Greetings! My old 5.1 system is already 16 years old, and for the past ~5 years, I’ve been constantly repairing it at service centers.
Recently, the control panel (control pod?) broke again. And I guess it’s a time to let it go. But one thing I don't want letting go is the awesome Z-5500 subwoofer.

I recently purchased the Edifier MR4, and I’m really missing the bass that my 5.1 system (with a large subwoofer) provided. So, I want to pair my old but beloved subwoofer with my new budget monitors.


Question: If I purchase just this ☝️ adapter and connect my subwoofer directly to the motherboard (C-SUB) using it, will it work? Maybe someone already tested this adapter?
Edifier MR4, unfortunately, has NO subwoofer output.


Thanks!

Hi! 👋 I'm from Ukraine, and I'm here to find a solution. My English far from even being good, so I hope you guys can understand me.
I’m not technically skilled, but this forum seems like the kind of place where I can get help. Thanks!

Hello,
I will be modernizing old Yugoslavian radio called Iskra Savica SN120.
In the process I will remove all electronics and I need a suitable amplifier.
It has oval (10x15cm paper membrane) full range speaker -full range with high sensitivity.

Enclosure is not completly sealed, it has backplate with many holes, like radios did have back in the day.

Those radios (when working correctly) have really nice warm sound that somehow fills the whole house, it also has strong mids.
This is the sound that I would like to keep.

Here is the schematic of original amplifier and I'm thinking of building the same one, except for better power supply:


What do you think of it? Is this class A?
Do you see any room for improvements?

Edit: I had just realised that AC187K and AC188K output transistors are germanium... can I substitite them for something newer? Also should I substitute other transistors with something newer?

I know that this amp goes nice with the speaker, would you recommend different amp anyway?


This is not the exact speaker, but it's similar enough.





Thank you

Howdy from Grafton, Ontario. Been an audiophile for ages. Currently using AGD mono blocks, Reference 3a Grand Veena speakers, and a diy dac. The dac was my first attempt at a diy project. Thinking About delving into open baffle speakers now.

Hey guys. My name is Liv, i built a few aliexpress pcb amps and did a speaker table a few years ago. Im interested personally in all the new stuff and what we can diy, currently building in my head for now an amp with a dsp and checking datasheets for ic's.

Professionally me and a friend are self employed and doing mostly networking projects but somehow a project manager threw our way a pa system and we are stuck. I will make a thread once I am allowed to.

Thank you for approving my account, i've been lurking here for quite some time but its first time I actually want to post 🙂

Modifying Monitor Audio Bronze BX2 Speakers (2010-2015yr model).
Part 1 of 7

I completed this project in December 2020, & submitted a shorter version of this write up in July 2021 to the blog of the web shop that I purchased the capacitors, resistors, & inductors from.

Monitor Audio Bronze BX2 Speaker Upgrade | HIFICollective

The following writeup is a “reference page”, more in-depth & contains the parts list.

Disclaimer:-
I do not have any microphones or sound measuring equipment, so no charts/measured tests have been carried out. I am only going by what my hearing tells me. I am qualified in certain aspects of electrical design & have actual hands-on experience on various builds from PCs, Hi-fis, cars, houses, & at one time I worked for the local electricity company!

Intro:-
“To modify or replace”, that is the question I recently asked myself, regarding the Monitor Audio Bronze BX2 (2010-2015yr model) speakers that I purchased new back in 2013. These speakers were highly acclaimed when they came out, & still sounded good. However, being very picky, they suffered from bass boom/resonance via the cabinet, occasional sharp highs & a slightly muddy midrange, with the sound distinctly coming from two speakers & not a wide “soundstage”. This despite toeing them in, moving them away from the walls, bi-wiring them, & trying various other well-known mods & obscure tricks!

I did an extensive amount of research on the web, some info from this forum, some from the blogs on Hi-Fi Collective (especially the one by P.A. Coupe who is Reference Fidelity Components), the huge reference website of humblehomemadehifi.com, & a few others. I was also spurred on after watching videos posted by G.R. Research on YouTube, who analyse numerous main brand speakers with the proper test equipment, then upgrade the crossovers etc. & then retest them. Many times, the expensive speakers have cheap crossover parts, & cheap speakers after modification, can produce better results than the expensive speakers in unmodified format! Many of the modifications I carried out are well known & essential for any decent speaker build/modification. However, some are less well known & others I deviated away from convention!

Some of the design considerations:-

1. Keep the crossovers the same design, as I wanted to verify that improving the quality of components, without changing values or crossover design/type, would alter the sound for the better, hopefully! Also, I do not have a calibrated stand microphone & suitable measuring software. This being the best way to fine tune crossover component values using actual sound measurements from the drivers.
2. No more than £20 to be spent on any single capacitor, resistor, or inductor.
3. Make the internal cables easily removable from the board & back panel connectors, as per the original crossover.
4. Reduce extraneous metal from the signal path where possible, especially from the binding posts!
5. Internal cables & inductor wire gauges to be equal to or thicker than the component leads, with the LF inductor being thicker wire gauge than the HF inductor.
6. Remove other traits from the components, i.e., inductors to have low resistance, resistors to have low inductance, capacitors to have low ESR.
7. Tighter component value tolerances, i.e., 1% or 3% at most, instead of 5% or 10%.
8. All electrical contacts to be non-magnetic (to reduce other “influences”), brass or oxygen free copper, & gold plated, if possible.
9. Solder used to be lead free silver solder (tin/silver/copper by Shenmao).
10. All fixings to be non-magnetic, & stainless steel, to reduce other “influences”.
11. Reinforce, deaden & remove resonances from cabinets.
12. Make the modifications look “factory” or better than “factory”.

I'm curious about recommended alternatives to wool felt damping for a center channel.
Locally, there is a suppier of 1/2" thick F-13 wool felt, but the minimum order is for several yards at $150/yard, so I'm researching alternatives. Here's what I've located, but I'm not sure how the various materials compare and which would satisfy the needs of the enclosure:

• 1/2" F-26 wool Felt - very reasonable at $28.50 for 12"x72"
• 1/2" F-15 wool Felt - $50.50 for 12x72"
• 1/2" felt rug pad - $42.36 for 12"x72' (includes shipping) 100% recycled felt made from new unused carpet fibers and yarn
• 9mm recycled PET Felt - $35 per 24"x24"
• 1/2" 60% recycled polyester panel - $65 for 24"x48' (includes shipping) spec sheet/product data
  • perhaps this is an option to cover the wall behind my TV?

Very interested in your input. Thank you!

Hi this Mosfet is very pricy , just wondering if it could be used as direct replacement for irfp240 or irfp140 in the
First watt f6 or f5m clones. And does the extra price translate to better quality sound or not???

I stumbled on this photo of our cat enjoying audio...sort of...and thought I'd post it. If you have a photo, post it. I'd love to see it. Mama Katz resting among RCA and speaker cables I'd put aside while we rearranged the living room for the Christmas tree.

Design by Pete Millett, more info can be found here: http://www.pmillett.com/r120_se_amp.html

Lovely sounding tube amp with the hard to find R120 tubes as power tubes, driven by an EF36 pentode (with screen voltage regulated by a VR tube) and a cathode follower
This gets you a nice 4,5W into 8 ohms.

The IDHT R120 has been called the European 2A3, and has been one of the favourites of Jean Hiraga, it has also reached cult status in Japan. So few tubes are left in these parts, especially measuring NOS and being matched, like these pairs.

Parts are all chosen to be as exact to the original design, so Kiwame resistors, Elna Silmic II capacitors, Mills cathode resistors and custom Martin Mug output transformers
Power supply is a 5u4gb rectifier, followed by a common CLC supply and each channel is decoupled by an additional LC, driver stage has an additional RC rail.

The power transformer has a PCB designed by Pete Millett to easily switch line voltage, so 100-110-120-200-220 and 240V are all available!

SOLD

Hi y'all! In working on a 15kw vttc which is essentially a class E. Normally these use a silicon diode on the input but I wanna go full old fashioned and use a mercury rectifier. I have two 1.25a 10kv 872a that I can use. While I fully understand the danger I don't know the most about electrical characteristics. Mostly I wanna know is how well to they handle overloaded RMS current and if I can put two in parallel? I know they don't like high peak but I think for short periods and reduced lifespan I can over current. If I put two in parrales i am concerned just one will fire and drop the voltage to where the other will not

Good day, just another newbie with a project in mind...

This is a 3 way crossover:

The biggest issue is that the two smaller coils dont have a label so i dont know the value.
I have drawn the circuit here:

is there a software or webpage that can put this circuit in, and it will tell me the corresponding frequencies? i will have to put in guess values for L1 and L2. maybe L2=1.5mH and L1 = 0.8mH?

the midrange is a tang band titanium wide bander. right now the tweeter is crossed over very low. i estimate somewhere in low 2k based on listening. i want to push it way way higher so that i am mostly listening to the wide bander and the tweeter kicks in much much higher. i also need to bring the tweeter level down 3 to 5 db. i am assuming that will be done by increasing that resistor value from 3 ohm. i know what an L pad is, but in here i only see one resistor for thre entire network. i could add additional resistors if needed. I have those fancy dayton audio 20Watt 1% resistors in 10ohm, 5.6 ohm and 2.3 ohms.

For the woofer i need to figure out what is the cut off currently. i am planning to use the

Dayton Audio DS175-8 6-1/2" Designer Series Woofer Speaker​

the orignal woofer says on it: BC143G. i thought its some B&C. but i cant find anything about it.

Good day gentlemen, i plan to build a sub for my saloon set up. Already have a pair of three way towers with 10" woofers that goes around 40Hz deep, but as you all know every extra Hz down there is wellcome. I have a mint condition KENWOOD KFC-W2510 laying around, crossover and more than enough amp. I've been countless hours playing with WINISD, and researching, but i cannot decide the basics of the build. My goal is to get some extra low end from 40 Hz down. HOW LOW DO YOU THINK I CAN GO WITH THIS DRIVER? any suggestion for the tunning frequency?

Hi Guys!
I have a new, unused, unassembled enclosure from Modushop: https://modushop.biz/site/index.php...t&product_id=977&search=pass&description=true

On top of that I have PCBs for Aleph J (plus transistor kit from diyaudiostore.com) and F5 PCBs.
Enclosure - 365EUR
Parts - take 20% off official price
I will post with UPS anywhere you want, based in Poland.

Looking to build some home made audio systems

Hi all
I have a project under progress which is a stand-up paddle board (SUP) conversion to a go-kart for the water with hopes for a 3 m per second cruise speed under human power using an electric transmission. The sup is being setup to wear four wheels with pneumatic tyre tubes for enhanced roll resistance. Traction is being applied via the rear wheels wearing bladed fins over the tubes in the way of tyre treads

I would like to turn the rear axle with a small BLDC motor geared very low. For power, I am wondering if it is feasible to run a larger BLDC with a foot crank and use that as a generator to get the voltage and current needed by the smaller motor

To start out, I have some RC aircraft and truck motors to try for the axle and ordering a discounted hoverboard to get a pair of hub motors out of it for the generator side. These are rated 250w each. These will run a small sprocket and driven from a bike crank. I am hoping to create enough power with this to run the RC truck motor well enough for 3 m per second cruise speed at an easy rhythm. A battery will also connect to the system for aux power against wind and such

May I please have some assistance on the electrics. I think I am good with hooking things up, but there are certain things that I am struggling with a bit. One is how to convert the output from the generator side to DC. I have 10x shotkeys rated 3A. Would I be able to use these? What would you guys recommend?

Thanks and regards
Randy

While investigating mods for one of the preamps mentioned in my onboard bass preamp thread, I googled "gyrator calculator" and all the ones I found give you the centre frequency and Q for given component values, which is fine if you want to analyze an existing circuit, but the opposite of what you need if you want to modify one or design your own, so I put together a little LTSpice simulation that calculates the components for you and lets you visualize how much you will deviate from the ideal response when you use standard values.

Background: one of the most commonly used circuit topologies for implementing a graphic EQ is shown e.g. in the 1980 National Semiconductor Audio & Radio Handbook (free download from TI), see "2.17 Octave Equalizers" on page 2-59 (page 68 of the PDF). Each pot wiper is grounded via an LCR series resonant circuit where, instead of using an expensive and bulky inductor, the inductance is "synthesized" with an active element (opamp or transistor), a capacitor and a couple of resistors, i.e. a gyrator. The reference above explains its operation in detail and provides the formulas to calculate the components for a given maximum boost/cut gain, centre frequency and Q value.

It also mentions that linear pots have very little effect around the centre position and a lot of effect very close to the extremes, so S-taper pots (aka W-taper) are recommended. I'll address this in a later post, showing how a reasonable response can be achieved with linear pots (plus some caveats).

The simulation has two similar circuits, one with the calculated components and one where you enter manually the closest standard values, that way you can plot both and see how well they match:



I've parametrized the pot position to show the maximum, centre and minimum positions as well as half-way between centre and extremes. I've assumed 20k W-taper pots, which happen to be the type used for the tone control of the often cloned Tubescreamer pedal, so they aren't as hard to find as other values. A couple of good sources I've used in the past and have had no complaints about are Tayda and Musikding. Based on the curve shown in Alpha's datasheet, those half-way positions would correspond roughly to 1k and 19k for a 20k pot, as shown.

So, to use the calculator, you simply edit the parameters at the top left, run the simulation, then enter the closest standard values to the calculated ones in the circuit on the right, run the simulation again, plot "calc" and "actual" to compare them, tweak as/if required. Some notes:

• The formulas have some approximations and the response you see for a single filter will change significantly as you add new ones. In particular, the max/min gain will decrease, so aim for a few dBs more than you need. In the 10-band example of the NS handbook they calculate for ~17 dB to get an actual maximum boost/cut of ~12 dB.
• R1 should be large, at least 68k or so to keep the approximations in the formulas acceptable.
• R3 will be the worst case load presented to the input buffer and eq opamps (the latter in parallel with the input impedance of the circuit you connect the EQ to). They use 3k, there are many decent opamps that will happily drive ~2k without too much THD. YMMV.
• To get the value of C2 closer to a standard one, you can tweak Q, which is generally not critical. Increase Q to decrease C2 and vice versa. This will also affect C1, but once you have C2 where you want it, you can tweak R1, which will affect C1 but not C2. Increase R1 to decrease C1 and vice versa.

The sim file is attached. As always, comments welcome!

Edit 7-Nov-2024: Sim file for version V2 (see post #10) attached.

Hello from France

Fan of music of (almost) any style for years. Now retired, it gives me more time to improve my HiFi equipment, enjoy it and also discover new artists (internet radios, often recent Blue Grass and Country…).

I use a first system in my living room/office (antique Naim Uniti mk1 and Tannoy Stirling) which is used for several hours each day.

A second system in the lounge « Full separate elements Accuphase » and Tannoy GRF which is mainly used for the few evening Opera or Classical concerts live on the FM radio "France Musique" and CDs.

My main interests in technical matters are : the adaptation of speakers to the room (positioning, passive and active processing), and improvment of FM radio reception, not so easy in my rural sector !

Does anyone know of a bridgeable or mono chip amp with the adau dsp chip in there? Something already in a chassis with power supply ideally. Its for a sealed sub i want to eq.

Hi all!

Been here for many years, not posting much, but reading a lot. I live in Sweden.

Have neen building speakers since ages, and was once part of Basslist.

This is my current build, which is kind of stationary 😅

I little bit about my self and my projects.
HI-FI enthusiast, electric guitar player, CAD/CAM engineer CNC programmer/operator by profession, electronics / Raspberry PI / Python programmer hobbyist.
HI-FI NAIM Pre/Power amplifiers/DAC B&W speakers
Sub-woofer (built from scratch including the MDF cabinet) comprising of...
Maplic GA28F MOS-FET (kit)
QK80B low pass filter
Power supply (from an old Denford CNC Milling machine) with 2 x 1 Farad capacitors.
VOLT speaker driver

Hi,

I am trying add gain at the OPA541 op amp output stage of a hybrid circuit, Broskie’s Super Triode. (More Super-Triode Amplifiers)

Mr. Broskie mentions that he uses 1M resistors for the OPA541 at - feedback and + to ground to keep the dc offset “extra low”. There's no input resistor. I’ve never seen an op amp used in unity gain arranged in this manner.

This is where I get confused. I'm used to simple inverting op amp circuits, with input and feedback resistors.

With this circuit, is NO input resistor needed for unity gain?

What’s the arithmetic for the gain in this circuit?

If I want the OPA541 generate some gain, (say 10x), would I use a 100k input resistor with the 1M feedback resistor?

Does anyone know a resource (webpage or section of a book) that can help me directly understand this use of an op amp to help me figure out adapting these circuits?

Thank you very much - ziffel

I have an Audio Innovations 300 first generation amplifier with good sound. I have always wanted to use it as a reference to make a clone, reduce its size, and make some other changes: the original 120R cathode resistor was shared, and I changed it to four independent 240R resistors. The preamplifier and ink cartridge amplifier are powered from B+to increase reliability. DC280V is powered by a voltage regulator, and the schematic diagram of the regulator is from ARC, using operational amplifiers as servo adjustments+ 280V is approximately 150MA of current. Four ECL86 PCL86 heaters are independently powered, making it convenient to replace different vacuum tubes, with a voltage of 6.3VOR13.V

Also, I would like to ask you a question: When adjusting the operating voltage of each testing point, do I refer to the actual voltage tested by the original amplifier, or to the voltage indicated on the original factory drawings? Because the actual test voltage of the original amplifier is different from the voltage on the drawing, it has caused me to have doubts.

Looking for the US magazine Audio, issue August 1989. More specific, who can please make a scan of the review of the preamplifier Sumo Athena by Bascom H. King (page 92 - 104). Could not find an archive of the magazine, that apparently stopped publishing in 2000.

As a side note, the issue also contains an article on the future of the lp.

Anyone?

I’m new to the site and live in Brisbane, Australia. I’m looking forward to interfacing with people with the same passion I have for music and gear.

Sold.

For sale this almost new pair of the new Tetoron 30mm domes. Small waveguide does the good thing to the overall performance and improves the integration with the midrange.
Not soldered, measured, played for ~100hr in total.

EU only.
140Eur for the pair.

Well it was available locally 🤷‍♂️

Needs a little attention ( The case for sure )

Hi.
I bought a used amp which is great in all aspects other than the popping on powe on and off.
I cleaned all the pots and switches etc.
Does anyone know of how to remedy this?
I read that the caps related to the switch may be at fault .
There is a small ceramic cap on the the small PCB that the power switch is mounted on.

I'm grateful for any advice form the really skilled people on this forum.

Hallo to all

Here is a new client build I will (hopefully) soon work on- Ellipticor-84 of Troels Gravesen.
http://www.troelsgravesen.dk/Ellipticor-84.htm

Those scan speak drivers are really High tech dream stuff, yet ultra expensive.... that being said I am dying to know what magic they can produce.
So, no judging! just enjoy the high end porn.

So, lets hope this thing get wings, I´ll keep updating


Here is the original build of Troels









and our different take, using brass and Acryl Glass.

Hello everyone.

I have a SR01 5V board built. The regulator is hand soldered by Per-Anders Sjöström, shop owner, this is the one I purchased HERE

I can post anywhere (at the buyers cost)

I have tried it and did not like the sound (which is why I puchased it to try). I was feeding an Allo USBridge with the 5V. It works perfectly, but in my system I preferred my old iFi device to the DIY experiment with this board.

Any offers?

Have a good Christmas

Rich

Hi all! A very nice person has given me his (deceased) father's bass amp. It's a Fender Rumble 100 v3. It works fine. However, I have read some suggested ways to improve the original Rumble, to increase clarity & clean headroom. I don't know if they apply to the V3, which (by contrast) has one speaker and no porting. So this might all be moot. The particular mods I'm considering are:
1) sealing all around the internal baffle with plumber's putty. Why plumber's putty? Seems messier than caulk or construction adhesive. FWIW: I haven't pulled the speaker or chassis, so I don't know if such a baffle is in there.
2) Seal the speaker frame to the mounting hole with plumber's putty. Doesn't all this airtight sealing prevent the cone from moving freely? The original Rumble apparently was ported, mine is not. And what if I later wish to replace the speaker after it's glued to the box? See #5 below.
3) line the speaker cavity with fiberglass insulation. I have some Corning 2" thick acoustic fiberglass batting. How does one adhere this to a cab interior? I've only previously used this insulation for studio wall/ceiling panels, where I wrapped muslin around the fiberglass and stapled the fabric to plywood.
4) replace electrolytic caps. The amp is about 10 years old, but still working. Why not wait until the caps blow?
5) replace the stock speaker. I'd rather try free/cheap improvements first. Or should this be the first thing to do?
Do 1-3 apply if the cab isn't ported? Any suggestions on a 12" speaker?
Thanks!

So I bought this sub a long time ago and it has failed again after being sent back to JL 4 years ago for a complete rebuild. Seems that the plate amp is pretty crappy. I tried replacing the caps that are usually the culprit but that didn't solve the problem, it doesn't power on anymore. At this point I don't feel like throwing more money to JL for another amp plate that will go bad ... since for the same money I can build another Martybox/18" Dayton UM-18.

Does anyone see any immediate problem with powering this via a Behringer NX Series amp? This sub was in my bedroom and is barely exercised like the theater UM-18 subs are, but I'd like to use it still as its a nice cabinet and the JL drivers are good.

Néère: Hahn, Duparc and Chausson​

Véronique Gens (soprano) & Susan Manoff (piano)
only one word fablous....
you can use this cd to test the human voice from your system

Hello. I'm a complete noob when it comes to DIY audio. I have handyman and web-based software skills. Looking to dive into DIY home theatre audio.

Hello,

I bought a used JVC car stereo to use for the computer audio. I currently use one of my Technics amplifers but thought I could use the JVC car stereo for the computer. Another plan, for the car stereo was to create a boom box with it, already have the JL audio speakers for it. If i went the boom box rout i would still need the aux functioning.

Currrently i run my Technics amp through the computer via 3.5mm to rca cable (home made and very good - no issues with it).

The JVC car stereo, was a good buy and unit looks in great condition and came with all the brackets, remote and wiring harness. I was able to power it, etc with a power adaptor, hook up the speakers. I got a cheap 3,5mm to 3.5mm cable - sound was quite slightly distorted and humming noise as in grounding. I put the Multimeter probe into the JVCs 3.5mm aux input to its chassis and i had no continuity.

The ground loop islolator i got, make things worse, it was not the most expensive nor the cheapest -- around 25$.

This is my thought i like to share, and whether or not its possible without harming the PC or JVC stereo. I would ground the earth of the plug to the chassis of the car stereo.

Another thing, could it be the power adaptor as it has a screw terminal and maybe its best i cut and solder the wire.

A while ago, I posted some data showing an increase in odd-order harmonic distortion caused by reticulated foam in the throat of a compression driver. Later, I discovered that this is a well-known effect of porous absorbers at high SPL.

Today, I decided to see if I could measure any nonlinearity caused by relatively thin polyester grille cloth in front of a woofer. I used a cardioid dynamic mic (it has lower distortion than my measurement mic at high SPL), so the frequency response is not terribly accurate and the overall SPL is incorrect (not a problem in this case). The woofer is an Eminence Deltalite II 2512 driven at approx. 6.3V RMS (~5W@8ohm; around 105dB mid band at 1 meter in half space). The mic was placed about 20° off axis and ~7.5cm (3") from the grille.

Here's the distortion with no grille cloth:


And with the grille cloth:


As with the foam, the repeatability of the measurements is good. I also measured a second woofer (same model) and got similar results. I doubt the effect shown is audible, but I was surprised by how significant it seems to be.

Hi. Looking for tube socket for 3A/110A, CV1664 tube, I think they are the UV4
I need two.
Thanks
SB

Crazy Austrian/German thread in hififorum.at :

Can Toole's preference criteria for a living room friendly loudspeaker be met
with this simple baffle and driver driver arrangement?

The proposed crossover frequency is below 500Hz:

Proposed driver arrangement for the mid and high frequency range:
https://www.hififorum.at/node/703371/page3#post703675

Simulated frequency response in the far field "on axis":
https://www.hififorum.at/node/703371#post703446

Placement of woofer and simulation of baffle step regarding woofer:
https://www.hififorum.at/node/703809?p=704449#post704449

Here is some discussion of a very similar driver configuration - using
only little smaller dimensions - regarding "off axis response",
"sound power" and "estimated inroom response" of said
midrange/highrange driver configuration.

Since i am the author of the posts linked and the driver configurations
proposed, i am here to help, if e.g. "DeepL" should not translate well ...

Dear friends
Did anyone tried the adapter from da20400 to pcm63 like in the added pictures

Thanks for any reply

God bless you all

First various URLs with images of the asked X2 capacitors:
https://www.technikundnatur.eu/revox-mehr/die-rifas.html
Mike's TRS-80 Pages
capacitor - Replacement cap (filter / choke) for oscilloscope power supply - Electrical Engineering Stack Exchange
Beware Rifa Class X Capacitors! - UK Vintage Radio Repair and Restoration Discussion Forum
https://www.eevblog.com/forum/chat/old-rifa-capacitors-and-a-disaster-story/
and
https://www.mikrocontroller.net/topic/170923
Why do these versions in particular fail so often (unfortunately often associated with very penetrating odors and very time-consuming cleaning of the environment - today happens on Linn's Brilliant SMPS) ?
Thank you for clarifying of this.

The complete set of PCB's i am offering for sale at £80.00, P&P extra, boards originally purchased from Elektor.

PREAMPLIFIER 2012 (110650-1) (LINE-IN/TONE/VOLUME BOARD)
PREAMPLIFIER 2012 (2) (110650-2)
PREAMPLIFIER 2012 INPUT BOARD (110650-3)
PREAMPLIFIER 2012 FRONT PANEL BOARD (110650-4V110)
PREAMPLIFIER 2012 POWER SUPPLY BOARD (110650-5V110)
PREAMPLIFIER 2012 LLLL BOARD (110650-6V120)

Bought this receiver as the amp for my keeping room home theater system sight unseen "...unable to test all functions." Well it was DOA and resetting was of no use. Read that the DTS chip was the usual culprit since the speaker matrix did not display on the front panel and the cure was to rework the chip. So I bought some liquid flux and I already had a hot air rework station (thank you AliExpress!) which I'd never used except to shrink tubing. So I applied the flux to the edges of that chip and with the unit off, but still plugged in, I applied heat at about 340C and all of a sudden it turned on by itself, the speaker matrix was displayed, and playing. However this was short-lived and I've done it a couple of times more with the same result (except it didn't turn on by itself) and if it's on but dead heating the chip edges would make it go live again. Do I need more temp on the air; do I need to bite the bullet and completely remove and resolder the chip? Anyone with some experience here or suggestions? Thanks!

I'm looking for a small meter that could be panel mounted or mounted outside a chassis to measure from 0 to 150 mV for setting the current on an output tube. Something more eloquent and permanent than a DMV 🙂

Milkduds

😉
I have got a NAD 302 from a friend. He has implicitly asked me to give this device a helping hand;-) I plugged it in and: I was shocked at HOW bad the sound of this device is - completely washed out, gray, flat, small, completely unclear, powerless, not a single tone but just a bunch of "phase errors" (thought I had connected an LS wrong - I haven't listened to Buy HiFi for many years;-) But it's not defective or anything, but this sound is a consequence of the construction: the unnecessarily many circuits and components and running paths! And this sound is exemplary for analog consumer hi-fi - by the way: the big pre-end combis sound even worse!
So here's a quick and easy guide to getting a few classes better: I first bridged the entire preamp junk: i.e. from the potentiometer to the power amplifiers. To avoid having to remove the circuit board, I simply disconnected the coupling capacitors C 301 (L) and C 302 (R), directly at the potentiometer, at the capacitor body and used the remaining stubs as solder sockets to connect a thin wire to each of the input capacitors C 401 (L) and C 402 (R). Because I can reach the underside of the circuit board at the output stage, I removed R 401 and R 402 and routed the cables through the circuit board and soldered them. I simply cut the PCB paths to these power stage inputs here too.
Any cable used here will sound much better than all the bridged junk.
How does it sound? Just do and listen;-)

This should also be done with all the other NADs;-)

Looking for a pair of these woofers.

Getting PCBs made has never been easier. Today there are dozens of PCB fabs which accept orders online. You simply upload your PCB design (in the CAD format called "Gerber files") to their website, specify quantity, color, yes/no gold, etc., and the website immediately gives you a price quote including shipping to your door. If you like their price and throughput time, you say "Yes", pay with PayPal or a credit card, and the fab builds your boards. It's simple and easy. Just like buying groceries online or purchasing stuff you don't actually need, from eBay or Wish.com or AliExpress or Amazon.

When I post a new audio project here to the diyAudio Forums, I include the PCB manufacturing Gerber files so that other members can have PCBs built if they wish. In this thread I'll be using the "PhaseDots tester" from 2015, as a running example. Gerbers for PhaseDots are also included below, if you want a small test-case to use in PCB ordering experiments.

An easy way to find PCB fabs who do online business, is to visit the website www.pcbshopper.com . It will give you price comparisons for quite a few different PCB fabs. One of those fabs is called JLCPCB.com and I have made a "walkthrough" of the ordering process at JLCPCB, attached below in .pdf format.

As you'll see in the Walkthru, ordering PCBs is just like ordering anything else online. You register at the seller's website, getting a username and password. Then you tell the seller what you want to buy (by uploading the Gerber zip archive), how many you want, what color you want, and so forth. The seller tells you how much it will cost and how long it will take. You type in your ship-to address, pay with a credit card (or PayPal), and that's all. The seller starts fulfilling your order and ships you the goods. Of course you can log in to the seller's website every now and again, to check on the progress of the job, and to get the package tracking number once the goods are shipped to your address. Just like all other e-commerce transactions in the year 2023.

There are too many screen capture images to attach in a single Forum posting, so I've collected everything together as a single .pdf document, with one screen capture image per page. I hope you enjoy the walkthru, and I'm confident you'll decide that PCB ordering is not mysterious, not difficult, and not frightening. It's just like buying other goods and services, online.

_

Hi Forum,
This thread is a description of my latest DIY speaker project I worked on during 14 months.

“Building the best 3-way full range speaker in the world”
This statement needs of course some clarification. The best speaker in the world does not exist. If there is something I have learned during this project is that a speaker project is all about compromises. Even if money is no object (and I had a serious budget), it is still all about compromises.
Size, width, depth, selection of units, selection of enclosure material, filter components, spikes, rubber feet, volume, closed or ported……. And so on.

A few years back I rebuild an Electro Voice Interface D speaker into a more modern version with the original drivers and a new filter and new enclosure. The end result was definitely a better version of the original. The enclosure was way more ridged and the filter components from a much higher quality than the original. This speaker was very impressive, live sounded live ….. at loud volumes. The set turned into a 5.1.4 Dolby Atmos system and for movies there was nothing better in my opinion. Dynamics were fantastic, and the AVR did some decent Audyssey room correction by equalizing the speakers.

So early last year (2017) I started to get less satisfied with this system. As good as it was for movies it didn’t tick the box for stereo anymore. At loud volumes it did okay, but it lacked resolution and I just never listened to stereo music anymore. I considered to buy a good equalizer but never found one that ticked all boxes.

Jumping 16 months forward I have listened to (stereo) music in the last months more than in the last 12 years (since I moved in my current home). I consider the below project my best speaker achievement. However, it was also the most difficult one.

Back to the project:
A friend asked me early last year if I could help him with a medium sized speaker and after a few discussions and checking out components I decided to replace my Interface D remake with something new. The criteria for me was building a decent sized front speaker. Full range (<30Hz – 25kHz). Powerful, high resolution by using the best components DIY builders can find and an enclosure that is very rigid, heavy and good looking.
We first built a prototype of the two way mid sized enclosure to test the selected components. This speaker would be my friends front speaker and for me it would serve as the surround speaker with built-in upfiring Atmos unit as the separate top unit I built for my previous system was visually less attractive.

The selected components:
Tweeter for all units is the great Scan Speak beryllium D2908/714000 unit. Influenced by Troels Gravesen as some other decisions I made.
The Mid/LF units are Audio Technology 18H521706 SDKA in a d’Appolito arrangement. We wanted some LF authority in the 2-way system so double the cone size helped here. And you would be amazed how well this worked. The 2-Way sounds awesome. To get a slightly easier load we ordered these units with an Re of 7,5 Ohms. This speaker has a friendly 4 Ohm load.
The woofers for the 3-way front speakers are the fantastic Audio Technology 10 C 77 25 10 KAP with a sandwich cone. These speakers were also ordered with an Re of 7,5 Ohm as I used 2 in parallel.

The 3-way has a vented LF enclosure tuned at 28Hz, but also the mid is vented. And the mids are so gorgeous, lush with warmth and resolution that I consider that as the best part of the speaker.
I also built a 3 way center speaker with the same components but added an Audio Technology 15H52 1206 SDKAM to get a better horizontal dispersion of two vertically placed units.

Some generic enclosure specifications:
MDF 25mm for most parts side panels, 31 (25 and 6) for the large speakers. 18mm for all bracing and dual layers for top and bottom.
The front panels are 3 layers of 13mm HDF (1100kg/m3) and 5 layers for the big speakers. Glued together under a 30-ton hydraulic press and 5 axis CNC machined to a golden ratio curve. These baffles are covered with a 1,4mm leatherette that visually works very well with the speaker units to an aesthetic unity.
As an extra layer and to make them even more appealing in our living room I covered the enclosure with massive 20mm solid walnut panels that have a slight angle at the front and back to make these panels a bit less solid from the front. They are finished in a natural Tung-Oil.
The front panel is connected to the rear panel with 10 pieces M8 stainless steel threaded rods to remove the last internal resonances by putting some tension on these rods.

One thing is sure for me: I am listening to more music than ever before. More music sounds better and it sounds great at really low volume levels as well. The speakers can go loud. And they go deep, very deep with authority, control, resolution and most important musicality. Old stuff recorded decades ago sound great, and also high resolution contemporary music as well.
I hope the below pictures say enough.

Hallo all,
I need some help plse. I'm servicing a Pioneer SA 940 stereo amp for a friend. Before I started I switched the amp on through a DBT. I have a 100W lamp in and it glows quite bright and does not go dim. I have tested the OP transistors and the drivers and all are fine. When I remove the heatsink with the OP transistors then the lamp flashes on the inrush current and goes dim which is good. But when I put the OP trannies back the lamp does not dim. I have reflowed a few dry joints on the +/- 15 V regulators. I did not had time to check the bias which I will do tomorrow. Should be between 6 and 20mV. Could it be that it is a NON switching amp that causes excessive current draw for DMT to glow bright ? I do not want to switch it on without the DBT.
Much appreciated
Jan

Dear all, again i am in this condition, i sold the old SA-8800 and bought a new one, and for the second time i have the same problem. I was not able to solve it the first time, hope someone this time can help me. The unit was quite noisy on inputs so i put it on the bench and saw some troubles of noise and spikes on power supply, then at about 15w power the negative part of the sine waveform start to clip if i add more power at about 20 w the protection shut it off. I was able to recap and change some transitors on the input section and power supply, now the power is steady, nice and clean and the pre do its job as it should. The problem left is the Power amplifier. I make all adjustments described in the manual succesfully. the only thing that i can find not in line with the scheme is the voltage on emitter of Q13 i have -26 volts instead of -46 i check q13 and q17 they are good, how can i test the zener d1 and d3? anyone can help debug this fault? thanks, i attach the Scheme

Hi all, I am seeking a set of schematics and/or service manual for a Stereo Voice 120A Amplifier Receiver. This beastie is hybrid of tubes and solid state.

I've seen other chatter around the web that the unit may be a re-branded Kenwood or a Sansui chassis, but there are no markings inside, rear or bottom of the unit to indicate such.

Thanks in advance.

I’m building a stereo amplifier with 2 x KT150 in Push-Pull. One channel is finished and working properly. The second channel is almost done, but starts oscillating loudly at approx. 1.5 kHz..

I’m working on this problem now for more than a month. When testing I have to use hearing protection, as it oscillates really loud. I tested and tried a lot and I’m about to give up on this. It seems I have created a very stable and very reliable oscillator ☹.

The diagram is actually very simple, see attachment. The driver stage (not shown in the diagram) is disconnected and not powered to make sure it’s not the cause of the oscillation.

Normally the B+ is around 560 Volt and bias voltage is coming from an automated bias board. Due to the oscillations I’m testing now with a variable B+ (0 - 600 VDC) and a fixed negative voltage of 53 VDC. I’m using separate lab supplies for these test runs. This excludes the amplifier’s B+ and bias supply as a source for the oscillation.

Some comments / remarks:

- oscillation happens only with a speaker connected, NOT with a dummy load connected. I tested with several speakers and all speakers cause this oscillation.

- oscillation happens in UL mode and in TRIODE mode (G2 to plate, with 1K still in place).

- oscillation does NOT happens in PENTODE mode (still with 1K in place for G2). I can go all the way to 600 Volt without oscillations.

- I checked over and over that the screen, cathodes, grids and plates are not cross-wired between the two tubes. They are NOT.

- I checked the OPT using a 1 kHz. signal on the 4 Ohm tap, measuring the amplitude and phase on the primary windings of the transformer. The phase measures OK for each side / tube and the amplitude on the UL tap is lower than on the plate tap. See image attached. All measurements are according to the label on the transformer (see attachment). I checked the other channel’s transformer as well, and the results are similar / identical.

- On the attached recording I start with a voltage of 390 Volt and go slowly to 410 Volt, back to 390 Volt and again to 410 Volt. Oscillation starts around 395 Volt. This is with UL mode. Of course the voltage causing the oscillation is depending on the bias voltage. And with TRIODE mode it’s different again (but it will definitely oscillate with a certain B+). On the spectrum analyser’s screenshot you can see the oscillation’s frequency and harmonics.

- The oscillation frequency is somewhat depending on the output transformer’s load. With a 4 Ohm speaker it’s around 1.5 kHz. With an 8 Ohm speaker (B&W) the oscillation’s frequency rises to around 2 kHz.

- The speakers are NOT near the output transformers. With 5 meter distance the oscillation remains the same. Shielding the transformer or changing the speaker’s direction does not make any difference. Using alternative temporary wiring to the speaker makes no difference.

- carefully moving or touching the wiring in the amplifier and to/from the amplifier has no effect.

- changing tubes from the left channel to the right channel has no effect.

- careful matching of the KT150 tubes does not make any difference.

- lowering the G1 resistors from 100K to 50K makes no difference.

- placing a temporary (grounded) shielding between the two KT150 tubes makes no difference.

- I checked multiple times with and without measuring equipment (scope, wattmeter, soundcard, voltmeter, etc.) attached. Again this makes no difference.

- I tried grounding one of the output transformer’s wires to ground. Grounding / not grounding one end of the output winding makes no difference.


What can cause these oscillations? What else can I try?

Regards, Gerrit

Edit: Zip-file with .m4a audio file added.

Anyone has tested/DIYed/modified following boards ? I would change to original IC and probably capacitors too. But would like to know if layout is bad/ok/good/well made. There is concern about TDA ICs failing. Does this board have proper design criteria to keep ICs safe ? or can be modded/thiel network added or other things so as IC is protected ?


or



thanks and regards.

Picture: Login to view embedded media
According to my measuring the center to cater diameter is 2.25 inches or 56mm

Do you know what manufacturer model is this?

I'm looking for the Glass Audio 1/89 article by Joe Curcio about his Dynaco ST70 modification. I have a old photocopy that has faded over the years (yep 45 years ago). Can anyone help? I sold my Glass Audios years ago.

I'm in the process of finishing my cabinet, it looks like a brick because it's so square, lol. What can I do to give it a good finish? Varnish is out of the question because I used plywood and I think the wood is kind of ugly. I was thinking of wrapping it in black leather or something similar.I'm trying to get a finish similar to Marshall or Vox cabinets, you know?Does anyone have any ideas?

Hi Folks, I picked up a Nakamichi CDP 2E (same as 2A for European market), which is faulty. Chipset is CXA1082BQ (servo IC), CXD1135Q (DSP), CXD1088Q (digital filter), CXA1081M (RF Amp), NEC PD75108 (MPU). Sony KSS-152A and TDA1541A dac.

The online service manuals do not include the schematic, nor expected voltages/signals.

Symptoms

• Spindle spins (clockwise) from power on, irrespective of a CD loaded.
• Sled/feed motor spins towards the center from power on, irrespective of a CD loaded.
• Display is jibberish, some segments light up. If I press play, an additional segment lights up. 'disc' led is flashing. Responds normally to pressing repeat, mute.
• Laser comes up upon powering on, but given all of the above makes no attempt on focusing.
• Tray open/close is ok.

Analysis - performed at "power on but no CD loaded" state

• Spindle
  • transistors feeding the motor seem ok, fed by +/-11V and receiving a 3.3V signal from the servo IC (waveform + DC).
  • checked "MON" (motor ON) signal between Servo IC and DSP, there is some waveform with a peak at 1V. What is the expected value here?
  • This would point at something wrong with servo IC, or incorrect inputs into servo IC.
• Sled/feed motor
  • The leaf switch indicating max sled position is working fine.
  • According to the block diagram the sled is driven by a a different section of the servo IC. A fault in both sled and spindle suggests faulty servo IC?
• Servo IC
  • Input voltages are correct
  • "C864" (VCO frequency) pushes out a nice clean square wave, Makes me think the Servo IC is fine? (at least that part)
  • Next suspect if not the Servo IC: DSP IC
• Display problems
  • I cannot see how problems at either Servo IC or DSP would result in jibberish in the display, as this is driven from the MPU.
  • Suggest problems with the MPU?
• Clock (16MHz) - often the culprit in case of erratic problems
  • Arrives in good shape in the Digital Filter IC
  • Not entirely sure how it is propagated further to the other chips
• Temperature with IR gun - none of the chips run particularly hot (servo at 30C, the rest at 23C after some minutes)

Hypotheses

1. Servo IC is faulty or incorrect input signals
2. DSP IC is fault or incorrect input signals
3. MPU is faulty or incorrect input signals

Servo and DSP are replaceable, MPU is not... still hoping for a dead cap somewhere though.

Any ideas on where to look further?

I have been an audio enthusiast for years. I have built speakers and have used the program Boxplot for test and tuning. I even had to replace many speaker surrounds do to age. My recent quest has to do with a subwoofer I built. I purchased a panel amp a number of years ago. It is a class AB. I want to stop the start-up speaker pop and that is why I am here. I'm wondering if someone may recognize the model. Thank you. Gary

Hello hello, engineer and producer here, but really excited to start building speakers, specifically PA. I am wondering if I should start a little smaller before jumping into the deep end with a pair of synergy horns 🤣

Thanks for having me 🙂

My name is Richard, and I’m a cloud solutions engineer based in California. I’m also passionate about DIY audio projects and currently looking to build an amplifier on my own.

eBay item number:135340971326

“Used and functional, seem to measured accurately.”
Brand Sencore Model LC75 Capacitors and Inductor Analyzer.
Power up and seems to work, measuring the 25uF in the photo.
The test leads is not original to the unit.
Pull out chart for instructions how to use look excellent.
Asking $400 for DiyAudio member, or best offer.
Sold as-is due to age, and no way to confirm all functions and accuracy of the unit.
Buyer paying for shipping and insurance

I was looking at an old article/schematic and noticed it had fuses connected to the output cathodes. I don't think I've seen that generally done - is it because fuses are too non-linear compared to a low value resistor? I like the idea of an easily replaced part if a tube goes south.

I calculated a simple R-L-C filter for correcting the sin(x)/x function droop that is present in zero-order-hold NOS DAC. It can be used with the common inverting operational amplifier topology. See the attached picture and Excel file.
Comments welcome.

I got my hands on a behringer ep 2000 which has a short on all transistors of one channel, every leg of them. Fuse on the rectifier for that channel dies instantly.
What can i start diagnosing? Why would everything be shorted to gnd? How is this possible?
Is it likely to burn 8 transistors all together?

In other threads i see that emitter resistors are mentioned often, in my case they seem fine and test the same as the ones on the working board.

I am going to buy a bunch of fuses to test the rectifier without connecting the amp pcb to it. Could a faulty rectifier damage transistors? Or is it likely something else like misuse or idk what.

Happy to provide pictures and schematics if needed

Thanks for the help.

I have been searching for the Thiele-Small data for the 605B, but with no luck so far.

I found:
http://alteclansingunofficial.nlenet.net/Thiele-Small.html

Which includes the 605A,
But how close are these?

Maybe someone measured their units?

Kia ora!

My name is Bruno and I am a software engineer, but I play with some Arduino projects from time to time. Now I want to work on some audio devices, I am pretty noob though. I hope you can help me.

Cheers!

Hello everyone!

FIRST OF ALL:
As some of you know I was originally planning on building a 3-way ScanSpeak, (mostly) Revelator active floor stander. This is the thread regarding that design:
https://www.diyaudio.com/forums/multi-way/322048-18w-12m-r3004-active-3-a.html

Long story short - that plan turned out to be destined to fail.
Some of you also stated in that thread that it wouldn’t be good use of the 18W’s. I am glad you did because it made me do thorough testing which I otherwise wouldn’t have done. So, thanks to all of you who helped with that design, sorry it didn’t go anywhere. I hope you guys will also help me with this new design. I have learned a lot from what you said in the old thread and this is what the new design is based on.


I am still gunning for a small 3-way floor stander in the sub-30L size. I am still using the new Hypex FA123 to make them active. I have now used one of these modules for the testing done on the previous design and they are amazing!. I really like them.
I am still using my ScanSpeak R3004/662000 tweeters. To my ears they sound awesome and I was surprised how they measured in my old cabinets which aren’t exactly well designed with regards to diffraction – maybe I was lucky.
I decided to start all over with the remaining drivers to be able to choose ones that are better suited for my needs here and now. This sadly means selling my 18W’s -all 4, and my two new 12M (which btw. also sound very good to my ears!).
A lot of you guys recommended the SATORI line from SB’acoustics. (some used price as an argument I don’t see why, the price of a 18W is roughly the same as a 7” SATORI). I never heard these drivers, but considering where they are coming from and all the warm words, I have decided to try them (they are also much less demanding with regards to cabinet size. So far I am going for the SATORI MW19P-4. Now I will be using it as my lower midrange/upper bass driver. My simulations show that the 4 Ohm will be happy (Qtc of 0,620) in 13,4L. In such a sealed cabinet they should have a natural roll off with a F3 between 80 and 90Hz. The 8 ohm version would be able to go a little deeper, but would have a Qtc of 0,71. Not exactly sure which would be better for this build.
I have read that my tweeter should be able to perform well to 1700Hz, covering most of the area we are most sensitive too. This means that the larger driver will not harm midrange dispersion.
Then I have also learned that there is no substitute for membrane area in the deep. Soo I have decided to go hunting for a 10” dedicated Subwoofer driver to handle the lowest frequencies. The 10” means that the driver will have to be side mounted. As far as I have read this means, I should cross to this woofer at 80Hz or below. This suits well with the natural roll off of the 7” SATORI. So I guess this design will mostly be a small 2-way with a build in Subwoofer. I have been looking at a couple of different 10” drivers, mostly:
Vifa NE265W – 4 and 8 ohm version
SB-Acoustic SW26DBAC76 – Both 4, 8 ohm and dual voice coil verison.

So far I have chosen the NE265W in the 4 ohm version. This driver should achieve a Qtc of 0,713 in only 15,7L !! :O It also have a sensitivity and power handling better suited for my FA123 than the SB driver. At 100W one of these Vifa drivers should deliver 95dB (1m) at 30 HZ! And if I compare with the single 18W I made some tests with then this driver has a little more than twice the membrane area and 40% more travel at 100W. The numbers say it will perform better than 2 18W in less volume than one 18W would need!. I am very excited over this driver! …. At least it’s numbers.

My new design can be seen on the first four pictures.
Another new thing is that the design is actually just a 2-Way active bookshelf with an extra Sub output, which is then stacked on top of a passive Subwoofer. The fifth picture show what the 2-Way would look like alone (with a different front and rear plate and side covers of course). The sixth picture show what the Subwoofer would look like without the 2-Way on top.

This will give me some flexibility for the future. I can rebuild the Sub without having to redo the whole thing and Vice-Versa.

Hello everyone!

I have a DHT (841) with filament bias , 0V on the grid. (3.5ma/300V anode)

If I want some A2 action using a mosfet source follower (DN2540N5-G), can I directly couple (no capacitor) the gate of the mosfet to my input (0V) , and still have the source at 0 volts?

Thanks🤙

Took the wife to dinner tonight to Parachute HiFi. New place they opened up here in Chicago about 10 minutes away from our place.

I guess this guy's other restaurant is a 3 star Michelin joint. Prices weren't too bad.

It seems he likes hifi. Specifically this Adire brand. There was some smaller stuff on the back wall. A lot of those was that same brand. Only these two big ones were playing of course. They hit pretty low. Rolloff seems to be around 38 Hz. The highs were quite crisp. I assume there's a compression driver behind those interesting looking horns. Midbass was oddly not so great.

The Mcintosh units there are way out of my price range so I know little about those.

Decent vinyl collection here as well.

Anyways, was pretty interesting so I thought I'd share it. You can check out the pictures for yourself.

Opening new thread , to make things easier to follow and comment .

Everything started with collective brainstorming in Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans thread , and resulting prototype posted in #618 , Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans

Tnx to all Greedy Boyz involved ........

as I wrote , SissySIT ( in fist time called SUFI-SIT , but then I realized that too much seriousness is ..... too serious 🙂 ) is practically THF51-S Tokin SIT nested in Babelfish M25 circuit (even pcb) , with necessary change in some parts values .

so , schm and last/final pcb iteration are these :

(observe that I finally decided to match my pcbs to DiyAudio UMS ...... taking in account Jason's and 6L6's stance - better keeping things less complicated , than asking for few more taps in existing UMS..... so , besides SissySIT being Sissy , ZM is Mighty Sissy , doing things to save Greedy Boyz from some drilling/tapping efforts)

This subject started in another thread

Super Regulator, collecting the facts

but it seems a discussion on its own, so I moved it here. The idea is to build a low noise amplifier with 60dB (1000x) to use it as for noise measurements. Initially I built the circuit from the Linear Technology application note 83

http://cds.linear.com/docs/Application Note/an83f.pdf

but I wanted something with even lower noise so I put together a simple discrete circuit using paralleled jfets (2sk170v). However, I used no feedback so setting the gain to 60dB with low tolerance is something that relies on a very good AC voltmeter. Jan recommended using feedback to be able to calculate and implement the gain accurately. What comes next has been moved from the other thread.



This is what I built 🙁

The subtler issues escape me, as you can see.

Hi all,

I have a Yamaha P-2200 amp that's VU meters jump to, and remain at 100% when powered on.

The VU meters were working find before taking it in for a service, and to have the power supply changed from 100v to 240v.

After I received it back, the VU meters jump straight to 100%, and remain at 100% until powered off..

Any ideas on how to resolve would be appreciated!

Audio Innovations 500 output transformer - Solved

Hi folks,

Hope that someone can poke me in the right direction - how to go about output transformer (replacement or rewind?).

My AI 500 is currently out of service, this is the model with 4 & 8 ohm taps - the 47R 11W (the one just after rectifier, between those two 220uF/400V caps) went up in smoke & fire. It literally burnt.
I naively thought (to be more exact i hoped) that this was down to its age/deterioration so bought some 10W47R from Maplin, soldered it in, switched it on, a pop in speakers and dead silence followed. No hum or anything, just pure Sound of Silence 🙄

To cut the story short - apparently left channel output transformer primary & secondary windings are shortcircuited, DMM shows 12 ohms between yellow wire (i assume B+ wire on in schematics) and any wire on the secondary side (blue, red or green)
It also seem to be circuit-open between yellow & green or blue on primary side.

The following are the readings should someone benefit from it or eventually advise if those are normal (sensible) values):
(-the color of wires matches schematics)

Left channel:
B+, green = 0 Ohm
B+, blue = 0 Ohm
B+ violet = 22.9 Ohm
B+,black = 55 Ohm
green, blue = 26.5 Ohm

Right channel:
B+, green = 20.1 Ohm
B+, blue = 46.7 Ohm
B+, violet = 22.5 Ohm
B+, black = 54.9 Ohm
green, blue = 26.1 Ohm

The broken transformer has resistance of 12 Ohm between B+ and minus/earth (blue wire on secondary winding)

The good one shows resistance of the values 0.550 MOhm between B+ and minus/earth (blue wire on secondary winding) although this number likes to go up to 0.8 - it actually fluctuates.

Can someone please advise:

1.) buying a replacement - where from?
2.) rewinding - where/what company does this & what
are the parameters/specification of this transformer or where to get these from?
3.)buying second hand if anyone happens to have one 😛

In case of buying a replacement, would it not be a better idea to replace also the working output transformer so that those two are similar in parameters?


No idea why this all happened but could it be that i had Xduoo x3 hooked to it via AUX therefore simply overloaded it?
By the way, when listening to the vynils - I could turn the volume pot to max and it would be loud.
When listening to CD, anything over 90 degree knob - the music was way too loud.

The rest of the components inside seem to be fine, no strange looking colors or burns, can supply photo if anyone needs it.
Also i believe that it is all still original components inside.

So i hope that there is a solution to my current misery 🙂
I can imagine this may to be quite costly repair,hope that it will turn to be some reasonable price.

Thanks for reading & help.

Hi,

I am going to design enclosure with vent for my speaker system with vituixCAD2 and I am sure that the software version is the same as my college's.
We attached the same parameters of drivers, vent and enclosure, but our result is different.
Did someone also have this problem?

Thanks,

In @perrymarshall's thread about his open baffle/bass reflex hybrid I accidentally hijacked it a bit, with Perry suggesting I consider his Cottonwood Live Edge Beryllium design with the drivers raised.

Funds are a little tight right now so I decided to attempt the build but with less expensive tweeters. I don't really know what I'm doing here yet, so thoughts are welcome!

Here's what I've cobbled together thus far:

• a used miniDSP Flex 8 and Umik-1 microphone
• a pair of SB 15OB350 woofers
• a pair of SB26CDC tweeters, and working on getting a pair of 8" oval somasonus waveguides. I couldn't swing the TW29BWGN, but that or the TX could be future upgrades.
• a pair of the PRV WG175PH horn tweeters Perry's used for multiple designs, for the back side of the baffle
• passives to equal to the Live Edge Beryllium Cottonwood design (47 uf film caps for the front tweeter, exact cap and resistor values for the rear tweeter)
• a 5-channel amp stolen from my HT system, to be replaced with Eric A's 2x150W amp modules in the near future
• free 1.75" thick used doors to chop into test baffles. First thought is 15" woofer at 24" off the floor, slightly tapered toward the tweeter at the top, triangular wings for the woofer zone.

I'm not expecting this to be my end game forever system, but rather, a fun learning platform that hopefully sounds great as well. Over time I might add a mid-woofer and push the woofer to the floor, or try other things.

Now that I have the raw materials on hand I'm a bit lost on how to start getting this set up in the Flex 8.

Anything you could suggest to get me in the ballpark would be deeply appreciated!

Time to start this long over due thread
I just need to find one now 😛
Maybe the posters in the DH-200/220 Mod thread can use this thread instead for these models 😀
We are working on adapting the DH-220C design for use in DH-500 & P500 chassis
There are some new OPS boards in trial for those heatsinks.

Hi All,

I'm picking up an old project. The previous owner stripped all the drivers from these horns, so I've been slowly regathering all the parts necessary to complete it.

The horn originally had an TAD 2001 installed on it, but a decade or so later, claimed these were NLA and told techs to replace with Celestion CDX1730. These two drivers have a different exit angles. 2001 has a reported angle of 8 degrees, where the CDX1730 has a 20.16 degree angle. How different will the end result be? Common sense is telling me just to go with the 1730, but I do prefer the BMS 4550 in general, or something newer from the 18Sound catalog. All of which have a lower angle than 20 degrees. The horn crosses at around 1.2K.

Just stick to the 1730? The TAD isn't an option for me as the price of them, even used and blown have gone stratispheric on the used market.

As the title suggests, I am a newbie regarding audio amplification design. Although I am soon to graduate with an electrical engineering degree, to say that amplification was skimmed over during one of my many courses is an under-statment. I'd ultimately like to be able to purchase broken vintage or current amplifiers from people, fix them up, and resell them while also getting to experience a wide range of audio performance through benchmarking. My biggest issue is... where the heck do I start? from different amplifier classes to different era's of design, im finding my self being rather overwhelmed. If anyone has tips, resources, or good places to start by all means throw them my way. Thanks a ton!

Edit: regarding workbench, I own a Siglent SDS1202X-E 200mhz 2-channel digital osciloscope, a cheap 40 dollar smart voltage source with current control, an anti-static mat, and a decent soldering iron (which I can use with self proclaimed skill).