewhere in the future.

Parts
Most parts were readily available. I mostly used Elna Silmics and replaced some elco's with MP caps. I have found a source for most transistors (especially the SD669 and SB649 are a bit harder to find). The power transistors are still readily available from Mouser so I kept those into the design as I just really like these shiny metal things if only for the looks 😊

The hardest part was to find fitting balance and volume control pots with the center tab for loudness. In the end I ditched the tone and loudness control pots and figured I could do without since I never use those anyway. This actually made me decide I could just go for a 3120 version. The volume control is a nice quality pot from Alps (which by itself costs a small fortune).

I used two toroidal transformers (2x24VAC for the poweramp and 2x30VAC for the pre-amp). The smaller pre-amp transformer has a bit more headroom for the required output voltages. The powersupply does run a bit hotter than the original design because of the bigger voltage drops, but nothing out of the ordinary. Just added a suitable heatsink and we’re good to go! The result is a nicely separated powersupply for the pre-amp and poweramp. Wires are all helutherm 145 with JST connectors in various shapes and sizes. Gives it a nice quality feel. I soldered all the signal wires.


Build
Now that everything is there, it was time to find some nice case to put it all in. I did a small CAD drawing and decided that it could (and should) fit into a 80mm high case. I’ve used a cabinet from an Italian supplier (MODU Pesante). I’ve got an oversized heatsink that goes right into the middle of the amp. The poweramp PCB’s are mounted with some L-shaped aluminum pieces to the heatsink so that it comes out in one big module if unscrewed from the bottom.

I’ve finished the design with amber LED’s and some retro push buttons because why not... The logic board is nicely positioned behind the LED’s with male connectors on the PCB, precisely aligned with the front. This was a bit of a puzzle on the PCB design. But pushing these buttons gives me the rewarding sound of multiple clicking relays and that is just fantastic as it sort of makes the thing 'modern' 👍

In the end I decided I will just skip the pre-amp output on the case and wire the pre-amp directly to the power-amp internally. I might add these typical NAD 3020 jumpers to the back in the future to play around with. The connections are there on the PCB (main in / lab in / pre-out).

So here is the end result!





All in all it was (and still is) great fun. Hope you like it!

P.s. I’m still contemplating if I should upgrade the PCB’s with prototype boards from PCBway or similar but it’s not cheap and you end up with 5 copies and I kinda like the idea that I’ve built the entire thing from scratch (including the boards). Let me know what you think!

Update:
As per request I've included the PDF files and BOM. I do a separate post about the software, that's a whole new story

Update 2:
As of writing all of this, I was trying to panelize the boards and correct some design issues I had in my own etched boards. Just noticed there were some small errors in previous PDF's (there was a couple of rotated footprints). I've updated the PDF files to correct this. Furthermore, there was some interest in the schematics as well, I've included the KiCAD schematics, see attachments.

Hello everyone. I got an idea looking at Peter Morris PM90 speaker if it could be used as line array cabinet with appropriate waveguide, then someone has offer "half" version of it with only one 12" and I really like it.
My idea is that single 12" design tilted to side.
Like a small line array high-end cabinet with fixed angles using coaxial dcx464 on "DOSC" waveguide crossed at 650Hz, together with mb12n405 on folded horn of PM90.
It could be active powered by DigiMod 3004pfc4 using two channel in bridge 1x3000w for mb12n405 and other 2 channel 2x1000w for dcx464.

Here is the pic of how it should look being only 650mm wide, array should consist of up to 5 cabinet with 5* to 20* angle for each cabinet with all 5 cabinets making vertical dispersion angle of about 62* and horizontal, it should be about 100*.

Regarding waveguide, something similar has been used in VIO L1610 crossed with dcx464 at about 500Hz as their specs tell.

This is just an attempt to connect two designs into one from a person that doesnt have much knowledge about designing speakers, so I would kindly request a help to see if this design have any potential.

Let's assume that the dcx464 would work well on such a horn from example of the VIO L1610. What would be advantages and disadvantages of mb12n405 midbass arrayed 2-5 cabinets on each side above dual 18" subs for live sound reinforcement? Will it have same quality, coverage pattern and possible lower crossover point to subs compared to PM90 or single 12" design may not work that good ?
Volume for the 12” would be about the same as in PM90 speaker.

Price 50€,with 160 GB hard drive.

My friend bought these types of resistors for the L-Pad in his crossover. His tweeter needs a fair bit of attenuation. At a theoretical white noise load at 20V RMS, I think it was about 20-40W through the resistors. This design already uses two parallel resistors to split the load. link to similar product, not necessarily this exact listing


I believe that such a load is very unrealistic in everyday use. To my understanding higher frequencies need less voltage for the same perceived loudness. If we simulate the crossover with pink noise instead, the power of all components drops significantly (total power around 4W).

My question boils down to:
1. Are there any reasons related to the sound quality to not use this type of resistors?
2. How much power could these resistors handle without being attached to a heatsink?
3. Should we even worry about the power dissipation? Will they ever see such a large load?

Bonus question: Why does simulating with pink noise in VituixCad reduce the power usage of components by a factor ~10-20? It seems like too big of a difference.
(Below not his exact system, but similar. I do not have his files. Black = resistors, Red = Woofer)

Dear friends!
There is a DAC (digital ground, 3.3V supply) and a headphone amplifier (analog ground, +-12V supply). Both are located on the same board. How to connect both grounds correctly?
The figure mistakenly indicates 5V. In reality, it is 3.3V.

Some people are interested in more powerful CFA amp, and this is 200W//8ohm and 400W//4ohm.
It uses lateral MOSFET output transistors like Hitachi 2SK134/135 and 2SJ49/50 or similar from Toshiba 2SK1056 2SJ162 or from other producers.
Interestin part of this amp is use of TPC compensation, but unusual one with one capacitance branch connected to the output instead to the VAS collectors.
That brings 20kHz distortion down significantly.
This thread is open to discussion and suggestions as it’s tried in simulation only.
As CFA uses very low feedback resistance there is significant power dissipation on series resistor, and I show two schematic, one with lower FB resistors and other with double values. I case if Rf is 220 ohm at full power dissipation go up to 14 W and in case if Rf is 480 ohm it halved. Still this resistor should be parallel combination resistors to distribute power dissipation. first is low FB resistance, this gives lower distortion and higher slew rate.
Damir

Zener protection diodes moved from drivers emitter to drivers bases on suggestion from JohanB (not good idea) 200W MOSFET CFA amp - Page 87 - diyAudio

Argument about stability: What is important is the outer feedback loop
200W MOSFET CFA amp - Page 67 - diyAudio

Better protection suggested by Wahab: 200W MOSFET CFA amp - Page 88 - diyAudio

First listening 200W CFA, post #740: https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-74.html#post4278243

Index:
1. 200W CFA VMOFET, the last schematic and the BOM is here on post #770 200W MOSFET CFA amp and the .asc zip file is here on page #775 200W MOSFET CFA amp

2. 100 W CFA assembling instruction on post #911 200W MOSFET CFA amp

3. PS regulator BJT version assembling and testing instruction post #912 200W MOSFET CFA amp
PS regulator layout errors post #919 200W MOSFET CFA amp
PS Regulator BOM post #988 200W MOSFET CFA amp

4. Corrected 100 W CFA schematic and BOM post #947 200W MOSFET CFA amp

5. astx real amp 200W measurements. post #851 200W MOSFET CFA amp

6. some RNMarsh real amp 200W measurements. post #787 200W MOSFET CFA amp

7. 200W CFA assembling instruction with schematic, balanced add schematic and corresponding BOMs.post #1230 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-62#post-5311565

8. 200W CFA VMOSFET printed board rev. 1.3.2 has some silk screen errors:

200W CFA VMOSFET-dado-1_3_2
Silk scree errors:

D21 rename to D8 and revers
D20 rename to D5 and revers
D23 rename to D20 and revers
D5 rename to D23
D22 rename to D21 and revers
D8 rename to D22
Q9 rename to Q5
Q7 (on the left) rename to Q9 2SC3503

explanation on page #1289 link http://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-129.html#post5539928

9. 200W CFA board rev 1.3.2, corresponding balanced add board and PS regulator MOSFET board with BOMS. page #1405 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-71#post-5725721

10. 200W CFA some soldering explanation, unbalanced input and balanced inputs, post #1415.
There is silkscreen error on 200W boards rev.1.3.2, input connectors wrongly marked, IN SIG GND should be GND SIG https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-71#post-5740471
post# 1506 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-76#post-6031569

11. MOSFET PS regulator testing, post #1416. https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-71#post-5740493

12. MOSFET PS regulator oscillating in some cases, remedy on post #1456.https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-73#post-5904223

12. 100W CFA board rev 1.4 and PS regulator (BJT) rev 1.3 post #1491 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-73#post-5904223

13. BJT PS regulator short connection in rev 1.3, look how to rectify it #post 1535 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-154.html#post6158297

14. Shared gerbers for 100W version #1,588 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-80#post-6929696

15. Real measurement 200W/8 at 5kHz #787 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-40#post-4314881

16. Real measurement 200W/8 at 20kHz #1143 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-58#post-5283298

17. More measurement #1172 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-59#post-5291859

18. Review #1281 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-65#post-5457648

19. 200W gerbers https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-84#post-7701236

I had the good fortune to have them nearby way back in the day. They were the Very Cool Thing that Very Cool Audio Kids did and I loved it. I seem to remember if you brought in a tube piece they would exchange tubes on the spot if you were out of spec. Fun!

I've been working on an old power amplifier (SAE MK3CM) that has a problem with one channel. It works OK for a short time and then the positive side of the output waveform starts to clip, somewhere around 5V. Most of the voltages measure reasonably close to what the SM says they should, but one clue is my nose. I can smell something getting hot. So I decided to make myself a thermal IR camera to determine what's getting hot w/o burning myself or potentially connecting my body to up to 150V (the supply rails are +/- 75V).

I found a relatively inexpensive IR camera that has a 32 x 24 pixel array, the MLX90640. Sparkfun and Adafruit will sell you a board with one on it for about $70 -- and that doesn't include the display and Arduino-ish board needed to process and display the thermal image. However, I already had a Teensy 4.0 and a 320 x 240 TFT display so I just bought the camera chip from Digikey. The camera only has 4 pins -- Vcc, ground, SDA and SCL -- so I just soldered it down to a piece of perfboard.

Adafruit has some example programs for their version so I downloaded them and modified one for my particular display (it has about 4X the number of pixels than the one they use). And it works surprisingly well. So I cobbled together a setup to view the component side of my power amplifier and did find significant differences between the two channels. So here are a few photos showing my admittedly crude setup:


The above photo shows the display. The camera is attached to the tripod using a "C" clamp with some scrap 3D printing failure I had lying around. The amp is shown in the lower right side.


Above you can see the Teensy 4.0 and a better shot of the camera. The camera chip actually is on the bottom side of the board, because I installed it upside-down....oops...

The above image shows what the "good" side of the amp looks like, thermally speaking. The two hot spots are two cascode-connected transistors whose inputs are the front-end LTP's. In normal operation they should dissipate about 76mW.


This is a photo showing the faulty channel. At least one of the transistors -- which happens to be associated with the positive side of the output waveform -- clearly is running hotter. So I have narrowed-down my search by quite a bit. BTW, my hand, which is around 80F, only generates a yellow color so the hot spot is pretty warm.

One initially-challenging problem was figuring out just exactly WHERE those hot spots are. I tried using my finger to point at the hot spot but it was just too big. So I made a hot spot "wand". Just a 120 ohm 1/4 watt resistor taped onto the end of a wood dowel. I adjusted the power supply driving it so it doesn't overload the camera. And here's my high-tech "hot spot":

I have an EAR834p clone, and the power supply died (burnt resistors, failed zener). I am rebuilding it. I am good with the standard PSU filtering, but this is my first time working with a silicon voltage regulator Transistor and a zener stack.

I am getting a situation where the regulated voltage ramps up to 285 pretty fast, but then continues to creep up past 310V. Zener stack is hot too. With 72V each across the 68v rated zeners. I suspect that is what led to failure.

I am getting about 360V b+ unloaded going to the Transistor, an FJP13009.

The FJP13009 data sheet says a minimum of 400v. Does that mean my input B+ is actually too low to be properly regulated to 385?

I am redesigning a QUAD ESL 63 speaker and I need to draw some 3D parts so they can be manufactured (probably 3D printed).
What kind of software should I use for that, I assume AutoCad DXF output should be available?
I don't mind paying a (small) fee but it should not have a steep learning curve, and the parts I need are relatively simple.
I'm not designing the next space station.

Any recommendations?

Jan

in putting together the ingredients to have a good crossover/speaker measurement and design station, some doubts are emerging about the various connections between the sound card and the speakers.
and if instead of using active speakers (which I do not own) but which I see most people using, I exit the computer with the USB sound card (new), go to an amplifier and then to the passive speakers? (just completed)
could this be a valid path?

I've been working on a bass 8k (power supply seems identical to MD8000.1 so I've been browsing repair posts for those as well). I've replaced IC9, IC3, and IC1 and any accompanying SMDs that needed replaced. I replaced both power supply, output fets, and gate resistors. With the rectifiers pulled to isolate the power supply I can't get it to build a square wave on powerup. IC1 builds a perfect 40khz square wave, IC3 not so much, it tries to build a very odd signal initially and then goes flat once the amp goes through it's power up cycle. While testing R150 went up in smoke. I'm running out of ideas and looking for some guidance. I will be buying Perrys book as soon as I have the funds as well

Any help is greatly appreciated, I have a lot to learn and am very appreciative of any guidance and tips. Thank you!

I have for sale some NOS Thoshiba semicondutors, minimun quantity to buy is 4 for any part reference:
10 pieces 2SC1815GR 7€/lot
4 pieces 2SA1837 10€/lot
4 pieces 2SC4793 10€/lot
4 pieces 2SK851 25€/lot
All supplied mosfets/transistor are measured to be matched.
Payment by PP
I have more parts from Thoshiba that you could check here:
https://www.ebay.de/usr/rocksandsound
Regards

Hello
My name is Krzysztof
I live in Poland
I am interested in building audio devices
DIY is my hobby
I greet everyone warmly

Hello dear Diyers,
I began practising electronics during the 70's in high school, then abandonned it for many decades, only working from time to time on tube amps. Retirement in 2023 allowed me to rediscover audio electronics, with Aerius Martin Logan complete refurbishing, heavy modifications of French "Yves Cochet P3" tube preamp, various modifications on Jolida and Audio Research amps, and recently, the building of an ESP P101 mosfet stereo amp (photo).
Kind regards

Hi,

I need a simple passive notch filter for 1 Khz..

I found this configuration with a calculator: http://www.learningaboutelectronics.com/Articles/Notch-filter-calculator.php#answer1

I built it as shown and all resistor and capacitor values are within 1 %.

When testing I see that the dip is around 1700 Hz. and not 1000 Hz..

So according to me something is wrong. Is there anyone with a second opinion?

Regards, Gerrit

Full-bridge IRS20957 Class-D Amplifier - Electronic Circuit

Power Amplifier fullbridge irs20957.rar - Google Drive

Im planning to build it but with single supply. Any recommendation that how to do single supply?

Hi diyAudio,

I'm a new member of diyAudio based in Canada, with a 50 odd year passion for all things audio. Looking forward to learning and sharing insights with you all!

If you want the ultimate in ripple rejection and ease of use, this regulator is for you.

Key features:

• True floating regulator design
• Phenomenal ripple rejection (20 uV output ripple in my setup!)
• Soft start
• Stable with capacitive load
• No need for expensive and bulky high-power resistors
• 2x2 inch (50x50 mm) board footprint

It's now 32 years since Mike Maida authored National Semiconductor Linear Brief 47, describing a high voltage regulator based on the LM317. Lots have happened since then. National Semiconductor was acquired by Texas Instruments for one... And semiconductors have improved tremendously since the 1970'ies. So given that it's been 32 years to the month since LB-47 was published, I figured I'd do an update of Mike Maida's original regulator.

The main drawback of the original Maida regulator is that it requires at least 5 mA (10 mA worst case) to flow in the regulator for it to regulate properly. Typically, this current flows in the feedback network. For lower output voltages, this is no big deal. But for higher output voltages - such as the ones typically used in tube circuits - the power dissipated in the feedback network becomes quite significant, necessitating the use of 5~10 W rated resistors.
In addition, implementing soft start on the original Maida regulator is actually a bit of a challenge as it requires the use of high-voltage PNP or PMOS devices. These are becoming increasingly hard to source.
Modern voltage regulators also have much lower drop-out voltages than the LM317, hence, less power is dissipated in the regulator. As a result, the only heatsink needed is for the cascode device.

My "21st Century Maida Regulator" is based on the same topology as the original Maida Regulator; a low voltage regulator with a cascode in front to drop the voltage. I chose the LT3080 as it has a low drop-out voltage and needs only 300 uA (typ; 500 uA worst case) to operate. As described above, this minimizes the amount of power dissipated in the feedback network. Hence, only 2~3 W rated resistor types are needed.
The LT3080 is a low dropout regulator and only needs 1.4 V (worst case) across it to regulate. This minimizes the power dissipated in the LT3080. It doesn't even need a heat sink.
For the cascode I use a beefy NMOS - STW12NK95 (10 A, 950 V). I've used these in my other regulators and they work well. They're also capable of surviving the conditions present at regulator start-up without running into SOA limits.

My prototype regulator was adjusted to 420 V out @ 200 mA. There is no measurable ripple on its output. With 16 V RMS (50 Vpp) ripple in, I measure 20 uV (yes, micro volts) RMS of ripple and noise on the output of the regulator. Attached pictures show the transient response as function of load current and load capacitance. It looks rock solid to me...
The start-up time comes in at about 10 seconds. This does, however, require a resistive load. Without load, the start-up time is about one second as the output capacitor is charged through zener diode D2. The start-up is smooth without tendency to overshoot.

Using the values in the schematic, I only get about 1 mA running in the feedback network. In order for the LT3080 to regulate properly, at least 300 uA must flow in the LT3080. Hence, with Iout = 0 A, the current flowing in zener diode D2 must not exceed 700 uA. With R1 = 68 kOhm, I get 700 uA when Vin-Vout > 48 V. This isn't enough to guarantee reliable start-up across worst case mains variation, hence, the 330 kOhm "minimum load" seen across the output terminals in the image of the regulator prototype. I'll probably end up burning 1.5~2 mA in the feedback path to ensure that the regulator will start up and regulate properly. I'll also increase R1 from the value in the schematic.

After running for a few hours feeding 200~210 mA into my 300B amplifier, the LT3080 has reached 35 deg C. Clearly, no heat sink is needed for the LT3080 - the cascode still needs a heat sink, obviously. I have no audible hum in the speakers and the amp is dead quiet. I like it....

I plan to offer boards for sale on my website. I haven't done the cost calculations yet, but I figure I'll land around $10.

~Tom

Hi

Im new young guy from denmark getting into tubes, is there any other ppl below 25 in here?

hello friends,

i am from austria and have been working with high-end audio electronics for 35 years.
my particular passion is amplification technology.
i am looking forward to exchanging ideas with like-minded people.

all the best
simon

SpeakerSim - speaker simulation software

Hi.

I have made this speaker simulation software.
It works on Windows, Linux, and Mac OS X (requires Java 8 or newer).
Goal was/is to make simple all in one speaker simulator.

It currently has Bass Reflex, Closed box, Aperiodic, and Open Baffle simulator, baffle diffraction, passive filters, active filters, room simulation, power response, listening window response ...

I hope it is useful. Any suggestions, wishes, or ideas are welcome.

Download