I'm a serial amp builder, and I assembled my dual mono Modulus-686 a few years back. It's an impressive beast, used off and on in various systems. With the many amps that I'm compelled to build, it's been sitting idle too much of the time. So, I've decided it needs a new owner who appreciates its many strengths.

Component list:

• Modushop Dissipante 3U 400mm enclosure
• 2 x Antek 400VA 22VAC toroidal transformers
• Neurochrome
  • ISS soft start
  • 2 x Power-686
  • 2 x Modulus-686
  • 2 x Guardian-86
• Neutrik balanced inputs
• Neutrik SpeakON outputs, plus binding posts in parallel
• Front-panel pushbutton and rear toggle, configured as a 3-way power switch (for flexibility)
• High gauge silver-coated PTFE hookup wire

Some pictures:

The total parts cost was CDN$3300, and I'm letting this go for just CDN$2200. (If you're in the States, USD$1600.) That's heavily discounted, and saves you the trouble and time to build it.

It's a heavy beast, so shipping costs will probably add another $200-300, depending on where you are. I'm willing to deliver it in southwestern Ontario, between Toronto and Windsor. Let me know if you're interested.

hi all 🙂
A little background...I come from a background of room acoustics and resonant acoustics, built electric guitars and pickups! + sound engineer and some experience in building active studio speakers

I would be very happy to hear from your experience on a subject that is very interesting to me and I probably don't understand it enough

In the question I am currently isolating all the other variables and referring only to the material from which the membrane is constructed(No need to explain to me that there are many other variables and it depends😅)

When I look at speakers from different companies and of course hear some of them, I feel that there are indeed features in terms of sound texture that are common to similar materials even when the speaker and the company are essentially different!( timber=tone color or tone quality )

for example:
Scanspeak Ellipticor (textile with extremely powerful neodymium magnet)
kef aluminum drivers
Accuton Ceramic Cone
Purifi proprietary fibre mix
tpcd
Diamond
Beryllium

In addition, the very combination with a different type of magnet affects the texture of the sound
good example is:
Satori TW29B-B Beryllium Dome Tweeter with[/B] Ferrite Magnet
vs
Satori TW29BN-B Beryllium Dome Tweeter Neodymium Magnet

Actually, what I'm trying to ask is how you look at the matter...when I try to design a speaker, my feeling is that the material from which the speaker drivers is built actually affects the basic nature! of the resulting sound, and therefore how do you combine different materials whose basic "nature" is different?

I dissasembled the amps described here for a different project:

https://www.diyaudio.com/community/threads/my-experience-building-a-drd-d3a-300b-amp.61776/

I'll be selling different parts of these amps.

Here I'm selling a pair of Lundahl Amorphous Output Transformers LL1623AM 80mA complete with custom metal shield covers.

Price is 600 Euros + Shipping of your choice.

I dissasembled the amps described here for a different project:

https://www.diyaudio.com/community/threads/my-experience-building-a-drd-d3a-300b-amp.61776/

I'll be selling different parts of the amps.

Here I'm selling a pair of amorphous C-core anode chokes from Tribute. 75H-15mA.

This is the best that money can buy. Sadly Pieter from Tribute is not selling his products anymore to anyone but OEMs.

Price is 500 Euros + shipping of your choice from Spain.

As above , new from spare/ original box

include shipping 800 USD. compatible crossover also available for sale.

Looking to buy 1 piece or preferably more of Powersoft DSP loto or DSP 4. Located in Slovenia, Europe

I was pondering this the other day: "How good are our what we build compared to what the giants build?"

There is clearly a wide range of talent here. With me being right smack at at the bottom and I'm sure some titans of DIY right up there at the top.

Having myself only heard a couple of actually high end units in my life (one was a $30k system and one was $110k) I am definitely not the best to answer this posed question. I also listened to those systems many years ago. Long before I ever built one.

I was watching the highlights reel on the High End Munich show and saw, to my amazement, that most of the featured units use the same drivers that are available to me. I see Peerless woofers, Seas Mids, etc. I did see quite a few custom drivers which I am sure are made bespoke for those builds.

Are we fooling ourselves that our builds are anywhere near the polished unit of these are they just doing the exact same thing in an incredibly fancy box (in this case, enclosure)?

Let me know you thoughts on the topic and especially let me know if you've listened to a DIY right next to a high end off the shelf unit.

Selling a turnkey set to build, for example, a no holds barred 46/47 drives 45/46 SE tube amp.
This builds an LCLC PSU, with driver decoupling by an additional LC. Signal circuit all transformer coupled with an input transformer, interstage and output transformer.

Set contains:

1x PC-3004 power transformer
2x A-4004 10H 250 ma chokes
2x A-394 30H 40ma chokes

2x TD-2 600-10k input transformer
2x A-342 5k:5k 30ma interstage transformer
2x F-2004 5K:8-16 100ma 8W output transformers

All transformers by Tamura

Asking 2600€ for the set

All transformer are in excellent condition and will ship worldwide
(if you pull my arm long enough, i might build the amp for you...)

I defer the the experts on this site: damping in a subwoofer cabinet is pointless. L/F frequency wavelengths are far too long for the damping material to have any affect, right?
Can somebody explain why almost every manufacturer of small subwoofers stuff their cabinets?
I'm sure I've disassembled more subwoofer cabinets than most and have amassed enough damping material to supply Mike Lindell.

BAF2015 Amplifier - A SIT Mu Follower, Revisited with Feedback

In 2019 I built the SIT version of the BAF2015 amplifier, with the THF-51S as the active device. At that time, that was my third solid state amp build. It started with the original diyAudio Sony VFET amp, a push-pull amp, then my second was the Michael Rothacher choke loaded L'Amp with 2SJ28.

The 2015BAF amplifier was a common source mu follower and with a 60VDC or so power supply. Being common source and mostly single ended, it also had a good amount of distortion, with second harmonic dominant. I was good with that, as I had diyed single ended triode amplifiers and preamps before getting into solid state, and they had a good amount of distortion, also second harmonic dominant, and I enjoyed that sound.

However over time I got into common drain SIT/VFET amplifiers and I realized that I preferred their lower distortion. Their distortion was still second harmonic dominant, but to my ears the lower distortion allowed for more clarity and realism in the sound. So my common source amplifiers got converted to common drain.

Recently I read diyAudio member ra7's post about the upcoming FW SIT-4 with feedback to lower distortion, and his positive experience with adding feedback to his choke loaded common source SIT amplifier.

https://www.diyaudio.com/community/...et-tdv-amp-using-2sk2087c.388926/post-7554089

So I thought, I am going to give feedback a try. Instead of Rahul's choke loaded version, I will add feedback to Nelson's BAF2015 SIT amplifier.

Adding feedback, the resistors in the feedback network increases the input impedance of the amplifier, which is also seen by the SIT. Combined with the SIT's high gate capacitance, that negatively affects the low frequency response. To alleviate that, an input buffer will be added between the feedback resistors and the SIT gate. The SIT will be biased by biasing the signal at the gate of the input buffer, as done by Zen Mod in his version of the BAF2015 amplifier, the Singing Bush. I will use paralleled J113 for the input buffer, but SK170 may also be used instead for possibly lower distortion. For the feedback network, it will be similar to the Zenductor's feedback network, with a trimmer resistor so the feedback can be adjusted. As Nelson mentioned in his Zenductor writeup, the feedback lowers the gain of the amplifier and increases the input impedance of the amplifier.

I did some LTSpice simulations and the results were promising. Of course simulations and real life results do not always correlate, but they give an indication that at least the circuit will work electronical ly.

My original common source BAF2015 amplifier was changed to common drain a while ago, and I will keep it as-is. It is currently providing great music and some heat to my room. The plan is to convert my remaining diy amp that still has perf board/strip board amplifier boards. The amp is the Zen Mod design Redneck DEFISIT, with a 22V-0-22V bipolar power supply in a FW sized chassis. The 22V-0-22V bipolar supply will be used as a +44V unipolar supply. The anticipated power output will be around 20Wrms @ 8 Ohm.

So if you have a FW style amplifier that is looking for a new life and if you have some Tokins collecting dust, this may be an interesting project. I am looking forward to building and hearing this amplifier.

Howdy,

First time posting, new dude to the site. Holy Cow, there is a lot here!!

Right now I am into upgrading older speakers for personal use. I have completed a couple CSS kits and Gr-Research kits, which have been pretty successful. Moving into more specifics and trying to get to the next level of "Rookie", the "knowing just enough to mess things up" phase.

I am upgrading a pair of AV123 MTMs, the later version with the upgraded tweeter. The first item on my list is capacitors on the crossover. Because the values are a little out of my league, is there a site or information that helps with cap upgrades.

Danny at GR-R does have kit, kind of wanted to learn a little more this time and see if I can figure out something better or different. The existing caps are:
mpt 22.0j 250v
mpt 15.0j 250v
mpt 10.0j 250v

I do have some caps from an upgrade that never happened:

Jantzen Audio 47uF 400V​

Jantzen Audio 15uF 400V Crosscap​

Jantzen Audio 8.2uF 800V Z-Superior Cap​

I will scanning the site for the next few days to see what rabbit hole I should go down, probably just increase the confusion.

Thanks for letting me hang out,

Craig

Have a pair for sale, only one alu plate stating its X5P

Sounds great but im breaking down diy projects to downsize to just 1-2 stereos (instead of like, 6).

Asking US$2000 excluding shipping which will be from Singapore

I'm looking for a schematic and/or the service manual for a Cerwin Vega A-3000 I. I would appreciate it if anyone who has a schematic for it would either post it or email it to me.

Thanks,
Adam
webmaster(at)scriptpile(dot)com

Hi, introductory post. I like to restore 70's and 80's midfi and hifi gear as a hobby.

When I tried to post (15 song album collection, post 58259, page 2916), a shadow post joined it with no way to delete the shadow, and there was no blue post' button. I tried rebooting, to no avail. I can't delete my post, either.

Hi All,

I need some advice on a particular project to fit my needs, and I expect would be useful for others. I have been using Raspberry Pi computers with DACs via I2S. These work pretty good using Moode (Thanks, Tim). So far so good.

I really would like something more portable, that could run for a few hours on battery power.

I have a transportable version using the full size Pi boards (3b, etc.). I can run it on line voltage with an internal switcher, but I also put four AA LiFePO4 batteries and a DC-DC converter to drop it down to 5v. The AAs will run it for about an hour. When the batteries are out of it, I can plug 12v into it. A bigger LiFePO4 battery (12v 10AH) will run it for about two hours, which seems surprisingly little.

Here are my requirements:

– Minimal size, whatever that means—maybe old-school Walkman cassette player?
– Run for 4–8 hours on internal or external battery power
– Run on 12v from a car
– Be able to use USB SSDs in the terabyte range, since I have a large library
– RPi with Moode or other Pi player software

I have built a smaller version with a Pi Zero W and an Allo Mini-Boss. My first thought was to use an M.2 memory module with a USB adaptor. I also included a postage-stamp sized headphone amplifier in it for a little more signal. No batteries, but a DC-DC converter and a 12v input in addition to the 5v.

I got the Pi Zero running and set up, but for whatever reason, the M.2 memory wouldn’t mount. Plan B was a 1TB MicroSD card, less than I wanted, but it did mount and compile the library. I also picked up a 2 TB USB-C portable SS drive (Crucial X6). I have been unable to get that to mount.

This small Pi player does play, but it has a loud ticking sound at about 4–5 hz in the headphones, and some scratchy noise as well. These sounds are always at the same level, so when the volume is turned up, the music gets relatively louder making the ticking somewhat less obvious, but it’s nowhere close to usable. I have shorted across the inputs and outputs of the headphone amp board, thereby bypassing the amp, and the volume lowers but the ticking does not go away. The case is aluminum and titanium with a plastic insert on the lid where the Pi is to allow WiFi signals to pass. If I put my hand on top of this, the ticking gets quieter.

The ground is not connected to the case, but when I temporarily connect either the power or signal ground (should be the same here), the sound does not change.

I have heard this kind of ticking before on RPis, and have no idea what could be causing it or how to fix it. I have a Pi Zero 2 W on order, as well as a couple of different USB cables to fit this tight space. We’ll see if any of that makes any difference. Any thoughts or suggestions of things to try?

Ultimately the goal is to come up with a workable, low-power and compact design, than perhaps design a case that can be 3D printed to make it easy for anyone to implement.

I think ceramic, but the square shape is throwing me off. It is from a Harman Kardon hk775 circa 1982. 47pF. It split apart. Small, maybe 5mm square. Service manual does not list this.

This amp uses Irfz44v in the power supply. What is the gate resistor value for these fets? All of them are so badly burned I can't get a good measurement or read the top of the resistor.

Also what are the drivers? They are marked UY and WY and appear to be sot-89 package.

$2500.
Pickup Altona north. Victoria, Australia.
Can post.
Original receipt from hifi exchange.

The Luxman CL-34. 240 volt. Selling my seperates as i no longer have the space since i moved and will be simplifying my setup.

Classic and legendary luxman preamp. One of the top made from luxmans golden era.

If you search through audio forums on Audiokarma etc This model is actually preferred over the CL-35 and CL-36. It has less noise ( extremely quiet!) , is a bit more detailed, faster and imaging is supposed to be better due to the simpler layout and superior cicruit design. Its not to tubey or spongey compared to the

CL35 and 36 but has the warmth and sparkle without compromising detail.
I would describe the sound as Outstanding imaging and depth . Smooth , clear and dynamic. The dynamics are glorious. Not overly tubey , but sweet and open without sacrificing clarity.

IT HAS ONE OF THE BEST PHONO SECTIONS EVER!

$2850.
altona north. Victoria . Australia
Can post.
2021 model.
Hugh built and assembled entire amplifier and case.
Unbelievably musical, transparent , wide presentation , Prat and clean power. I had it custom built in 2021. Only selling to downgrade as my house only needs a tiny system so this amazing amplifier is wasted in my home.

220 watt rms mosfet ss into 8 ohm class A/B
400 watt into 4ohm . Both channels have seperate boards and toroidal power supplies.

I've heard alot of amps and she really shines above them all in detail, soundstage, depth, low end grip and clean headroom. Hugh has put alot of time, love and contemplation into creating this amp. He built this entirely for me about two years ago and she is a beautiful piece of work.
Recently checked and serviced by the master himself.
Amazing low end power and grip mixed with the tube like soundstage and presentation. Many people agree it you Would be very hard pressed to find a better amp below 10k.
She will be missed.
Kind regards.

Hello everyone -
I'm going through the calculations of the late Ray Alden's excellent Speaker Building 201 book and I'm scratching my head about some of the formulae.

Specifically, in several sections on page 73 and 74, the numerator for some inductor calculations are shown as Rt, which is also used to describe the nominal resistance of the tweeter, but here the context seems like it should be Rw, for the woofer.

Of course, in cases where the woofer and tweeter are 8 ohm units, the point is moot, but if one is substituting real-world value, this could affect the resulting calculated values.

Am I missing something here?

I'm an old guy that builds amps and speakers. I've been at it since the 80s and still have the bug. I'd feel strange if I did not have an audio project of some sort pending at any given time. I currently have an ambitious amplifier project I could use some help with. I can do more research here and perhaps post more details later. I don't make very good CAD files for circuit boards. That particular art eludes me...

Hello from Toronto, Canada!

A new member thinking about DML and omnidirectional speakers. I've been reading about this here and in other places, but had not tried to make one yet, but hoping to do so.

Newbie here, been a long time music fun, but only getting into real Hifi now.

Have an Atoll IN80 to drive B&W 706S3. Absolutely stunning for vinyl.

I’ll be posting in the Solid State section for help since after three months of good daily use, my IN80 died.

See you all in the next thread,

Ark

Hello!

I am here to better understand how three capacitors, a resistor and a coil interact, which transmit the sound to a paper cone, in the hope that this understanding will help me become as human as possible.

I have no experience in electronics, I don't have testing equipment, I replace the parts by completely removing the old ones ... even if some are good ... which is abnormal, for this reason I need the advice of those who have access to the world of electronics .

I will be happy to share with you all the new experiences in this fabulous world!

I wish you all Good Luck!

Not new to audio really. I was putting systems in cars 30 years ago. I just got back into it last year after being gifted a 10" subwoofer and 200 watt amp. My how things have changed. So, just like 30 years ago, I sunk a pile of money into my trucks sound system and just like 30 years ago, I'm not satisfied but I'm building a home system instead of replacing perfectly fine system components in my truck. I designed and built my trucks sub enclosure using winisd and a little help from the 12v.com and I'm now ready to tackle building speaker boxes for my home project. The horn type has my attention for subs. I'll be posting the questions I have soon. They're already piling up. The science behind all of this blows my mind.

Hello! I come from greece and i am a university student studying accounting and finance and i also try to get into the real estate business. I came here to learn as much as possible things about audio since its one of my hobbies and also share the little piece of knowledge I currently have.

Hi,
I've just got an oscilloscope and testing amps around the house. A TPA3255 board (Chinese's wuzhi audio ZK3002) outputs its pwm at idle on both channels...(BTL mode). How can I get rid of it? Add more filters??
AP

Hi
I try to handle this tweeter. Do you thing I should keep trying to get rid of the bulge at the end? If so, any idea?
Thanks

I'm looking into a larger format CD build with a 15" woofer that must make it to 900hz or so.
I currently have a SEOS 15 and BMS 4550 that will suffice until I choose a 1.4" beryllium CD and waveguide.

The 15 inch woofer must be able to supply great midbass and I am not considering the TD15M because it has too limited an XMAX and too fragile a cone.

The two choices I am looking at are the 15 used by Earl Geddes in the NS15 (15nbx100) which has an exponential cone and the 15sw115 which has a radial cone shape with the following respective responses:

15nbx100
https://www.bcspeakers.com/en/products/lf-driver/15-0/8/15nbx100



15sw115
https://www.bcspeakers.com/en/products/lf-driver/15-0/8/15sw115



Dr. Geddes crossed over the 15nbx100 at 1000hz. To get the greater XMAX and motor strength, is the 15sw115 OK to use in its place?

First.
To feed the regulators you need a 2x15VAC transformer and rectifiers.
See first image.

The discrete regulators for positive/negative uses 5 transistors each.
The negative regulator is a mirrored circuit.
Test run shows very good data and precision thanks to 2 current sources.

Looking for any Wadia CD Transport or CD Player schematic with ST optical output.
Thanks.

Hello,
i purchased a bunch of PA drivers in the winter and finally started my build a few days ago.

my goal is to build a PA for small/medium clubs and small/medium open airs.

after some research i settled on the following setup as a first try:

2x 2-way Midtops : Conical Multiple Entry Horns with 2x Eminence KappaPro 10A and 1x BMS 4552 ND

2x Subwoofer: a custom design 4,2m folded horn/reflex hybrid with 1x 18" PD1850/2 driver

i will use a Behringer DCX2496 Ultradrive Pro and some cheap thomann t.amps for a first test phase, then hopefully switch to passive crossovers and decent amps later...

here are some pics of the first midtop being built:

























i've never worked with wood before, so don't be too hard on me please.

the stupid virus will now delay the build a bit, hard to guess when i will be able to finish this project, but ofc i'll update with some more pics and measurements once i get a chance.

please feel free to drop some advice or feedback...

cheers, lisette

Bought them on a whim and never did anything with them unfortunately. Thought about making them coax as one of the phase plugs was loose but I never pursued that either! (Plug now secure)!
£85 plus shipping

Hello,

I have a few PCB's left over from a restoration I did on a totaly wrecked Citation 12.

See attached files for schematic capture, pictures and some performance measurements made on the built amplifier.

I want 22€ for a pair of boards including shipping to anywhere in the world.

see hi rez images: Login to view embedded media

1. from various nelson pass, diy audio, and vintage restoration projects over years
2. all are new
3. only sold all together
4. will not provide any more pictures, more details or list anything
5. there are many more not pictured that will be icluded

There are a bunch of TI LM3886T and also parts for the pass F6 power supply and many many others. these are from 10 different new and vintage projects.
price $100 shipped conus as is. only friends and family.

only for sale until September 20th 2024. after that even if this post in online, they are not available.

Got hold of a Hoges rebrand ECC82 that I can't identify. Doesn't look like the ones I've got (Siemens, Telefunken, Philips, Valvo) and a quick net search didn't yield any results.

Short plate, only two plate ribs, one rectangular hole on each side of the plates. Possibly one or two seams on the top of the glass. No date codes. The number 13 is molded between pin 1 and 9 and - very strangely - there is a green print on the inside of the same spot that appears to read "BD-", handwritten. Any sleuths out there?

I am Peter age 63, buiding louspeakers starting at 14 years old. Now for over 25 years we build homecinemas in Belgium, the Netherlands and sometimes all-over Europe

SOLD - thank you.

This is an excellent condition pair of Sencore 39G292 100mHz low capacitance probes. These are the mates to the SC3100 Sencore 'scopes, but I've tested these with my Tektronix 2236A, 2465B, and Rigol DS2072A and they work great. They are bulkier than Tek probes, but if you have an SC3100 and want the correct probes, or want a good set of 100mHz probes for a good price, check these out.

Asking $60 which includes shipping (just increased again) to CONUS and PP fee.

Thank you.

Strange. I get different replies from different sources for this question. Could some kind, wise soul advise me please? 🙄

I've a pair of Bouyer RB 90 speakers (picture below) which I'd like to use as a stereo pair. They measure about 88cm x 40cm x 30cm. On the back they're marked Impedance = 16Ω, power = 80W.

1. Can anyone recommend a model and specification of Bouyer stereo amplifier that goes with these speakers?
2. Do I need to use a preamplifier too?
3. What should be the impedance of the main, stereo amplifier?
4. Does the amplifier's power rating refer to 'per channel' or 'both channels' and which should I apply here?
5. Does the amplifier's impedance refer to 'per channel' or 'both channels' and which should I apply here?

An online calculator says I need an amplifier of 72W to 96W max., but is that per channel (left and right), or for both?

In a nutshell: which model of stereo, Bouyer amplifier should I look for?

Thanks for your help.

A friend of mine and myself got hold of a pair of AUDIOLABOR SPONTAN speaker boxes. The boxes and units are in good shape, but the crossovers were heavily messed with and it appears that not much (if anything) original is there - so, we need to rebuild from scratch.
Searching for info, we found the archive page maitaineb by Mr. Andreas Schubert https://audiolabor.de/index.php/2015-08-05-14-38-29/spontan and basic tech. reference https://audiolabor.de/images/audiolabor/info/spontan-info.pdf From what we;ve understood, it is a first order with cut frequency at 1600 Hz. Not able to get info on the origin/model of the speaker units from them.
' Would appreciate if anyone has any additional data on the units or the original crosover data/schematics.

I am giving my speakers a little TLC after around 30 years of loyal service (in my possession only for a small part of this). Part one was replacing the tweeter ferro fluid. That went well and brought a small but worthwhile improvement. Part two is what seems a very simple Xover; Can you see any parts which may have deteriorated over time (coils except) or anything that you would change for a more up-to-date component? As you can gather, I don't know much about this. - Part 3 will be the exterior. Thank you.

Pair of Tamura TKS-27, in great condition

Step-up transformers for MC cartridges, DACs or input of tube amplifiers

Prim: 0 -150-200-300 / Sec: 100K

Ratio 1:18 / 1:22 / 1:25

Perfect for eg Denon DL-103, Ortofon SPU,...

Made famous by Sakuma in his amplifiers

550€

Доброго времени всем,помогите разобраться.У меня усилитель CAYIN 860 в нем стоят лампы 12ax7,12au7,6n6 и четыре ct88,в мануале что у меня есть написано что лампы должны стоять 12ax7,12au7,6cg7 и 4шт ct88,кто может мне объяснить и у кого может быть схема с лампой 6cg7,буду очень признателен.

Hi folks,

I'm looking for a simple dc protect and turn on delay circuit for a Nad 3020 preferably with pre existing pcb or at least gerbers, could anyone point me in the right direction or have info on something they use? Usable tapping point for voltage is 30.5v

I am planning to make a headphone amplifier based on LIneUp's Nawaho design.
The basic change is the BTJ output stage.
The first simulations with KSA1381 / KSC 3505 transistors at the output (all the same)

First sims are promising - distortion, stability (olg), squarewave are good.

I am thinking about the PCB design and I have an idea that worked perfectly for me with the headphone version of the Cello amplifier

A dual-mono design with two independent stabilizers, two transformers and only one common ground point - on the headphone socket

The power supplies are also based on the Lineup design
Proven in several projects and work great

What do you think about this design?

Do you have any suggestions?


Regards

I am in possession of a nice pair of modern full range field coil speakers.

I've been advised to build a passive power supply for the field coils, about 10V supply. Despite that I am really impressed how efficiently 100Hz ripple is suppressed by these passive PSUs, there are two things that are missing in such a supply, current regulation and current stabilisation.

The field coil has the inductance of 200mH, Rdc=11 Ohm at 20 °C, however it might rise to 13.6 Ohm when the copper wire reaches 70 °C.

According to Faraday's law the magnetic flux is proportional (before saturation) to the current flowing through the coil. And if we apply the constant voltage, and when the Rdc rises the current will slowly drop. So at first I thought about the traditional CCS, so constant current, constant magnetic flux, but I didn't think about the fact that the voice coil electromagnetic field will induce the current in the field coil, so CCS would instantly countreact to the current change and would have a negative impact on the sound.

So I added an opamp integrator and a low pass filter with a very low cut off frequency that slows down the process of adjusting the field coil current of a few seconds.

I know it's not rocket science, a capacitance multiplier, it's actually quite simple, but still it has a low output impedance, no instant feedback, flat frequency response to the EMF from the voice coil, I compared it to the dedicated passive PSU and it's almost identical plus regulation and stabilisation. I know that using these two stages is an overkill, the second would do the job but I like it that way. The Sziklai pair would have a smaller voltage drop across the power BJT (so smaller power dissipation), but I was worried about the oscillation so I used Darlington.

However, maybe I am missing something here, I am not doing electronics on a daily basis so maybe more experienced colleagues could help me find some weak spots, some improvements before I start designing PCB.

I have added LTSpice simulation for anyone who would like to use it as it is or do some changes.

Hi folks. I would appreciate you to check my logic before I buy the parts.

I have a CLCRCRC power supply for my Luxkit A3600 amplifier. The first amplification stage (the last RC in the power supply) has a 100Kohm plate resistor and needs about 15uf capacitor to provide the low ripple I'm after. To achieve it, I have a 3x 15uf multi-section capacitor. I will employ one section for the driver stage, which leaves me two sections for the input stage - an opportunity to split the supply for the right and left channels.

I have some questions about how to do this as I would need two:

1. dropping resistors - I go from one 100Kohm plate resistor to two 200Kohm resistors to keep the plate voltage the same?
2. capacitors - I presume going from 1x 15uf to 2x 15uf in parallel means the ripple rejection remains the same?
3. bleeding resistors - I go from one 330Kohm resistor to two 660Kohm resistors to keep the voltage divider the same?

Actually, I am an old member, but I cant remember the account data
I am into valves and diy speakers
In this moment I would like to see what other members work in field coils

Hi folks,

I am looking at diving back into tube amplifiers and am seeking recommendations of where I should start to look. I am happy to look at completed amplifiers or kits and have a budget of around $2000. Low power amplifiers are fine as my speakers are around 91db and very easy to drive.

So any suggestions to start me back on my tube journey would be very much appreciated.

Thanks

Brendan

Selling my NAD T975 7-channel power amplifier. Fully working, i have used it few years multiple hours daily without issues. Beautiful confition, only slight scratches on top, see pictures. All the details here: https://nadelectronics.com/product/t-975-seven-channel-power-amplifier/
140w rms all channels driven @0.03 thd.
I have used it on actively crossed 2ch system but recently switched to passively crossed system and no longer have use for this amplifier.
Sounds awesome, class A drivers, class AB power stages. Densitivity can be adjusted separately for each channel.
Stable down to 2-ohms
This amp weighs a lot but I can send it safely to almost anywhere.
Price (final price) 500€, it's a bargain and not negotiable.

(x-posting from a few other sites)

EL84 Push-Pull amplifier with premium parts.

I built this amp as an end-game EL84 amp for myself but have power-hungry speakers that require more power so would rather sell it to someone that can enjoy it.
It is built using the Tubelab Simple Push-Pull PCB, with high quality parts such as a Hammond power transformer and choke, and custom made Sowter transformers with 25% UL tap which is optimal for EL84.

Solen PP film and foil coupling caps, Furutech input RCA jacks and Tellurium copper binding jacks.
All tube sockets (6x 9-pin, 1-8 pin for rectifier) are high-cost, Japanese made Amtrans ceramic.
Chassis is 3mm aluminum, CNC milled, powder coated and laser engraved by Landfall systems.
Output power is clean up to 10W.

I measured the amp with ARTA software and it is flat all the way down to 20Hz.
It has switchable 4/8 ohms, but uses full bandwidth of the transformer in both cases due to the 4 secondaries that is standard on the Sowter transformers which leads to great bass.

It has a single input with no volume control so is intended to be used as a power amp with an external preamp.
Asking $1200 + flat $30 shipping, which is below the cost of parts.

NOTE: This amp does not include tubes. I can include a premium, top-of-the line tube set, fully matched with a curve tracer at an additional (reasonable) cost.

Hi all,

Pondering doing the crossovers in a set of L300's to the Pass design.

Some things are not clear to me:

The reverse phase of the midrange. I believe a lot of JBL woofers are reverse phase from standard, not sure of the high frequency drivers being in proper phase either. There is no mention from Pass regarding this, and I have some concerns about that being taken into account. Because if not, then the woofer and mid may actually be wired in phase with each other. Curios if Nelson could answer this?

Also, he mentions we can use the original Lpads, but the revised NP schematic shows using 8 ohm Lpads for the mid, where the original midrange Lpad in the cab is 16 ohm. So another point of confusion for me.

Anyone have any experience with the Pass crossover in the L300 that can shed some light? @Nelson Pass ?

Thanks very much
Paul

All 8 transformers for $375 (shipping to CONUS included)​

These transformers were used during amplifier prototyping.

Because we were experimenting with various filament voltages, we spec'd these Monolith Power Transformers for two B+ secondaries (375-0-375 and 275-0-275) with no filament windings.

We have been running current hungry damper diodes (4 of them), with each one drawing 1.8A, and hence that 12A filament transformer.

Here are the details:

• 1 pair Monolith Power transformers: 120V primary, dual B+ (275-0-275 & 375-0-375)
• 1 pair Hammond 167L12: 12.6V/2.5A
• 1 pair Hammond 167T6: 6.3V/12A
• 1 pair Hammond 167N6: 6.3V/4A

The leads on the Monoliths are all original length (about 11"). The center taps on the filament transformers were snipped and the leads are various lengths.

Thanks for looking (scroll down),
Thom

One Ha114

30K pp to line

150 Euro plus shipping

I swapped dacs and no longer need this device.

This is a great unit if your dac does not have asynchronous USB and you want a solid converter to coax or aes.

Was $500 new 10 years+ ago and cheapest one I saw recently sold for $200. How about $175 and I’ll ship it for free anywhere in the CONUS.

No original box or cables will be included.

My friend gave me a Parasound 2125 in a trade and the unit plays music fine but the standby mode won’t engage.

As soon as the amp is plugged in it turns on and pushing the standby button won’t engage it so the unit is always on.

Hoping to get some help on where to look and get the amp working right.

I attached the schematic below.

Hi All,

I am the original purchaser of a Hafler DH-110 preamp and an Amber Series 70 amp that are both in pristine condition although they have been out of operation for several years. Given their age, I am fairly certain I'll need to do some level of restoration - recap. I started looking into this and found some interesting threads specific to the Amber here at diyAudio and thought I should join.

But I'm really here because a couple years ago I got the bug to get a beautiful Marantz 2230B working again. It had been in my garage idle for over a decade and needed help. I did a minimal cleanup and quickly realized I was over my head, needed help and found a great tech that knew vintage Marantz well who completed the job. Meanwhile I needed speakers for this vintage setup and picked up a pair of B&W CDM 1SEs which I cleaned up and replaced the ferrofluid in the tweeters, bringing them back to life. Not long after I upgraded my turntable, purchasing a classic Linn LP12 which is currently a basic unit that I've managed to collect a few very reasonably priced components that should result in a nice upgrade in sound. I've built this system on a very limited budget by being willing to put some sweat equity into each component. Hopefully I can learn from the folks here with more experience and contribute some along the way.

Have a vehicle that doesn't have Bluetooth, the head unit is integrated with the climate control at the hardware level making it difficult to replace. Is there a Bluetooth adapter that could be connected inline with the rca line output from the radio then to an amplifier available? I need to use my phone not just to stream music but for calls the adapters I see just give you either an FM output which means I would have to leave the radio on a particular frequency which wouldn't allow me to use it normally or has an aux out which I would switch to when needed both these options wouldn't really be flexible. Need the radio to play normally then when a call comes in its muted and I can just press a button and answer the call.
Any suggestion would be appreciated.
Thanks.

Hi,

For a while I've been deep diving in refurbished ESL 63/988 (can't afford any of the successors). Aside from the numerous debates between believers and non-believers, I'm a believer... I'm a particular fan of the staging depth and transparency of the quad with concentric delayed rings on the stators. The only issue, for me, is the height of the stereo image. I find it simply too low and my room does not allow for raising them sufficiently, due to a slanted roof.
Now here comes my question: Did anybody try to switch the "mid-high" panels on top of the 2 "bass" panels (in case of the 4 panel variants)?

It seems so obvious... but I can't find any information of this "tweak" being done before by someone. Or am I a total shmuck overlooking some fundamental aspects...?

Please feel free to share any thoughts/experience.

Many thanks!
M

I just finished building the Aleph JZM and it's sounding great! Thanks to this community for helping me getting it up and running. I currently have a 10A fuse at the IEC as per the instructions. I notice that on the First Watt site, it says a 3A fuse can be used. I'm wondering if I can use a different value fuse from 3A to 10A without any issues?

thanks

Hi El Donkey

I have one of these amplifiers (Beard AS P50 Power amplifier), and both meter lights are out and would like to replace meter bulbs. Have scanned unit but access to replace bulbs perplexes me and really don't want to disturb things unnecessarily to access. Did you ever manage to replace the meter bulbs yourself ... and if so how? I was hoping the amp designer would see this as a servicable part and allow relatively easy access?

PS my P50 amplifer also hums a little (not intrucively and only slightly noticeable when no music playing)) but I (no expert) just accepted this as transformer generated noise which was part and parcel of a vintage valve amplifier? The sound it produces in my humble opinion greatly outweighs the faint hum. Had amplifier for about 30 years but not from new so no idea if there was no hum when new.

Any tips on meter bulb replacement for this amplifier greatly appreciated.

I have a Beard P50 power amp. Its part of an all valve setup feeding a pair of rebuilt Gale 401s

The P50 was aged when I got it. I first recapped most of the signal and all of the psu sections.
Bypassed the input level pot
Fitted Mazda tubes and GEC KT88s

It has ran for a few years of light use since (tubes don't have many so hours on them).

It does still have some low level hum but not sure if this unavoidable. It can be heard when close to the speakers with no signal playing.

I previously looked at this, added a balance pot as per instructions on here to the AC heater lines. Adjusting that did not do much.
I also fitted a few diodes to lower the heater voltage by 0.6v as due to running an isolation transformer my incoming mains is a shade high.

Not sure what the source of the hum is.

I will be taking another look at the amp in the coming weeks. I still need to fix the panel lights but have not figured an easy way to access those as sandwiched between front panel and chassis. Not sure if removing the rack mount handles and all panel knobs will release the front panel or a chassis strip down is required. Lots of hidden screws that would be invasive to reach.

I have new diodes ready to replace the 240v input rectification. Just as an age replacement and better spec.

Any aged looking resistors I replaced when did the caps.

My next thoughts are the signal wires.
These run from the rca's at the rear to the front of the chassis. They are solid core, layed neatly on sticky pads but not twisted.
I will check to see if the path can be improved/shortened.
Thoughts on these please,
try new twisted signal wires? If so what type.
I want to order any bits I may require first. I will then post pics for any further advice. I may have some earlier ones I can dig out.

Another mod I was thinking was to add some extra caps to the large psu items I replaced. I gather the P80 version of this amp had these but have no diagrams for either despite several attempts to find any. The Gale 401s like some grunt to wake them up so maybe lots of reserve in the large caps would be useful.

All the tube sockets are original. I nipped in the female legs rather than replace last time. I don't get any of the rustling leaves sound so assume they are not a weak point sonically as is.

Thanks Rob

Hello everyone, I recently started doing DIY, so I hope that I can learn something new from the older and more experienced members, and if I get stuck somewhere, you will help me.

Hi, from Wellington, Aotearoa/NZ.
I recently took up DIY electronics and have been lurking here a while but hopefully I might be able to contribute and get help.

Hi I am a new member. I was a ham operator for years, mainly working with Airforce MARS. My license K1GZH has expired, but still tinker a bit. have been given some old equipment, and would like to get it working

Hey guys ,
Happy to join this forum.
happy to help about analog and digital projects.
also seeking some helps about how to get working cheap chinese boards =)
Best,

Hi forum,

I’m a professional artist (painter) with a HiFi hobby that took a back seat to health, and because it’s America, selling a lot of my gear to pay bills. I’m better now and looking to repair some pre-sickness gear and build some speakers. Things I make tend to look good and have questionable functionality!

Has anyone measured the new production EL34, 6CA7 and KT77 tubes? Mainly I'm taking a shot in the dark hoping the tubes are great for HiFi use. Some measurements would be great.

Like it says on the tin. Is there anything like this out there? The only one I can think of is the one from SB acoustics. Other than that, I'm stumped.

Hello !

I'm replacing the opamps on a Rotel RC-850 phono stage. The replacements (LME49710NA) have a lower maxium voltage spec, 36V rail-to-rail vs the 44V of the preamp's stock NE5534 and NE5532. The power supply output is +/- 19.4V. It is a simple bipolar PS using a 20V zener reference and voltage follower (schematic below).



I plan to just swap the 20V zeners (D908/D909) with 16V ones. This will be perfect for the phono opamps but the line output and headphone op amps will now see +/- 15.4V and +/- 10.1V respectively. The latter is a bit low but I can probably adjust it by reducing the voltage divider top resistor R908 feeding the voltage follower supply to the headphone amp. For reference the relevant schematics sections are attached.



What are the effects of reducing an opamp's operating voltage in general? I'm guessing less headroom would have an effect on signal to noise ratio, but I believe +/-15V is sufficient for a line amp, as it is a supply voltage often seen for opamps?

That being said, the NE5532s might get the upgrade treatment as well at some point, so I will choose parts suitable for the lower voltage rails then. For the moment I'm only concerned with the phono stage performance as I only use it, directly through the tape loop output.

Hello together,
can anybody please confirm that I can use a PurePi II (with RPi and co.) and switch it on and off by cutting the 5V usb-c power supply? When I read the manual correct it should be possible.
Would you recommend a RPi4 or RPi5 with the PurePi II? I‘ve read that there are problems with powering the RPi5 over GPIO.
Would you first invest in an better SC-Pure clock or an IsolatorPI III when using a Transport Digi II?
Thanks a lot for your help!
(Yesterday I’ve tested RPi with Gentoo Player connected to RME Adi2 Pro and I was blown away by the 3D soundstage and micro details…now I want to build something witch is using the I2S of the RPi)
Thanks!

Anyone attending Pacific Audio Fest today?

Inspired by this thread........ https://www.diyaudio.com/community/threads/covers-that-are-arguably-better-than-the-originals.7546/

I have heard John Cougar Mellencamp's version of Wild Night, a great Van Morrison song, one too many times. He should remove it from circulation, if that's possible.

Original

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Travesty

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I replaced the capacitors and transistors on this driver board and would like to set the bias. Can it be done with the information given in the schematic? If yes, what would the test points be?

* newbie alert ! * Please be specific regarding placement of positive & negative leads of the DMM as well as AC or DC voltage. Thank you.

.

For sale:

Bokrand Sonoro 12" tonearm with headshell and phono cable (wired up to the headshell)

This is Alfred Bokrand's most recent model based on the Ortofon banana tonearm. Previously, this model was called AB-309

Due to the considerable waiting time and the not always easy situation with Bokrand, I had already taken a different route, so I am putting this tonearm up for sale.

This is a unique opportunity to get a Bokrand arm, because who knows if he will ever make more in the future...

SOLD