Hello, I have to change the 4 big electrolytics in the PS of my Threshold Sa/3.9e.

What brand do you suggest for best sound/reliability?

In the forum 'Thresholdlovers' I find written:
go from Mallory (31000 microfarads / 75v) to United Chemicon Ucc (33000 microfarads / 85v) or RIFA (33000 microfarads / 100v) or CORNELL DUBILIER (xxx / xxx); add 4 Elna (470 microfarads / 100v); bypass with 4 Vishays (0.47 microfarads / 630v in parallel); change resistances from 10% to 1%; bias adjustment to 1.6.
What do you think?
Thank you.

Thanks

I am in the UK and have just purchased an early Cyrus 2 amplifier (Issue 04). The reason I bought it is because 1) I love restoring Cyrus One and Two amplifiers and 2) I've never seen a 120V model.

Seeing as I have a spare transformer from my 240V donor unit, I was wondering if anyone her could give me some advice on whether, in terms of resale value, it would be worth converting the amplifier to 240V or restoring and selling on the amplifier at its original 120V specification?

I would probably be putting the unit up for sale on eBay once it is ready so I'm hoping that, if it remains at 120V, it would pick up some interest from buyers in 120V lands due to the inherent rarity of 120V models.

On the other hand at 240V, these amplifiers restored still have a strong resale value in the UK and in Europe.

Any advice gratefully received!

Do ported speakers really act like an IB above the port resonance frequency? I’ve seen this quoted, but is it true? Has it been researched and is there any evidence? I’m wondering about this for the following reasons: an IB enclosure volume has an effect on the bass units performance (f3, transient response, etc.) At the port resonance frequency the hole in the enclosure will be “plugged” by the oscillating air in the port, but what if the speaker was reproducing a solo piccolo piece? Would there be enough low frequencies in order to set the port into resonance? If not, would the speaker essentially be an IB with a massive leakage?

Hello
Due to ongoing health issues I’m selling my matched quad of NIB TUNG SOL KT 120 tubes
This quad has sat unused since purchase from parts connection and are ready for a new owner to unlock their potential.
I am now asking $380 usd including shipping to CONUS.
The tubes will be double boxed and insured and I’m sure the buyer will be delighted.
I’m away from home until 5/3 and at that time I will post pics of these beauties.

Located in Oakley, Ca. pick them up, save $20 and you get a complementary door prize which won’t suck.Edited post as I had listed EH as the brand where these are T Sol
Thanks for looking today.

Hi guys,
Just bought a pair of markaudio CHR 70 drivers. I was planning on making concrete enclosures for them, but I then thought how could I do it easier save making all the wooden moulds. Then it struck me how about a 1m 160mm pipe inside a 200mm pipe, then fill the void between them with concrete with the top and bottom being capped off.
Any advice on whether to do a MLTL or ported, I was looking at the Mark 8 design a ported 1m long floorstander with an internal size of 112 x 160, hence my choice of a 160mm pipe, should give about the same internal volume.
Any advice would be appreciated.

Neil

Here is another project inspired by Danny: it is based on the same principles as the BoosterPhone, low supply requirements, rail-to-rail output on a low impedance, in this case 600 ohm and decent audio quality without too much complications.
It is designed to match older sources, delivering 150~200mV to modern equipments requiring 700mV or more. It thus mimics a passive step-up transformer, but without the impedance penalty: a 1:4 step-up transformer increases the impedance by a factor of 16, which can be problematic. Instead, the output impedance is much lower than the input.
Although the X-FoBooster requires a supply, unlike a copper & iron one, it has no power switch and lasts forever on a single charge: the supply current is comprised between 55 and 85µA.
First, the simplest version optimized for 3.7V:



This is the graphical version, based on the real prototype. The sim uses the native transistor types of the LTspice.

Now the 5V version:



Here is the non-inverting version: a bit more complex, but it has a self-centering quiescent output bias, and a THD of 0.03% against 0.1% (at 0dBm/600ohm, actually measured)







The values shown as comments are the ones used in the physical circuit. The others are suitable for the sim.
All the transistors are also 2SA1015/2SC1815, except the lower output transistor Q6, which is a BC547C.

The output is referenced to the + supply, and it requires a DC link to work properly. If it used on a cap-coupled input, it is necessary to include a dummy load of 1 to 2K.

I didn't build the various versions as complete projects, because I have no use for them (for the moment), but I breadboarded them, and the measurements are based on the breadboarded circuits.
The 3.7V version can use the same battery management as the Boosterphone, and it will last even longer

Got a little different project going some car audio.
I've obtained a new ute (little mini truck for my American friends) its a 2008 single cab flat tray Mazda BT50.
Just started working on it today making the sub box and planning out the door speakers... man I hate using fiberglass. Being such a small cab there is no real room for the sub in a conventional shaped box so Im making the box as a center console between the seats and it'll go up the rear cab wall to the window, I can only manage approx 30ltrs(1 Cf) of volume which is ok for most 10~12" car subs but Im lacking in width(230mm between the seats) so Im going to run 2x 8".
Parts list so far
2X Dayton UM8-22's
Door's will contain a Dayton RS225-4 for midbass duties, some Philips GTM 4" for midrange I've had them for years never used, and Im thinking of using some tweeters I've had for years also Jaycar response 19mm or the ones supplied with the GTM's.
Also have a Dayton 408 DSP to allow me plenty of adjustments and I'll be reusing an Alpine MRX-V70 5ch amp from my old ute, the UM8's will be wired for 2ohm on the sub channel and the RS225's on two channels and the GTM/tweeters on the remaining two channels, if there's not enough watts for the RS225's I will bridge the four channels into two and buy a small 2ch amp for the GTM/tweeters it'll all depend on how its measures when I get it up and running.
The Midrange and tweeters will need a passive xover made or I could use the ones supplied with the Philips GTM's... I'll have to do some testing/measuring may even end up buying some small coaxials or another set of 4'' splits(Focals would be nice).
Anyways that's where I'm at, I'll post up some progress pic's in a few days.

Hi all,

This is a bit more of a thought at the moment than anything.

I have a pair of alpair 12pw woofers lying around which were originally going to be used in a WaW set-up, but for a few reasons I don't think that'll be happening anymore.

I am curious about true ribbon tweeters and I'd like to see what they can do. I am concerned with using them in a two-way as I understand they don't usually reach too low.

The alpair 12pw can reach high with no issues, but I'm concerned about directivity if crossing about 3k+

I was wondering what everyone's opinion would be on this? The 12pw measures about 13cm from edge to edge, measuring from the edge of the surround. It's quite a flat profile cone, but there is no directivity data unfortunately.

My budget is only around £100 per tweeter so I was originally considering the fountek neo cd3.0 as I understand it's quite a popular unit

So in summary, I would like some opinions on the following:

1) Would crossing at 3-4khz cause noticable issues with directivity?
2) Are there any ribbons that can reach lower than typical?
3) I am also concerned about time alignment of the drivers and I don't know if I'd be able to do this passively. Any input on this is welcome
4) Any honest opinions welcome as this would be my first ever speaker/xover design. I don't mind some trial and error, as long as the driver selection is a good on paper and it has the potential to be a good speaker

Thanks

Hi,

I picked up a Yamaha XH150 which you guessed it is an high impedance amplifier, and I'm looking to see if you can mod it to an low impedance amplifier?

(I saw in another thread it was possible on a different 100v amp link)

I've attached the service manual that also has schematics.

Any help will be greatly appreciated?

Thank you!

I've tried email, and PM to no avail. I hope he sees this, if so, please PM me.

Thank you~
Gable

I am working on active crossover design for my speakers.Trying to figure out best way to take measurements.Unfortunately outside is not very quiet for measurements.
If i have to do them indoors what is the best way to get good measurements.

Hi !
I'm looking for 3-4 pcs LT8365 dc/dc conventer for battery power suply electrostatic headphones amplifier 🙂
I will consider any offer.

I'm looking to make a simple impedance buffer, something that has a high Zin and a low Zout - whilst avoiding the high idle power dissipation of a Class A design. I don't want any feedback (except for degeneration perhaps).

Power requirements are low (e.g. <10W) so cross-over distortion at low power is perhaps the limiting factor.

Candidates include double EF, Krill O/P, Sziklai buffered EF, Diamond buffer.

What would you recommend and why ?

Please drop me an email if you have a pair for sale.
hl5bxw@gmail.com

Hi,

I just finished my first version of a discrete dual opamp: Purple Gain.

Selling aca preamp open air version. It has a plastic film cover which broke when fixing. The pre works perfectly. Ship to Europe only
Price 180 EUR or best offer + shipping
PayPal is fine

Hi,

does anyone have (or know where to find) spice models for these tubes (6Э6П-E and 6Э6П-ДР)?

Hi, what would be the pros and cons of different materials used inside a box to reduce the volume. Would a bag of sand say be better than polystyrene blocks, considering the polystyrene has some give?
Steve

I am new this forum. I enjoy speaker building and have done several projects over 15 years, mainly based on 2 way designs (Dayton Audio projects and Madisound kits). Most recent is the CSS Criton 1TDX.
I am very intrigued by the idea of a full range driver speaker not using any kind of crossover network. I mainly listen to jazz, acoustic and "unplugged" popular music. I was thinking of the Pensil 10P as my foray into this world. I have enough 3/4" baltic birch (bought before the war) to make the enclosures. I would actually veneer thick (about 0.20") quarter sawn white oak in a vacuum press, making the panels even thicker and stiffer.

I have read that the Alpair 10P is "sensitive" to the choice of upstream components. In my case, my sources are a Rega Apollo CD player and Blue Sound Node, feed into a Schiit Audio Freya plus, feeding two Schiit Aegir amplifiers. Would this be a reasonable set up?

Hello everyone.

I have an aged Aragon D2A converter, as well as a (roughly) 12 year old eBay board purchased on the suggestions here at the time. I will probably finish that up as well, but I put the brakes on when I found this eBay listing. I like what I see, as far as board layout is concerned; they offer the proper power supply board (separately), which I would stick in another box with transformer(s), and pricing seems decent to me. Dual mono via completely separate chips; ganged together. Balanced output is attractive to me as well. The only "upgrade" offered is the "better" clocking module. I'd probably splurge for it, because I'm trying to get to a "last" DAC for me and my CDs.

Has anyone built, and more importantly HEARD one of these boards? I don't see much room for improvement in the components chosen- at least not enough to warrant removal and replacement. But, is it a good implementation? I can't tell- digital is well beyond my capability.

This will not be a "cheap" build, so I'd like some guidance from those more deeply nested in the digital decoding world, before I start ordering parts...

My father in law (now suffering dementia) has one of the pictured valve preamps built in a glass spherical shape. Can anyone point me to further information about it? Thanks!

wanted: TDA1541A S1 or S2 Crown

Looking for a Philips TDA 1541 S1 or S2 genuine part.
For a fair price.

Alex

Yesterday, we (4 of us) finally have time to do some listening tests on:

TDA1541A
TDA1541A S1
TDA1541A S2 (a real one, not a fake 🙂 )

in my modified NOS CD960.

The tests were done blind, so needed to teach my GF to how to pull and insert the TDA1541As, that was very very scary

The sound:

In conclusion, the normal chip has the most energy, the S2 is the softest, S1 is in the middle. Texture details were pretty much the same.

For pop music, the votes were divided, 2 of us prefered the S2 version and one liked the normal version, the final one liked the S1.

For jazz music, again the votes were divided, normal and S2 received 1 vote each, except S1 received 2.

For classical music, 2 prefered the S1 version and 1 liked the normal version. The final one couldn't decide between normal and S2.

So in summary, the score line is:

.....................Normal......S1.....S2
Pop...................1............1.......2
Jazz..................1.............2......1
Classical..........1.5...........2.....0.5
---------------------------------------------
Total................3.5..........5......3.5

As you can see, the results were a bit of surprise for us , we thought that the S2 should win hands down, but I guess you just never know what will happen in blind listening tests.

So "in our system" with "our ears", overall we prefer the S1. Of course, this is by no means conclusive.

Wouldn't it be nice that one can switch between normal, S1 and S2 on the fly ... 😀

P.S. Just a side note, to be perfectly honest, when the tests were done blind, the difference in sound was quite small, I really would not lose any sleep over it, whether my system uses a normal, S1 or S2 version. But for now, S1 will stay.

New ad listed, updated.

So the question is what can you do when your manifold for an IB sub is too big for the wall space available? In the particular situation I am looking at the wall in question has built in book shelves and cabinets over most of the area. Of course you could remove the cabinets or bookshelves but the powers that be would be unlikely to approve. So there is several inches of space below the cabinets. So one wonders if you could use that space as a snout for entry. It would kind of resemble an odd slot loading or a bandpass of sorts. I am not sure how to model it in Hornresp but perhaps something like a MLTL but only the port enters the room.

Thoughts?

Has anyone found a good source for output filter inductors for class D amps? Winding sucks! Thanks.

My 20y? old NAD 502 has developed a problem: after closing the drawer, with or without CD, nothing happens. No spin, nothing. After a few seconds the drawer opens itself again. This problem increased over time and now the issue occurs all the time.
I cleaned the lens, with no effect.
Any suggestions what to do?
I know it’s not economical to spend much money and I’m not sure I would go down the route of exchanging the entire laser unit. However, there is some emotional value in the old NAD….
Thanks!

What about quality and live time expectancy of this unit especially concerning the laser unit (optical pick up) ?
http://jmf-audio.com/dmt37_en.htm
https://6moons.com/audioreview_articles/jaysaudio/4/

Long live laser units for CD use only there was not many.
This included only certain models from Hitachi like HOP-M3 (DENON Linn Karik), Sanyo like SF-91 (Cambridge Audio CD-4/CD-6(CDT), Optima Series from JVC, used also in Japan's best available transport JVC EXU-901a - go to
https://www.diyaudio.com/community/...ct-1-ct1-better-than-vam1254-cdpro2lf.149032/
and Philips CDM-0, CDM-1, CDM-3 and professional versions of CDM-4.

By far the shortest lived laser units were those from SONY KSS-series, even such from top class cd player devices like SONY ES series and Accuphase (e. g. KSS-272A, KSS-274 KSS-190A).
This is the reason, why retail prices for NOS versions (new old stock) are up to € or US-$ 2,500 (!!!).

A friend of me want to buy a SACD capable CD player and have heard from others, that models from brands like e. g. Shanlin Ayon, McIntosh, Project despite very high purchase prices are very unreliable.
The reason therefore is the fact, that the equipped mechanism parts, especially the optical pick up it is the cheapest available for the mass market - check out this URL's:
Price replacement parts:
https://www.ebay.de/itm/265606415758?hash=item3dd760458e:g:JpcAAOSwPLFiOHOk
https://www.ebay.de/itm/265604093786?hash=item3dd73cd75a:g:cYMAAOSwUnJiNpOQ
https://de.aliexpress.com/item/32415646038.html
used in CD-PRO 8 from StreamUnlimited
https://www.project-audio.com/wp-content/uploads/2019/04/CDBoxRS2T-EN.pdf
https://www.audiosciencereview.com/forum/index.php?threads/lets-talk-cd-players.9104/page-6
Login to view embedded media The fact that the mechanism's backing plate was replaced from a solid block of metal milled from the solid, doesn't extend the lifetime of those parts that are in use in a DVD player that costs less than lunch.

Post #4, #6 and #8 under
https://www.diyaudio.com/community/threads/streamunlimited-dedicated-to-high-end-cd.337527/
don't gives little hope, that the situation here will improve again especially in order to SACD playback.

But maybe the transport mentioned in the headline is like one know it from earlier times of the CD era - possibility there are some experiences in the meantime. Thanks for comments.

P.S.: I would still trust JVC the most here, since older DVD players from this brand also have no problems with short-lived laser units (and vintage cd player models from this brand with OPTIMA units also still works).

I am parting out a 300b amp . Schematic by a famous designer. I have 4000$ in this amp. I want 1600$ for the Tango NC20'S.
1000$ for the Elrogs . I will leave the Hoshimotos 30 watt transformers on it . I want 1600$ for the amp no 300b's , but the rest of the tubes
are there 6f6 [ 42] 12au7 and a 5u4.

Hi all,

Just want to share my speaker project, a small 2 way ported using 1x SB15MFC-08 midwoofer and 1x SB26STC-04 tweeter.

The box design is using 9-10 litres MDF 2.5 cm thickness, with dimension 19x35.5x28 cm (WxHxD), port dimension is 4.3 cm inner diameter and 17 cm effective length giving a box tuning of 45 Hz (you can adjust this to higher fb, around 50Hz, to get a better midbass definition by adjusting the port length). I do flare the two side of the port. Damping using 1 cm felt inside the box except the front side panel, you can add a little wool or anything else by experiment. Simple square bracing between tweeter and woofer, chamfering the woofer inner cut to give woofer a better airflow.

The crossover is using 2nd order electrical and acoustic with acoustic crossing point around 2.5Khz. The phasing is not good, but the frequency response is still within +/- 3dB as you can see at the attachment. Measurement done with microphone on axis to tweeter with a 25 cm distance, since my room is not good for measurement. To give you some idea about the off axis peformance, i measure it around 20-30 degree off axis response (black = normal on axis, red = tweeter polarity reversed, yellow = 20 degree vertical off axis, blue = 20 degree horizontal off axis). I use series resistor to level the tweeter and woofer. Baffle step compensation circuit is used to compensate around 2dB.

Speaker impedance you can see as attachment. Speaker placement can be tried to some 50 cm from the wall. The speaker attend Indonesia Loudspeaker Design Contest (IDLDC) 2017, but got lost there. So, here i share them.

Regards,
Roy

Hi, I am cleaning off shelves and have two RCA Transistor manuals, two National Semiconductor Linear IC manuals both from 1980, and one Motorola Power Transistor data book. All are at least 40 plus years old. Free to a good home you pay USPS Flat Rate shipping via my PayPal account. They are boxed now and ready to go to some semiconductor historian. Smile. My vision is simply too poor to enjoy them now, so they can be yours. One of the RCA manuals is rough, but I think it is complete, likewise one of the National books is a little rough, but complete; the two National books may be very similar.

Scott Henning
shenning@durango.net

Hello all. I was given a toroidal transformer (VTX-146-160-224) that has 24v secondaries. I thought I would use it to build a gainclone. I purchased a couple of the cheap XY boards and made modifications suggested on this forum. I'm also using one of these:

https://www.amazon.ca/gp/product/B0828FCC5L/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

My rail voltage after the rectifier board is about 39v. I'd like to bring the voltage down a bit and was wondering if I could use a premade step down converter like this:

https://www.amazon.ca/gp/product/B07X8XPXP7/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

If so, would I place these after the rectifier board or would I need to drop the voltage before the filter capacitors? Sorry, this is all new to me so please excuse my ignorance.

Would it be better to use an LM317 regulator (with a power transformer) to reduce the voltage?

Thanks so much!

Allen

Gang,

Using the new ESS dac chip and not real keen on the filter selections. Has anyone done a slow roll off or a minimum phase slow roll off in an ESS DAC via the registers?

Matlab is $880 a year and I know the QED2000 is probably cheaper, but I haven't done this stuff in decades.
Thoughts?
Thanks,
Gordon

Checking to see if there's any interest here in my NHT (Now Hear This) XdS monitors with matching stands in excellent condition. I assembled some passive outboard crossovers based on John Krutke's (Zaph Audio) network that he developed for them. These monitors were part of a flagship fully active integrated system (with subwoofer) that retailed for $6,000 originally and was awarded a Stereophile Class A rating back in the mid 2000's, check the review online. My outboard crossovers are not pretty but they do the job and sound good (Clarity Caps, 16 gauge inductors, Lynk resistors). Midrange is particularly good with the SEAS Excel W15 magnesium drivers ($242 EACH at Madisound!). Just a different phase plug and shielded motor on these. You'll likely want to pair a sub with them, bass rolls off early with 5" drivers in a sealed cab. Shipping probably expensive, they are not puny lightweights by any means. EACH speaker and stand weighs ~45 pounds. CONUS only please. Asking $400 plus actual shipping cost from 64024. Excellent speakers, just trying to fund some other projects.. I do have the original boxes somewhere in my basement.

This would make for a very large cabinet which would not be an issue for me, but I would be very interested to learn if anyone has built one based on the JBL 2245H 18" Bass unit or a big TL using a similar 18" driver.

PMC use the 15" Volt (RV3363) in the large BB5 system, which has an fs of around 29Hz. The line length is effectively 4m or 13' according to PMC the actual physical length is a bit shorter at just under 3m. Using 1/4 wave criteria works out at approx 2.9m, so close.

I did consider the bigger Volt RV4564 which has a resonance of approx 26Hz which would offer greater performance than the BB5. Based on the BB5 specs 1/4 wave comes out at 3.3m (PMC effective length = 4.6m)

Anyway I am interested to learn if anyone has used the 2245H? I will model with it as a matter of interest.

I happen to have a pair of 2245H drivers doing very little, so propose a stereo pair of enclosures.

I have two unused AD1865 N-J chips available £20 each plus shipping at cost.

I bought a Dartzeel NHB-108 clone from AliExpress (Queenway) a little more than a year ago. It sounds absolutely fantastic, and I have been really happy about the purchase.

However, one channel has started to fall out from time to time. Sometimes it happens after 2 minutes of listening, other times it will play for hours before failing.

Seller has asked to me adjust bias and check the output transistors.

But... Since its a dual mono construction and one of the power LEDs has stopped working as well, wouldnt it make more sense to check the left channel PSU? I am tempted to just try swapping the PSU from one channel to the other to check if that will move the problem to the other channel.



The LED is always off, so it doesnt follow along with the sound coming and going. But its the same channel.

Hello,
I had bought G+M GM-1050 100v line amp with built in digital FM tuner. I can even get usb player module for it.
It was a bargain for 30EUR, I was buying it for the the casing, but now I`m thinking... This thing looks quality, it`s Swiss made.
Is there any way to modify this for low impedance speakers without transformer? 4 or 8 ohm...
This is my first time looking into 100v line amp.
I get no continuity from speaker terminals towards amplifier board... even with amplifier turned on.

I can`t find schematics, will post pictures to get an idea...
Pictures will be there in 10 minutes, I need to get home first...

Thank you

I have tried multiple values for resistors and filtering capacitor, but I don't get correct offset at the output, and filtering is not giving me needed results. Attached are LTspice schematics and LM3886 model.

Two screenshots are showing correct and incorrect frequency responses for the servo filter.

I have this CD Player
A very nice and scarce LUXMAN D-03 ( laser toshiba OPH-32 )
But out of order : It no longer recognizes the presence of CD discs.
Knowing that the laser is still shining, I think it is still alive and its problem is located on its servo card.
Unfortunately, as I do not have any technical document, and without schematic diagram, I am stopped to repair it.
If somebody have these or its service manual...
And infinitely grateful if you could help me.
I would be happy !!
Please, please
Thanks from France,
Raymond

Pardon me for my poor English


aymond

How does a the air energy from the bass woofer of a synergy horn, reflecting back into the cone, not cause a ton of distortion? As the holes in the horn for the 15" woofers seem far too small, inadequate in size to allow a proper amount of air to pass through to avoid said issue. For near and midfield listing, is there advantage to horn loading woofers rather than having an array of multiple midrange drivers around a tweeter on a flat baffle to achieve the same coaxial effect? I get an increase in sensitivity is achieved though if using an active crossover, who cares?

Is the color of the background behind the user initial a random color, or has it some meaning? If random, I would recommend to give it some meaning. Some ideas:
Time since registration: greeen = less than 1 year, yellow = less than 5 year, red = less than 10 year, blue = more than 10 year.
Or it could refer to the geographic location (continent: Europe, North America, Asia, etc.)
Or it could refer to the number of posts since registration. Or it could indicate the time since last seen online (green = currently online, yellow = online in the last 24 hours, red = online in the last week, etc.)

Hey, Ive just designed my own LM1875 based amplifier thats fed by a SMPS through a filter PCB. On this filter / regulator board i have 2x lm317, one set up at 32v and another at 12 with both of these having a voltage divider to provide a bias point for the TL071 and LM1875 on the amplifier.

I've noticed that the 16v (VD 32v) output are only putting out between 5 and 11v depending on the position of the 10k pot on the amplifier board. I assume the Pot is changing the load on this? Is there a way or a change i can make to the PSU filter board to stop this loading occuring? I'm getting reduced output as i get asymmetric clipping due to a low bias point on the LM1875. Sorry for the handwritten schematic 🙂

Hello everyone,

I have a problem with Keithley 2015 THD. On the first output of the generator, I do not have a sinusoidal signal, but on the second channel I have both a sinusoidal signal and pulse (of course, switched not at one time). What could be the cause of the fault? Is there any service documentation with diagrams of this meter available? Where and what should I measure?

I bought this meter as used. I wonder if by connecting a signal from the generator to the tested equipment and at the same time having a connected oscilloscope, with a short circuit with a PE wire, it can work correctly? Could such damage occur as a result of a short -circuit of the negative potential of the generator with the Protective Power of the PE? The easiest way to write a question is: can the generator output sockets be connected directly to the PE protective cable? Because I noticed that they are factory isolated from the metal parts of the meter housing and probably for a specific reason.

I want to measure the harmonic distortions of the audio amplifier channel with this device. So I want it to work in the loop without using an external generator, because I think that the internal generator will be the most precise and most tolerated, thanks to what the meter.

What is your opinion on this matter? How is it best to measure audio signal distortion with this meter?

Greting
Aleksander

Looking for a schematic for Audioromy M-88A

I'm looking to drive this tank pulled from a 1990s Ampeg with tubes (originally driven by solid state). I don't know the input impedance, but the input DCR is 30 ohms. In the amp I'm modifying, I have a single 12AX7 section and a 6AU6 to play with. A little reading tells me driving the tank from the pentode plate may be a good way to go (then using the 12AX7 triode for gain recovery.) What I don't know is what current/voltage I can/should put into the tank, and if I have to be careful about burning out the input coil. Help appreciated!

I have very rarely posted on DIYAudio the last three years.
I had finished my feature documentary about dancers in the GDR and their life
under the communist regime.
So "Keep Moving" has several meanings - not only to move as a dancer
but also to get over the Berlin Wall, getting used to Western society
and to adopt to changes in life - because in a dancer`s mid-thirties
his body is literally worn out -he is forced to find a new job and establish a new life.

Being a film editor and sound designer for 30 years,
making a feature length documentary is nothing new to me.

But Keep Moving was also my debut as a producer, director, cameraman, sound mixer.

The result seems to be fairly good as I was invited to the
Berlin International Film Festival, Berlinale -
one of the most renowned festivals worldwide -
as well as on other festivals.

Not bad for a feature made without
any funding and edited and mixed in my sleeping room - DIY

Keep Moving is available here:

fishermansframe.gumroad.com/l/abtyf

with subtitles in English, Chinese, Spanish, French, Greek, Polish.
When you click on the film poster, you can also watch the trailer.

All the best,
Salar

Hi!
I would like to build a (small) 2-Way-Speaker from a proven Design.
I choose the Revelator Woofer because I would like to listen a bit more an the "beautiful side" - and prefare actually Classical Music.
I only got a small room 3,5 x 4,5m and its not a dedicated listening room 🙁
Listening distance is small 1m or 2,2m
The Speaks will stand right in front of the backing wall.

My question(s):
What size of woofer should I choose: W15 oder W18?
(I would prefare w15 because I would expect it has enough bass for me but delivers a finer midrange)
Which are your favorate designs for the SS woofer?
(I live in Deutschland - the American Designs, for example from Meniscus are complicated/expenive to order for me)

Thanks and bye
Rundalf

So I've been playing with a design using old soviet germanium transistors and running into a stability problem. This is the schematic that I prototyped with all values the same except using a P602 transistor for the VAS stage. The instability happens when the voltage is increased to a certain level, say 20 volts. It breaks into oscillation and the current spikes along with lower output transistor getting warm. With a speaker it sounds like static and looks like random noise on the scope. I tried 100 ohm base resistors on the output devices and large and small power decoupling caps but nothing makes a difference. Finally managed to catch the start of the oscillation with my scope across the base resistor of the lower output transistor. Who knew these slow leaky GE devices would be oscillating at a few Mhz.

Hey buddies!!

My diyaudio first watt f6 amplifier will is out for sale, it was assembled with up most care and sounds great, Lol damn great!!. All the component were sourced from diyaudio expect the chassis, it has more heat sink area than the first watt f6 chassis and is very high in quality.
Little description of the circuit: This F6 is a class-a mosfet power amplifier, with a jet driver stage, It utilises small signal transformer for the phase inversion, so both the output mosfet are n-channel,. However, this transformer greatly contributes to the overall sonic character of the amp which is very highly regarded and considered to be similar and having all the benefits and positive characteristics of a tube amp, and making some observers speculate that much of the positive (tube amp ) sound is the transformers, not the tubes. Lastly, the f6 is a regular kind of amplifier- a voltage source amplifier, which requires nothing out of the ordinary from the preamp or the speakers. Also, the power output is 25wpc into 8 ohm. 50wpc into 4 ohm.

I think this little description might help!!!
PRICE: USD725
SHIPPING WEIGHT: 35.00(lbs)
Mint condition and function well.

Hi,

I designed the following SEPIC converter for experiments with the solar panels I'm soon buying. The schematic diagram, both copper drawings and the assembly drawing are added to this message. The solar panel system I spoke of consists of two 100 W panels (Voc~20 V, Isc~10 A), so one knows pretty sure the worst case conditions. Basically, you cannot draw more current from the panels than the rated short circuit current is.

Anyway, this converter works perfectly when there is a small load at the output (the output voltage is set to 14.4 V). But when I start to draw more current through the converter from a 12 V test supply, an irritating noise appears, and it gets louder as the current increases. So I thought the inductor core must be saturating. It isn't maybe made clear in the schematic, but the two inductors are wound on the same core, E42/21/20 with approx. 3 mm air gap (quite large one). I tried to simulate and calculate the inductors and core to withstand maximum of 10 A, but something has gone wrong. The inductors consist of 15 turns, two 1.2mm (diam.) enamelled copper wires wound parallel.

I fear I have made one crucial mistake: I salvaged this core from a defective SMPS, and it might be that the ferrite core itself is permanently magnetized and therefore saturates far more easily. I could fix it if I heated the core above its Curie temperature, but since that isn't an option, I guess it's time to make a new inductor set. Could there be any other reason for premature saturation? Thanks for opinions!

The schematic

The bottom copper

The top copper

The assembly

CLOSED ETI GOLD BAYONET PLUG four couple + EIZ EZ 310 GOLD

In bundle 80 euro plus shipping

I could do with some help with fixing my PM-94. 🙂

The Marantz has been recapped and all solder joints expected. It appears to function well however there are the following problems:

1. The left heat sink gets really hot while the right one is much cooler. The first step of biasing the left channel to 36 mV is possible, however the second step of biasing to 180mV not (initially it appears to work when turning the trimmer, but then it jumps back and forth in value).
2. Biasing the right channel works in both steps, however the heat sink gets warm but not hot. My feeling is that it's working in class a/b (perhaps this could be related to the quarter A settings?).
3. Have some difficulties to get the DC offset set to 10mV (and it seems to fluctuate).

1. What would be the most likely cause for this erratic behaviour of voltage jumping to different values?
2. Could the quarter A settings cause the right channel to work cooler (in class a/b) while bias settings in both steps are set to resp. 36mV and 180mV?
3. The DC offset changes with the bias and is difficult to keep at 10mV in the right channel. Any idea what might cause this? (am able to set it to around 8 or 14, but then it changes)

All tests were done at least after one hour.

Hopefully someone can point me in the right direction.

I've been looking into getting a manual coil winder mainly for making my own inductors but apart from the usual Chinese ones it seems that there are not many options, especially in Europe.

Can you recommend a decent winder new or used, ideally with a tensioner?

These AVO look great but I guess it's pretty hard to find one.

Thanks!

Hi there and thanks for stopping by.
I built a phono pre using 5842 tubes designed by Joe Tritschler. I'm using it with a Yamaha MC-1s cartridge and a SUT I also built using some Shure audio transformers. It sounds very good. Quiet, revealing, and steady through most all of the frequency response except that it lacks some bass authority. It does not lack much at all and I am wondering if using the step up transformers would change the loading the cartridge wants. Without plugging in numbers, can anyone tell me if this is a credible theory and maybe give me a little bit of theory I could use to figure out possible adjustments?
Thanks to anyone who might take the time to help.

Anyone know the source of these "no name" inductors? I'd like to upgrade them, but need the pad footprint dimensions. These are from a 3116 based TinySine TSA7800B amplifier (LINK). They're dual coil inductors and have approximate dimensions of 10 mm X 9 mm. It's hard to get an accurate measurement due to the nearby components. Any information appreciared.

Hey all, I have decided on a FAST/WAW setup ( = full range -ish speakers + subs ) and I am currently thinking out the amplifier part of the system. I'll be trying my best at a B1 preamplifier DIY prefab kit designed by Nelson Pass, which utilises the Korg NuTube. Schematic is attached. This will be my first amplifier building project ever. Hype is real!

I understand the bare basics of passive crossovers but I'm new to amplifier design and I have no friends with relevant knowledge on the subject matter, thus I present the following questions to whomever of you would be so kind as to lend me their knowledge 😊

• I have a 100k variable resistor pot that I would like to use instead of the 50k pot that comes with the kit. Could one just swap it out? What effect would it have?
• With the goal of a WAW setup in mind, I'd like to connect a power amplifier (main speakers) and also a DSP unit + subwoofer amplifier to the output of the preamp. Does this change (or halve or double) the required value of the output resistor (for example 2 times 50k) ? Or leave it like is? What effect would it have?
• In order to add the effects of a 1st order line-level passive high-pass crossover (LLPXO) to the main speakers, should one simply add a capacitor in front of the 100 ohm resistor (and tailor the value according to the 100 ohm load it sees) ? Does that affect the signal that the DSP unit sees or needn't we worry about that?

I can't wait to order a kit and get soldering, I hope the setup I have in mind can be realised with a small set of modifications

Have a nice day, thanks in advance, cheers

Hello,

I am relatively new to transistor electronics though have been working on tube amps for several years.

I have an 80s Yamaha G100-212 III amp which has an incredible and well-known clean channel. I've attached the schematic. Would it be difficult to take the simple preamp (Channel A) section of this channel and match it with a TDA2030A or similar power section to make a small form factor clean guitar amp?

I am building a small amp from Nightfire Electronics that uses this power section for which I have a schematic as well.

Any help appreciated

Doug Frenia

Being one of the best sounding speaker kits back in 1983's one can make - or so they claimed and it had a good reputation. It was called Hifi 60/4 (meaning 60 litres and 4 drivers). Vifa P21rex woofer, Peerless KO40mrf mids and Dynaudio D21 tweeter. The thing is designed to give smooth overall response in a typical room environment to a listening position as well as to give deep bass response down to 25Hz or so. Crossover freq: 500 and 5000Hz.
Anyway I just finished the first one and took a quick listening session. No, this cant be true, how can one even listen to this speaker as it is? It sounded just horrible! Midrange was badly peaking and one notey. That was not what I was hoping for.
There must be something wrong but I dont know what exactly. I took some measurements from the midranges with and without crossover (measured at 1meter distance).
Here are the results:






Waterfall (some weird things happening):


So as can be seen, it is heavily peaking around 3kHz. Even worse with crossover. Any idea what is going on there?

Here is the speaker itself and some measurements by the hifi-magazine which is the source for this speaker kit.




And finally the crossover:

I have build 2 of these and 1 has developed a fault where after switch on everything is OK and I can leave it with no signal for as long as I like BUT as soon as a signal is applied the standing current goes crazy 10A+. It blows the +ve fuse but not the -Ve fuse and even stranger is that the speaker does not deflect. Also before the fuse blows you would not know anything was wrong judging by the sound from the speaker. Any help much appreciated

Hello,

I like a lot the new forum, especially that it's now usable on mobile.
The only thing that bothers me a little bit is the unread topics are in bold, but the difference is very subtle so when some are read between unread, it's s not easy at a first glance to differentiate.
Or perhaps I missed a setting somewhere ? I'm using dark theme BTW.

Thanks

Any thoughts on the best cable to re-wire my Quad 606-2? I’d like to keep mains bundles separate from signal runs. I’m particularly exercised over the poor quality of the wiring to the speaker binding posts - clearly OFC wanted, but does it need to be esoteric (ie, expensive)?
Neil

This is my second Amp Camp build. Like my first one, this will be a drawn-out affair. However, I’ve got it pretty well planned out and I’ve already made some progress in construction.

My primary motivation for this build was a pair of fan-cooled copper heat sinks I found at the local electronic salvage store a few months ago, which cost me $9 each. I knew I had to figure out some way to put them to good use. The fans are pretty quiet at low speeds, and I figured they would be good for a small ACA build… so here we are.

Unlike my last build, this time I’m going to alter the circuit a little bit based on a suggestion made by Zen Mod in the official Amp Camp thread. I’ll be switching out the IRFP240 mosfets with IRFP150s, “crank[ing] up the voltage,” and halving the values of R1 - R4. That should produce an “ACA on steroids” according to Zen Mod. We’ll see how that works out. If it doesn’t, it’ll be easy enough to swap in the standard components. My plans for this amp are to use it to drive moderately-sized subwoofers, using my current ACA mono blocks to drive a couple of small two-ways.

In order to fit my case design and to keep everything neat & tidy, I’ll be making my own 2-sided PCBs, something I’ve never done before. I laid out the board using Adobe Illustrator:



You’ll note I’ve included circuitry for a mosfet-base fan controller. I’m not 100% sure I’ll be using that circuit, so that part of the board may change.

The heat sinks (with fans) will be connected with a piece of aluminum angle, and the PCB will mount to the heat sinks. Aside from the power jack, switches, LED, and in/out connectors, all the working parts of the amp will be included in this assembly:





The case framework will be made of welded steel. Wood at the front and perforated steel at the top and rear will complete the case:





In addition to the usual metal work and wood work, there’ll be some other fun stuff like etching and plating, so hopefully some of you will find this interesting. Stay tuned…

😀

Edit: If you have Sketchup (and I suggest you download it if you don't), you can download my model here:ACA Concept to .skp model (zipped).

Hello everyone! back in '20 I built an amp which has served me well, I decided to add a volume pot. I added the pot as shown in this diagram and pictures. I connected only one channel at first, it seemed to be working fine, then my amp died!
The amp is this one: https://www.3e-audio.com/amplifier-kits/tpa3251-2ch-140w. The fault light is on now 100% of the time with nothing connected. I don't know if I shorted the input to the heatsink or overloaded it by only inputting one channel.

So, I had a little TPA3116 amp board, I took the time to set it all up as shown in the pictures. I turned it on, the light came on, no output. I had ANOTHER one of these TPA3116 boards, I eliminated the volume POT and hooked it up, and it works. I tried the first one, and nope, its dead.

Something about this pot circuit is killing my amps. I took the meter to it, there is no continuity between any leads ground/signal or L/R. Continuity is present between all grounds. When turned up all the way, there is continuity across the pot at 2.2 ohms on each channel, but not between them.

Are the caps in the right places? Previous advice was to have the input caps on both sides of the pot connected with the negatives to the pot, is that correct? Could a bad pot be causing my problems?

Just received a pair of Peerless 830874 on my doorstep.
https://www.google.com/url?q=https:...0QFnoECAQQAg&usg=AOvVaw1zJ_P1_ueAc2StgwnlBHEJ
One of them has a magnet assembly off center. Not purchase from parts express. Above is just for reference.
This is all I could find in a quick search of Google addressing this ..
https://audiokarma.org/forums/index.php?threads/speaker-magnet-off-center-klipsch-woofer.841026/

Realizing that the polepiece/ backingplate alignment is much more important than the magnet itself, I would still have thought that axial alignment of all parts of a speaker would be more critical than this. It's not really a 'cheap' driver either at 53usd.

Sorry for the bad cell phone pic. The edge to edge of the backing plate and magnet is 5mm on one side and 10mm opposite it. Is this a concern? The glue on the inside between the cone and the half roll in this one, compared to the other, is REALLY sloppy as well. Did I just get a factory second here?

Would you please recommend digital Interface with high quality ADC to be used to rip vinyl
I am biased to RME Babyface PRO FS
does anyone know what adc Is used In RME Babyface PRO FS

Hello, I'm trying to learn about build little boards for some of my units that are messed up.
This boards are not that complicated compared with the usual ones that I see here, they are single side and usually semi burned, with broken pads and traces or several repair attempts.(hacks). These have been a hobby of mine from a while now and I have a ton of fun rebuilding them.
For that purpose I'm using easyeda, I find it easier to learn than KiCad or Eagle, but since I'm hook and kind of obsessed with this I'll learn them along the way.

With that said, I made a first one, is for the power supply of my Sansui BA5000 and I wonder if you guys can point me if I'm in the right direction. Basically I made a ground plane on the bottom layer and else on top, but since I'm barely know what I'm doing be brutal, if my layout is useless I have no problem starting again with some pointers. That how I learn.

Cheers.

Sometime ago the white smd leds that works as dB signage of my mastering AD/DA converter start to burn out. When only some few remains from 32, I decided to replace them.
I got the smd leds values from a source and found an equivalent, due the original part is not in production anymore.

I checked polarity and I was a bit confused at the beginning, but proceeded with soldering. When tested the unit, all leds, included the VU ones (green-yellow-red) lit without any sound signal. Not full bright but enough to realize something was not ok. Needed to buy a mignifier glass and analyzed the circuit with a better eye, and understood that I need to solder the leds the other way around. Desoldered all, and the white leds shine better, and the VU leds lit barely standing still. Injected signal and for my surprise the white leds lit but instead of permanently lit from 40dB to 0dB as it should, they act as an inverted VU, that saying that depending on the decibels the VU leds lit and increase in the scale, these white leds turn off in sync. Exactly as a negative mirror of the VU.
I asked for the schematics to the manufacturer of the unit, but they stated that disclosing schematics is forbidden. So I draw one myself the best I could.

Can you guys help me find out?

This current source was first described by Peter Williams in the July 1967 issue of Wireless World and is shown in the first schematic. The most commonly used variant replaces the zener diodes with leds as shown in the second schematic. Williams himself noted that it is theoretically possible that the circuit may not self start, indeed I suspect that most simulations will not self start without a "kicker" resistor. However, in real life, the circuit reliably self starts regardless of ( within sensible limits ) voltage, current, temperature, transistor matching, deliberate transistor mismatching, and the presence or absence of light. I have verified that the circuit self starts at -20C, so if the circuit is kicked into life by leakage current through the transistors it must be very small. In addition to the tests I have used this circuit as a two terminal current source in a myriad of amplifier projects over the last 20 years with no problem.
My questions then are:- (1) Has anyone observed this circuit, or a variant of it, failing to start and (2) Has anyone got a convincing explanation, other than miniscule leakage currents, as to why the Williams ring of two current source always starts so reliably.
Finally, in the third schematic the leds have been replaced with transistors and this circuit too, self starts reliably. I find that two terminal current sources make pcb layout easier and this variant has very good PSRR, potentially very low noise, and fairly low temperature sensitivity. I'll switch to using this variant rather than the led version.
Any comments, particularly as regards shortcomings of this circuit are welcome.

Hey Guys,

I’m about to build my own speakers, and I’m in need of a router for the driver holes. The wood is 40mm thick ply. I plan to first route the recess for the mounting flange to mount the drive flush , and then cut out the holes for the drivers. After that I may do a 45 degree chamfer.
so I’m contemplating what router to get.
this will be my first router, and I don’t know when I will build the next set of speakers. Any suggestions, like what power rating, corded or cordless, other tips?

as a note, I don’t mind renting one before purchasing, but I’m assuming that I still need to get new router bits and templates .

Hello guys,

I need help, i wanted ptbl mode for this board but i didnt know how, it says i need short circuit linp and linnr and outputs inside that mini chip?

Is there a "rule of thumb" for the maximum MPH of wind that is acceptable during outdoor speaker testing?

A batch of 50 Original (Mouser) 2sk170bl
100€ shipped
Payment via Bank transfer or PayPal
Mail contact
luccicottoatgmaildotcom

Hi All, I just got a Luxman A-2003 tube crossover and know nothing about it. I can't find very much about it on the web. It was a kit that did not sell very well as far as I can tell. Cheers.

Hi apologies if this has already been answered, just wanted to double check because there are many different versions now.

I have the original tu8200 and tu8500.

My tu8200 volume pot is noisy and id like to replace it. What is the best volume pot upgrade for this version of the amp? I am ok to solder wires point to point if needed.

Also, is there an upgrade option for the tu8500 volume pot?

Thanks

I'm trying to figure out what could cause this. I turn the amp on and it takes nearly 2 minutes to come on. Very slowly sound and the VU meter comes up.
Happens only if left off overnight. If turned on after an hour or so it's just fine. It also otherwise works normally.
At first I thought it must be the two big main caps as one was slightly bulged. So I've changed both but it didn't fix the problem.
Fuses are not blowing so there is not excessive load so I can't think of what could it possibly be? It must be somewhere in power supply but apart ftrom the main caps there isn't much there to cause problems. I did check surrounding caps but all are ok too. I'd welcome any ideas, thanks.

Hello platform managers, when trying to pay $25/year, it says "Oops! We ran into some problems. This item cannot be purchased at the moment".

50$ seems to be ok... so are you going to bring back the 25/year ?

thanks !
Charles

Although I like to design and build speakers I really want a commercially available speakers. Since there really are no brick and mortar stores anymore my primary channel of purchase is preowned or from online retailers. However I recently watched a video of Danny Ritchie absolutely lambasting Vienna Acoustics speaker. It scares the crap out of me that I would spend 6 or 7k on a speaker that is worse than I can make, and I am only a hi level beginner lol. I am looking for a mid size floor stander to use with my GR Research Subs. I will be using CJ premier 12 tube mono blocks. room is 14x22x7. I am looking for a relaxing sounding speaker nit uber detailed. I want detail of course but not the absolute last word in detail. Having a tube amp helps. Also I am wondering if I should consider only 8 ohm versions as tube amps dont deliver huge amounts of current. Again I am mostly interested at looking in to BRANDS. Then I can drill down into models. Thanks