Hello.
I would like to reason with you.
The only way I know to hear acoustic transducers that I have never heard and different from the usual and omnipresent cone magnetodynamic is to go to a specialized shop and ask to listen to AMT, tape, magnetoplanar, electrostatic, then I don't know if there is something different that is worth listening to. However, some problems come to mind:
I don't think I can find speakers that use the aforementioned transducers at full range of frequencies and therefore listening is limited to medium-high frequencies.
There is another problem:
in the shop it could happen to find speakers that make use of the transducer technologies I mentioned above (AMT, tape, magneplanar, ESl) and each of them powered by a different amplifier from each other. It might happen that you hear a great but bad speaker when used with my amp, so do I have to take my amp to the shop?

Selling a pair. In great shape. Drivers are in BIB boxes now. If you are local you can have the boxes too. Kansas City area is where I am located. These are rough MDF boxes. Used MDF I had laying around to test out a design.

Will cover shipping USPS priority with tracking and insurance in the states. Will ship worldwide if you OK paying shipping.

I am not sure what these are going for these days because I was unable to find any for sale. Make offer?

I take paypal, money orders, venmo, and I suppose bitcoin/alt coins if needed.

Good night,

I am working on a Class D amp half bridge using IRS20124s Driver and 4227 mosfets.

The B+ and B- are at 80v. The unit works but the main filter caps were blown due to bus pumping.

Could anyone advise/help to solve this issue?

Thanks

A nice pair of these maybe forgotten decent speakers. I really like them. I bought one pair to base my XRK Ref monitors on as the box size was as big as the wife would accept and wasn't a million miles off the design. It worked well with the RS225.

I never actually listened to that pair of Laser 60s. I just gutted them.

These came up on ebay and I took a punt on them for a potential other speaker project. I listened to them and was really surprised, I really like them. Makes you wander sometimes!

Anyway I need to free up some space....I just bought a pair of Laser 100...to use the boxes. Maybe I ought to listen to them!

Really nice condition generally. Worst bit being the chip in the black on the baffle.

£50

A pair of Leak 2020 speakers for sale. Very cosmetically tatty. Bought as a project that I never persued. The tweeters were damaged and so I replaced them with some Vifa full range drivers. These came from CPC and they seem unable to post drivers to you without them rattling around together ans getting damaged. Hence one has a 'mended ' dust cap. I did get one as a free replacement but that too came damaged....I gave up!
They don't look good and they don't sound great either. A project to say the least but the die cast bass drivers seem in good condition.

£30

Hi,
because of so many amps coming along i would like to build two mono enclosures as a playground for further projects. I will use one BIG heatsink for up to three channels of Nelson and / or Mighty Zen amps for my active speakers.
Sometime i will need only one channel of them for passive speaker. Is there any problem of ageing for mosfets on unused channels?
The another idea of this is to change only amplifier boards and not the power supply and enclosures all the time which is time consuming.

For sale this nice little AV amp. I used it only as a preamp feeding a 3255 power amp for the stereo pair. I used to use a Denon AV amp but the smaller footprint of this helped me squeeze more kit on my rack!
Lovely condition and come with remote and manual. The remote seems very glitch however. We only really wanted to use volume.control but that rarely worked. Nor did the power button. I thought there was a clash with my Ian Canada ESS controller as sometimes I would see that trying to change volume too. Alas it is still flaky with that turned off.

Asking £100 for now plus delivery. I dont have the original box but will be very safely packaged.

Hi,
Newbie needs help.
I use an old Audio Technica AT670T SUT where I can choose load, 3,20,40 ohm

I would like to solder my intact transformer (wounded for my EMT) but of course, no load available ;-)
How can I add this load?
Silly question, newbie I told you ^^


Also could you tell me what Dave put into the can?
See pics
https://www.intactaudio.com/images/Tran_images/SUT 300B_SM.jpg
Thanks

Hello,


This is my first post here in the diyaudio forum and I hope I am posting this thread under the right section. (Note to admin: Feel free the move the thread to the proper section of the forum, if necessary)

First about the setup:
Amplifier/Speakers: Rotel RA-314 + Hitachi HS-540 8Ohms

Turntable: Technics SL-D2 with Audio Technica MM AT-VM95E cartridge.

The problem:
Turntable is too loud (or MM input Z of the amp is too low), so that when I am playing vinyl, I have to turn the volume knob all the way down to the <1 over 10(max) so that the house does not collapse on me (ok, little bit exaggeration here).


Normally I use the amp with a media PC connected to the TV via HDMI and the 3.5mm headphone output of the TV is connected to the AUX of Rotel. Speaker out volume of the TV is at max and the PC volume (Windows 10) around 10/100 and Rotel volume is around 2-3/10.

So my aim is keeping the volume knob of the Rotel where it is and only be able to turn the source knob from aux to phono. So that I will be able to listening from the turntable while the volume (gain) of the amp is not ridiculously low and enjoying the amp a little bit more.

Until now I tried a pair of RCA inline attenuators, but they only reduced the sound quality.(In comparison to no attenuator and the volume of the amp below 1/10). I also built a box with a Pot inside and it only introduce the noise and hum. (Development goes further on that)

Now I am considering whether I can modify the input stage (preamp) in the Rotel so that I can reach what I want or not. But my electronics knowledge has been reached to its limit really fast, as I started looking into the input stage topology of the Rotel.

Disclaimer: I am neither a amp builder or an E/E Engineer. I have a basic understanding of electronics and op-amp theory (so long an opamp have 5pins), also very good soldering skills.

There is a screenshot of the Rotels preamp stage at the attachments from the service manual. It appears to me too complicated, due to the lack of experience. So is there an option for modification here? It seems like, as if I increase the value of the R701 R or R401 (for right channel), it might do the job, but I am probably wrong.

Another screenshot from the service manual is the gain diagram of the amp (also at the attachment). There I see the input is 2.2mV whereas my phono cartridge puts out 4mV. Am I also wrong here?

Back to input stage of the Rotel. I have seen some basic phono preamp designs and videos and in one of these someone told that one has to put a resistor between the ground and non-inverting input of the op amp as a driving (or load) resistor for the phono cartridge (4.7k for the my cartrige). I only see R701 as 3.3M.

All in all I am little bit confused right now and appreciate any advise or help.

Thanks and Regards,
Oz

I know there are plenty of computer literate people on this site. I've decided that it is time to create a digital version of my LPs and CDs.

I've got around a thousand LPs and about 100 CDs, I want to convert about 500 of the LPs, I don't need to re-create the LP covers as I have a pictorial memory ( I can visualise all my LPs) I have included the CDs but having recently bought a Marantz CD6007 and IMO it beats the crap out of my previous 63KI and the original 63 - it has superb CD and h/amp boards and from someone who has the same CDP the media player board is the same.

What would I need to hold 500 LPs and around 100CDs and what are the reliable brands to look out for, also what kind of life should I expect from such a unit.

The small silent PC and external SSD would be used exclusively for replaying music and nothing else.

To display my art of whistling to Mp3 music I bought Lewinner699 - Great sounding! Lewinner L 699 Professional Karaoke Microphone Wireless Speaker Portable Bluetooth microphone for phone support record TF play|Microphones| - AliExpress
The only problem with that is that its noise reduction chops the music sound at low music volume levels. As soon the Mp3 music level increases the noise reduction stops chopping the music.
It's OK for singers, yet I need to lower the Mp3 music level so that my whistling is clearly heard. Now its music level is far too high and at a low music level its noise reduction chops and cuts the sound. I contacted Lewinner technical service, but they refuse to help me, fearing I try to copy their circuit.
One way I thought of, is inserting a resistor in the music path, which decreases the music power, but then allows increasing the music volume Pot (without increasing its loudness) so that it overrides the noise reduction.

Sadly, I can only take a photo of the circuit and carefully search for the music path emanating from the TF-card driver.
I have basic electronics hobby experience. All I need is a bit of guidance on how to search for the music path so that I don't destroy anything. I'll let you know how if I succeed.
--------------

Do we know of any discussions on sonic properties of this? I haven't found much. Surely it does a little something, right?

And what about your PPIs? Seems 30ppi is readily available, is that considered good stuff for the high end crowd?

Examples:
Speaker Grill Foam Filter | Foam Factory, Inc.

The Foam Factory, Open Cell Foam, Speaker Foam, Filter Foam

WTBuy. Allo Digione or Intel NUC for music server. UK seller only please.

My Dyna/VTA 70s have a generic 1N4007 diode in the power supply circuit. I just recently saw a post that the Schottky diodes are quieter, so I wondered if it's worth pursuing an upgrade for? If so, which Schottky is a good sub for the 1N4007? Maybe a C3D06060F? TIA!

So, I managed to get all kinds of used goodies: A Dynaudio Esotar2 subwoofer, Esotar 650 woofer/mids, ScanSpeak tweeters, and a pair of Morel Ultimo TSCM 634 midranges. I've also got a SB Acoustics with a much smaller sealed box (nothing built for the 1200 yet), a JL Audio RD900/5 amp (bridged, powering the Morels and Scans in parallel, with a Clarity-Cap protecting the tweets), the little sub plugged into the sub channel, and a JL Audio RD 400/4 collecting dust until I get the wiring done and I can tune everything with the Audiotec Fischer Helix3 DSP, and its calibration mic and software.

I also have two Kenwood Excelon media players, for my Highlander, and my older CR-V (my beater). I want to make sure my wife has the most phenomenal-sounding system.

I realize the JL's are probably the bottleneck of all this, and eventually I'm going to obtain Morel Piccolos and Dynaudio Esotar 110 tweets. Question is; do I put it all in my wife's Highlander (rear fill), or would I be wasting good equipment that way for little return?

Hello lads,

will very likely get my car with no adequate sound system due to semi shortage so looking at doing it myself with dealer saying warranty would be ok. I want to use a mid and am looking at these - LaVoce FSN021.00 - 2" Full-range

Has anyone used that brand and if I`m lucky - this particular fullrange? Specs look a bit too good to be true to me.

The company is a joint venture between Elletromedia (Hertz, Audison ranges) and a Chinese producer of miniature speakers. They seem to be eager to enter the pro market but Hertz & Audison speakers I`ve had on hand and measured were worse than the stock units in the cars they`re intended to replace...

Hi guys

I am really hoping that someone on here can help me identify a problem with a Thorens TD 125 mk II TT I recently bought.

I am so keen to get this fixed as this was my fantasy TT in my teens.

There is absolutely no sign of an power on the TT, essentially it's as if the TT was not plugged into the mains.

I have a basic multimeter and basic knowledge of electronics.


I can get AC on both sides of the fuse under the black plastic cover.

Both poles of the micro switch mounted under the chassis are working.

I have read a similar thread on here but that person had power going to the strobe.


Thank you in advance of an help

Graham

(UK)

So I'm always browsing the interesting soviet parts that turn up on ebay and came across this vacuum fluorescent display tube the IV15.

IV-15 Original 100%! a-g DM160 / 6977 tiny VFD tube Soviet Magic Green Glow NEW | eBay

Looking at the datasheet its a small directly heated triode. This has me wondering what the curves would look like? What if this turned out to be an incredibly linear tube at low voltages

Just registered after randomly searching for leads on an audio issue. Saw a thoughtful post by one of your members. I have an interest in electronics, as applies to audio, but also other applications, Have not had the time to pursue this due to many life issues. I have what would probably be called a rudimentary knowledge of electronics and circuits. I know most of the language, but my skills are only basic. I have done some minor repairs to tube and solid state vintage equipment. Some of my repairs held up for a while! And so far I haven't injured myself. I own some old record players, a Rockola jukebox from 1970, a couple electric guitars, a Hammond organ, with tone generator, a solid state amp. I consider electronics and electricity in general, are good subjects to help us keep our brains from turning to mush. I find music to be the same way, both listening and playing. I probably don't do enough of either.

I was trying to add some pin jacks to my SE board and scewed something up. I took it apart and one of 1 watt, 10 ohm resistors was shot. Ok, problem solved. Nope, still can't get any bias. What should I check next? Thanks.
Ishold add that all other tubes light up,
like normal. I must have shorted something to grnd.

I have a Samsung TV with only an optical audio output. I purchased a basic DAC so that I could connect it to a stereo Receiver (Arcam A75). When I switch the TV to optical audio out, I can only hear this weird electronic clicking sound.

Samsung TV optical audio problem on Vimeo

Any idea what this problem is and how to fix it?

Thanks,

Jeff

Hi can anyone please tell what this is? Thanks

This is a development of:

PCB: low voltage On-Off switch drives AC mains relay \ includes soft start .. H9KPXG

The default behaviour mimincs the above, but with two independant outputs rather than one on a single 99x99mm PCB.

However, the use of a microcontroller allows the following additional features:

• Simultaneous or sequential switching of the two outputs
• Flexible LED control
• Infra-red receiver to allow operation from any IR remote

The general information at the beginning of the thread linked above is still applicable to this version. I have touched on the development of this version later in that thread.

This design has successfully been operating a pair of power amplifiers amplifiers for which it was originally designed. The first version of the PCB had a couple of 'non-idealities' which were easily worked around (missing relay Zeners, error in arduino footprint), which I have corrected in the version of the PCB shared.

I have also created a GitHub repository for this project, which includes schematics, BOM, firmware, PCB Gerber files, and details of operation, firmware and build, please see: my projects on GitHub

- Richard

Hello !

I want to build a pair of very good studio monitors, something like:

Barefoot Sound
Kii Three
Dutch & Dutch 8C

I need a little help. I have many questions. For the begin , let identify the drivers. (Sory for my bad english)

Kii Three:
Low = Peerless_SBS-160F35AL01-04
Mid = Dayton PA130-8
Hi = seas H1499-06 27TBCD/GB-DXT

Barefoot mm 35:
Low = Peerless xxls series
Mid = VIFA NE149W-08
Hi = ScanSpeak Iluminator R3004/602010

Barefoot Footprint01:
Low = Peerless SLS-P830667
Mid = Dayton Audio RS100-4
Hi = PEERLESS XT25SC90-04

Dutch & Dutch
Low = ?
Mid = SEAS Prestige L22RN4X/P
Hi = SEAS Prestige 22TAF/G

Amplifiers:
Barefoot = Hypex Ncore
Kit Three = Hypex Ncore
Dutch & Dutch 8C = Pascal

Looking for the internal schematic for this mic, it provides balanced output and requires phantom power. I'd just like to
understand the internal circuitry.

Pete B.

A while ago, a friend acquired a couple of push-pull RCA8000 amps.

The first time I saw them I said, "those top caps are exposed. They look like a death-trap to me".

I put a meter on one yesterday and sure enough, the exposed part of the top caps was at 560V. Less than I was expecting but even so.

Is anyone aware of where I could get some safe top caps for these tubes please? I've searched online and I've not been able to find any. Maybe the tubes were originally intended to be used safely enclosed.

Hi all-

So my BDP-S570 is acting up and I want to replace the laser (or complete drive mechanism).

Are there any reliable sources left for a part like this? Thanks...

Hello,

Fixed my Nak CA-7A preamp balance pot and broke something in the phono stage in the process so the sound is now distorted. Looking for help.

EDIT: this problem was due to swapping +35 and +9.2 V power supply rails. However, the right channel head amp suffered damages due to the swapping- see post #6.

The Nak worked well including both MC and MM phono until ~this August when balance pot began to act up then sound from the left channel disappeared. Took it apart and gave balance and tone pots (which actually are stepped attenuators) a good Deoxit cleaning. This fixed the problem with dead left channel. Also, re-checked the MC, MM and Line amps offset adjustments-these were slightly off but I got them to spec.

Attempted to fix another problem- if tone control is engaged, slight hum from the left channel is heard if low or middle tone controls were rotated past 12 o'clock to the right. Checked all connectors to and from the tone control PCB, found nothing wrong and re-flowed their PCB connections as a precaution.

When tested preamp in the system, sound from phono input is distorted with no bass and lower middle at all. This was with both MC and MM cartridges; the Nak never did this before. The signal from line inputs, tuner and tape, was perfectly fine with good bass and lower middle.

Checked offset adjustments: MC was fine; however, the MM amp offset, measured at the pin 7 of IC 102 (L. Ch.)/IC 202 (R. Ch.) is way off: -9.1 VOLTS Left/ -8.9 volts Right and insensitive to the adjusting by VR102/202 pots in either channel. The service manual calls for IC 102/202 pin 7 voltage at 10 mV (millivolts) and it was very sensitive to the VR 102/202 pot rotation. Importantly, I could set it at 10mV before attempting to fix the tone control hum. This IC 102/202 is not in the signal path but rather some kind of controller. The MC phono stage works as a head amp feeding signal to MM; this explains why both MM and MC sound bad.

So, I apparently damaged something in the phono preamp section during the "repair" process. All of the re-flowed connections were checked; fuses are fine, and the line amp sounds fine. What that could be?

Schematics is attached. Any help will be greatly appreciated.

Looks like higher prices and shortages are here for maybe good.

The Rising Tide of Semiconductor Cost - by Doug (mule) - Fabricated Knowledge

Hi everyone,

This is my first post on this forum, so your patient help is greatly appreciated!

So, this is the story of my problem: I bought a working NAD3240 with the idea of doing some minor upgrades (capacitor and thermal paste replacement, fixing broken speaker terminal). After I had done all of these steps, I wanted to do the voltage/current alignment. Going through the procedure in the manual, I discovered that there is no bias current on one of the channels. The only other debugging I did was to check all the voltage points on the schematic, but these all measured roughly correct.

In the meantime, I also ordered an 8-ohm load resistor to do some more debugging.

Please share your suggestions on what the most likely culprit would be. Where should I start debugging from?

About me and what I have available: I am an electronics graduate, however I have little experience in analogue circuits. I am interested in learning more about analogue amplifiers (at this stage the NAD in particular), so if you have any materials that will be relevant for me, please don't hesitate to share them! I am using the lab at my workplace, so I have at my disposal a scope and DMM.

Thanks for your help in advance. I hope that with your guidance I can resurrect this amplifier.

Regards,
Boris

hi!

first of all, I'm from Bahía Blanca, Argentina, and we don't have good and capable technical services here, with expertise with this amps, so I'm doing some research to solve this...or at least to find the cause, and them try to find somebody to solve it.

I own a SU-G90 amp (in my family since brand new), and after running some time, and more quickier as higher is the volume level, you hear some "electrical" sound, and then the amplifier goes to a "freeze status", turning off the following, for example: the surround (lowering the rear level), the superbass, the dat/vcr input...

After that happens, you can manually turn on everything again, and works properly for a few more minutes, and then "fails" again...

What do yo think it could be?
is that an overload issue?
is that a high temp issue?
is that a bad solder issue?

when the amp does that, i feel it hot.

I have checked it, and the fan works, and fan's speed is related which amp "charge"...higher volume, higher speed.

I will check the board for bad/cold solder joint.
Maybe I will clean and renew thermal paste.
Maybe I will add a new fan.

Any advice or suggestions are welcomed.

Thanks in advance.

Regards!

Hi All,
I am new to all of this, never before have I made a speaker but would like to try. I don't completely understand everything but I'm keen to make this Bluetooth speaker.

This is the list of parts I'm planning on buying please can somebody please tell me if this will work.
I don't have a big budget, trying to keep things on the cheap side, and because it's my first ever build if I mess something up don't want it to be pricey.

ZK-1002L MINI Bluetooth 5.0 DC 5-24V Wireless Audio Digital Power Amplifier StV7 194912630292 | eBay

QTX 3 Way Crossover - 3-way 6dB, 8 Ohms, 400W 5015972052945 | eBay

Professional 8" Inch 8 Ohm Replacement Speaker Cone Woofer Driver Spare Part 5055839136586 | eBay

Black 166mm 6.5 inch 60w RMS Bass Mid Range Round Speaker Driver 8 ohms | eBay

Piezo horn speaker tweeter piezoelectric head driver loudspeaker treble H BwZSK | eBay

https://uk.deals2mall.com/18650-3s2p...y-charger.html


Should I do this with the crossover or maybe a 2.1 amp?

Do I have to connect both channels on the amp or not? will it get damaged if I only use one channel?

Can I connect one channel to a crossover and the other channel straight into a woofer?

I understand I have a lot to learn and any help and suggestions would be appreciated.
Thank you

I'm thinking through the layout of a phono preamp, and I had a weird idea re: tube orientation. My understanding is that the rule of thumb for tube placement is to have 1.5 tube diameter separation between tubes. That assumes the tubes' bases are mounted in the same plane. I have this idea to have the tubes mounted sideways with the tops facing each other in opposition. The spacing would be fairly minimal, but allowing enough space to remove/replace tubes as necessary.

The next layer to this question is re: the rectifier tube for the same amplifier. In the same thought bubble, that tube is oriented in the same plane across the vertical centers of the preamp tubes, but 90° out like so:

_!_

Where you're looking down over the top of the amplifier, and the top of the ! is the rectifier tube. The dot of the ! is where a line drawn through the vertical center of the three tubes would meet.

An alternative to this would be to have all three tubes mounted in a ring such that it's an even 120° between each tube rather than 90° with only three quadrants populated.

How stupid is this? Would either scenario cause any issues? Accidentally solve any issues? How much separation would there need to be between tubes/types of tubes to avoid causing problems if there are problems being caused?

A third alternative would be to have the amplifier tubes in one plane, and the rectifier in another a la:

=

but I think that would result in the same spacing requirements as if the bases were all co-planar.

Hi


I am trying to fix a problem with this 8 channel powered mixer. According to my friend, he says there is a power drop. He says normally when he plugs in a line signal into the 1/4in input, with the master volume at 3/4 , he can increase the channel volume level to more then 1/2 before the "Deltacomp" yellow light turns ON. Now, with the same signal and master volume at only 1/2, the yellow deltacomp light turn ON at less then 1/2 the channel volume. I checked the 6800uf filter caps and they are within the 10% drift range. I would like to know generally what causes this clipping and power drop in an amplifier. Can someone please share some knowledge on this matter.


Thanks


Carlos

Hello all,

I was thinking of building a bookshelf speaker. I am aiming for around 500$ for parts and wanted something with a small form factor. I also wanted to try something with a ribbon tweeter as I have never built anything using them in the past. They will most likely be used on a desk as near field PC monitors to play a variety of music genres. I expect them to be close to a back wall.

Finally, I wanted to use this build as a test ground for some upcoming projects. I am eyeing the build of a small thor (modified from D'appolito's design) or Statement II's, but with a curved baffle. Current Thor design shown below.

I found a few bookshelf speakers with a small form factor, but the one that stood out for the expected use were the Speedsters by Paul Carmody shown here.

I originally wanted to use TangBand's new coax driver for their looks and performance, however cannot get them easily in Canada. So I stuck with an MT design.

The rear ported Speedsters near a back wall may not be ideal. Hence I originally thought of making one with a front slotted port like this, but the curved sides made it more difficult.

The baffle will be made from 0.5" MDF. The curved sides will be laminated 0.125" MDF. The front will be solid walnut. The rest of the enclosure will be veneered with walnut. I was looking in different finishes and liked the look of walnut although I am open to other options. I was also thinking of incorporating some metal elements or woven carbon fiber plates on the front baffle for a cool effect. These are still just ideas...

The curved enclosure kept similar dimensions, however the front had to be widened by 0.5" to 6.5" to compensate for the curve. The front is 6.5" and back 3.5" (outside dimensions). The inside volume is 0.185ft3 (vs. 0.19ft3 in Paul's design).

Before I start my build, would anyone have feedback on the following:

1. Any other speaker design to recommend (small-ish form factor, nice lows, known performance at price point)?
2. Any issues with the curve and with the wider front baffle (its only 0.5" wider now...)?
3. Any experience with the Speedster's rear pot near a back wall or any suggestions with regards to that is appreciated.
4. Any ideas for finishes to add an extra wow factor?

Thanks for your help.

Hi there,
I'm just trying to make my Fisher 500tx work again and it seems I lost or cant find the pictures I made when I took it apart. Now I'm stuck at the mpx board with all the jumpers that are supposed to be fixed on the pins on the board. I got most of them back on the pins but there are a few where no picture on the whole internet is made from the right angle to figure the exact position.
Maybe someone can help me a show me some detailedpics of the board with the jumpers attached.
Thanks a lot!!
Best regards
Arne

Inspired by the Fokin, LuFo, and SuSyLu designs I want to build a symmetric follower amp based on a balanced choke for some SuSy magic. Also, I'd like to have some tube glow for voltage gain in front. See attached circuit (very much simplified).

The LuFo/SuSyLu is a finished design of a (balanced) follower stage using LU1014 JFETs with cascodes to increase the voltage capability of the LU. However, one could also use some power SITs (like a THF51 or similar) to build the whole thing with less parts. The SITs may also perform differently in this application, but I don't really know.

I have most of the parts (THF51 SITs, LU1014s, various tubes, heatsinks) to start messing around with this, but I don't know if I should go with the SITs or the LUs. Yes, I could try both and then compare the simple THF51 vs the cascode LU1014, but I'd like to hear your thoughts on the SIT vs LU question. Which way would you go, and why?

Hi

I use two of these G2 amplifiers (one per channel) to drive two home-built ‘bass modules’ each with a single Dayton Audio DC-160-woofer. Long story short I put them (and the bass modules) in to my main system which consists of Tannoy R2 floorstanders, 2 x BK Gemini II sealed 10 inch subwoofers (one per channel), Arcam A28 amplifier, Arcam D33 DAC and Naim CDSi CD player. They really have helped with stage height, punch and music generally coming alive.

However, and it’s a big one, if the Arcam amplifier is switched on, when I switch the Nobsounds on at the wall (both switched off on their own switches on the amps themselves) it clicks the Arcam into protect mode. I did this once with the volume turned up and it sent a big pop through the main speakers + BK subs and I had to turn the Arcam off at the wall to get it out of protect mode. I have tried both Nobsounds individually and they both do it, yet nothing else does this on the same wall socket. The Arcam uses a different socket. Clearly I don’t want to damage the Arcam (which cost much more than the Nobsounds). I assume that the Nobsounds send something up the RCA cable and into the preouts of the Arcam when they are powered on at the wall, despite the fact that they are switched off themselves! I assume this is also happening when the Arcam is off but I just don’t know about it. I am concerned that the amps are not safe, certainly for those units upstream of them!

Is anyone else aware of this issue with this design of subwoofer amplifier? They do not seem to do it in my office system using a different main amp (AVA). Is there anything else I could try/do to stop this happening? I have just got the system pretty much exactly as I wanted it. The alternative is to replace the Nobsounds with something else that has an adjustable LPF such as 2 x BK electronics plate amplifiers or a single Dayton Audio APA 150. Unfortunately, short of cheap Chinese amps, we don’t seem to have the same choice of off-board LPF amplifiers in Europe/UK as is available in the USA - the OSD amplifiers don’t seem to be available for example.

Any advice on this would be greatly appreciated.
Regards
Alex

Very long time I haven't been here. After trying a full-range and finding it not to my taste I decided to go back to more conventional speakers. I had a couple of Visaton DR45 and TL16H around for years. Most obvious choice would have been the Monitor 890III but after looking at the woodwork.... I decided to go with less ambitious woofers and a simple prismatic bass reflex. Housing at about 100 liters is a bit too small for those 2 woofers. But it should give me to about 60HZ.

First try of the parts. Looks OK to me.



Speakers:
bass: 2x W250S 8 Ohm
mid: DR45 + M300
high: TL16H

Still a bit work to do. Fitting the BR pipe, wiring, bit of damping and a coat of varnish. Then the amplifiers...

I'm just not sure about the low-mid range. Having that crossover at 800Hz looks high to me.

I have a Hitachi receiver 1 with a blown channel. the transistors are one 2SA1492 & 2SA3856 per channel. The other smaller heatsinked transistors are 2SA957 & 2SC2167 one each per channel. I cannot find the outputs transistors anywhere.. Can anyone recommend a suitable drop in replacement for them? Will that require I change the smaller transistors as well? I think the smaller ones may be blown on the blown channel as well but dunno for sure.. I accidentally friend my multimeter with a microwave transformer and a poorly thought out voltage divider so I cant check em yet..

Kits arrived today -- Yay!!!

I'm sure I'll have a few more as I go along. First question -- what exactly does the optional feedback capacitor do?

I'm assuming that it trades off sound quality vs. amplifier stability? If so -- I'll drop it in. I will be hooking up to a wide variety of sources and speakers (building it for use with my keyboards); some not exactly audiophile grade.

Wes

I'm sure this has been covered somewhere but having trouble getting specific guidance on where to place ground reference for center taps using two separate transformers in tube preamp build.

The power transformer HT winding (330-0-330) feeds an EZ81 (indirectly heated) rectifier and I'm using the transformer's 7.2 v winding (has center tap) for feeding the EZ81 filament using a dropping resistor to reach 6.3V.

Since the power transformer's 7.2 winding couldn't handle the combined current of the 6 valves filaments with the rectifier filament, I'm using a hammond 18 volt transformer (has center tap) for feeding the 6 preamp tube filaments. I've read as many forum threads here and there stating to float it as I have stating to ground reference it due to potential noise

I've included a sketch of the two supplies for reference.

I'll list different options for you to look at and let me know best practice for this so I don't end up taking anything to ground reference needlessly and don't cause other problems.

18 volt filament supply feeding preamp tubes:
-Take center tap to ground bus or cap center tap and take 0 volt leg of bridge rectifier to ground bus?

Power transformer:
-Take center tap 0 volt leg of 330-0-330 winding and reference to ground bus?
-Take center tap of 7.2 volt winding feeding EZ81 filament to ground bus or leave capped?

Parts Express has this iMM-6 measurement mike really cheap. I'm wondering if anyone has any experience with it? If it is anything more than a toy, I'll give it a run.

I would like to build an amplier with GU50 Parallel Single End (PSE).
Anyone have schematic show me pls.
Thank alot.🙂

I am looking for a set of faceplates for the B&G Neo3 or an adress in the european union where I can still buy some.

Any tips, or someone have some spare, let me know

Had someone message me on ebay this morning about a transistor matcher/curve tracer I sold them.

Apparently it stopped working.
So they decided to have a scope about.
He says I have applied 24 volts to a 3.3 v reg that has max input of 16 volts.
He says that I have made a stupid mistake.

My reply is that you can apply 24 volt rail to a 3v3 reg if 3v3 reg ground is at 12 volts.
I took a 24 volt supply and split it into +/-12 volts using a class b transistor pair with a 12v zener on transistor bases.

I’m currently converting an integrated amp into a preamp.

All is good apart from the noticeable amount of hiss when I am between taps on the 250k centre-tapped volume pot.

little to no hiss at full CCW position, centre, and Full CW positions...

Noticeable hiss anywhere in between these positions.

I’m guessing this is happening because the path between the pot and the preamp state is acting more like an antenna between the taps where it’s
62.5k ohm away from the signal or ground at the 25% and 75% positions...

Would using a lower resistance pot solve my issue? or using a relay-array volume control? (I would lose the “loudness” function of the centre tap however)

I’ve tried lining the inside with copper for RF/EM blocking material but it didn’t seem to help much for the hiss. It did help for the blips and bloops coming from the Wifi router.. I’m using the LM4562 for the preamp stage which I hear is very sensitive.

The Boss 1.2 board , not including the Rpi, draws 6-8ma at 5.1 volts which seems like a tiny draw to justify a $$$ audiophile grade switch mode or linear power supply. What I'm stalled over is how much of a deviation from 5.1V these boards can tolerate. Using a Ni-MH or NiCd pack is interesting but that means I either under volt it at 4.8V or over volt it at 6V.

The website doesn't tell me what voltage range it can tolerate but it does say that there is onboard regulation. This makes we think it is regulating the voltage down to 3.3V. So I'm thinking higher is fine as the regulators will burn off the extra 0.9V if I go with a 6V battery pack. Any thoughts? Thanks.

hello! i need your inputs, why my solid audio amp has a 65v single rail voltage? it has only 3 big bulk capacitors in parallel. im thinking it will not be loud as other that has dual rail voltages. other 1500 watts amps has dual +-80v to make 1500 watts. thank u

On occasion, I've used phono preamplifiers that are powered by wall warts of the AC-DC variety, and I've noticed that preamplifiers without any rectification beyond what is in the wall wart are very sensitive to any sort of AC being picked-up by the wall wart's cord.

I've also used the inexpensive but not bad Rolls 2-way crossover. Although this unit does have on-board rectification, it is similarly plagued by power-cord induced noise.

On the TC-750 phono preamp I've been modifying, the designer included some 1000uf 25v caps on the DC input that should block any AC picked up by the cord (I think). But I've removed these because the rating was insufficient for the higher voltage I'm using (I'm running a 24v adapter instead of the stock 12v).

I do intend to determine a way to shoe-horn some 50v capacitors in there (perhaps one above the board, one beneath), but in the meantime, the device is sensitive to routing of the wall wart's cord.

And I've even figured out a way to do that, to keep it nearly as quiet as running on 24v battery (qty. 16 AA).

But I was wondering, if the problem is coupling with AC magnetic fields, would chucking the DC plug in my cordless drill and spinning the two-conductor flat cord be a possible aid in reducing the coupling? While it is a very small cord and the conductors very close to each other (which should work nearly as well as a twisted pair), I wonder if twisted, would be even better?

A more expensive option may be to use the Inter-8 weave cable, or a DIY version of it. But this would require a little more effort/expense, as I'd have to cut the existing cord off the adapter I'm using:

INTER-8® Weave Cable

Anyways, I thought it was sort of general interest as so many here have fought wall wart issues, so figured I'd ask.


I did post this over at the Steve Hoffman forum but wasn't sure how much response I'd get there, so I'm sort of "cross-posting" this here due to the more technical nature of this site.

Hello,

I'm the happy builder of two Jordan configurations:
- A modified VTL (folded for wall mount)
- A modified MLTL31 (also folded, square face)

... and I love this speaker.

Well, I loved it as the first pair of JX92S died during a party and was replaced by EAD100HD which do not have the same mids.
Since this accident I cut the VTLs at 80hz and a 12.5 inch sub takes care of low frequencies.

For a reason I don't know I'm dreaming of a pair of line arrays, that go down to something between 80Hz and 120Hz. I love the accurate placement of the Jordans and would like to try a config that gives a wider soundstage, yet with accurate placement.

I tried the JRX6 in the past and they were fantastic, but as single speaker they also died from over use.


I looking after the Markaudio CHN-50 for cost reasons (12 speakers each side), did nobody tried it ?
Will it be better than the VTLs ?

There are used everyday with TV, and HiFi listening is mostly for concerts (I like it like at the concert, so loud)

Many thanks for advise!

François

Anyone familiar with these? I ordered a couple. May use for guitar amp or something.

Basler Tube Amp Output Transformer 1500 Ohms CT - 4,8,16 Ohm 120 Watt BE32780001 | eBay

Bought Dynaudio, Morel, and Helix gear; What to do now

So, I managed to get all kinds of used goodies: A Dynaudio Esotar2 subwoofer, Esotar 650 woofer/mids, ScanSpeak tweeters, and a pair of Morel Ultimo TSCM 634 midranges. I've also got a SB Acoustics with a much smaller sealed box (nothing built for the 1200 yet), a JL Audio RD900/5 amp (bridged, powering the Morels and Scans in parallel, with a Clarity-Cap protecting the tweets), the little sub plugged into the sub channel, and a JL Audio RD 400/4 collecting dust until I get the wiring done and I can tune everything with the Audiotec Fischer Helix3 DSP, and its calibration mic and software.

I also have two Kenwood Excelon media players, for my Highlander, and my older CR-V (my beater). I want to make sure my wife has the most phenomenal-sounding system.

I realize the JL's are probably the bottleneck of all this, and eventually I'm going to obtain Morel Piccolos and Dynaudio Esotar 110 tweets. Question is; do I put it all in my wife's Highlander (rear fill), or would I be wasting good equipment that way for little return?

Is it possible to unwind a transformer 35volt and 750 VA?
Which value do I unwind it to? I have speakers with 8 ohm impedance drivers, maybe 4 ohm tweeters.

Also trying to put this LM3875 chip amp from chipamp.com together, not 100% sure how. Any good links? chipamp.com is no longer a website.
http://diyaudioprojects.com/Chip/Beast/nigc_kit-users_guide.pdf
https://audiosector.com/wp-content/uploads/2019/01/LM3875-kit-instructions.pdf

I put a chipamp LM3875 kit together 20 years ago. Sounded really good with Eton 8-800 2-ways; LPG tweeter.

I also have 171 VA 28.5 VDC transformer, but it doesn't look as nice.

Should I get a RFI power plug for this amp?
I was hoarding some for years, but I think I threw them out.

I like the finished product to have nice parts.

Hi all,

I am going to replace the laser pickup of my Naim CDX. It is equipped with VAM1205. I read somwhere that this is a Naim-tweaked version of the original Philips one, but carefully looking at it I found no sign that it differs in any way from the factory default one, except for the detail that follows that I found on other VAM1205 not Naim-related.

What I noticed instead is that the one I disassembled from the player has a 10k resistor in serie between the laser power pot and pin 14 ADJ of the TDA1302T diode amplifier.

Other parts I found around as drop-in replacement have a 0R jumper instead of the 10K resistor.

It looks like there are at least two versions of this same pickup on the VAM1205.

Are they interchangeable? I noticed also version with 10K resistor has a blue pickup slider motor cog and 0R resistor versions have a grey cog.

Just sharing this, I stumbled into a huge repository of Russian DIY projects with schematics and write ups.

УМЗЧ.РФ | Усилители мощности звуковой частоты

Looking for a minimum of 2 pieces of Maxim MAX420CPA Chopper Stabilized opamp in 8-pin DIP style. No Chinese sourced components, only those obtained from a US distributor like Digi-Key or Mouser.

Looking for a minimum of 2 pieces of Maxim MAX420CPA Chopper Stabilized opamp in 8-pin DIP style. No Chinese sourced components, only those obtained from a US distributor like Digi-Key or Mouser.

Looking for a minimum of 2 pieces of LT1010CT buffer but could really use 6. I need the T package which is a 5-pin TO-220 style. No Chinese sourced components, only those obtained from a US distributor like Digi-Key or Mouser.

Looking for a minimum of 2 pieces of LT1010CT buffer but could really use 6. I need the T package which is a 5-pin TO-220 style. No Chinese sourced components, only those obtained from a US distributor like Digi-Key or Mouser.

https://youtu.be/822Idq4uojs

All the necessary PSU voltages are present and OK, amp worked fine yesterday, today it just flashes the blue light if load (8 ohm driver) is connected, blue light is very dimly lit if no load. The basic multimeter I have shows DC spikes at output during the flashes. Any advice?

Hi !
Repairing or recapping old (circa 1970) amps and receivers, I am confused by the markings of the capacitors.
The photograph shows for instance 4 types of caps found on a Pio SA-5300.
3 ELNA and one Sanyo.
The big Grey ELNA has the markings "CEW(85L)" and 47 with a S in a circle.
The medium grey is marked "CERB" and 53 with a U in a circle.
The orange one shows "CERB" and a 51 with a U in a circle.


I suppose that the second line means a factory or some sort of a datecode.

But what is the meaning of "CEW" or "CERB" ?
Most of the capacitors on this amp are the grey "CEW"
I suppose "CEW" is the standard type (cheaper, lower quality).
And the "CERB" are higher in quality ?

But why a grey "CERB" and a orange one ?


The small blue is a Sanyo 1µF 25V marked M408.
I read somewhere that these Sanyo are solid aluminium ones.
What are the differences between them and the usual electro caps ?


And most important, what new models use to replace them ?
I like the Nichicon, but is it necessary to go to the "Fine Gold" or higher quality caps for a 2x10W amp of 1960 vintage ?
On the SA5500 are four tantalum caps, but they are not a problem, I systematically replace the small ones with film caps, and the larger ones with electro ones or film ones (if space permits).


I am on the process of rejuvenating this small amp (which was working well before) the usual way : changing all the electro caps (I replace the low voltage ones with 50V new ones, 'cause I can't stock all capacities AND voltage, and the new ones are smaller) and the PSU diodes, putting new mica pads and new gease, DeOxit on the switches, selectors and pots.


I thank you for your reponses.



.

I'm looking for a source of quality bayonet adapters for SME type headshells that don't cost a fortune, and are good quality. I see some stuff on places like parts express, but they don't inspire confidence with the pictures. Any thoughts on where to source these for DIY headshell projects?

Thanks in advance!

This started out as looking for better driver options for the V-baffle sub of the LX521 compared to the Seas L26RO4Y that the sub was designed for.

Here's a list of drivers that I either had sitting here or I could get from stock and at a reasonable price. I threw in the venerable Beyma 15K200 that I also have a couple of. The original housing can accomodate two XXLS12 in the original V-baffle if it is made about 1 cm wider (which is possible if you use thin sides as SL did with his prototype). The 15 inch RSS would probably have to live a solitary life in an S-Baffle (but it has about the same displacement as two 10 inch L26). I think it should be possible to put two 15K200 in a W-baffle and just make it fit.

I entered the parameters in WinISD to see what kind of efficiencies I'd really get, and I plotted the SPL of 1000 l closed boxes as an approximation of the FR in an open baffle.

Happy Black Friday!

I just stuffed a phono preamp board and now I'm out of PCB-mount (radial) 100uF 400V (or 450V) caps for power supply PCBs. I need to refill the pantry.

What's the current thinking on the best deal in 100uF electrolytic capacitors for tube amps? Just pick a Nichicon, United Chemicon, KEMET, Panasonic or other known good mfg and make sure the cap is low impedance/low ESR, 105C rated?

Is there an especially good bargain out there that someone knows of? Or an exceptional performer that's worth extra money?

WTB: Line Magnetic LM-216IA


thanks!

Hi guys,

End of the party sale:

CNC MM fully populated board+ power supply boards+ Talema TRTV 30212
Never connected, thus new ;-)
125 eur+shipping

Hi there!
I am thinking of replacing my old Accuton tweeters (C23 / 6) with soft dome tweeters.
I'm strapped for cash so at the time I would have identified these 3 products, but I'm obviously open to evaluating alternatives in the same price range:
Morel CAT 308
Morel CAT 328
Scan Speak D2905 / 9500
The tweeter will be crossed around 2.5k / 3K with an Accuton C79 / 6 midrange.
I aim for a natural and transparent sound, compatibly with the cost.
What do you think? I have been away from the transducer market for many years, so I have no experience with relatively recent products.
Any of your comments could be useful to me.
Thanks

Hi,

I am using big and heavy horn speaker.

When i disassemble that before, It was very difficult to put back together.

And i dont remember which wires are positive and negative.

In the case of Woofer, it can be checked by batteries, but in the case of Horn (Tweeter), is there a way to check?

I want to replace my existing JBL Studio center. I wanted a 3Way center with an AMT tweeter, but my size restraints has made that nearly impossible, so I started designing a two way instead. I liked what I saw so much that I also designed side surrounds with the same drivers.


Tweeter: HiVi RT2H-A which is sort of like a horn loaded ribbon which might sound close enough to the Mundorf AMT tweeters in the L&R mains and can be crossed fairly low at 1700 hz. This is the closest thing I can find to a spec sheet.


HiVi RT2H-A Speaker Driver Isodynamic Ribbon Tweeter Shielded 30W 8 Ohm - Audiophonics

Woofers: 2 SBAcoustics SB15CAC30-8 5" ceramic woofer- 8 ohms in 5.7 liter sealed chambers. I'm using the same mid woofers as mid range in the fronts so they should match up nicely. Here the spec sheet.

https://www.madisoundspeakerstore.com/pdf/SB15CAC30-8.pdf

The side surrounds will use the same HiVi and one of the SBAcoustics mid woofers.

Has anybody used the HiVi tweeter before? If it is good as it modeled I will go with it. I was able to get a LR4 acoustic slope with a single cap and a parallel notch filter. The mid woofers only needed a 2nd order electrical filter to match up almost perfectly. At this point I'm using traced FRD and ZMA files so it will require buying and measuring the drivers on baffles to be sure.

I don't know where I got this from, but given the discussions of late regarding (over) voltages, I thought this table of common rectifier specifications might be useful to the forum.

I have found the voltage drops listed to be a pretty accurate rule of thumb.

A couple of types are left off.

A 5W4 has about the same specs as a 5Y3, but will drop a few more volts.

A 5T4 is a metal 5U4.

A 6087/5Y3WGTB is an indirectly heated verson of the 5Y3.

There are many others.

Win W5JAG

Is this Cap Sic-Safco 470uf any good for output coupling in headphone amplifier(OTL)?

For Headphones impedance 62 to 600ohm!

It was a rainy day, so contemplating things.

Like most, I have had a long history in audio from high school days with a Knight mono tube hand-me-down to now. Spent time building my own tube, bi-polar and MOSFET amps. Learned a lot on which defects in amps played better with which defects in speakers.

I wound up with my own 60W MOSFET for many years. Used an early "Muse" DAC that had an audible improvement over even my old Rotel CD player that was very good. Sounded quite good IMHO. Better than the Rotel, Hafler, B&K, Parasound amps it followed. None of them bad, I just liked mine better. Musical and relaxed. Measured pretty well too. I have my own speakers, but they still hold up well or better than any I can afford. Seas based.

Anyway, I decided to "upgrade" one last time. I figured, next time will be a table radio in a nursing home, so have fun now. 😀

Started with an SMSL then Topping DAC as they were so highly rated. Unstable, distortion spikes, issues. Anyway, got a Schiit Asgard pre/DAC/head amp box. Very clean. Very. Then I got a Parasound 2125 amp as my old one needed re-capping, never put in any output mute or safety features. Very disappointed overall. Put them in removing my old Nalamichi ps-5 preamp. Clean, but harsh to my ears. Measures .00-something insane low distortion, gobs of power, plenty of power supply for dynamics, just not as friendly. I know, "Friendly" is not an easy to measure parameter.

Where this is going.

The new electronics are at least an order magnitude lower distortion. As time has passed, they seem better. Not sure as nice as I remember, my old stuff, but looking back through rose colored glasses et al. So the point of this thread, can we re-train our expectations for a lower distortion, or do we just naturally prefer the low order even harmonics? Have I lived with a "cleaner" system long enough it is what sounds correct now?

Or is something else at play? I remember fondly amps like the Aragon, Nak Stasis, Levinson 20 something, Roland, an early Krell, Linn, Quad, and a few others.

In my thinking about replacing the Parasound, I have listened to several higher end amps recently. One might expect as the price goes up, the differences would be smaller. Not what I am hearing.

Moon, Atoll, and Hegel sound very nice. Or I would say I don't find them to sound. Krell, Rotel, Marantz, Halo, Arcam all sounded decidedly different. On paper all are superb units. Why in the $2000 to $5000 and up range such a difference?

In conclusion, I am going to rebuild my old amp and see which I prefer. Sorry local stores, not going to plunk down the bucks for a new amp just yet. And if I do another pair of speakers, they would be my own again as I have not heard any under about 4 grand I would want to live with. 5K for speakers would not pass the WAF. She wants the master bath done first.

Hi,

A while back i was given a Lem Baby tape echo unit but without the baby..so just the tape unit.
There where written labels on the attached wires so hooking it up shouldn't be a problem..hmmm well
The thing is, that this echo unit is part of a complete unit with a mixer..so i think the tape echo was used like an aux in its original configuration with the mixer...
On the two pcb's attached to the tape unit there is a bridge rectifier + smoothing caps and at the moment im feeding it 12V AC. I replaced the old tape in the cassete with fresh new tape, cleaned and demagnetized the heads and the unit is recording en playing nicely untill the tape completes its cycle..the old recording is still there in full effect...

so no erase...hmmm

Bias is present everywhere on the heads and i get about 1 ohm on the erase head..continuity test on erase head is also okay..

So what i would like to know is what kind of AC is the tape unit expecting? And im guessing that with the correct voltage the bias would work within its specs...

Schematics would be nice..

What should be done as part of an "Inspection & Service" for an amplifier?

EDIT: I want to learn the process I professional tech would take in servicing an amp. My intention is not to make more money selling something with misleading claims. *I just want to learn what a professional service would entail*

EDIT 2: I have no intention of making a guarantee, express or implied, about the quality of inspections or service! Whenever I sell something, I like to go over it and see if anything is obviously broken or could be repaired, and I note that I've done that. I want to learn the process a proper tech would take so I can be more thorough, for my own experience and practice. When I sell something I would state what I have done, and the state the amp is in based on my testing. No warrantee or guarantee implied!

I have Hafler DH-500 that I want to sell. Before I do so I want to do give it a proper look-over. I've already given the amp a basic function test. Seems to work. My next step would be to set the bias and DC offset and see if they hold their values. I don't have a distortion analyzer to confirm the specified THD+N, although I could test some of the other values.

Hello folks!

I started working on the crossover in Xsim for my ATC SCM25a "clones" (or my closest approximation thereof), and realized that making a 3-way passive 4th order Linkwitz-Riley crossover was going to be a huge undertaking. So after talking to some folks, I think DSP is probably the way to go considering the tweaking that will surely follow.

I am a live sound and studio person, and the hifi world is a little bit foreign to me. Of course I've heard of the MiniDSP 4x10 HD, which looks like a great, albeit costly, option. My first thought was why not use something like the DBX Driverack 260 or PA2? These can be found pretty easily for a great price, particularly the former. I've used these to crossover PA systems, but never in the studio. Would love to hear yalls thoughts.

Thanks!

So I will say nothing is 'new' and the designs and ideas are probably about there but I've been on a bit of a journey to understand the technology (tubes) understand the designs and the tools.

My guiding principles are:
* Low noise
* Tube stages - with a little help from solid state if needed.
* Headphones - capable of 32ohms
* Class A / AB1
* 6SN7 and 6AS7 based

Design topologies I've experiemented at in my earlier stages:
* SE 6SN7 -> 6AS7
* 6SN7 phase split using concertina -> 6AS7 PP
* 6SN7 input -> 6SN7 LTP -> 6AS7 PP
* 6SN7 other variants of 6SN7 drivers, differential amps, etc
* Negative feedback
* 6SL7 ..
* A 6SN7 version of Marcel's Valve DAC - including driving 6AS7 PP...

So from a LTSpice perspective I feed comfortable with the 6SN7 and 6AS7 and 'ideally' getting what I want...

So with the last piece it's got me thinking of the first stage - and how could I combine common components for the Valve DAC (requires six 6SN7 for both channels).

Then last night I thought - ignore everything you have done, focus on point 1 - noise. After reading around.. focusing on low noise designs for tube amps, removal of caps, reduction of resistors, paralleled tubes, differentials, and ensuring the majority of gain happens in one stage. Some of the ideas I was thinking about:
* Max 3 6SN7s - a total of 6 triodes available
* reduce resistors, capacitors in path
* Earliest gain possible
* Parallel - increase SNR
* Differential - reducing common noise
* Cascode - increasing gain without needing a coupling cap

I found a different back end stage - balanced but given the topology and the use of non-balanced headphones I would prefer PP with an output cap plus crowbar for safety.

So this morning I have decided on this topology:


The volume control is phase based.

I've just done the first run with some guesstimate non calculated cap and resistor values - even the bias on the tubes is not correct at the moment. However it looks promising:



So I think I will continue down the path of this topology as it's looking promising without correct values or negative feedback.

Any thoughts would be welcome.

For sale what written in the title.
Asking 100€ + delivery cost
EU delivery only.
PM me if interested.