Hi All,
Need an advice to troubleshoot my Pioneer PD-75 CD player. Unit was working fine till one day. Now, putting CD into the tray is closed and after 5-7 second the tray is opens. I opened the cover and found that the laser head is not moving to the center of CD. The lens is not lost ( this is a common problem with this players), Also, the laser head was working excellent till now. I will appreciate any suggestions.

Sioux
Here is a higher power version of Choctaw.
Output 26 Watt with +/-25VDC supply.

Bought a AVT150H
Upon first use only the clean channel worked.
Now i opening up to look at it and the TDA7293 chips have been replaced before and have failed again. One looks to have let out smoke.

I amp hoping to replace the AVT50-62-00 with a class D power section. If anyone can assist me with this undertaking.

Can these even be done? Thanks!

hi, I would like to kindly ask for any help/advice.

I have had these speakers for almost 20 years, and I'm thinking about upgrading its crossover.

Speakers are 8 Ohms and with cross-over frequency 3kHz.

I plan to use Mundorf components, 4,7uF and 10uF capacitors - I guess both are for the tweeter. These are visible on this upgrade:
I'm not sure if the existing original is the same design, I guess I will find out once I will open the box 🙂

But I'm not sure about inductors/coils. Based on calculations, I should use 1-1,5 mH inductor for the woofer and 0,4-0,5 mH for the tweeter.
I guess these values will not be marked on the existing crossover and I'm not sure if I'm correct and will not corrupt the sound.

This is how probably original crossover looks like: https://bowerswilkins.encompass.com/item/12592525/Bowers__Wilkins/ZZ10340/

thank you in advance for any input,
Tomas

A friend of mine built a tube output stage a couple of or three years ago using old radio PCBs, and it totally got my brain buzzing—I had to try it out myself. Meanwhile, I came across Pilovis’ low-voltage PL504 output stage and figured it’d be a good experiment since the plate voltage isn’t crazy high. 🙂 That’s been in the works for about a year now.

Unfortunately, Pilovis’ design didn’t really click for me, but I did get a taste of that sweet “tube sound.” Then I built an ECL86 output stage that I’m pretty happy with. It’s not perfect, but even with used radio parts it sounds decent. I put it together using Alex’s “RH universal” circuit and a switching power supply. 😉 Now I’m starting to dive into winding the output transformers…

Shorting the secondaries provides a very smooth mute with no switch-pop noise. However, is this safe for the device connected to my input? The device in question is a Shure Wireless Receiver with a 100Ω output impedance.

This keeps bugging me after seeing a video (forgot where) about how to optimize active crossovers. In it the presenter deftly uses tools to create absolutely ideal LR4 crossover slopes. My question is, does it really matter if the speaker works correctly?

Here's an example. I overlay an ideal LR4 high pass filter for 3 kHz on top of the tweeter response with a filter. In the context of the total speaker, I have the output response and phase matching I want. Is there much value in fixing the area between 2 kHz and 4 kHz so that it more closely tracks the ideal LR4? My intuition is to leave it alone, less filters is better and that there's no practical benefit in attempting to peen this curve to "ideal." Am I wrong?

Hello, I'm from China, I'm a technician a friend recommended this forum for me to know more about audio and technical issues. I'm excited to be here and to learn more

Hello,

May be this subject has already being discussed. I understand that this might be frustrating for some people to go over it again. But here is my question:-

A year ago I was trying to troubleshoot a Denon AV receiver. Denon (as an example) uses Sanken Complementary transistors. This amp is 5.1 output receiver. So I need 5 Complementary types (as an example 2SD2390 Complement to 2SB1560). Apart from being complement to each other, they have to read the same Vbe and same hFe. (Matched) I understand that. So when I applied to a store providing these, the question was " Do you want them Matched pairs ?" I replied yes.

Now I am in the process of repairing a QSC RMX2450 completely burned both channels. Measuring around, I understood that the transistors are fried, drivers, power transistors, etc. QSC uses in this instance Toshiba 2SC5200 and 2SA1943 complementary pairs.

I read in this forum that these are constructed in very tight tolerances so they do not really need to be matched and incidentally the supplier did not ask me whether I want them in matched pairs. Searched a bit on the web for matched pairs, resulted in no hits for matched pairs. However for the pre-drivers MJE15032 and MJE15033, there was a question do you want them matched pairs ?, and there was a hit for matched pairs on the web.

Dazzled !! Can this be true ?

Seems I have made a mistake in assuming I could connect my ucd250 modules directly to my Najda dsp.
The nadja has 6v outputs and approx 2kohm impedance and the ucd250 needs 6.5v, and has 1.8k impedance.
I'm assuming I need some sort of buffer stage to go between them, any suggestions for a basic buffer kit?

So I'm wanting to build my own two-way with a 15" bottom end and looking for something to get close to the venerable JBL 2235.

In Australia the SB Audience Bianco-15SW400 costs $299 has some very similar specs.

Both modelled here in 130 Liters. How does this look?



Opinions appreciated!
Cheers.

Hi everyone. XrayTonyB built a cool little tube amp kit from Douk Audio on YouTube about 4 years ago, and I want to try one myself. I haven't done anything with electronics in a while, so I want to check with someone who knows before I go messing with the circuit at all. It has two "magic eye" tubes in it that I really don't want. Since I plan to wire the kit point-to-point instead of using the included PC board for the audio portion, if I could eliminate those two tubes and the associated components, it would save me a whole lot of work.

Here is the schematic with the connections and components that I am considering eliminating marked with red. Can anyone confirm that I am not going to mess anything up in the other parts of the circuitry by doing this? Sometimes weird dependencies happen. It seems to me that they are completely isolated from everything else.

I would just ask XrayTonyB since he is a member here, but I don't seem to have the ability to send private messages to anyone. Link to his build videos: Login to view embedded media
With his few small mods, I think it would be a neat little amp for me to build. It tested good after he built it and put it through a series of tests on his bench.

Also, has anyone built this amp recently? Does anybody have one that they built recently, and if so how do you like it? It seems that current versions eliminate the loudness control that XrayTonyB cut out of his when he built it, but I haven't been able to confirm that yet.

Edit: updated schematic to show final values.

It appears the KSA1220AY parts for the M2x IPS6 boards are no longer available in small quantities.

Does anyone have these on hand in the USA that is willing to sell/share enough for 10 PCBs (10qty)? I will share the extra boards I ordered from JLCPCB and the KSA parts with others at cost.

I believe I can acquire all the other parts myself, so I just need the KSA parts to finish up a complete BOM.

Cheers!

Greetings and Good Day!

After many years, I have finally got around to finishing my 8-channel amplifier. I will post pictures soon, to aid in troubleshooting.

Components used:
SMPS: MicroAudio Cobra-S2 https://micro-audio.com/store/product/cobra-s2/
^Datasheet: https://micro-audio.com/store/wp-content/uploads/2022/05/COBRA-S1-1.pdf
Amplifier Modules (4): https://shop.icepoweraudio.com/product/300a2/
^Datasheet: https://shop.icepoweraudio.com/wp-content/uploads/2024/04/ICEpower-300A2-Datasheet-1.4_.pdf

The issue is as soon as I turn the SMPS on, it goes into protect mode.
This only occurs when an amplifier module is hooked up. It will sit, powered on with no errors if no amp module is connected. Therefore, I feel the module is sending a DCError signal to the SMPS, sending it into 'protect' mode.

BEFORE I hooked up the SMPS to the amp module, I verified all voltages:


I do not have anything hooked to the 'Basic+ Control Connector', as I am not using BTL. Perhaps I need something from this section hooked up to the SMPS?


I also am not using the 'Aux connectors J4 & J5' on the SMPS. I didn't see anything here I needed. There is a pin for FATAL (error/fail) but so does the J3 connector (and evidently it is working, as it is sending the SMPS into protect).
J4/J5 (not in use):

J3 (HIGHLIGHTED pins in use):


Perhaps I need to hookup J3:5 and J3:6 above? 'Amplifier enable (Opto isolated) E' and 'C'??? I could not find anything on the amp module that made sense to hook them up to.


I really appreciate anybody's help in advance--I'm definitely confused!

Thank you!

Hello everybody, I hope everybody is doing well. I recently purchased line stage 6sn7/300b based pre-amplifier. It uses toroidal power transformers as outputs transformers. The sound of the pramplifier as it was received was ok but not exceptional compared to the LTA pre I have been using. To see if the SQ improved I bypassed the input select rotatory switch, the balance potentiometer and replaced the remote controlled attenuator with a Goldpoint ladder attenuator, replaced the gain adjust potentiometer with a simple voltage divider circuit. The SQ has improved a good amount but not quite to the LTA pre level.
Can you advice on improving the output transformers? the ones installed are meant from converting 120/115 Volts 50/60 Hz to lower voltages for regulated power supplies. I am curious about kind of bandwidth of these transformers have when used in the audio frequency band. I guess I could buy the 2 models used and run a test...
The other potential improvement is to replace the coupling caps, installed are metallized propylene (MKP) in parallel with a paper in oil caps. All theses parts the potentiometers, selector switch, attenuattor and capacitors are common inexpensive parts.
I know the design is good and the preamp has the potential to get better SQ from it. Thank you in advance for your replies. I am interested on learning more about tube amps in general. Take care.

Selling two like new FaitalPRO 6HX150. Planned to use these for some stereo towers but decided to go another direction.

Used in testing for about 1hr, not given high power.

Looking for $150 shipped each or $250 for the pair within CONUS.

Driver specs:
https://faitalpro.com/en/products/Coaxial_Loudspeakers/product_details/index.php?id=351020100

2sj18/2sk60 2 pairs
200usd + shipping 15usd
+PayPal fee or ff option
Or Revolut

With one of my RYTHMIK subs (bought as a kit) when I plug the power cord into the IEC input there is a flash.

Been going on for a few months and decided to take a look yesterday.

These have an input voltage switch and when I took all of the shrink wrap off of the switch it did look suspect.

So I start to map out the wiring and it doesn't look like anything I have ever seen, which is not saying too much. I look on the transformer and it says this transformer has two primaries but one is center-tapped. I have never seen that before which helps explain my confusion.

Easy enough to identify what is what - I feel confident I have it wired with the primaries in parallel but wonder if anyone can explain why this arrangement? Does it have something to do with the dual input voltage? I cannot imagine why this would be needed. Is there a country with 180 volts AC? Assuming center tapped mean it is in the center.

Before I turn it on I would like to know if there is something I am not aware of.

If someone knows the information it will be appreciated.

Thanks and take care,

I decided to simulate the SWTPC Universal Tiger using newer high speed, high beta output devices. Here is an old thread with the schematic: http://www.diyaudio.com/forums/showthread.php?threadid=41926

It does not simulate well with the original output devices, lots of crossover distortion and so on. However, I don't trust the On-Semi models for the old devices. The newer devices make a dramatic improvement. I was only able to do this using Andy C's improved, actually degbugged, models for the output devices, thank you AndyC: http://www.diyaudio.com/forums/showthread.php?s=&threadid=20460&highlight=

I don't know if I'll finish this, but attached is the LT-SPICE model for the improved output stage. I doubled up on output devices so that it will be safe driving 2 ohm loads, and increased the driver bias current. I suggest rail fuses for protection and of course a front end is required. I don't trust the output stage for thermal stability, it should be analyzed. I thought people might be curious to see it in simulation.

Andy's models must be added to the LT-SPICE library, as well as these below. Anyone checked the mje15034 and mje15035? :

.MODEL mje15034 npn IS=3.92866e-12 BF=260.938 NF=1.02215 VAF=15.3399 IKF=0.160087 ISE=1e-08

NE=2.54491 BR=26.0938 NR=1.10885 VAR=153.399 IKR=1.60087 ISC=1e-08 NC=1.89024 RB=0.41209 IRB=0.1

RBM=0.41209 RE=0.0001 RC=0.208002 XTB=0.897431 XTI=1.39234 EG=1.206 CJE=1.61534e-09 VJE=0.698417

MJE=0.382854 TF=1.03079e-09 XTF=1000 VTF=100000 ITF=42.9041 CJC=1.04458e-10 VJC=0.441587 MJC=0.23

XCJC=1 FC=0.8 CJS=0 VJS=0.75 MJS=0.5 TR=1e-07 PTF=0 KF=0 AF=1


.MODEL mje15035 pnp IS=5.81508e-15 BF=313.373 NF=0.85 VAF=40.5017 IKF=0.897023 ISE=6.74258e-16

NE=1.04249 BR=0.958017 NR=0.894461 VAR=148.639 IKR=7.05393 ISC=6.74258e-16 NC=2.84461 RB=3.62039

IRB=0.1 RBM=0.1 RE=0.000923293 RC=0.233799 XTB=2.92628 XTI=1.01325 EG=1.17461 CJE=1.5597e-09 VJE=0.99

MJE=0.554057 TF=1.35882e-09 XTF=1000 VTF=467.207 ITF=58.3338 CJC=1.58888e-10 VJC=0.4 MJC=0.23

XCJC=0.786287 FC=0.8 CJS=0 VJS=0.75 MJS=0.5 TR=1e-07 PTF=0 KF=0 AF=1

Pete B.

from AudioAsylum

https://www.audioasylum.com/cgi/vt.mpl?f=hug&m=153563

I wish I could find a used PAP-C1... If you have one and aren't using it, please let me purchase it! I'm located in upstate NY, and will pay for shipping from anywhere (on Earth).

Thanks!!

Does anyone have a Windows XP install disk they could give or sell me? Or a copy with the password decrypted.

I need a pukka XP machine to run the software I wrote myself in da last Millenium. Yes. I've tried the various Virtual machines but none of them give me the functionality I need. To put this into perspective, I run a DOS window under Win 98 on the XP machine.

Machines that have XP drivers are all more than 10 yrs old. I found one but I lent my pukka XP install disc to a friend who promptly lost it

For sale are four B&C DE250TN-8, brand new. I bought 12 DE250s and 4 that were sent were the TN version and it's too late to exchange them. Looking to get $115 shipped each, or $425 for all four.

Hi,

I'm approaching this starting with an RPi5 & 8-ch DAC (DAC8X), I'll use CamillaDSP.

I want to pickup a stereo set of speaker woofers and tweeters as well as some amplification that will give me good sound so I can experiment with active crossovers. Budget AUD$1000.

I can solder and cut timber.

Thanks.
Richard

Hello all,

Purging some audiophile resistors used in speaker crossovers, all have a 10W power rating. Leads are plenty long for use. All are 50% or more off from retail. All include shipping/Paypal costs and will ship to USA/Canada. I will also take $100 for all the resistors listed below.

UPDATE: ALL RESISTORS SOLD!

Duelund 1R2 [black] - $15 each (2 available)
Duelund 2R2 [brown] - $10 each (2 available)
Duelund 6R0 [brown] - $10 each (2 available)

PathAudio 3.9 ohm - $15 each (2 available)
PathAudio 6 ohm - $15 each (2 available)

Thanks for reading!

Best,
Anand.

I recently could acquire a pair of Quad IIs in need of restoration for a very decent price although without the tubes. I want to share my thoughts on and experiences during the restoration and would of course like to get a few opinions.






Both amps are not very clean - pictures of one of them are attached. One of them (pictured) had at some stage the resistors and the cap on the tag board replaced. It also has an additional fuse for the power tubes. The other one seems pretty much original with all the original resistors and caps.

My goal is to keep the amps as much in an original state as reasonably possible and do not make any irreversible changes, which of course rules out any changes to the chassis and keeping all the original parts even if they are no more used. On the other hand I will do an upgrade to modern safety standards which implies proper use of mains ground amongst other things. I will not use the Quad 22 preamp.

Chassis:I will add a notebook style connector with 3 poles using a 3d printed adapter. The fuse holder will be replaced by a modern one and fitted with a 3d adaptor. A mains switch will be put in the opening of the old mains connector again with a 3d printed adapter and finally a RCA socket in place of the 6 pole connector again, guess what, with a 3d printed adapter.
The chassis must have been spray painted at some point in the past and cleaning it removes the paint anyways, so a repaint is in order.

Tag board: Here I am yet unsure if I should replace it completely with a PCB or try to clean it and just replace the components - it is really very grimy. Any opinions?

Power tube sockets: Yet unsure if I should reuse them or replace them with either screw mounted sockets or also creating a small PCB. Currently I tend to reusing them.

Wiring loom: There may be some risk of broken insulation, but I would take the risk if I keep the tag board. Of course it is also grimy....

Filtering caps: They are no more in really good shape, so I will probably create a PCB for it and a 3d printed holder which fits in place of the old canned caps.


There would. of course also be the option to create a complete new PCB with all the tubes using the original circuit and mount that together with the original power transformer, output transformer and choke onto a new chassis. But even thinking about it amounts to heresy I guess....



Toni

In this series of posts I will give an introduction to SpeakerBench. The presentation is based on a 2-part article Claus Futtrup and I wrote this year for audioXpress magazine. Rather than a general discussion, we focus on a specific application: leakage loss as identified with our proposed advanced transducer model. The advanced model is compared to classical Thiele/Small modeling, with reference to detailed in-box measurements.

Hi all, I'm new here and looking for help with my Rotel RA-611

Hello,
I am selling an AD1862 DAC board to be completed as shown in the photo for 65 euros + shipping.
The components all arrived from Mouser. The chips were purchased from Paddy Garcia on Diyaudio.
I can ship cheaply to many EU countries.
Best regards
Guglielmo

Hallo,

the forum software asks me to introduce myself, but too much talk about privacy probably isn't something I was prepared for when signing up for a forum on technical oriented talk.

Back in the 90's , I bought a pair of diy ACR Axton AX-80 that I still own. Maybe one of the highest value/price products ever made.Of course, it's not high end, it was ever easy to find even more accurate loadspeakers. But it's still getting expensive then, despite the years havin passed.

A funny detail of those speakers is the 50mm soft-dome kalotte that deforms instantly and heavily on touch, but also restores instantly.

Audio Power Amplifier, 2 Channel, ± 2.5V to ± 17V, SOIC, 8 Pins LME49720MAX/NOPB

Same chip as LM4562

Quantity 100

Sealed in cut tape and anti-static bag direct from Farnell


Hi

I don't post much here (long term lurker) but I have been on ebay since 2003 with 100% positive feedback.

These op amps were bought directly from Farnell for the refurbishment of a mixing console but it never happened so I offer them for sale here.

Price through the forum is £150 delivered anywhere in the world, payment by paypal (goods and services - I'll cover the fee). If you would rather you can purchase through ebay: https://www.ebay.co.uk/itm/285980142866

Hopefully someone will get the use out of them.

This GB is Closed.

Amplifier description and discussion -. Q17 - a QUAD405 audiophile approach to perfect sound
This is a full open source project. All documentation, source files, including gerbers, are available at github.
I had no intention to start a group buy, but I get daily mails with people asking to subscribe or to sell to them boards etc.
You may subscribe by adding your name to this google doc.
https://docs.google.com/spreadsheets/d/144EP7ZezFLFgZeNq8q8LCgoa5Lb6z94TKbopFC7S6aw/edit?usp=sharing

Please do not subscribe if you are not sure if you want to participate. Once you put your name on the list, I'll take you in consideration and when target is reached I'll go further with PCB order.
Gold plated PCB is Cu 2oz, 1,4mm thick, FR4, Black. Price per PCB is 27euro and include 2SC2240BL/GR transistors.
Other PCB's are standard Cu 1oz, 1.4mm thick, FR4, black. Price per PCB is 15euro and include 2SC2240BL/GR transistors.
All PCB's for active power supply include 2 Saligny Standard - new version.
For those who prefer a ready mounted module, there will be a very limited batch, at 250euro/module single output stage, or 300euro/module double output stage. Parts are hard to obtain, so do not miss this one.

Shipping to EU is 22euro.
Shipping outside EU is 38euro.
All prices do not include VAT and Paypal fee - for EU. I can ship without VAT if you buy on your firm and is EU VAT registered.

Thank you for your interest in Q17 amplifier. I'm sure you will enjoy at fullest.

Regards,
Tibi

I was discussing my current blues harp preamp design with my dad, and he mentioned that Borbely may have had some concern with FR4 boards...maybe a non-linearity of the material's dielectric constant with varying electric field strengths...something I wouldn't think of as being a huge issue in the audio spectrum, but...I wouldn't know.

I'm wondering if anyone is familiar with his comments on the subject, and maybe could furnish a link to an article somewhere?

Sorry if this is in the wrong place.

Hi everyone. I'm looking for information about bias adjustment.

Anybody ever attempted replacing a socketed op-amp in some audio device with a circuit board plugged into that socket? There are discreet component opamps that are available to do that if that is what you are into, but is it common to say add an active filter circuit into an existing product with this method? I was looking at a Fosi box x5 phono amp that has no subsonic filter but does have socketed opamps for users to fiddle with. Pulling that op amp and plugging in a small PCB with the same op-amp and some filtering caps/resistors around it might be a non intrusive way of modding the original circuit to incorporate added filtering stages to try out.

Hello all,

I have some NOS Airpax double pole mains circuit breakers available for sale

They are high quality, unused, hydraulic-magnetic, fast-acting, 250VAC, 7.5A breakers with an attractive white toggle

• 35mm (1 3/8") cube, push-on 1/4" tabs and requires a 12.5mm (1/2") hole for mounting
• Perfect for medium-sized, transformer input, amplifier projects
• Doesn't require drilling an extra hole and mounting a fuse!
• USD 20 ea plus postage

Data sheet: https://www.sensata.com/sites/defau...04-25/ourproducts_snapak_series_datasheet.pdf

Cheers, Ralph





https://audiofile.net.au

Hello all,

I have a NOS Lambda MB1236 Mains Noise Filters for sale

This is a dual stage Common-mode & Differential-mode noise filter for mains connection

Rated for voltages up to 250V and 36A (!) with screw terminals for input & output

Data sheet: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/1048/MB_Series.pdf

Ultimate filtering at the point of power entry to a sound studio or within high power equipment

I'm thinking USD 80 plus postage or open to offers

Cheers, Ralph

https://audiofile.net.au/

Hello all,

I have a pair of Hewlett Packard HP 17505A Chart Recorder Amplifier Modules for sale

In very good physical condition but untested. USD 40 plus postage takes 'em both

Cheers, Ralph

Hello all,

Here is a roll of NOS Hewlett Packard HP FSMC-28480 / 9270-1037 Chart Recorder Paper

USD 25 ea plus postage. I have two rolls

Cheers, Ralph

Hi,

I have purchased two REL T5 subs from a guy locally. Don't ask but I was unable to test them since he had no power cables and he was at his work so I just grabbed them. Came home and both dead. No power whatsoever. Changed the fuse, still nothing. I opened the amps and saw both amps same spot with leaked caps and resistors got bad too looks like. Talked to REL and they said "looks like those need to be changed". I have some soldering skills but not for small spots like this.

Can someone help me in South Florida (zip 33326) to fix this or at least direct me to a place with fair prices? I don't want to pay more than $50 (both) to get these fixed. Otherwise, it is not worth it for me.

Here are the photos of the amps.

BTW, the drivers look brand new. Not even a tiny issue on them.

Thanks for the help!

Hi, I'm a retired Nortel Networks engineer and now doing part time vintage HiFi repairs/restorations in the RDU area.

Simple question: What the heck? I used to be "good with computers," but now I'm not as good as I was. I know that the sample rate for the audio device is correct, and I know that there is some performance/priority tweaking that Windows 10 can do for USB devices, but I don't know where to look.

The screenshot is the result of "Calibrate Test Leads," but I see similar blue fuzz any time I try to do a resistance or impedance measurement. Using the cables provided by Dayton or any other probe leads that I have handy.

I've tried a couple of USB Type-C to Type-B cables, and each of the 4 Type-C ports. This is an all-Type-C machine, and I don't even know where the Dayton USB cable is, but I can look if you really think that's the problem. No devices attached to any other port, running on battery, same result with Windows in Airplane Mode or not.

Intel i5 MacBook Pro (iMac14,3 A1418)
Windows 10 Pro via BootCamp (not parallels)
DATS V3 (H)

I am building a 3-way system, and a friend gave me a pair of EMINENCE F151M in good condition, but I saw a pair of EMINENCE N151M for sale on the internet, would it be advisable to buy them? Has anyone had any experience with these drivers?

I have a Sony TAN-15F amplifier, which sounds beautiful, but is rendered unusable by a transformer that hums loudly enough to be very irritating when music is not playing. The seller told me that it was quiet before it was shipped to me, so I decided to take this as an opportunity to learn something about transformers. How hard can it be, right? 😉

So far I've managed to open the metal housing of the transformer, which was a pain as it was a folded metal box coated in lacquer - and held together by the lacquer, too.
The grey metal band wrapped around the core appears to be stuck in place with yet more lacquer, which limits my options for further disassembly.

I have identified that, if I squeeze hard all the way across the left and right sides of the sheet metal band that crosses over the copper strip, I can considerably reduce the hum to a level that should mean it wouldn't be audible (or at least not irritatingly so) after boxing back up.

Since this transformer isn't of traditional construction (see the pictures) I don't have an option to just "tighten everything up" in the normal way. There is a gap between the grey metal band and the copper loop - if a suitable approach would be to pack that with something, what's a suitable material? Or does anyone have other ideas for possible solutions?

Goldpoint 100k stepped attenuator populated with Dale RN55 resistors. It's 24 steps. $140, price includes shipping to CONUS.

I purchased this book from Earl, when he premiered the Gedlee Summas at the Rocky Mountain Audio Fest. Book is in good (not mint) condition. You can read it online for free, but it's nice to have a hardcopy. It's signed by Geddes. Shipping costs me about $15, and I'll sell it for $25 delivered (including shipping.)

If you live in the Las Vegas area, you can have the book if you pick it up.

I just don't want to donate it, as I'd prefer to see someone use the book, not have it wind up in a dumpster somewhere.

I've loaded a speaker driver into WinSL (which I'm completely new to) , the speaker database gave me the WinSL file to use so the numbers are ok .It's the Faital Pro 10FE200 8. 10" bass driver. I've entered "Vented" with a tuning of 30HZ to see the ports and I get results I don't understand. I always assumed that if you used two ports of the same diameter rather than one , they would be around half the length so that the volume of air they contain would remain the same. But I get double the length for two ports of 6.8cm diameter each than for one of 6.8cm diameter. It also offers a Cross Area that is half as big despite the port diameter remaining the same . And some figures are greyed out , is this simply because they are not for varying?

I recently re-capped my old SAE MK III amplifier and thought I was done with its rehab but discovered another problem. The output-protection relay contacts had become resistive and noisy. Knowing there was little to no chance of finding an exact replacement, I looked at the relay protection circuit in the service manual, and also found an online series of youtube videos describing the repair of a MK III that included replacing the output relay. In that video the original's relay coil was indicated to measure 830 ohms, which is an in-between value for a lot of currently-available 24V relays. Most are much lower, which would be a problem in terms of exceeding the manufacturer's maximum power dissipation specification (900 mW). Why do that if you don't have to? So....

I looked at a number of 24V relays from Omron but they all would require an additional series resistor capable of dissipating several watts. But the coil resistance of their 48V relay P/N LY2-DC48 is high enough @2.6K to use a 1.2K, 1W series resistor, while keeping the PD in the relay coil below the max-limit. The available drive voltage is 75V so THAT is not an issue!

It's about $14USD from DigiKey (2025 prices).

Just putting it out there for someone else now or in the future. The lifespan of industrial electrical components tends to be much longer than consumer-style devices so (hopefully) this info will be useful for some time to come.

BTW I checked the bias voltages that set the idle current in the amp's output stages. After 30+ years they are pretty close to the value given in the service manual. I can't complain about that!

A second BTW: the service manual is incorrect w/regard to the measurement points, at least in the text description...it says they are the collectors of Q13/Q14, which are the driver transistors for the output board. The schematic is correct, indicating that the points are the BASES of those transistors (but the most-convenient measurement points are the collectors of the transistors driving Q13/14 i.e. Q9/Q10). I didn't find any comments on the internet regarding this...but it has to be the case.

I am attaching a simple preamp using two NPN transistors. The gain is 350 times and the distortion is just under 0.1%. Since the no signal voltage at the collectors depends on the supply voltage, it is in fact approximately Vcc/2, this preamp requires a very clean power supply that is regulated.

The preamp tries to linearise the base emitter characteristic by using a resistor in parallel with the base-emitter junction. It achieves local negative feedback using a resistor connected between the base and collector. The preamp also uses global negative feedback.

Since the preamp does not self oscillate and is using global negative feedback without a Miller compensating capacitance, it is interesting to investigate why.

Hi,

This is my first build into the tube world and I'm currently shopping for outputs. I'm building Tom's DG300B SE amplifier and it requires 5K primary and I'd like to get 4 and 8 ohms taps. Tom suggest 15W+ outputs in the manual so that's what I'm aiming for.

Here's what I found so far and I'd appreciate all the feedback about the models/brands if you're experienced with them and I welcome any suggestions as I'm new to tube amp building.

So here's the list I've eyeing

Monolith Magnetics S-11
Hashimoto H-20-7U
SILK (SEC) S-525F
James tranformers JS-6123H (but way overprice on ePay) Unobtanium...

Thanks for your help

I found this article interesting, it might even be useful:
https://www.electronicdesign.com/te...a-comprehensive-and-speedy-op-amp-spice-model

Hello. My name is George and I am looking for help regarding service/maintenance for my Unison Research Unico amp.

This is my first pcb pretty much. Hoping to get some comments and criticisms. My main question TBD is the hammond case has a pc slot that looks tb 2mm but i dont want to pay for 2mm board right now. Will i get proper bonding between exposed copper and hammond pc slot with 1.6mm thick board?
Gerbers attached
Schematic Attached (PLLXO SCH>PDF)
Not sure how to share kicad project but i would be happy to
A chart at this sight is helpful for choosing values
http://www.troelsgravesen.dk/High-Pass-Filter.htm


Purpose
-Rca to Xlr with filter for SE source to Hypex amp
-First order high pass filters (capacitors in series array using dip sw) x12 position for both pos and neg
-General attenuation I.e. Dac--Resistor in series---amp (resistor in series array using dip sw) x12 position for both pos and neg
-voltage divider (example use case, drop dac output to just use the upper end of dac volume cntrl)
-Resistors to ground array using dip sw x12 position for both pos and neg
-Splitter if you want to to 1 xlr/rca in ---2 xlr/rca out
-Avoid buying vandersteen HPA for a pair of speakers i have

Profile
-I think i made it to slot into Hammond 1455N1601 160mm/103mm
-Height will depend on connectors and caps but the 53mm should work just fine for most everything
TO DO front and rear panel cutout sheet

to save money on build
- use jumper wire instead of dip sw
-only install a few cap/res that you know you need (or clean your floor)
-cardboard enclosure

Resistor package imp0805 metric2012
Cap footprint various from 5mm to 30ish lead spacing

Looking like an all out build with basic caps and res will be approx $200 for a pair Ie Left/Right

Shopping for a couple of transformers for latest build with and noticed something I had not previously. I wanted either 18 x2 200-300 VA. First I looked at 200 VA, and saw two types, an AS version and an AU version. Pretty sure I had AS versions in past. One type, AU stated only one rubber pad, while AS states two rubber pads.

Further confusion when I looked at 300 VA, only AS version listed, one rubber pad. As already stated, normally have AS version with 300 VA, but what up with only one pad? I must be missing something, plenty of pads around here, but I must be missing something. I have ordered scads of these transformers over the years and never noticed all this! I am missing something and I find nothing on their site explaining. Last build I ordered 18 x 2 250 VA Avel Lindberg from Parts express but the pair from Antek would same 40 bucks on the pair.

Thanks for any schooling here!

Russellc

Can anyone suggest where I could find one of these earlier Shurter fuse holders

§ The Motivation:

We have a couple of OLS loudspeakers, over 20 years old. OLS is a small company in Breda, still designing and selling loudspeakers, so they must be doing something extremely good. So, more than 20 years ago, together with a friend of mine we build 4 kits ‘OLS Emotion-III loudspeaker together. At that time, named after one of the original designers: Charles van Oosterum, who now owns Kharma, the non-speaker-kit successor of OLS. (Look at Kharma.com for their loudspeaker range) I still love my old OLS beasts, due to the Focal tweeter and Audax low-mid driver. but I found out that I needed amplifier improvement.

We had a Harman-Kardon amplifier, one of the 5 in 1 beasts, pretty old now, even without dolby. I decided to skip all these option and to turn back to basics: Back to stereo only. The reason is obvious: See attached picture 😕

First I ordered a budgetary Rotel amplifier, with some whistles and bells only to be able to play directly from a streaming server, but the sound was too cold: All the warmth was out and the mid-range sounded undefined. Again, I needed something else…

On DIY Audio I scanned around for amplifier concepts and schematics. Suddenly I clicked this link:

http://www.diyaudio.com/forums/soli...hematics-later-models-wanted.html#post1998327

(Many many thanks, tiefbassuebertr ;-)

And then I found info about the Cyrus-III amplifier. Immediately I liked the concept of the amplifier stage: It is setup extremely basic and smart: Very good designed differential amplifier/current source, followed by a voltage amplifier, which is collector coupled to a 3 stage current amplifier. A bit conventional maybe -in today’s view- but very very well designed. This design is aged in todays perspective, but it certainly can stand a good test against modern amplifiers. So I decided to look out for a 2nd hand Cyrus-III. After a couple of weeks I found one for EUR 250,- in a reasionable state. Quickly picked it up, paid for it, went home and connected it to my old OLS speakers.

I was stunned.

This is what I have missed for a long time: Warm, but extremely well defined in the whole frequency range. You can isolate each tiny instrument individually, clean, smooth, but not confronting you in an aggressive way. Here the golden combination of the Focal dome tweeter and the Cyrus-III really came to praktise: Man, was I satisfied. This is 3 years ago now. After more than 20 years in service I decided to open it up and to improve it with new capacitors. This turned out to be a very wise decision: The capacitors used were 85deg. types regular ones, over 20 years old, so near to death. After doing this I connected it back to my speakers and listened again:

I was even more stunned.

With my music choices, mainly progressive jazz: Charles Mingus, Tony Williams, Allan Holdsworth, Lester Bowie’s Brass Fantasy, from horns to drums, from piano to guitar, what a fantastic amplifier. The definition simply is amazing !

In the time being I had some friends and one customer over to listen to this restored amplifier. Today we already refurbished 9 Cyrus-III 2nd hand amplifiers: 3 in and around our house, and 4 with and for friends, and 1 for one of our customers. Now it is time to share this with you here on this forum of what we have done.

Plan is to do this in a couple of posts, hopefully with photo’s attached to show to you what we have done. The question is: Can *you* do it? Well, if you are able to solder SMD parts you can: It is actually basic stuff, replacing some caps here and there. We did not change the concept of the amplifier by itself, because we find that this stands strong, even today ! 😀

hello
i need 3d model of balance mechanism for quad33, or only model of top part and i will glue it on my broken, there is no more 3d model online i check every place, was before year or so on few pages but now its not available online anymore so need help, dont wnat o buy new part this is easy fix so need help if anyone can send me 3d model

hello,
I would like to reproduce the instruments as if I were at the opera or in a live concert. A few years ago I heard that to achieve this result you needed 16 speakers distributed throughout the room. I find that my experience with a pair of fullrange speakers is already much better than with a multi-way system on this point. In your opinion, how many speakers are needed to achieve this objective?

Bose Wave Radio has no audio output but the individual components appear to function correctly. CD player, radio, and display module work. But no audio output from radio, cd player, or aux input. Any components to focus on before going after all of the caps?

One pair 400 USD include postage and PayPal fee.

3 pairs available.

Hi Everyone,

Looking for someone with a REL T5 to check voltages on the connection between the input board and the amp. There is a 4 pin connector going from the Amp to the Input board as pictured. I need to know the voltage of the power supplied to the input board. I assume its the Red and Black cables and the yellow and which are the signal inputs for the amp.

Help is appreciated.

Cheers,

I acquired a pair of Avance 190 speaker cabinets last the weekend. I believe they date to the 1980s. The cabinets are about 96.5cms (38ins) tall, curved and tapered from bottom to top and with an angled back baffle. I've calculated the internal volume to be about 40 litres (1.4cu ft).



The cabinets are made of a concrete material and are in pretty good condition, though all the original drive units are missing or faulty.

I'm hoping to repurpose them with some full-range drive units in a bass reflex configuration and will be glad to hear recommendations for some suitable units. Not too expensive as the plan is to gift the finished speakers to a family member.

Thanks.

This plug-and-play kit enables you to install an OM 5 cartridge in place of an SP-series cartridge. The kit includes all necessary components, including a specially designed adapter that ensures a secure and proper fit.

Price List:

• OM 5S – 185€ + shipping
• OM 5E – 195€ + shipping
• Super OM 5E – 225€ + shipping

The adapter provides a simple, reliable connection between the OM 5 cartridge and your existing setup, ensuring an efficient and hassle-free installation.

Hi everyone!

I am curious how this board measures and if anyone has done any listening tests?

Seems like a nice project.

There is small input board that can accept Amareno USB, coax, toslink, and has screen wwith buttons.

I might go for it since everything together is $100 and adding PSU and case should be result in around $150 for the whole project.

Still thinking on this though

Hi everyone,
I am trying to decide between 2 speakers from Troels. To me as a novice who never built a speaker before, they seem very similar and it is common knowledge that the man himself does not answer any speaker choice questions.

The 2 speakers in question are the following two:
http://www.troelsgravesen.dk/FUSION-22.htm
http://www.troelsgravesen.dk/Faital-12-430.htm

Both of them are marketed by Troels as alternatives to the Faital 3WC-12 with deeper bass, and that is exactly what I am looking for.
But then, I have no clue based on what criteria I should make my final choice.
To me as a noob the specs seem very similar. But then I may be missing some critical difference on which I could base my decision maybe?

If it matters:

• Large living room (50m2)
• Power Amp: Hegel H390
• Primary genre: electronic music

I am working on an NAD cassette deck I picked up at a thrift store with a bad LA6458SS opamp (9 pin LIP). The only options I have found are Ebay or NTE1529. The NTE appears to be a drop in replacement but I am a bit leery, and ebay is always a gamble.

Should I go with the NTE, ebay, or something else?

Thanks

I am planning a DIY electronics project with the goal of designing an amplifier that can drive speakers with high fidelity and power for my home audio system.

I am going to use either the BD246C or TIP42C transistor as the core of the amplifier to provide the amplification needed to drive the speakers to high volumes. These two transistors look similar, does anyone know which one is better?

I have been trying to find a way to model a offset driver transmission line with coupling chamber but without success.

I can do the offset driver TL but don't see a way to add a coupling chamber.

Something like this T+A speaker:

Hey there,

I am currently learning Akabak and my method for now is to rebuild existing designs in fusion 360 and simulate them with Akabak, then comparing them with real world measurements.

While this worked out pretty good with the HD15 and the Invader-Bin, I would love to find more actionable, reasonable data to compare them with my simulations.

Maby someone here build a speaker with an accessable plan and has some measurments?
Or maby you have a thread in mind in the internet like this one: https://forum.speakerplans.com/hd15-measurements_topic105533.html ?

Cheers,
C

Hi all, I am thinking through my Av system which is predominantly old Hi-Fi and wanted to see how the gain structure works for my subs and measure how I increase and decrease gain to possibly structure in a better way.

Say for the Left speaker I go from my BR 4K player to a naim 32.5 which then goes to a mining DSP 10x10 HD (I reduce the gain by 10db to match the LFE channel which is direct into the DSP) and then this all drives 5 subs in a matrix set up)

So for say one sub from the left channel I am Xmv from the BR player which is changed at listening volume to Ymv leaving my pre amp then Zmv leaving my DSP then Tmv leaving my internal preamps in my subwoofer amp then finally Smv leaving my power amp

What is the best way to measure this with REW, the generator and which function ? my subs are only <65Hz

I found this micro amplifier with TPA3116D2 on Amazon, two boards for about $14.00!



Given the size and low cost it could be useful to replace the internal amplifier in an active subwoofer, but I have a couple of questions:

1. the first thing that catches the eye is that it has no inductors, no LC filter on the output, so I wonder how the modulation signal does not reach the speakers?
2. To use it as a mono amplifier you have to modify the chip configuration as per the datasheet for the PBTL mode I guess, can't I simply bridge the two channels? (It would be too easy! 😆)
3. Without a heatsink up to what voltage can it be powered?

Thanks

Hello,

I believe that many MarkAudio 12P Full range driver owners built Super Pensil or Bented Bookshelf Speaker Cabinet.

I am wondering if anyone has tried this Changtse MLTL Cabinet design suggested on MarkAudio 12P Product page? (See attached cabinet design from MarkAudio Website).

It is narrow but very tall and rear vented design. I thought that it looks very interesting and wondering if anyone has experience this kind of cabinet for full range driver.

Thank you and look forward to hear your thoughts.

I am using this as a single thread for my questions relating to a current driver I am making - I'm trying to design a simple class G output stage for driving current into a coil*, this circuit is used inside a larger circuit. I am trying to use an op-amp to feed the output stage directly as I don't need any signal gain.

Having amended the circuit as per stigigemla's advice I now have a working circuit but I have a couple more problems -

• The response is much lower bandwidth than I was expecting - the bandwidth of the output devices is listed as 1MHz, but I get roll off around 10KHz - what dictates the roll off of this amplifier and how can I choose transistors to push the roll off up to around 150KHz (if possible?)
• When testing the real circuit in the flesh there is an oscillation of a couple of hundred mV overlaid on the output. It doesnt seem to be feedback in the global feedback loop, because changing C1 and C2 dont seem to affect it, but when I cut the global feedback it no longer appears. The real circuit does not yet have the 0.22R emitter resistors which I will add in the next few days when they arrive.
• There is a large spike in the output when the outer transistors turn on, what is causing this?

* I have added amended the circuit pics to reflect the changes I have made and to clean up the confusing power supply labelling *

I am in my 40s and have built my first DIY speaker in high school ...

but my focus lately was more on learning than building ...

when i started i needed good speakers and thought DIY was a good way to save money ...

since then i have decided that i have no interest in building anything that can be purchased commercially and that DIY for me is about expressing myself and not about fighting capitalism ...

if you DIY to fight evil greedy capitalists and their profit margins that is fine, but to me there is nothing evil about businesses making profits and if somebody like JBL, B&W, KEF, Genelec etc. make good speakers they have every right to charge for it whatever they want even if it costs them 1/10th as much to build it.

my goal is to design speakers and subwoofers that for whatever reason the big boys failed to design. the big boys have very specific ideas about who their customer is and what that customer needs and they will never build something for which they feel there is no market. this is my opportunity as a DIYer.

a DIYer doesn't need to worry about having a market for his speaker because he is the market. this gives us freedom the big boys do not have. freedom to express ourselves.

if you disagree you are wrong but that is also your right.

I also have a pair of CELESTION CDX1-1430 in good used condition and CDX1-1747, a friend sells me a pair of CDX1-1720, I am new to the forum, I want them for a 3-way system, 1 12" subwoofer, a 10" midwoofer, and of these 3 different Celestion models, which would be the most recommended?

hew one here from croatia, right now working on my quad33

I am building an stereo amplifier using two separate mono boards. Each board accepts a max voltage of +/-55VDC. I would like to provide +/-50VDC to each board. My problem is that I am using a 40-0-40VAC toroidal transformer that, after it has passed through a rectifier board, produces +/-58.5VDC. I’m hoping there is a way to reduce this down to +/-50V while maintaining a viable ground scheme for the input voltage to each amp board.

The rectifier board has 6 output terminals: 2 – positive, 2 – negative, and 2 ground. Each amp board has a positive, negative and a single ground input for the voltage, which is perfect. I have a couple of buck regulators that nicely reduce the voltage, and I would hope to use one to power the B+ and one to power the B- rail for both boards. That raises some questions:

1. Can I use 2 buck converters total: 1 BC to power 2 amp modules (i.e. send the +50V out to 2 different B+ rails)?
2. Do I need 4 buck converters: 2 BCs for each board. Each rail getting its own dedicated BC.
3. Either way, how would I handle the ground connections from each of the BCs to the amp board? Since there is only one ground input on each amp board, I’m doubting that it is okay to connect the two separate grounds from the 2 BCs to the one GND terminal. In effect, by using the buck converters I no longer have a 50-0-50V sources but rather two 50V sources.

Side-stepping the issue of simplicity, do I need a absolutely need a lower voltage transformer (i.e. 35-0-35)? I have been running the amp from a 30-0-30 transformer, but it only provides 40V to each rail.

Many thanks,

Jonathan

Hello everyone. I'm an ex pacemaker engineering tech who worked for a company that was located about 40 miles straight south of Houston, right on the gulf. I'm 65 and have been interested in audio since hearing my first set of Maggies at Beatty's Stereo in Kansas City around 1980. I am currently refurbing a pair of 3.6R's. This is my fourth set of Maggies. Began with a used set of MG1's, sold them and bought a new set of 1.5's, traded the 1.5's in on a new set of 2.7QR's that I still have. And about a year ago, drove about 4 hours each way down to Dallas and picked up this set of 3.6R's that I'm restoring, and upgrading ALL of the internal crossover components.

I have built a pair of W frame dipole subs a la Sigfried Linkwitz, using four Acoustic Elegance Dipole 12's. Using dsp to set an 8mS delay to the Maggies, this is the best subwoofer match to Maggies I've ever heard. I've bought four of the Dipole 18's to build another set of the subs to high pass around 30 to 32 Hz, thus relieving the 12's of anything below about 32Hz. But I haven't got the cabinets for the 18's built yet. I'm just a working guy, so it took me a long time to save up the money for these expensive drivers.

Meanwhile, during some house remodeling, the midrange of one of my 2.7's quit working. Haven't got a chance to tear into it yet, cause my workspace is completely covered with this tore apart 3.6.

I think I'm going to enjoy being a member of this forum. Looking forward to hearing from you all. Will keep my progress posted for anyone interested.

Is it possible to make a very small horn to TAD 2001 with cutoff at 5000 Hz = higpass at 8-10K?


Inspiration:

Hi I have to repair BAD homemade amplifier..
a Chinese board was used, there is a scratch to the up and down of the volume,.. on left and on right obviously the potentiometer are changed, and one of channels has the transistor that don't work fine it has a very low gain.
When I detected it with a tester components, is see it as a resistance, while when measured with the multimeter it corresponds to an NPN transistor but also results in a resistance in the two terminals,
the test with multimeter.... The collector is in the middle..

The audio signal is the yellow wire, and the out of the transistor go to pin 8 of the tube.. on a cathode, then low impedance.

Someone knows something ?? Someone know some reference ? Schematic ?? Transistor kind ?

Thank you for now




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