Hello all,

Here is a quartet (x4) of NOS, vintage, Mustard caps 0.15uF 400V 10%

All are brand new, from the same batch and individually tested

I'm thinking USD 30 plus postage or open to offers

Cheers, Ralph



https://audiofile.net.au/

Hi

Not sure if you follow along with DIYAudio/BAF but this presentation may be of some interest to you.
Tom's one smart dude with lots of experience. He was kind enought to post his slide set for us to view. Mark J. has posted his too on his free matching jig pcb.
Tom has taken a jelly bean part like the LM3886 and turns it into a number of hi-performance amplifier designs and other audio designs.
Ever wonder why a lot of smart EE's circuit designers never discuss sound quality of their designs?
They let the instrumnets and others speak for them.
Folks ask me how our designs sound? I always say "good", or they would not be evaluating it in the first place.
I want to hear what you have to say.
Nelson Pass says "its entertainment not dialysis"
Some even get a chuckle out of Burr-Brown tagging their audio IC's as "sounds plus" 🙂
It's the marketing and sales that put their spin on it.
posts #655
#669 for the utube links
Enjoy your enlightenment if you are able to comprehend some of the finer details of circuit design and analysis.

Hello,

A few time ago I made a 40w Push-Pull amplifier with EL34 tubes, based on this description by Claus Byrith. : EL34 Push-Pull

The sound is nice, no any hum on 91db speakers. Last week I did some measurments:
Square wave at 100hz/1khz/10khz:






The frequency respponse is also good: the -3db is at 4Hz and 50kHz.


But what I don't really like is the spectrum:




As you see the distorsion factor is good but the spikes around 1khz base frequency at 700, 800, 900, 1100, 1200,1300 hz is prety high. Is about -60dB the highest.
After some research I found the problem is comming from the power supply which has about 7V pp 100Hz ripple at B+ for EL34 plate+G2. For the phase inverter and input tube the ripple is almost 0,
If I tried to change the filter capacitors from 220uF to 470uF the ripple became aprox. 3.5V pp and the spikes on spectrum lovered to -67db. Still visible.



Any comment about this? Is it acceptable or need more filter on power supply? Unfortunatelly I have no place for a choke because the design is ready.


Have a nice day!

Just getting started on my first build and these babies arrived today. Is this considered acceptable to you veteran builders?

Hi everybody,
I need some help to build diy speaker

My first question is if you have a diagram like this,
what frequency you will cut it for twitter-woofer?
And what the reason?

Curve is look the same and a question from me
Is that ok to cut it freq between 5500 - 6000 hz?





Just say thank you for your help before

Hi everyone, I'm trying to make a discrete 3-stages amp headphone amp, I've studied some EE courses but basically I'm a dumb student.
I made a simple differential input stage with 2SK170 in Multisim, with resistor on the source side to limit the gain, but I have no idea how to design a second stage to amplify the output signal from the drain of Q1 (the white line), basically I try to make a BJT common-emitter amplifier which is able to amplify the voltage with limited gain by setting the emitter side resistor, but when I change the resistance of R8 and R7, the amplitude of signal from the collector of Q3 only becomes even smaller, where did I get wrong?

Hello, I have just bought a used Fostex DMT-8VL and it has a dead Channel, I am trying to find some advice about what could be causing this?

I don't know anything about repairing multitrack recorders or mixers, I bought this item thinking I was buying a fully working digital multitrack but it turned out to have a few problems which I think after a closer look were caused by liquid at some point in its life, I noticed that all the faders were rough and giving inconsistent audio from the input channels, and channel 8 was giving no audio at all, I stripped the whole recorder down and gave it some TLC all the faders have been thoroughly cleaned channels 1 to 7 are perfect with consistent audio all the way up the faders and they slide nice and smoothly now, the only issue it still has is the silent Input Channel 8.

What I have tested so far
If I turn the levels to their limits I can just about hear the audio from input 8 but its very faint, if I switch the L/R-Mon switch to Monitor I can hear the audio signal coming in from the channel 8 jack and I can raise lower the volume and pan the signal left and right using the pots in the monitor section but the fader, eq and meters have no effect when in this mode so I suspect that the problem is after the Monitor section?

I used input 1 to send and record the audio signal to Input Channel 8 and the Channel 8 Led Meter responded to the signal and recorded the track but I can hear nothing on playback the fader does nothing to the signal yet the meter for track 8 is peaking away showing that there is a recording there?

The recorded output from track 8 cannot be heard from the stereo outputs but it can be heard loud and clear from the rear direct out for Channel 8 so I am assuming that the recorded track bypasses the channel 8 fader section altogether?.

So I am stuck without any schematics or previous knowledge on mixer repairs, I am hoping someone can put me on the right track so to speak?

Thanks in advance
Dale

I need one with dome intact but fried coil.

.

I am new here and I hope to get some information on my actual problem

hello everyone, I inherited from an old place two hybrid bass cabinets, cube type, without woofer, and I would like to understand which cones to mount.
I would like to simulate them, I downloaded horn resp and I really don't know where to start, please help me!
the measurements above are external including the 18mm wood, the ones below are internal measurements.. the cone magnet is outward
thanks!

Hello,
I made several headphone amp with quite high expectation. I have one I like, it is a single ended class A tube one, but it is a monster.

Solid state ones, I did built a few and also listened a few very famous and with good reputation.
Most solid states I just did not like. Like beta22 is extremely well detailed, but also makes me tired after 10-20min. I also tested tube amp which was not my taste, easy listening, but lacks details somewhat.

I was surprised to see the Sennheiser's HDV-820 use TPA6120's. In balanced config. I did built a normal 'inbalanced' one before and I kind of liked it, but it was very depending on the PSU, (I found most headphone amp does.), tried with batteries also, the best PSU was some scrapped Agilent 6627A, which is a monster too, but I just could not make a better PSU. That time I did not hear the "superreg's".

Now I checked the HDV-820 with my source and my headphone and I have to say I was surprised and liked it. I found it very detailing while it is still not made me tired. That is the balance what my normal, 2A3 PSE amp does and fills the room and this is eaxctly what I was looking for in headphone amps + some portability, at least less than 10kg.

So now, I want to bring the best out of the TPA6120A2, with superreg and with the old monster HP6627A. I've just ordered some PCB's, it is coming.

Do you guys know more of this chip? What voltage level is the best to use (for 300 Ohm headphones)? What feedback resistor? What else, to get the best out of it?

Thanks,
JG

Hello everyone,

I'm glad to be part of this great community. Recently, I've been working on a few interesting projects related to audio processing and microcontrollers. One of them involves combining an ESP32 as a DSP (digital signal processor) for real-time audio signal processing. It's a small but powerful project that combines different technologies such as the DIR9001 and the TDA1387.

I'm not here to push my project, but rather to share experiences and learn something new from all of you. If you have any questions or ideas, I'd be happy to discuss them!

Thanks for welcoming me to the community!

Hi everyone, my names Mark,

I work in a school and part of that is looking after all of the A/V equipment from classrooms to concerts. Everything is always breaking or tight budgets so I'm always looking to fix inhouse etc.

I also keep a little 60's Rosetti valve guitar amp running

(WIP)
Dear readers, happy to be corrected...

There is some confusion because the numbers were re-used over time (since the founding of the company)
And history, well, it depends on who you ask...

"Before day one
The foundation of Scan-Speak was laid in the 1960’s when Ragnar Lian, a Norwegian student at Århus Teknikum (Aarhus Engineering School) and Ejvind Skaaning, a local machinist and scooter dealer, joined up around a business called Quality Sound Research (QSR). QSR’s and Skaaning’s reputation led to a groundbreaking relationship with Scan-Dyna and Dynaco (founded by David Hafler). This ultimately led to a large quantity of speakers being ordered that became the famous Dynaco/Scan-Dyna A-25. Skaaning’s striving towards perfection drove him towards in-house driver development and manufacturing to be able to customize the drivers to exactly the needed specifications instead of accepting compromised solutions with off-the-shelf drivers from external manufacturers.

Kick-off
February 1st, 1970
Skaaning founded Scan-Speak with the purpose of manufacturing drivers for the Dynaco/Scan-Dyna loudspeakers. Ragnar Lian (ex-SEAS) and the Dane, Mogens Hvass, were hired to develop and start driver manufacturing at Scan-Speak, first for the A-25 and later for other loudspeakers. The business was successful and grew fast and by 1972 already had 40 employees.

Creating a product line
In addition to the 1½” D3806 tweeter and the 8” woofer that had already been designed to fit the Dynaco/Scan-Dyna A-25 speaker, the team of Skaaning, Lian, and Hvass developed a 4½” midrange, a 10” woofer, and the ¾” dome tweeter D2008 in the period of 1971 to 1974. Both tweeters- in slightly modified versions - continue in Scan-Speak’s current product range.




First things first
Let's start with the originals, now known as the "classics"

Scan-speak drivers start with letters for tweeters, or numbers.

First letter

D- Dome tweeter eg. D8404/5520
R- Ring radiator eg. R2904
H- Horn loaded eg. H2606
M- Midrange eg. 12M
F- Full range eg. 10F
W- Woofer eg. 25W
S- Shielded woofer eg. 15S
WU- Woofer Underhung eg. 18WU
WE- Woofer Ellipticor (elliptical voice coil and 6 neo slugs) eg. 38WE

First numbers- approximate diameter of voice coil in the case of the tweeters (in mm), or frame size for other drivers (in cm)

D2008- Dome tweeter, 20mm effective diaphragm diameter
D2905/9000- Dome tweeter, 29mm effective diaphragm diameter (voice coil 28mm)
D2904/7100- Dome tweeter, 29mm diameter dome, voice coil 26mm (large roll surround)
12, 13, 15, 18, 21, 25- eg. 12M- 12cm Midrange; 25W - 25 cm Woofer

Digits after first numbers: nominal impedance (ohms)
D2008 - Dome (tweeter), 20mm voice coil, nominal 8 impedance.
D2905 tweeter- Dome tweeter, 28mm voice coil, approx. 5 ohms
D2904/9700 - Dome tweeter, 4 ohms
18W/4545- 4 ohm
18W/8545- 8 ohm
18W/16545-16 ohm

/ numbers- variants
eg. D2008/8511: vented pole piece; 8512: +ferro fluid; 8513: +ferro fluid + foam on face plate
D2905/9000 (original)
D2905/9300: low resonance rear chamber
D2905/9500: + flush mounted screws ?others
D2905/9700: + copper cap
D2904/9800: + copper cap + aluminium dome
D2905/9900: + copper cap + larger 110mm faceplate, "waveguide front"
(the first product to be branded "Revelator")

But after the Revelator branding, new tweeters received different magnet systems:

2nd digit of variant: magnet technology
5- ferrite magnet
4- neo magnet
6- neo magnet
7- illuminator

D3004/6600- "Aircirc" magnet system with 6 neo magnets
R2904/7000- ring of neo magnets
18WU/8741- illuminator
18WE/8542- 5 small neo magnets in circular arrangement5

3rd digit- magnet size variants

3- eg. 18W/8535- 90 mm diameter magnet
4- 18W/8545 - 121 mm diameter magnet
but... 18W/8545, 21W-8555, 21W-8565 all have 121mm diameter ferrite magnets (?why)

10F/8414- 43mm magnet
10F/8424- 58mm magnet
18W/8531- 110 mm magnet

The last digit: cone material:
0- coated paper, ('standard' or sliced paper)
1- uncoated paper, ('standard' or sliced paper)
2- paper/nylon fibre
3- polypropylene
4- multilayer/weave- eg. coated fiberglass, Kevlar, or Phenomax
5- paper/carbon fibre
6- Kevlar
7- aluminium
9- foam filled sandwich paper

Tweeters:
2- textile dome
3- silk dome
4- beryllium
6- thin ply carbon diaphragm
8- aluminium dome

Letter suffix- Voice coil former/bobbin
Paper (original bobbin material), later Aluminium
G - Glass fibre
K - Kapton (polyimide)
T - Titanium

eg. 15W/8530K vs 15W/8530G

No digits- initial version eg. 25W/8561, 18W/8542
- Final digits- more variations!
00 - introduced around ?2002 eg. 18W/8545-00
01 - magnet variants eg. 15W/8530K00 vs 15W/8530K01 (smaller magnet)
05 - silver colour frame (woofer), or gold frame (tweeter) for automotive markets
06 - gold frame (woofer), or silver frame (tweeter) for automotive markets
10 - current release (~2019) eg. 18W/8542-10
12- ??? e.g. 18W/8545-12 (received by mistake when author ordered 18W/8545-00 (~2007)

Magnet technologies:
SD- Symmetric Drive, copper cap on pole piece of woofers (original patent 1972 by Ragner Lian); previously used by others e.g. Philips
SD-1- a.k.a R3- 3 copper Rings- more economical solution to above; patented 1993, just after SD patent has expired)
SD-2- copper caps on tweeters
SD-3- Illuminator neo underhung motor

Every so often there are some odd balls that make it more difficult to figure out what is going on. After all, people come and go from Scan-Speak and different designers try to keep with heritage, but also create something new and it breaks tradition.

Oh, and then there's "Discovery" line-up, which try to follow the old naming conventions, but because they had previous lives as Vifa or Peerless units, they do not follow conventions eg. D2608/913000 was previously Peerless "High Definition Sound" tweeter, model 810921

I built a preamp based on the circuit of the Matisse Fantasy 2 years ago. While the preamp sounds amazing, it had a soft buzz coming out from the mid high and I am able to trace it down to the Khozmo 64 steps ladder attenuator. For some reason, the body is not able to properly grounded even installed to the front plate of the amp which is aluminium. The front part of the thread and nut just won’t do. So I attached a wire and ground it from one of the screw at the back of the body(please see the third picture, the black wire). But this connection doesn’t always work. Sometimes the buzz comes back out again and I have to readjust this screw or jiggle it then the buzz will go away again and it’s dead silent. Can anyone tell me what can I do to make this buzz go away permanently or someone using this same attenuator knows a method of properly ground this attenuator? Different than their earlier product, this one does not have the ground nut nor the ground spot marking. Many thanks in advance.

Greetings, Friends. Hope the turkey was good. I was looking at schematics over at DiyAudioProjects.com and found Bruce Heran's DIY ECC802S (12AU7 / ECC82) Tube SRPP Preamp with a nicely drawn Power Supply schematic with an interesting detail I've been missing:



Where the Earth wire is clearly connected directly to the chassis for safety, the b+ ground is connected to the chassis through a resistor/capacitor in parallel, a 0.1uF Type X2 cap designed for this purpose and a 150R 1/2W Metal Film Resistor. In a linked text, Heran goes on to elaborate on his grounding scheme and directs the reader to connect both the power supply's ground and the signal returns to the chassis, at a single point, through this filter network. Connecting those grounds directly to the chassis would create ground loops, but the filter network blocks noise from entering the circuit while allowing the safety features of the Earth wire to function. Up til now I've been connecting all grounds directly to the chassis and now must determine how best to re-wire some projects to eliminate this direct connection and hopefully excise some noisy demons that have been vexing me.

Which leads me to the phono preamp. How should the ground wire from a 1200 mk2 turntable be connected to the phono preamp? Does it connect to the Chassis/Earth or should it connect to the lifted/isolated ground network in the preamp?

What about the heaters? If heaters should be referenced to Ground, should it be the Chassis/Earth or the isolated Ground? I usually reference the heater circuit to a power tube's cathode anyway.

I've also seen talk about other methods of isolating the ground, including diode bridges and 5W wirewound resistors; any thoughts on those?

thanks for taking a look!

Hello all,

I am starting off on an overlty ambitious project for a novice and 1st time build and would like to ask this community for guidance.

Disclaimer/Constraints: All drivers and components have been purchased and I am out of cash so no component substitutions can be made at this time.

This will be an active 5 way open baffle speaker.

Drivers:
Bass section: 2 SB Audience 15 inch OBO woofers.
Woofer A will handle 20Hz to around 160-250hz
Woofer B will sit closer to the ground and will reinforce 30Hz to 80 Hz.

Mid Bass-Midrange: SB Audience 12 inch woofer 160Hz to around 800Hz.

Midrange: SB Acoustics Satori MD60N, 800Hz to 4500Hz.

Tweeter: Fountek Neo CD2.0, 4500Hz and above.

Crossover management:

Peavey Vsx 48E

Question: Given the number of drivers this is going to be a tall build. Would it be better to have the mid-range and tweeter mounted above the Bass section but below the 12 inch mid bass to mid range driver? I am planning on a minimalist baffle to mount these 2 drivers. I am afraid that mounting the 2 higher frequency drivers above the 12 inch woofer would put them significantly above a seated listening position. The 12 inch woofer would be angled down towards the seating position.

For the Bass module, I would prefer a H or U frame but for this initial build, I plan on keeping things simple and will go with a 24 inch wide baffle 1 inch thick baffle.

THANK YOU FOR YOUR INPUT.

NIK

Hello,
I have problems in measuring distortion with SDS1104X-E oscilloscope. (yes, this is not the best device to do so, and there are other solutions: I know, this post is about this specific method)

ok, so here is the problem - really interested if this is a setup mistake or an issue with the device although it is brand new

Test signal: - 1kz sin wave 1 Vrms on channel 1.
Math FFT setup: Hanning, 1Mpoints
BNC to BNC cable, no special probe, no attenuation
Grounded scope socket
No special devices, e.g motors, lights to interfere with

I get a pretty much the same measurement result independent of the source: Siglent SDG 2042x signal generator, same sin wave through MOTU M2 audio interface which should have very low distortion. the FFT shows a lot of harmonics as in the picture below.

Please share your opinion on this - I have tried multiple settings both on source generator and oscilloscope but always end up with this result.

I have been using MOTU interface with REW software to measure distortion and I am pretty sure the problem is not with the signal generation.

scope details

• sw version: 6.1.37R17
• hw version: 01-05
• FPGA version: 2021-11-08

It would be great if someone could try to reproduce this test, with the same source or different

The scope was bought as new but I believe is an old stock with perhaps older HW version.

Thank you!

I want to replace Phillips satellite speakers but I've no idea how to change the wiring. Each satellite has 8 x 2" drivers. I assume 2 are for the centre chanel, 3 front & 3 rear. The connector has 6 pins.
All in need is L&R front. But I've no idea how to read a circuit diagram.

Thanks.

Hi all,
I have recently replaced the VU meter lamps on my P5000 but the new ones are rather dim.
I measured the old lamps on a variac set to 12V and they drew 175mA each and so I ordered 12V/150mA replacements but as said, they turned out to be quite a bit darker.
Not sure what I am missing, I do have the service manual (it's available online) but there are no part values shown besides Accuphase part number.

+++
Ok, measured 18.9VAC on the lamp rail, considering the lamps are in series by 3, that would mean they are 6-6.3V parts.

The question rises up when a friend was looking for various new power amplifier devices and had serious doubts about the lifetime and reliability of Class-D variants when he saw the modules inside the devices, the images of which I uploaded.

What experience is there here?
Do the electrolytic capacitors have to be replaced early - i.e. after a short period of use?
Or can one assume a similar life expectancy for the well-known brands as for good conventional variants in analog technology (mostly Class AB) ?

At first glance the used electrolytics are in the same kind and same price class as in PC main boards and cheap SMPS modules - go to
https://hackaday.com/2019/04/12/ask-hackaday-experiences-with-capacitor-failure/ (nichicon)
https://de.m.wikipedia.org/wiki/Datei:Al-Elko-bad-caps-Wiki-07-02-17.jpg (GSC)
https://www.robotroom.com/Faulty-Capacitors-1.html (CapXon)
Thanks for comments.

P.S.: Interesting report
https://audioxpress.com/article/fre...-amplifier-module-doubling-down-on-a-flagship
https://www.audiosciencereview.com/forum/index.php?threads/nad-m23.30114/
https://www.audiosciencereview.com/...purifi-eigentakt-is-my-dream-amplifier.25376/

Hi folks,
I am looking to replace my existing full range 6 inches (dainty speakers, may not be a familiar brand to all) with either of the below options:

Cuboid 6 from Optimal audio
(https://optimal-audio.co.uk/products/loudspeakers/cuboid/cuboid-6/)

Flex point FP6 from Martin Audio
(https://martin-audio.com/products/loudspeakers/fp6)

Please suggest based on your experience whether this will enhance my surround channel experience or am I better off to look at something like the below which is meant for home audio

https://www.tagaharmony.com/en/products/3589/speakers/product/9131/platinum-s-100-v-4

Room size - 20x20
Source - Marantz SR5013

Dear Forum,

I know this is way too remote question to ask, but I found out that one of the blocks runs hotter, than the another however they sounds balanced to me.
I am using them with a Martin Logan CLSII pair.

Should I do the ,,biasing" as shown in the manual? Could this be that any of the 2SC2238B or 2SC3852's killed in action?

Thank you for your answer in advance!

Comparisons of focusrite 2i2 gen4 with generation 3 and other usb, firewire audio interfaces. Mdat you can find more here: https://drive.google.com/drive/fold...QRqwCC0mRVaoLX3O?dmr=1&ec=wgc-drive-hero-goto

Looking for a few 12" subs as I have a McIntosh Mc 2500 (did 735w from 10-100000 hz into % .001 THD @ 8 ohms both channels driven) that I would be using to drive them. I'm not concerned with the ohmic load as the amp is capable of 1 ohm if need be. I'd like for them to be in a sealed box and I'm happy to build it myself. I'd be using them for everything below 75- 80 Hz and would love if they would do 15-20 Hz on the low end. I'm not too concerned with total SPL, but 100 DB @ 20 Hz is a goal. Any recommendations?

Hello! I'm looking to make some very small, budget speakers as part of a 2.1 system for use with the TV. I'm very limited on space and will likely need to angle the pair and house at least one near a wall due to the TV being in the corner between a window and a fireplace.

Something like the nScan-Ken would be perfect, though it wouldn't necessarily need to be quite that miniature, but the £100 per driver cost puts me off.

I recently (poorly) made a pair of µMar-KenPlus and these are likely a little too big (though objectively small) and normally live in the dining room anyway. Photo is attached, for reference. Previously made a 2-way set using SB drivers based on a Troels design (with adjustments) but they were comparatively enormous.

I've been looking at the CHN-50P as a potential cheap and cheerful driver, but most of the plans I've found are larger than I'd want and I'm not sure if I could just "make them smaller" and lose some bass (as a simplification).

Any sage advice? Am I overthinking this? Maybe underthinking (and not doing any heavy lifting in terms of modelling a cabinet myself)?

Hello everyone,
Few days ago I just bought a chaniess PCB which basic schematic is something like that (attached).
Due to my poor circuit calculation skills, I assume that the zener(15V) regulator is currently delivering 9mA.

I would like to know:
1. Should I keep the 15V zener regulator?
2. Does the 15V zener ok for RMS 28V?
3. Is it possible to add a potentiometer (shown in the red-colored box, R5 + 5K POD) to adjust DC offset?
4. Will I get any advantage if I replace the Zener with LTP (as shown in the red-colored box)?

Thank you. I would appreciate your valuable advice and opinions. 🙂

Hi all,
This is Andrea from AAElectronics (https://www.aaelectronicspcb.com/). After a lot of request, I've started design for a PCB for Vox AC30 style amps, with the aim to make it flexible enough to accommodate seevral variants (e.g., EF86 channel, Normal, the AC15 version or additional mods). I'll attach the layout, PCB, and schematic for reference.

Would love to get your input on my design, and whether you'd like to see/add something to the PCB/schematic.
Have a great weekend!
Andrea
AA Electronics

Hi all, looking at changing my alps pot to a tkd.
As per attached pdf. Assume 1 in input 2 is output and c is earth?
First time at this, so just need a little guidance.
Thanks.

Ps. Worthwhile upgrade?

How can a transformer 2x175VAC produce 200VDC after rectifying?
It is a mystery to me.
What is the way to calculate such a Supply? Coefficient?

I tried posting a thread to ask a question about a DIY speaker project, but the site won’t allow me to post. It is telling me I must post here first.

I’d like to put together something like the An-e speakers. Does anyone here have experience with this? Cabinet build plans?

I’d also like to know if anyone might be local to NYC who could lend a hand, as I am disabled. Does anyone know any speaker builders who do this kind of work? Seas a24re4 and Morel Cat378 seem to be popular for Audio Note-inspired builds. Please let me know. Thank you.

Opened an account here to be able to post my condolences for Carl Huff who I can see has been an active member. Carl and I were close high school buddies who managed to fall out of touch with each other for decades. Please don't let that happen to you - keep in touch with your friends.

Hello,

Thank you for accepting me into the forum—I’m really excited to be a part of this community! I started my journey in speaker building about a year ago. At first, I didn’t have many resources to learn from, aside from YouTube and a few websites. However, after my last box design turned into a bit of a fiasco, I realized that everyone who said, “It’s not that simple,” was absolutely right. It’s much more complex than I initially thought.

I’m hoping this community can help me find answers to the countless questions that keep popping up as I continue learning and improving.

Looking forward to engaging with all of you!

Hello everyone, it's glad to be in this forum, looking forward to learn new things with ya 🙂

hello,

i tried now around 10-15 different dacs and specially recently some really nice sounding not much costing devices come around

somewhat recently i found out that i really like the sound of the black lion audio revolution 2x2 interface, then 2 weeks ago i was looking for the first time into portable dacs (not much of a on the go listener, im looking into this for desktop use), tried the moondrop dawn pro (good for the money, but overall compared to more expensive amps not a endgame solution), then bought the Fiio KA15 ... much better imo and actually pretty close to the black lion audio interface (maybe/probably a Cirrus Logic Dac chip thing, which i also wanted to confirm as the moondrop dawn pro relys on CS413131 and the fiio KA15 on CS43198 + OPAMP (i upgraded to KA15 since the base sound of the moondrop dawn pro wasnt sounding bad, it was just a bit thin/brittle sounding which you usually get with small amps)

not just sound quality seems top notch on the Fiio KA15 but also its featurset, the dac chip seems well implemented you even get a class AB or H mode option (which is a function of the dac chip made accesible by fiio), also all digital filters are selectable

So, since the chip seems well implemented, i was wondering, can this thing be used as a base to DIY something? the recent collection of portable dacs measure pretty similar to desktop units to be honest
i already hooked it up to my active speakers via a 3.5mm to 2x cinch and also can confirm here, it sounds pretty good (but good usb filtering seems still beneficial, had to use a isolator since there was audible noise over cinch)
would it be possible to use this as a frontend and build a "output stage" for it? the output opamps are SGM8262-2 inside KA15, not sure how these react to high impedance loads, does anyone know more here? i just assumed if it can drive low impedance it can definitely drive high impedance...

Seventy years ago I was gifted with a Lionel train set by Santa (or so I thought). I was so excited I peed my pants twice. My dad's factory had a railroad siding and I loved when the locomotive would slowly move by the office when years later I did some of the book-keeping for the company.

I promised my sons that the first one who sired a child would get the train set. It is now in wonderful order with #2 son and their kids!

Recovery bed ponderings

With folks making efforts with bracing and damping, I got thinking about the other extreme. I imagine a sub driver fitted into the entry of a balloon and inflated to atmospheric pressure or so

How would that go? Thoughts?

I want to use either the BD139/BD140 or the MJE243G/MJE253G pairs as driver transistors for a low power amp. I have around 100 BD130/BD140 pairs with an hfe of around 200 and getting numbers of perfectly matched (<1%) pairs is not a problem. On the other hand the MJE243G/MJE253 are a mixed bag with hfe ranging from 80 to 140. I get probably get around 15% of pairs matched to within 5%. I realist that by themselves the MJE243G and MJE253G are better transistors. Which would you use?

Hi everyone,

I’ve been restoring an old equalizer and recently replaced all the electrolytic capacitors. Everything has been working great, but I ran into a small issue with the last capacitor I replaced.

According to the service manual, this capacitor is supposed to be ceramic (non-polarized) with a value of 0.022 µF. However, the original one soldered on the PCB from the factory was an electrolytic capacitor, and its value was 10 µF. When I desoldered it, I didn’t note its orientation, and now I’m unsure about the correct polarity for the new electrolytic capacitor I’ve installed.

The capacitor is located between the ground of the LINE OUT/REC OUT connectors and the general chassis ground. I’ve installed the new capacitor with the negative leg facing the chassis ground, assuming it’s the lower potential point.

Does this orientation sound correct, or should it be reversed? Any insights would be greatly appreciated!

Thanks in advance!

Hello all this is Andrea and I'm the owner of aaelectronics, a project that I started 5 years ago with the idea of improving DIY amps construction 🙂
Nice to meet you all!

I have been out of the electronics game for a few years minus a couple foot switches and the like, looking to get back into it with this project.

I’m wanting to build a small personal monitor mixer to use when I’m gigging. One (1) XLR input that would be my mix from the monitor console. One (1) stereo 1/8” input jack to bring in all of my sounds coming from my computer which controls all of my keyboard sounds. One (1) 1/8” stereo output jack to plug in my SHURE 215 IEM buds and hear everything. I want to have a gain / level pot for each of the two inputs to control the mix between the two and a master volume pot.

I would love input and thoughts from others on best way to achieve this and things to make sure I’m paying attention to.

Thanks in advance.

So I want to know why/what can cause the stereo image to shift off-center when everything is spot on in terms of speaker placement/amp equalization. I've switched both amps and speakers and the image is slightly left no matter what. Soundwise it's not an issue but it just looks wonky from my listening position and it's distracting. It keeps me concerned about something related to placement or the amps. I use Acoustat Model 3 with the servo charge tube monos. TIA

Adapters include Amanero i2s output via U.FL, DIYinHK i2s output via U.FL, and DAM1021 Inputs. Inputs are i2s via U.FL, and SPDIF via header as well as 3v3 input for isolator. I'm just looking to get shipping cost only, which should be like $5. I can ship internationally, but would need $10-15. There are two full sets and one set that includes only Amanero and DIYinHK adapters.

Hi everyone,

from past grand HiFi-building plans out of love of Mr. Pass and Audio, I have quite a few unused pieces to offer.

I am starting with two sets of fully specced 5U Chassis by Modushop Hi-Fi 2000 of Italy, I believe those are the same as the Deluxe 5U Chassis.

In particular, each set consists of:

Dissipante 05/500B 5U 10mm SILVER 1NPD05500B
Inner baseplate for Dissipante 500mm 1BASEPD500
Couples of round handles 5U 1MT05158N
Couple of silver milled 5U handles 1MAN05B

Current price of one set is about 366 without VAT or 435 with European 19% VAT. (DIYAUDIO Chassis is 460 USD without tax and handles)

I am located in Germany, Berlin.

I will sell each for 300 Euros plus shipping - they are very heavy (20+kg per piece) but inside Europe I think Hermes will offer decent pricing.
They are still in the original bubble wrap, so I will forgo posting pictures, but if you need some, drop me a message 🙂.

Once I have worked out what else I have, I will post it here. There should be a few interesting amp boards (F4 F5) and their respective transistors / JFETs.

Hello all,

I have some Dixson Inc VU Meters from a Quad Eight Mixing Console for sale

Genuine & original parts date from early 1979, Made in USA

Meters measures 90mm x 71mm x 55mm deep

Complete with bezel (97.5mm x 57.5mm) & mounting hardware

Requires a 94mm x 54mm panel cutout for the bezel

Supplied with brand new Type 53 14V lamps

Perfect for vintage gear restoration

Have five (x5) of these available

I'm thinking USD 50 each plus postage or open to offers

Cheers, Ralph

https://audiofile.net.au/

Hey all, I'm fairly new to building amplifiers myself but I have built some smaller electronics in school as well as repaired some things on my own time.
I've been contemplating building a headphone amp for a couple years now and finally decided a couple months ago I'd try to build RJM's Sapphire headphone amp.
I'm now mostly finished building it and wanted to share my results in the thread for it.

Cheers

Joe. New to the forum. Wanting to get back into DIY audio projects and it’s nice to have a community to bounce ideas with.

There are many, many Kef B200s in the UK and elsewhere. Mostly SP1014. Both used driver units and 2-way speakers from Kef, Tangent, Monitor Audio etc. All going pretty cheap. Crossovers on these models were always between 3K and 3.5K, which was the style at the time. But several posts have suggested crossing the B200 over lower, like 1.5K to 2K with a more modern tweeter, maybe in a waveguide. Here's the data below, so what do you think?

Hello all,

I have some Harbuch 600 ohm line input transformers for sale

These transformers are high quality, Mu-metal shielded, stud mounted units intended for line input applications and have center-tapped 600 ohm primary and 600 ohm secondary windings

Pulls from a mixing console

The leads are approximately 150mm long

I'm thinking USD 20 each plus postage or open to offers

Cheers, Ralph

https://audiofile.net.au/

Hello all,

I have a quad (x4) of NOS 600 ohm line transformers for sale

Made by Control Dynamics, part number is CD1119

These transformers are intended for telecoms, voice-frequency applications and have center-tapped 600 ohm primary and secondary windings on an ungapped ferrite core

They measure approx 16mm cube

I'm thinking USD 10 for lot plus postage or open to offers

Cheers, Ralph

https://audiofile.net.au/

Hello all,

I have a quad (x4) of NOS Neutrik NC5MX 5-pin Male XLR Connectors for sale, still in their original packaging!

Full part number is NC5MX

I'm thinking USD 20 for lot plus postage or open to offers

Cheers, Ralph

Hello all,

I have a pair (x2) of NOS Cannon EP3 Male 3-Pin Connectors for sale, still in their original packaging!

Full part number is EP3-12-1C

I'm thinking USD 20 each plus postage or open to offers

Cheers, Ralph

Two more DACs for sale, fully built and working with high quality components, Need to raise some funds for more adventures 🙂

Both DAC boards have op-amp output and need +/- 5V supply. It is advised to test at 5V and then lift links to supply op-amps with 12 - 15V.

DACs need I2S input such as XMOS USB.

PCM1702 -SOLD

AD1865 - £40 plus shipping

Paypal either friends or add for fees.




Update Wednesday 30/10: One AD1865R DAC fully built available until I get more components, have DAC chips for 3 more after that

The Dayton DA135-8 list the xmax to 3mm. https://doc.soundimports.nl/pdf/brands/Dayton Audio/DA135-8/pdf_Dayton Audio_DA135-8_1.pdf
Isnt that very small?
Anyone tried this driver?

Hi everyone, just wanted to know if someone can help me with finding the problem off small crackling noise coming from my Sit3 left channel ? Is it possible to be capacitor failure on left channel power supply after living the amp switch on for days?

Hi guys,

I'm designing a low noise linear regulated power supply for my phono preamp which is now using a cheap wall wart power supply.
I need 18v with 1A max and I'm going to use a Belleson SPX regulator.

What I like to know is how much filter capacitance do I really need. I'm thinking of using 4 2200uF capacitors as a filter capacitor bank. I think it will be more then enough, but does it make sense to use a larger capacitor bank? Or what is the advantage of using a capacitance multiplier (capmx) with smaller caps?

Transformer will be 18V/1.6A and the regulator is an 18V version.

Hello,

I'm started to design master clock and need to know your opinion about this idea,

This OCXO idea is master clock for https://www.ti.com/lit/ds/symlink/lmk05318b.pdf ! The final master clock out will be trought it and will be fine corrected trought gps, thats for later. This oven also have oven controled voltage reference 2.5V which I going to use for J.D. regulator which will supply this OCXO. I done pcb oven design, picture 3, pcb will be canaled from all sides and an metal case will be soldered on booth top and botton layer, over those metal case going another metal case isolated by silicone. I thinked to do Driscoll crystal driver but it is complicated, instead I think I will do it with Comtrue CT7302PL since that ic have 190db dynamic range and an thd+n -175db, it will drive SC Cut 3rd ot crystal perfectly well and will give me master clock on their mclk out in TTL format. Oven is driven by darlington MJD122 and 40 resistors 1k which give around 25 ohm load, those 40 resistors will evenly heat the central part of the pcb on which is placed sc cut crystal and AD780 bangap reference which have temperature out which I have used for oven fine control. Waiting your opinion regarding circuit schematic design! Thank you!

Does anyone have good clean copies of these articles?
There are plenty of rough copies but I find generally that anything in this mag is hard to find, unlike WW which every issue seems readily available.
Maybe I've missed something.

So a friend has asked me to design a strain gauge phono pre-amp based on the Panasonic strain gauge cartridges.

I've got an EPC-460C and an EPC-465C on hand along with two NOS replacement styli.

(Even better I get to keep one of the cartridges when the project is done.)

I have spent several days reading VE and AK threads about these cartridges and how to amplify them.

Many people seem to like them without any sort of EQ, but based on measurements posted on VE and elsewhere this doesn't seem correct to me. Reviews back in the day show FR plots that by today's standards look pretty bad.

I might mention I have heard several modern strain gauge cartridges and thought they sounded absolutely terrible. I also heard a Panasonic with some limited EQ that didn't.

To be fair my frame of reference are a couple of Ortofon Per Windfelds. I have several others including a couple of SPUs, but I feel the PW is the most accurate cartridge I own.

From extensive study it seems like the following might be true..

• HPF at 50Hz

• Shelving HPF filter between 500Hz - 2.21kHz

• As yet undetermined rolloff between 2.21kHz and 10kHz..

All subject to change as I figure this out.

Hello,

I built the F5m amp with Nelson Pass PSU. I would like to add a small microcontroller inside the chassis to allow me to control the front panel LED(s). My board would draw under 200mA and the voltage regulator input has a max of 36V.

The Nelson Pass has +-24V rails fed from the transformer sourced diode rectifier bridges(2). Can I tap into the GND and +24V rail on the PSU board to supply my microcontroller voltage regulator or will that potentially cause a negative side effects on the F5m circuit/audio? My board would power a couple of LEDs at 20mA each or so and it will be using PWM so I don't want that interfering with the audio.

Thank you

What material do you recommend for making a linear power supply?

Hello everyone, I have some DACs and headphone amplifiers, as well as some preamplifiers and amplifiers. I now wants to create a linear power supply to power my DACs and headphone amplifiers, without the need for power amplifiers. My idea is to make two DC12V/3A and two USB 5V, with a total output power of about 80W. I want to use some better materials. Do you have any recommendations?

Welcome everyone to provide suggestions.

I have one output transformer Lundahl LL1693 250mA. I used it for experiments with 6S33S based amp. I think that amp sounded the best I heard. However, I decided to take another route due to the size and the fact that 6S33S needs at least 30 min of warm up time to sound its best. Happy to share my experience and knowledge if interested.

I still have the original shipping box. $200 + shipping. Feel free to ask questions.

hello everyone, I have been doing audio repairs for many years but you never stop learning new things.
I have found a lot of knowledgeable people here from whom I can learn new things and I hope to be useful for something too.

New to this forum, I recently rebuilt my speakerlab delta I type 4s with help from Paul from the loudspeaker store. I bought these as a kit back in the mid 80's. I have a Denon PMA-700V from same era and thought I would give it a little attention. It sounds great with the above speakers at low volume but I realized the speakers needed new surrounds, and the 8 in drivers were shot, hence the rebuild. With Pauls help, I added a true Nestorovic circuit to the coupled 8 in / 10 in bass driver circuit. So with these speakers revitalized, I thought I should take a look at the PMA-700V. Two of the 8200uf 63V power supply caps appear to have stained the glue on the PCB. Since the amp was working fine I am hesitant to just blindly recap it.

This project started 4 years ago, but lots of things happened in between and i was only able to complete the speakers today 🙂

Design

Here the speaker dimensions, as designed 4 years ago:



Drivers

• Beyma 15MC700nd: X < 350Hz
• AE TD12M: 350 < X < 1500Hz
• Beyma TPL-150H: 1500Hz < X < 20000Hz

(Crossover points will be dictated by real measures, but should be around those values).
Crossover will be Active, using a Monacor DSM-48LAN.


Boxes

Here the empty boxes, before stuffing and final coating:








Final Speakers
(sorry for the low image quality, i'm a really bad photographer)

Grills off:



Grills On:


One full speaker weight around 60kgs!

Some details

The backplate for the TPL-150H was removed, leaving the felt protection:



Drivers were stuffed with a mixture of:

• 4mm Bitumen pads glued to the walls
• Wool felt glued to the bitumen pads
• One high density rockwool 70 kg/m³ wall at the middle of the box
• Low density "fluffy" rockwool 30 kg/m³
• Raw wool

Initial Driver Measurements
(just for checking everything was ok)

A nearfield measure for both TPL-150H boxes (measured indoor, with ceiling at 1.8m at the measurement position):




A nearfield measure for both Beyma 15MC700nd boxes (measured indoor, with ceiling at 1.8m at the measurement position):


(i accidently removed the measures for the AE TD12M, but both tracked perfectly as well).
You can find detailed measurements for the AE TD12M on drivervault.

Finally, a nearfield measure for all drivers (measured indoor, with ceiling at 1.8m at the measurement position):


Next step

I'm now waiting to receive a 1200mm x 610mm x 3mm MDF board, so i can draw the exact positioning for the 0º to 180º measurement using the Ground plane technique, to get the required measures to use with VituixCAD for crossover development.

I'll be requiring your help for fine tuning the crossover once i have all the required measures, in order to obtain the best result possible 🙂

House cleaning. Two meridian system remotes for sale

€130/each + shipping at cost.

R

$300 shipped USA.

One pair never used 60 watt high quality Heyboer output transformers. Would make great 6L6GC pentode amp.

All new, $100 shipped USA.

The 2 chassis are old but never used. No top plates, just the chassis. They each measure 17x13x2.

The Hammond cage measures 17x10x5. It does not cover the whole chassis but does fit nice and snug over it.

Sold.

Hello,

I'd like to discuss with you some details in the phono section of the venerable Audio Research SP-10 preamplifier. It's phono stage comprises four 6DT8 double triode tubes per channel, which heavily resemble the 12AT7. Both triodes of each tube are paralleled, most probably to decrease noise by 3 dB. There are SS arrangements in each stage's supply which I believe are inductance simulators/gyrators. RIAA equalisation is done per NFB, which not everyone would follow. So far so good.

What I really don't get is the stage arrangement. I would have swapped stages 1 and 2, as I think, the cascode works best as the 1st stage. Additionally, Miller capacitance of the 1st stage is dramatically increased by 100 pF capacitors between the grids and the plates and adds to another 100 pF between grids and cathodes. A very heavy capacitive load for the cartridge, I think.

Does anyone have a clue what might have Audio Research led to design the RIAA phono preamplifier this way? Thank you!

Best regards!

Unfortunately I haven't a picture from this neon lamp, because it was already remooved.
This neon lamp is inside in the tubus (left side of the attached photo) of follow record player:
MICRO ƒŒƒR�[ƒhƒvƒŒƒCƒ„�[SOLID-5‚ÌŽd—l ƒ}ƒCƒNƒ��¸‹@

The manufacturer of this neon strobe lamp was Elevam:
Welcome to Miyata Elevam Inc.

Unfortunately it was not an article from the standard range. It was a custom made version for Micro.

Perhaps in Japan such lamps are still available.

Not helpful are normally used neon lamps in turntables like the photo number 3 and 2.
The greatest similarity I note to the both last pictures from attachment - found by a great overview of such lamps
Glimmlampen für Signal- und Beleuchtungszwecke

I am a musician , I use Hughes and kettner 20W deluxe tube amplification in my band and studio , my home Hi-Fi is a Arcam A39 speaker's mission 796 , I have recently added a Nobsound A3 tube amp to my home Hi-Fi stereo system , blessings

I've always wanted to build my own speakers and amplifier from scratch. And I did — they even sound decent. But there's always room for improvement, and I hope to find help here, and maybe even be able to help someone else.

Hi Mooly,
I have no way checking the connection condition?

During searching a connecting cable from my old stock I found a JVC radio set, consisting radio, cd player and cassette player. Please refer to attached photos
To my surprise the cd player still works with good quality of sound. The JVC radio set is >25 years old.

I'm now searching how to connect the cd player to my Denon HiFi amplifier for testing

Hello Everyone. Myself Sacheen Mahurkar from India. I am into vinyls & turntables.
I have been trying and attempted my hands on Moving Coil cartridge. Did lot of experimentation & research and then finally used Rosewood for the body, O.O3mm 6N high purity copper wire for the coils and currently using elliptical stylus and Neodenum magnet. Believe , its sounding fine. Would like to take this further. Please share some thought & views.

Have a pair of used Magnepan 1.7 speakers with an open supertweeter foil. Since this is aluminum foil, using silver or copper will cause corrosion just like in house wiring when copper or silver are touching aluminum wiring.

I found some nickel based conductive adhesive for a situation like this. It comes in a small applicator to paint on.

The glue on the panel with the open trace is the one that is brown in color on the right. The glue has been exposed to UV, so some of that will be removed once I find the foil break. It seems to be at one of the foil folds near the bottom of the panel.

I do have a full foil repair kit from Magnepan to use, but want to try a reoair first.

This pair has been converted to direct drive for use with a DSP crossover and Class D amps. Will be putting a 2 Ohm resistor in series with the supertweeter foil so the impedance is high enough for the Class D amp to have full frequency bandwidth to drive it to 20KHz. Below 2 Ohms, the typical Class D amp high end starts rolling off the frequency response.

Anyone that has tried a quasi ribbon repair would be great to get any tips. I have the acetone and alcohol recommended to clean the glue from the foil and cotton swabs to remove the paint and glue before repair.

I've been testing a Sabaj A20h and it sounds perfect as far as I can tell. The good price, perfect specs, and quality relay attenuator seem top class.

My idea is to combine a number of these units to make a multichannel attenuator - to be controlled by a 'master unit'. Does anyone have a schematic or experience of this hacking this? On first inspection the amp and attenuator sections are connected together by headers - I imagine that some of these are relay control lines.

I wonder if anyone has had a similar idea before and can help?

Hi, I choose this medical grade SMPS to try out Mark Johnsons AmyAlice filter. Results were OK but not comparable with my linear PSUs. The added necessary filter makes the SMPS quite usable (when deciding for SMPS) but it makes costs of course higher. Still a nice experiment just to keep in touch with recent cheap electronics.

However it keeps blowing mains fuses. It can not be taken into service as it is unreliable. I even upped the mains fuse to an unrealistic 500 mA and it just blows without any apparent reason. So today I got fed up and disassembled the PSU. While disassembling I heard a rattling noise. This appeared to be IN the plastic casing of the resin potted SMPS. So it is not fully potted either. When I measure it at the primary side and shake the module gently I can see a short circuit happening on my DMM.

Since this is a medical grade PSU I think this is worrying. Now I am not fond of low power SMPS anyway and possibly I maybe attract problems just like people afraid of dogs always seem to get attention of dogs but my question is if anyone has similar experiences with these modules.