I have a Quantech 2283 + 2181 IC noise analyzer that is in need of a home. Its a project and may need some work. I can provide manuals in PDF form. I have no IC cards for it. I have a layout for an IC card. Free, Local pickup only.

I am looking to identify the output Mosfet label D1 in this amp. This for the audio output section

I have 2 that are shorted. Any help would be appreciated.

Just a few notes on one of these i picked up cheap as dead.

The 1Amp fuse on the a/c transformer board was blown and I checked the DC power supply to find only 1.6Ω across the bridge rectifier! That might have some bearing on it!

I thought it might be one of the 2 transisorts on the output of the power supply, which seem to serve as stabilisers- but no!

It was 2 of the output transistors (darlington) that were shorted collector to base (1.3Ω) I removed the offending and at least had an amp with one channel working.

Ordered 2 new ones 2SB1254 + 2SD1894- and its all up and running. it does have the annoying selector switch issue which is probably caused by age/misuse oxidisation- but i doubt Ill be bothered to desolder it as its a fairly fragile looking device and threads on here are mixed about swapping them out for a 'traditional' type.

The reason the Darlingtons were shorted was probably the cracked solder joints on the sc2240 transistor -

Hello guys!

A fresh new APEX A40 PCB layout is here, the RED Devil Edition! In this thread group-buys for the printed circuit boards are arranged.

It's a bipolar BJT based Class-AB amplifier with symmetrical "current feedback" input stage topology and triple emitter follower (TEF) output stage, and it is state of the art of the APEX AB-Class Audio Reference Power Amplifier. Power rating is 100W/8R0 and sound is very pleasant.







Group Buy Information:

The PCBs are 122mmx105mm 2-Layer, 1.6mm FR4, 70micron copper, HASL finish, white silkscreen and red solder mask, as shown in the above pictures.

> The PCBs cost US$10 a piece. (One PCB is for one channel, so for stereo amplifier you need 2PCBs)
> After the GB list is full, each user will be contacted and sent the first invoice for PCB cost, and the rest (including shipping charge, packing and processing charge and PayPal charge) is to be paid before shipping the boards, for which the second invoice will be sent.

International payments are accepted ONLY through PayPal.
Delay between placing the batch order to PCB plant and delivery of the boards to me will be 20-30 days.

Click to expand...

Shipping Information:

All PCB will be send to buyer address using Registered Post with tracking number. Delivery date is around 10-30 days depends on country.

List Information:
Please write your diyaudio forum nickname (country) - number of boards.

Group Buy list is open for everyone that wants to get these nice Red Edition Boards for Audio Reference Amplifier APEX A40.

Group Buy - APEX A40 List

ronovar (CROATIA) - 2pcs

This amp uses IRFP260N for the outputs .

Wondering can I install IRFP4229 just for testing purposes?

Why is there not at least a 6” BE midrange? Is it too brittle? What about beryllium formers? Apparently it had amazing temperature related properties? Is it magnetically inert enough? The BE former could theoretically be literally part of the BE dome or cone (shape and contours and thickness is also important but there’s a company in LA called LA Guage that has extremely impressive abilities to mill it and a thin dome with any thickness and an extremely thin former could probably also be worked out but those are so thin i’m not sure if humans can machine .001mm or whatever it is either way as a number of stiffened foils which must be possible, this could change things what’s going on? I know how lethal it can be but this clip shows some great promise

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This popped up:
You have insufficient privileges to reply here.
when trying to help a member understand "matching MC transformer" method on the "His Master's Noise" article.
which privileges?

I'm thinking of using this configuration to power up a electro magnet. The load will be in the distance of close to 1.5mtr and if anyone can give any inputs on this it will be quite helpful.

I built this amp in 2002 and it has served me well, but when I removed and replaced some bulging caps recently I damaged the board. It still ohms out but it doesn't light up. I'd like $300 for the whole thing, including some older but still working JJ tubes, and some very nice KLE RCA inputs. The Hammond transformers (272FX Power and 1650F outputs) sell for $375 now on Mouser, so this seems reasonable. But I'm open to offers or to parting it out.

I also have a brand new Alps Blue Velvet 100k pot, diyaudio connection board and knob that I will sell for $20, and a matched quad of JJ El84s, balanced 12AU7 and 12AX7 purchased new from Eurotubes in late February that I will sell for $100 (currently $125 on eurotubes.com, more from other vendors.) Less than 10 hours, so not even broken in.

Could someone send me the schematics of the EAR 802 preamp ? Need to do some repair works to the power supply. Thank you.

I have one of these speakers in my collection but can't find much information about it, only people selling the manual on eBay. Does anyone know the specs for it or what the pot on the back is for? Thanks.

When playing full range, I'd imagine the MAOP 7 is the one to go for if money is no object. But with WAW, do I want the mono suspension Alpair 7MS (or Alpair 5), or do I want MAOP 7 with the fancy coating?

What 10 bucks gets you at the thrift store.
Three circle templates.
A stack of half inch MDF, great for testing small enclosure designs.
(To me this is the real value as ply is so expensive, hard to move from store, and is unsuitable for goofing off from a cost perspective.)
Four 3.3Ohm 5w.
Two 6.8uF.
Two 5uF.
Twenty four black screws.
Two 10 inch cone woofers. (Good for learning the relationship between T/S and enclosure with real world example.)


Jeremy

10 Qty - Peerless 8" W8-12T 12PS (Free)

4 Qty - Dayton Audio 10" RS2700S-8 ($5 each)

Buyer pays shipping and paypal.

Local pickup ok.

Vince
Wayne PA, USA

Saw an interesting video amplifydiy. They compared bamboo and acrylic. The bamboo sounded "richer" smother than acrylic. The acrylic had better top end and more detail. It's going to take alot of trial and error to get these things to become popular or accepted. Some their inexpensive build cost will drive the enthusiasm. For now seems midbsss and midrange is where there at now. Another point he made was the importance of attachment design and quantity and placement of them. Only way to move onis to keep thinking out side of the box. Keep on experimenting, I am have fun with the excitor. Pun intended. Michael

SOLD

ASKING $225 including Continental USA shipping

This is another project I will not build, seeing if another might have an interest in it.

Designed by Jason Leaman and others, this is a super heavy duty implementation of the F5 with a stout CRC or CLC power supply board.

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He used some atypical parts, mainly the SOT 227 footprint power mosfets and diode bridges. The boards are NOT UMS mount compatible so you must be provicient at drill and tap of heatsinks.

The signal boards call for mostly MELF resistors, but use standard 3W power resistors. ixys IXTN40P50P and IXFN140N30P huge mosfets are used and mount the boards to the heatsink. Screw connectors can board mount for wire attachment.

dimensions: 260 x 52 x 1.6mm

I include all parts needed for the signal boards except the input jfet J74/k170 pairs, the spade connectors for signal input and signal ground, if you want to use them, and SMD LEDs. The mosfets retail for about $75 per board.

There is a schematic and BOM included, support from Jason has been hard to come by, so I suggest you are an advanced builder, familiar with First Watt amps and power supplies if you take on this project.

The PS board is HUGE (244 x 189 x 1.6mm, NOT UMS mount compatible) and can be set up for CRC or CLC filtering. I will include the Microchip APT40DR160HJ Diode bridges that fit the boards, 16/ea Nichicon 15,000uf 35v capacitors, screw mount connectors, and fuse holders. No resistors, film caps or chokes included. There is no schematic or BOM for the power board. Pretty self explanatory, and he runs over it nicely in the linked video.

So, for less than the cost of the 6 SOT227 parts and the 16 PS capacitors you have a partial kit for an F5 type DIY amp. You supply the other board parts, chassis and chassis components.

Hey folks, dropping a line to encourage other hobbyists to avoid the Schurter push-push switches. They look great and work wonderfully for a while, but one of mine spontaneously stopped working yesterday and will not latch with the supplied push button.

I have this part in two of my builds:
1241.6821.1120000

https://www.mouser.com/ProductDetail/693-1241.6821.1120

Conversely, if you are into cycling your amps for stress tests or you prefer to hold your finger on the "on" button during the duration of a record, Schurter may be a good choice for you.

Greetings,

I have a brand new Hammond 274BX power transformer (box never opened). When ordering the various parts for a tubelab SSE build, I accidentally ordered 2 power transformers. Ships from Canada (SK)


Power Rating (VA) 198
Primary VAC 115 / 125
Primary Frequency 60
A.C. High Voltage Secondary RMS 750V C.T. @ 201ma.
Filament # 1 VAC 5V C.T. @ 3A
Filament # 2 VAC 6.3V C.T. @ 6A
Mounting Type Vertical ("X")

Full specs here:
https://www.hammfg.com/files/parts/pdf/274BX.pdf
asking price: CAD: $120 + shipping (~ CAD $20 to ship within Canada) - CAD $45 to ship to USA.

Hi, diyaudio!

Attached is a flac that plays a 100hz and 1000hz sine 3 times. They all stop at the same time but the 1000hz starts with a delay of 0ms, 1ms, and 2ms.

The levels of 100hz and 1000hz are the same so it can be hard to hear 100hz over 1000hz. Putting the ear near the woofer can help with hearing. Play the clip a few times and try to lock onto the bass tone.

The question is: do the samples sound similar or different?

I am trying to exploit a slower group delay on some of my speakers and this is my first go at a test.

Thanks!!!!

Hi - I have been so impressed with the knowledge shared in the diyAudio forums, thanks to everyone for their contributions!

Like many other newbies, I am trying to sort out my first full range system, and wanted see if I am on the right track (primarily regarding my choice of enclosure). My goal for the system is to get a good flavor for what a high efficiency, simple single driver system is like. This is what I am planning:

Driver: FE206En (purchased)
Amp: F2J Clone (parts purchased)
Preamp: Salas DCB1 (parts purchased)
Source: Old Sony CD Changer, Old Technics Turntable
Enclosure Options:
1) Woden Designs Vulcan (preferred if it works in my room)
2) Kirishima
3) Dallas II

The room is 31' x 14' (9.4m x 4.3m) with a 7'-6" ceiling height (2.3m). The speakers would be placed against one of the long walls and the listening chair is positioned against the other long wall.

Will a fire place between the speakers that extends 6" out of the wall at the top and 15" at the bottom cause a problem with the boundary loading of the rear horns on the Vulcan? The picture below shows a full size cardboard mock-up of the Vulcan next to the fire place.

Thanks so much!

SOLD

Asking $20 including CONUS shipping

For sale are a set of Singing Bush Power Supply Boards, Rectifier/snubber boards and CL-60 AC cap boards. I am not going to build an amp that needs these.

I also have a pair of KBPC3506 rectifier bridges that fit the boards I will throw in if you want them, let me know.

Shipping to Continental USA included in sale price.

Can anyone explain how the coupling with the voltage reference tube // 5.6nF cap works? The designer states that it is a fully DC coupled amp, but I can't get my head around how the signal passes in that middle stage if it weren't through the cap. His explication leaves me equally perplexed:

"Incidentally, notice that the voltage at the grid of the cathode follower driving the 841 is near zero volts. One could then ask why the complication of adding the DC coupling, and the reference tube. Well, indeed I tried that, and the amp measured OK, but sounded VASTLY inferior to the DC coupled circuit. Distortion cancellation anyone?"

http://diyaudioprojects.com/mirror/members.aol.com/sbench/a2part2.html
Thanks for shedding a light,
Simon

Hi, Im making lm1875 amp with ne5532 op amp only for balanced input and voltage regulator for the op amp and i have no idea how to ground it on one 2-layer pcb. Does i need use star grounding or just ground plane? All components are THT so i thought i put only ground plane on bottom and all other places on top. What do you think, can you help me please?

Has anyone ever tried to do the RJM passive phono with 12AY7 instead of the 6922? Mu is similar so it seems doable?

I have heard that the RCA circuit is not appropriate for AY7 due to lower mu (compared to AX7) but the topology is quite similar to RJM which uses a 40ish mu tube. As far as gain goes both RCA and RJM are two stage passive. So I would also be interested in hearing from anyone who has done the RCA phono with AY7s also.

Hi Guys
In the aleph J PSU, which is the function of the TH1 thermistor circled in red?



he is critical to safety?
In my Aleph J the metallic 4U chassis it's completely isolated except from the IEC earth. The GND PSU, all speaker terminals and RCA connectors are completely isolated from chassis and TH1 is not mounted.
It's correct or not safe for electric shocks?
Thanks

Hi!
Will those drivers work together?
I want to build a audiofile speaker.
I want to try.

hi i researched these and found info regarding one with a rectangular audax tweeter


there is also a model with round tweeter-anyone know the difference please








Vintage Audiomaster MLS-1 Bookshelf Speakers | eBay

I’m in the process of building my first horn and would very much appreciate input from experienced users. Many have helped me learn about horns from scratch in my midrange horn 101 thread – thank you very much!! It has been an intense learning experience.

The system is 4-ways fully active, DSP with linear-phase crossovers, time alignment. The tweeter is a Beyma TPL-150H, and the horn to be designed is targeted to operate from 400 to 2500Hz. Below the midrange horn, a pair of direct radiators per side in sealed boxes, and below that subwoofers in sealed boxes. One goal is to use this horn directly connected to a 45 SET. Another 45 SET for the tweeter. Below that is class-D.

Given what I learnt at my other thread I purchased Faital Pro M5N12-80 for these horns. I was advised to use a flare cutoff frequency about an octave below the intended xo point to minimize colorations from the horn at the lower end. I’m taking 215Hz for fc.

One significant decision is shape of the mouth: circular vs. rectangular. Circular has the benefit of a more even and predictable response, while rectangular (2:1 width:height) has the benefit of reducing the center-to-center distance between the TPL and midrange horn (which is still going to be larger than twice the 2500Hz wavelength). Feedback on this will be helpful.

A Hornresp simulation is attached below. It’s a tractrix profile extended to 90°, with a circular mouth. S1=Sd, and fc=215Hz. Mouth comes out to be S2=1990cm2. Both attachments are the same, but one is lower resolution. I can't figure out how to unattach a file here...

As of today I’m leaning towards a rectangular horn. Open to be proven wrong, though. Bruce Edgar’s Tractrix midrange horn is a bit of a baseline for me.

I’m thinking either tractrix or LeCléac’h with 0.7 factor and limited to 180° opening for the width profile. For the top and bottom sides I’m not sure if I should settle for the simpler to build conical (like Edgar’s), uniform or exponential profile. What do you think?
Keeping the 2:1 mouth aspect ratio, a 631 x 315mm mouth will have the same surface as S2 above (1990cm2).

I guess before I go further into the design I should decide:

• Rectangular vs circular mouth
• If circular: Tractrix vs. LeCléac’h
• If rectangular: profile for the width and profile for the height.

Any additional feedback very welcomed!

I'm planning on building 2x 1850s loaded with fane colossus xs 18 primes 1200w rms. . Im looking for a reasonable amp to make them purr but I'm struggling to find anything. My first thought was the behringer nx6000d but I feel it's worth throwing in some extra cash and get something more solid.

Hi!

I have some prototypes on ebay, "make your offer" listings. I am interested in feedback from real audiophiles who enjoy fine sound quality. Since 2019 when I started the project, I sold a dozen, with modifications that improve their features step by step. The design is close to the end production, but not finished yet, so you have chance to get the working prototypes and participate such a way in R/D process, helping me to self-finance it.

https://www.ebay.com/itm/185295464131

https://www.ebay.com/itm/185288710253

Hey guys!

I've been around this forum for a week or too now, having got interested in a diy - guitar amplifier project!

I have not much experience with electric circuit design, so I'd like to ask you seasoned pros for some guidance on the following problem:

I've acquired this '92 Hughes & Kettner Tubeman recently, an amazing recording tube preamp. Unfortunately I used a 19V AC power supply instead of the suggested 12V AC.... It worked for a few hours very decently, but now it's dead. I'm an idiot I know, but now I want to fix it very desperately.

So I got out my trusty old multimeter and checked some diodes and stuff, and I noticed that two diodes (D1 and D2) were not working properly anymore, they were conductant in both directions.

Now my questions are

a) What could these diodes, in connection with the rectifier B1 just below, be for? I can't make any sensse of this.

b) Could it be that using a 19V supply fried them (and/or any of the ICs? I hope not! :-( )

Thanks in advance!!

Attachment:
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I recently discovered my local electronics store has a whole pallet of these 33,000uf 63V caps and the owner sent me home with 4 free ones to try out. He informed me they have had them for 15+ years, so of course I am skeptical about them working.

What’s the best/easiest way to ensure these are properly charged and tested before trying to use 4 in a Pass Amp?

I purchased a variable power supply that can go up to 60V 5A. I was told I could slowly charge them by adding a 3K ohm 3 watt resistor in series. I was able to get a 3.4k ohm 10 watt resistor to use.

A few questions:

- how slow should I charge them with the DC supply? Or what process should I follow?

- is this method a way to test and ensure the caps work?

Any help or feedback is appreciated.

The 6KT8 is a wee 9-pin triode-pentode. Has anyone traced or measured the pentode section (specified as gm=10mS for Vak=Vs=125V etc etc) when triode-connected?

In the absence of measured triode curves, I will probably rely on those for the 6BN11 - the specifications are similar - but would appreciate real 6KT8 curves if they are about.

Hello

I need to clarify these rules, I know how to wire in series and parallel like anyone would but I don't know how this affects sensitivity's


Now for my example, assuming you had an amp that put out 100 watts at 4, 8 and 16 ohms, and a woofer that had an spl or whatever it called at 100 db 8 ohms at 1 metre with 1 watt

Now say we wire one speaker to the amp, its sensitivity will remain 100db/8 ohms/1 meter

Now say we wire 2 of the speakers in parallel making a 4 ohm load, I assume the sensitivity now rises to 103 db because a doubling of cone area at the same watts

Now say we wire 2 in series causing a 16 ohm load, I assume again that the spl now rises to 103 again because of the doubling of cone area,

Based on that does parallel and series sensitivity go by what the amp can out put at certain ohm loads

Or give me a realistic exmaple

Thanks 🙂

Hi, I heard a pair of this several years ago in a speaker called a Buckingham but cant recall the actual comany who makes them. This is a photo from an old brochure. They were over $5000 and might be a good canidate for a diy project. Thanks for the help.

taylor

Like the title says, I want to hear anything you have to say about these tweeters compared to one another, especially from people who have heard all three. Let's just assume that all three are ideally implemented in a speaker design. Some points I'm interested in:

1. Sound
2. Value-for-money
3. Your personal choice and why

Any insights are welcome though 🙂

Selling 1 pair of Werner Jagusch Altec A7 crossovers

For Altec A5/A7 with optional tweeter.

In excellent condition, both electronically as cosmetically

They should work in a number of different configurations of a 416/515 woofer, used with a 288, 801, 802, 806, 807, 808 as horn driver with numerous horns such as 511, 811, 1005, 1505,...
The horn circuit uses an autoformer to adjust the sensitivity of the horn to the woofer

Asking 400€/pair

I'm proud to present you my headphones amplifiers family:

The 1st one is a Class AB push-pull driven by an OPA2604AP, with a Gain selector:





The 2nd one is a Class A MosFET:





Then i decided to make 2 expansion boards, a DAC one and a Delay (antipop) one:

Hi.
I'm not super knowledgeable about amps but i know some electronics. So thought I might give it a try.

Setup:
Nad c352
Two Jamo CBR 1302 speakers

Description of problem:
When the amp has been on for a couple minutes, less than 20 min, the right channel goes loser and lower till it is totally quiet.
If i turn it off and on again it still has the problem. But if it's off for some time( a day or so) it starts normal again then goes quiet. So I'm thinking it's some temperature problem...
Anyone here have an idea of where to start?

My regards
-Noah

Recapping a ADCOM GTP500II. Capacitor C308 doesn't have a negative side marking. Maybe it doesn't matter for this one? Any help appreciated.

Need formula for selecting power supply filter capacitor for high frequency. 20,000 cycles, 6 amp load, and 28volts DC. ?

These are on eBay as YX1099 and WM-025 with the latter looking as a better design. After building the first one I found the gain so high it was overloading the input on a little Tripath amp. When used as additive equalisation, the amp would distort so subtractive equalisation was only possible.

The gain is set at 10 by the 100K resistor near the first op amp (inverting) in conjunction with the 10K input resistor. To solve my problem changing the 100K to 10K gives a gain of 1 which matches my source and amp with the volume the same as previous. As I didn't want to remove the 100K, I paralleled a 10K to give around 9K which gives gain of 0.9. I've mentioned this as there is a zillion of these things being sold and others may have the same issue.

I only used the PCB from the kit and used my own components as they are of known quality and ended up using LM4562. One thing I did add was a 100nF monolithic by-pass cap between pins 4 and 8 on each op amp under the PCB. I also run this via a 12VAC wall wart instead of a 12-0-12AC supply with a centre tap.

Hope this helps someone in the future and even though I used 10K, if more gain is required then use a higher value.

Very nice condition, musically sounded wonderful with no VC rub prior to removal from enclosure. Very nice one. DCR of only 5.9 ohms. Perfect original cone. $350 + shipping.

Hey,
I’m looking for a turntable for a friend with a budget of $500. Recommendations please

Found these tucked away... unused and still in their anti-static bags. Uses obsolete KSC3503ESTU + KSA1381ESTU mosfets.

https://www.diyaudio.com/community/threads/tssa-v1-6-docs-and-buyers-list.217616/

Can ask Sonnya for the build manual and BOM if anyone wants to try.

Thanks

It's time to declutter my life. Too many hobbies done half-heartedly.

I have a number of original ICs unused sitting in drawers doing nothing.

They would be better off in someones project(s).

Semi Qty £/each Notes
PGA2310PA 4 10.00
LM317KC 6 3.00/6
LM337KC 6 3.00/6
BUF634T 4 5.00
LM3875TF 5 3.00 Plastic Insulated
LM3886TF 5 3.00 Plastic Insulated
LM1971N 5 4.00 Discontinued/NOS

Prices are individual (except for LM317KC/LM337KC) and do not include postage.

Bought them from someone on the forums years ago. They are pulls but in very good condition. Only reason I see to think they are pulls are the tinned legs.
You pay shipping

i have a spare 58Vac {unloaded} primary winding which im planning to use for both negative bias voltage for grid bias and also positive heater lift for a srpp driver stage. i came across this cct which can do what i want but needs some tweeking. can i reverse the voltages polarity in such a way that the top fullwave rectifier does the -ve bias and the bottom halfwave rectifier doing the +ve bias? thanks for any help.

My project for the summer is to build a better "lifestyle" speaker. The criteria being it is a single bluetooth enabled speaker meant to be plugged into a power outlet.

My desired outcome is a fun speaker with a big soundstage so overall accuracy is low on my list. Designs that I have built and enjoyed in the past are the Cornu horn and Karlsonator.

Inspiration for this project is the Bose 901 but instead of 2 individual speakers I wanted to include two channels in a single enclosure. The thought being that using room boundary effects will increase the soundstage and provide more of a stereo effect from a single enclosure. To take things a step further I am wondering if I can use corner loading to exaggerate this effect further.

This is more of a discussion starter topic. Looking for feedback, ideas, or recommendations no matter how crazy or out there they might be. Just to reiterate, the intent is a FUN speaker not an accurate one.

Hi everyone.

Is there any reason I can't use the drivers from my two Kef 2005.2 subs in my car? The amps are blown but the drivers are good in my KEF subs, and I want some better bass in my car other than the 6 inch speakers in the door. Thanks.

Hi,

TI has appnote for building an active 2 way here https://www.ti.com/lit/ug/tidu035/tidu035.pdf
For time alignment it proposes a delay all-pass filter circuit to delay the tweeter, the delay is a fixed at 155us till 3.8Khz upper cutoff. Please see section 2.4 and 4.2.3.
Can anyone please explain whether this delay is really fixed at 155us from 20Hz to 3.8Khz?
I thought an all-pass filter give a constant delay in terms of phase angles and we know that a constant phase angle (in a band of frequencies) gives varying time delay, not fixed. But the proposed circuit is claimed to have a fixed time delay, how?

Thanks and Regards,
wondeflaudio

Hi,

Selling 3 amplifiers SKA GB150 from Greg Ball.
Preferably in EU or Worldwide
Transfo can be removed if you need other voltage and lower shipping cost.
Price 250€ / each without shipping
Special price for the 3 !

Mosfet
Max output 150w
1Vrms input
Class AB
Can make 50W into class A with some modifications

2 amps in HIFI2000 cases
300VA transfo - 230V
DC protection installed
Softstart
Few little scratches

1 amp in custom case
all metal apart wood face
Bigger transfo and caps bank - 230V
Softstart
DC protection kit has to be installed and soldered if you want
Some scratches
The bottom of heatsinks are rough hand cut

I have the manual for easy tuning.

I have an "Astronic Audio Response Equaliser type A1671", 60's model I think, could someone help me with connecting this up for electric guitar recording please.

It has 9 bands & on the rear panel there are two connecting sockets one has 18 pins & the other has 4. I dont' have the connecting plugs but can work around that.

Not sure how to connect this properly?
It has an on/off switch as well as a in/out switch & a Level Pot, there is also a red light so it seems to require power?

I have attached a very poor picture of the same model I found on the Internet.

Cheers

greetings everyone. just wondering who has built the rjm 6dj8 phono and would like to share their views and experieces here.Ive looked at dozens of schems but I keep coming back to this one to build. It will be my first try at a valve phono and this one looks pretty simple and i like the fact that it uses 6dj8. also what output level could I expect running a mm at 0.5mv thru this stage. Also are there any particular things to whatch out for in building this circuit. Any help would be greaatly appreciated.
cheers fergs

Time for the next step. I am working on a smaller ES horn made of beech. It is not solid wood, it is Leimholz (in German) which translates to "glued wood" - I am not sure how it is called in English. It is regular rectangular pieces of wood glued together. The thickness of this is really regular and the samples I bought were really flat. 18 mm thickness, the slices are now machined. They need to be glued into layers and machined in 3D. I need to pay more attention to the details and I think this will be a perfect horn for my CP755Nd drivers.

https://www.radiodiscussions.com/

From yesterday I'm participating there as 33GY7A.

Inquiring minds want to know

With the proper operation of an AB amp, is 150-300mV DC offset spike during power on/ power off normal?

The driver, a woofer in this case, moves noticeably given the voltage spike

Could this harm the driver?

No sound is heard, just cone movement is seen

EDIT: SOLD

Selling 2 pairs of CSS LDW7 woofers.
Used, good condition.
Some signs of wear, small scratches from mounting, etc
Asking $200 per pair

Please send me your zipcode for a shipping quote.
Thank you for looking

Hi,

Transformer for my Hiraga build showed up today.

(Will be making a thread of my experience once I have it fully assembled…)

Its a 300VA 30V CT.

Before I created a significant amount of magic blue smoke, thought I would confirm that my connection strategy is correct…

On the primary:

Orange and White - get connected to the line live
Black and Brown - get connected to the line neutral

On the secondary:

Red - Gets connected to PS board AC in.
Yellow - Gets connected to PS board AC in.
Gray and Blue - Get connected together, and get connected to PS board Ground.

Im really hoping I have that correct?

What I’m concerned about is the GRY/BLU getting connected to ground…

Really appreciate your time!

Thanks,

Per

This is I guess a feature request and not a problem per se. I don't think this feature is currently available, but it might be handy for many users. Let me explain...

I sometimes want to drop in and check the forum for the latest posts. I know that I last looked at the forum N hours ago. Every post shows a date and time when it was made, however, that is not in my time zone and am not even sure of the offset in hours from my locale (and that could change depending on which stupid daylight savings time ruse is going on or not). So the current time stamps are just not all that useful for the purpose of figuring out how old a post actually is, IMO.

I would love to be able to scroll thru posts from all forums on the main page until I reach the "time since post was created" of N hours. If this "age" was displayed instead of the time/date the post was created I would have a;; the info I need. By glancing at the age I would know when I have reach N hours and therefore looked through all the posts that have been made since I last visited. Is there already such a feature?

Is there anyone else who thinks this might be useful to them?

Can First Watt amps push this load? Or am I asking too much? Note: a 24 dB/oct hi pass filter set at 100 Hz will be implemented.

Did you know the OM styli fit on the 2M body? 🙂
Sometimes you have to re-invent the wheel when the patent expires...

I picked up a Crate G40c at a yard sale a while back. I'd like to get it fully functioning to take to jam sessions, as it's much lighter than either of my tube amps. Channel switching, chorus, and footswitch jacks all work, but the reverb is out. I've checked the tank itself, and there's nothing missing, broken, or burnt in the chassis. Any ideas for a next step in troubleshooting?

Bliesma 34 Berylium.
Somebody compare with another berylium tweeter?
Is really so good?

Newest one. JBL 442730-001 PTH1010HF-1 Waveguide - Speaker Exchange

Or even last gen before jbl "pt h1010hf" - Google Search

The mpro looks good too (patick bateman). I'm thinking about minimal colorations, as in no flat walls, no bent horn paths, no diffraction slot (parallel walls).

The newest waveguide seems like a winner.

Hi all, I need some advice and guidance.

I have a HK A300 stereo tube amp.
Presently the output tubes are biased throught the 12AX7 tubes.
I want to split the 4 output tubes from the 12AX7 preamp tubes to allow me to individually bias each output tube (orignal Schematic of output section attached)


1. Is my proposed wiring diagram correct and functional? Attached
2. I could use some help in determining the R values and wattage rating, and the C values.
My specific BIAS readings are attached.

I see that some tube datasheets provide a rating for the resistor, unfortunately there is none provided on this tube datasheet. Attached
I assume I need to calculate it. I estimate is at 143 ohms. 21.5 vdc / .15 = 143 ohms for each R, correct?

I've researched and researched, but only confused myself by finding lots of contradictory information.
I would really appreciate some help determining the correct values and an explanation of the calcs, or a few links to some explanations you know to be accurate so I can learn.

Other notes:
I will have a separate transformer wired to provide regulated 24Vdc to 12AX7 heaters
I estimate that the 12AX7 tubes are providing 143.33 total resistance
Resistance and voltage drop was measured from OT center tap to pin 3 of each 6v6GT
The amp is powered via a 117Vac bucking transformer at all times
This is a Harman Kardon A300 stereo tube amplifier from the 60's
The output tubes are 6V6GT EH. Spec sheet attached.

Thanks in advance

The plate amp in my NHT Twelve died. Was thinking about using the Ghent mono kit:

ghentaudio --- ICEpower 200ASC/300ASC Monoblock DIY Case-kit

and the PE ICE 200ASC:

ICEpower 200ASC Class D Audio Amplifier with Power Supply Module 1 x 200W

I am new to this, so I was hoping for some guidance:

1) Will this amp provide enough power for this subwoofer?

2) I would need to connect the preamp via unbalanced RCA - the Ghent kit has an RCA input? But without the RTX Module. I am confused about why I would need the RTX module (ghentaudio --- RTX (unbalnced RCA to balanced XLR Converting) Module) in this case? Is there any advantage to using it since the kit already has RCA?

3) I would like to add a 12v trigger. I cannot quite figure out from the specs how to implement this on the 200ASC. Does someone have any guidance on what I would run from a 12v input to the 200ASC (and where on the board) to enable auto on from standby with 12v?

Any other tips/guidance?

Much appreciated!!!

-m

I'm retrofitting a vintage stereo receiver with pretty much everything new except for the tuner stage. I've tried a couple SMPS's, but unfortunately the noise bleeds into the tuner, so I've decided to go linear instead using a basic Antec 400w with a Belleson SPHP regulator on the output. Was wondering if anybody has any experience using one of these regulators?

Hi all,

I’m looking for some advice on my first Hifi tube amp build. I’ve built several guitar tube amps already, so at least I know how to use the soldering iron, but I have no experience with low-THD audio builds, yet. Btw, I have learnt a lot from many discussions in this forum even though I have not participated actively until now. It's really a great resource!

I have looked into the various lowish power push-pull designs in the DIY community as for example, the Baby Huey, El Cheapo, Bevois Valley, ST-35 etc. I like the elegance of the Baby Huey but as I want to use 6V6 tubes, I don’t know if this will work? So I need your help here.

I have the iron already:

• Edcor PT with secondaries for 300 - 0 - 300V @ 200mA, 6.3V @ 4A and 5V @3A.
• Piemme Electra OTs, 25W Raa of 10k and UL taps at 35%.
• I have a quad of EHX 6V6GTs and a bunch of 12AX7, 12AT7s, 12AU7s, ECC99 and 6N1P which are available to use.

I’ve read most of the topic on the Baby Huey and also on other amps and did many LTSPice simulations. I have mostly settled on the Baby Huey scheme using fixed bias 6V6es, 12AX7 driver and source followers in between. For simplicity I would like to avoid the need for additional +56 or -48V supplies as used in some of the more recent Baby Huey schematics. I don’t have these windings on my PT and don’t want to include an extra additional transformer if possible. The Bias supply I plan to rectify from the HT winding as is done in many guitar amplifiers.

Here are my questions:

- Can I run the source followers from a filtered HT supply, with the source resistor going to ground instead of a negative supply? Would LND150 MOSFETs work? (As per the attached schematic?)

- I ran simulations using this scheme with LND150 source followers. THD figures are okay in the simulation with 0.5 % THD @14W and 1kHz. However, at higher frequencies THD increases dramatically. At 10k THD is 4.1% and at 20k it’s 5.7% (still at 14W output). What is the reason for this? What can I do about it? These values are determined without global negative feedback, using only the shunt feedback network. And of course the simulations are only as good as the models of the tubes and LND150 and I don’t know about their quality.

- With my PT the B+ will be more on the high side, probably around 380 - 390VDC. Should I think about running the 6V6s in cathode bias to reduce the plate-cathode voltage a bit towards the original specs?

- Would running the 6V6 with CCS cathode bias allow to ditch the source followers by increasing Rg1 to 470k?

- I still didn't really understand why the PI tubes need to be set to low current. I know this is kind of a pre-requisite for the Baby Huey arrangement, but I still don't really know why...? I have a couple of 6N1Ps I would like to use instead of 12AX7, but these need a current of around 3 - 4 mA per tube. However, 6N1Ps probably won't provide enough gain anyway.

- Do you have any other suggestions for me?

I’m open to other schemes but would like to use the iron and tubes I have. I’m not after the ultimate perfect HiFi experience but of course would love to build a decent sounding amp with the parts I have. I will run the amp with some old Heco speakers but may buy some more decent speakers later on.

The attached schematics are those I’ve used for the simulation. Full 15W power output is achieved with an input signal of 1VRMS. I have attached a screenshot of a table I made which shows THD for different frequencies and different setups of the amp. “Huey” represents the shunt feedback method connecting the PI and finals anodes by resistors. “Fixed B2” represents the setup with powering the PI anodes of a fixed node in the supply (“B2”) and using global NFB.

As you can see, THD of the Huey arrangement is best at low frequencies but is increased at higher frequencies compared to the fixed HT version.

Thank you very much in advance for your support with that project. I'm looking forward to your suggestions.

Cheers,
Yves

It is very important to know what kind of chips or transistors are in the photo.
Thanks!

Hello,

I have designed a femm model about a speaker motor and would now like to analyze it and find out how linear it is, how much xmax I have, etc.

Does anyone of you have such software, lua scripts etc and would you be willing to make them available? I would be willing to pay for that too.

SOLD

I just need an advice and i am no more than curious about the upgrade as i don't think i have heard the speakers in their full potential yet.That said the crossovers seem to be easily reached and there would be no butchering involved if i replace parts.

They are Quadral Aurum Phonologue Titan VII and the visible crossover board behind the ''mirror'' on the back is one of two crossover sections.As you can see it is populated by high-quality Mundorf MKP and MKT caps,which are ''cheap'' at retail,but parts of that ilk are not out of place in most commercial loudspeakers,retailing for up to six figures.I wonder if it would be beneficial if i replace the caps with Mundorf Supremes or similar exotic caps.Every speaker is built to a cost and caps like the Mundorf SESGO are too much for all but the cost no object products.

I see two problems.First,the price.It is a lot of parts and i can easily spend more than a thousand pounds,even without going overboard with Duelunds or the likes.Maybe the solution would be more affordable ones as the Audyn Reference.BTW,the latest Titan IX uses Audyn Q4.Second,i just don't see the space as it is a snug fit as it is and fancier caps with the same values and the same or higher voltage rating are much bigger.I can't see how would they fit.

Lastly,would it really matter if i replace everything with fancy caps.And is there a danger of achieving the opposing effect,degrading the sound.It is a very complex crossover,it's not like replacing a single cap in a ''purist'' design.

So the viability would revolve around space,budget and technical constraints.

Any thoughts?

Hello!

I have an H/K HK980 integrated amplifier, I would like to connect it directly to its power-amp, but it doesn't have such an input, so I thought that if I pull the signal cables that comes from the pre-amp and goes to the power-amp, then by routing them out, there will be a direct power-amp input. Yes, but if I pull-off the signal cables that going to the power-amp (that is, the +/- cables that only carry the sound) from the pre-amp, the entire amplifier is turned off with the keyword "protect".

What could be done about it? Mainly, I mean that the pre-stage part would perceives it as if the power amplifier is connected to it (to not go into protection). Sorry if the question is trivial!

Hi,

I've searched far and wide for LTSPICE models of FQPF9P25, FQP4P40 and FQP3P50 mosfets, but with no luck.
Here you can find the datasheets:
FQPF9P25 ( https://www.mouser.it/datasheet/2/149/FQPF9P25-110839.pdf )
FQP4P40 ( https://www.mouser.it/datasheet/2/308/1/FQP4P40_D-2314130.pdf )
FQP3P50 ( https://www.mouser.it/datasheet/2/308/1/FQP3P50_D-2314161.pdf )

I would like to ask how can I write the models for those three mosfets EG starting from the IRFP9240:


and the datasheet is here:
IRF9240 ( https://www.vishay.com/docs/91239/sihfp924.pdf )

I've found this page: https://people.ece.ubc.ca/robertor/Links_files/Files/ICCAP-2008-doc/icmdl/icmdl05a8.html
but didn't helped much.

Thanks in advance

Roberto

Thanks

Having been a big TPA3316D2 user and fan for over 2 years now, I am just starting to use the very low-cost TDA7492 amp boards available from China. I recently bought a pair from Aliexpress for about $8 ea shipping included. They arrived in a few weeks and I have since set them up, and even started modifying them in a way similar to the TPA3116D2 with regards to power rail caps and snubbers. I think this amp deserves its own thread to keep the 3116 thread on topic...



Datasheet here: http://www.st.com/web/en/catalog/sense_power/FM125/CL1503/SC983/PF214773

For the purposes of comparison of sound quality between the TPA3116D2 and the TDA7492's (both amps have same mods), I am using rather nice speakers that I just finished building - the ScanSpeak 10F/8424 & Dayton RS225-8 Ref Monitor shown here:



This is the current monitor's measured response and acoustic XO:



Group delay for this monitor (sealed Limkwitz transform bass) is +/- 2.5ms above 33Hz:



Here are the amps now connected to my miniDSP powering my ScanSpeak 10F/8424 & Dayton RS225-8 FAST reference speakers (http://www.diyaudio.com/forums/full-range/273524-10f-8424-rs225-8-fast-ref-monitor.html):



Having shown you the performance of the reference monitors, I can say that using these speakers, compared to the 3116, these amps sounded OK stock, but seemed a bit harsh and edgy on the top end, and lacked some forcefulness in the bass department. So I proceeded to add a pair of Panasonic OSCON 330uF 25V SEPF caps and a Panasonic 560uF 35V FM cap to the single stock 2200uF 25V cap that was there. I also added 330pF and 10R snubbers at the inputs of the inductors. With the mods in place, this amp sounds very very good! I think it has better high frequency resolution that the 3116, and the extra snubber smoothed out the harshness. The OSCON upgrade always helps - a lot better bass authority and the sound stage and imaging improved.



Here is how I added 330pF and 10R snubbers to the input side of the inductors, basically same location where the "bootstrap" snubbers would go on the 3116. Note that the TDA7492 does not have external bootstap caps.



I pulled the massive heatsink off of the board to reveal a Feixiang pcb - here is a high res layout photo. It looks like the Feixiang board pretty much follows the suggested circuit but as you can see from the photo, they added some stuff like a protection diode on Vcc, and a pair of small SMT by-pass caps after the electrolytics very close to the pins for the best noise suppression - a nice touch. Input and output filter caps are EPCOS films. The input caps have been upgraded from factory suggested 470nF to 1uF EPCOS film caps. The output filters seem to be using a compromise arrangement of 22uH and 220nF and 100nF film caps. Usually this would be with 33uH inductors. :



The amps run warmer than the 3116, but one of my amps runs hotter than the other and one of the inductors (far right) runs hot to the touch which is why I am looking at it closely to see what the problem is. It looks like the ferrite shield casing is chipped or cracked.

Here is the datasheet suggested schematic:



Here are the datasheet pinouts:



You can get these for circa $7 shipping included:
http://www.aliexpress.com/item/2015-Digital-Amplifier-AMP-Board-TDA7492-High-Power-Powerful-with-Radiator-Hot/32331617990.html

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For sail

HiEnd Power Amp with ready Holton modules

310W/8Ohms Holton with TOSHIBA Lateral MOSFET Output Stage amplifier dual mono

Two modules HPA-nxV500 VFED (HOLTON)

310 Watts RMS into 8 Ohms

550 Watts RMS into 4 Ohms

860 Watts RMS into 2 Ohms

Biased into Class A/B

Bandwidth 3.5Hz to 500KHz -3db

Dampening Factor 1300, 915, 248, @8 Ohms @100Hz, 1Khz, 10Khz

RCA Single ended Input impedance 20kΩ

XLR Balanced Input Impedance = 40kΩ

Single Ended Input Gain = 28.1dB

SNR -105dB

THD+N = 0.005% @ 10 watts 8 Ohms

Slew Rate = 90Volts / microSec



Power supply 220-240V with two 800VA toroidal transformers

60Ampers 200Volts Ultra-Fast Soft Recovery Diodes

50.200uF electrolytic capacitors in each channel (CORNELL DUBILIER, Illinois Capacitors, and SIEMENS).

Soft start system due to total 1600VA power.

Input Voltage 220 – 240 Volts

All assembly materials are the best in the market with Van Der Hull, Kimber cables, FURTECH XLR inputs,

MODU (Italy) enclosure with a 10mm aluminum front panel anodized in black color.

The amp is a monster of power with driveability the most power-hungry loudspeakers.

Dimensions: W450 L430 H190

Weight: 30 kg.



I send in all Europe countries (not in America, Asia, Australia due to very heavy parcel)

Price 1300€ plus 100€ transportation in Europe.
Tasos Architektonidis

demiurge30@yahoo.gr , Athens, GREECE

I have a couple of 10" AV123 subwoofers with replacement Dayton SPA250 plate amps. I'm using a miniDSP 2x4 for the subs only, crossed over at 48Hz Low Pass, LR2.

The Daytons are Class AB, rated for 155W@8Ω. Power seems to be sufficient, I've never heard them clip, but I'm wondering if I could get better sound quality by replacing them with an inexpensive stereo amp. The plate amps have a 12dB/octave infrasonic filter at 20Hz which cannot be bypassed. I don't need this filter, as I will continue to use the miniDSP. The plate amps' low pass filter also cannot be bypassed, only set at its highest frequency (180Hz LP, 24dB/octave). I assume these filters are adding some time delay? The subs are below and outside the monitors, and cannot be relocated or moved closer to the listening seat.

I would like your opinion on whether a base level pro amp like the Crown XLi 1500 (Class AB, 330W@8Ω) or similar would provide faster/tighter bass.