[UntilThen]

I can guess whose Telemachus it is.

 

[SonicTrance]

Very very nice! Now my Telemachus will have a brother across the pond! I absolutely love that volume knob. Please PM me the source! Also, why do those output transformers look bigger than mine, lol??

The transformers are bigger than yours because yours are custom made. They don’t need to be bigger than that but Sowter doesn’t offer custom services anymore.

 

[baronbeehive]

No, just lightning and kites…

... and steam. So this has to be permanently moored outside of UT's house:

.

 

[baronbeehive]

Yes you can use any 5V rectifier with a heater current 3A or less and 200+mA of output current.
The rectifier tubes have different amount of voltage drop across them which will alter the operating points for the audio tubes. Sound will change some with operating point.

Will be interesting to see the effects on sound, whoever has the amp in the UK... not me sadly! My amp's makers, the LD, opted for SS rectification.

 

[DecentLevi]

I had an exciting time all week trying my new output tubes Psvane KT88 T mk2 'TII' imported from China brand new and tested / matched. Out of all my input tubes, I found the black metal RCA 6N7 (VT-96) to sound best which I can run as a set of two in my special amp configuration (in the 6J5 sockets); then with RCA black metal 6J5 coming in second - above all 9-pin octal mini's, GEC L63; and a couple 6SN7's sounding great. Don't get me wrong the GEC L63 is no slouch, it was just a matter of synergy of which these seem to be picky with. Overall this Psvane, which is said to be the best of new production KT88's sounded quite full, resolving, great resolution and very good balance of all elements!

I then came back to the EL12 Spez (Tesla) output tubes to compare with some of my favorite input tube combos on the former. Immediately I'm elevated into a new audio world, where speed, clarity, and resolution are king and 'analogue' reigns supreme. Maybe a bit less bass quantity, but better quality and PRaT... making the Psvane KT88 sound a bit 'crappy' at this point. Next up was one of my two pairs of NOS tested / matched EL39 output tubes and folks this tube is a force to be reckoned with. A downright enchanting sound! All the former attributes but now with a slightly sweeter, smoother sound and more well rounded sense of timing and tone. Also these do and have had the quietest background of all my tubes, even more than the new KT88 and EL12 Spez.

Those tube designer folks back in the 1940's really had something going, and may not ever be outclassed.

Disclaimer: The above are IMO, and my opinion is likely to change depending on up/downstream gear upgrades.

PS - ignore the white ferrite clamps on the EL39's. They're not really doing anything on that placement, but I left them on for evaluation.

 

[Isaacc7]

The dual power supply is an interesting feature. My priors tell me it shouldn't make much difference but I guess there's only one way to find out, will be interesting to hear about any differences that are heard.

@SonicTrance really is a flexible builder. He certainly has been accommodating to me! A huge number of variations have been built so far but I don't think anyone has done anything with a pet bugaboo of mine, the volume control. It can have a big impact on the sound, it's a variable resistor that the signal has to pass through after all. I'll get to the sound quality aspect in a second but I'm surprised I haven't seen any remote controlled volume so far. That is a must have for me. Even if I were using headphones the headphone amp would be in my system rack. I'm not going to walk over to the system to adjust the volume. What am I, some kind of animal?

This post summarizes the different kinds of volume controls out there. He makes an LDR based product so he is biased towards that.

https://tortugaaudio.com/whats-wrong-with-audio-volume-control

There are remote controlled stepped attenuators, my Freya+ has one. And transformer based volume controls can even add gain as well as attenuate the signal. I avoided the whole problem with my Ultrasonic Studios amp by not having a volume control at all. If I did, I might explore the possibility of using an LDR based remote controlled one. They aren't all that expensive https://tortugaaudio.com/product-category/diy-preamp-components/ and are bound to offer an improvement. If I hit the lottery I might try something like https://intactaudio.com/atten.html but with the cheapest one starting at $720 it would be quite an investment.

Anyway, just thought I'd share my audiofool opinion on another potential tweak for your custom amp.

 

[Capunk]

Quick update on my situation :
I have found a temporary solution (despite I didn't have a chance to visit the shop to test it over there) to buzzing noise over pre-amp mode,
So basically due to bad wiring/electricity in my house, Oblivion constantly buzzing through pre-amp mode and even from headphones out.
I tried iFi Groundhog+ and tested in different electricity outlet with no differences.

But today, I tested with an electronic stabilizer (Automatic Voltage Regulator (AVR)) and the audible buzzing noise is gone!
just to make sure I'm not insane, I also switch back to the normal electrical outlet and the noise is back.
However just one catch, there was a subtle noise that was normally found on other amps if you set the gain to high, this was minimally audible through speakers but hard to distinguish if I use headphones (HD800 or Diana V2).
It's not completely silent but this is so far the best progress with this amp.

Current test setup :
- Denafrips Ares II DAC
- Audiolab M-PWR Power Amplifier
- Audiowalle TP2000 Power Conditioner
- APC AVR / Stabilizer
- Siemens EL81 tubes x 4 / Teonex 6AT6 tubes x 2

 

[UntilThen]

I'm just so glad that electricity down under is so bloody good.

 

[mordy]

Quick update on my situation :
I have found a temporary solution (despite I didn't have a chance to visit the shop to test it over there) to buzzing noise over pre-amp mode,
So basically due to bad wiring/electricity in my house, Oblivion constantly buzzing through pre-amp mode and even from headphones out.
I tried iFi Groundhog+ and tested in different electricity outlet with no differences.

But today, I tested with an electronic stabilizer (Automatic Voltage Regulator (AVR)) and the audible buzzing noise is gone!
just to make sure I'm not insane, I also switch back to the normal electrical outlet and the noise is back.
However just one catch, there was a subtle noise that was normally found on other amps if you set the gain to high, this was minimally audible through speakers but hard to distinguish if I use headphones (HD800 or Diana V2).
It's not completely silent but this is so far the best progress with this amp.

Current test setup :
- Denafrips Ares II DAC
- Audiolab M-PWR Power Amplifier
- Audiowalle TP2000 Power Conditioner
- APC AVR / Stabilizer
- Siemens EL81 tubes x 4 / Teonex 6AT6 tubes x 2

“If they make it, it hums.” This kind of noise when the gain is very high and too loud to listen is a reality by me. If tubes are quiet at such unlistenable levels it is an exception.
But I don’t view it as a problem because you normally cannot hear it, and even if it occasionally is noticeable, it is usually masked by the music.
Apparently, in some countries the electric grid is much more quiet and this is less of a problem; could also be related to 110/220V grids.

 

[baronbeehive]

It is possible that it may be picking up noise that is not filtered out as it would be by lower gain and greater GNFB, ie. the amp is supersensitive to frequencies that would not normally be a problem.

 

[DecentLevi]

I've really got my mojo on now. Incoming yesterday was Chord Electronics Mojo 2. I'm getting a SPECTACULAR, even 3D experience, and this is a master of all aspects! Tried with headphones directly, but with the Finyssey amp the experience is taken to a full new level in every dimension. Coming from an iFi DSD Black Label it's no comparison, and by my distant memory of the Chord Qutest it comes darn close, and at around 1/2 the price, not to mention ultra portable. Powered by my custom DC LPS and fed ultra pure digital coaxial signal with my Audio-GD DI-20 (DDC / digital interface) and a series of 2 USB purifiers it's getting along mightily well. My HD-600's have never sounded so good.

 

[DecentLevi]

(So far) my favorite combos by far revolve around EL11 as drivers - I'm enthralled with the EL11 input + EL38 output combination. Absolutely holographic, sweet, organic, detailed extended, and slams damnnn hard.

Though I had a bit of a scare yesterday with this combination. An actual fast clicking sound gradually morphed into a random static sound, then next power-on it became a full-time loud hiss which was all on the left channel. After hours of troubleshooting with various tube combinations, it was discovered that @Deyan 's adapter sockets (EL11 to KT66) were causing the distortion from dirty contacts. Tried again today after a thorough cleaning of socket connections with metal scraping and rubbing alcohol with a thin Q-tip and everything works perfectly now. Deyan you are the pro at custom adapters of almost any kind, but I'd strongly recommend cleaning the contacts before sending out your adapters, because some of the connections were fairly nasty. But they work very well and your service is top notch and I've had many great adapters from you, so I will still keep coming back.

This is one of my quietest tube combinations in terms of amp hum, but I also get a slight buzzing sound on either channel that drifts from time to time. It's a somewhat common byproduct of many tubes, and slightly flicking on the tube will quell this semi-bright yet moderately quiet buzzing sound for a second or so until it comes back. I wonder if external tube dampeners or absorption rings help with this? Warm-up for 10+min. seems to reduce it also. Maybe @mordy or @MIKELAP would have an idea.

 

[mordy]

(So far) my favorite combos by far revolve around EL11 as drivers - I'm enthralled with the EL11 input + EL38 output combination. Absolutely holographic, sweet, organic, detailed extended, and slams damnnn hard.

Though I had a bit of a scare yesterday with this combination. An actual fast clicking sound gradually morphed into a random static sound, then next power-on it became a full-time loud hiss which was all on the left channel. After hours of troubleshooting with various tube combinations, it was discovered that @Deyan 's adapter sockets (EL11 to KT66) were causing the distortion from dirty contacts. Tried again today after a thorough cleaning of socket connections with metal scraping and rubbing alcohol with a thin Q-tip and everything works perfectly now. Deyan you are the pro at custom adapters of almost any kind, but I'd strongly recommend cleaning the contacts before sending out your adapters, because some of the connections were fairly nasty. But they work very well and your service is top notch and I've had many great adapters from you, so I will still keep coming back.

This is one of my quietest tube combinations in terms of amp hum, but I also get a slight buzzing sound on either channel that drifts from time to time. It's a somewhat common byproduct of many tubes, and slightly flicking on the tube will quell this semi-bright yet moderately quiet buzzing sound for a second or so until it comes back. I wonder if external tube dampeners or absorption rings help with this? Warm-up for 10+min. seems to reduce it also. Maybe @mordy or @MIKELAP would have an idea.

I don't have much faith in tube dampers and absorption rings. As you mentioned, cleaning the pins and contacts sometimes works wonders. Sometimes just switching the tubes right to left and vice versa helps - don't know why.
It also pays to see if something in the environment brings on the electrical noise - a portable phone, computer, charger, etc.

 

[DecentLevi]

I got an old favorite headphone I used to own, ATH (Audio Technica) r70x, thinking it would pair better with this beast of an amp than one I had years before. And BOY WAS I RIGHT!!! I make no reservations in saying this sound is downright MIRACULOUS! Coming from a Senn. HD-600 (even with silver cable nonetheless), I'm now getting a spacious and delightfully 3D sound, snappy drums galore and more micro details. Overall a sweeter and faster sound with more emphasis on soundstage, as if the HD-650 and 600's really do have a veil - which has been lifted here, as well as my senses. I now may be able to hear the microphone type / placement, and just may be be getting a touch of heaven.

Of course I'm not proclaiming this to be a giant killer, but these certainly tout mighty bang for the buck (around $300). As an Audio Technica though it may not be for everyone, retaining some of their house sound of slightly off-kilter upper highs and treble (and a slight nod towards bright, but with great mids and bass), but IMO it's done in a pleasing way for a nice change of pace from the traditional strictly linear sound.

Comes with a whopping 9-foot cable and I also added 6 industrial quality ferrite clamps Star-Tec brand; 3 high and 3 lower frequency attenuation ratings, and to me it really opened everything up and brought the dynamics more into proper focus. Just as a temporary setup with a new custom XLR cable on the way.

 

[DecentLevi]

Much of the enjoyment of my Ultrasonic Studios "Finyssey" (Odyssey-Infinity hybrid) in recent weeks has also been thanks to the choice of dampening I've settled on. Coming from a "large" set of Bright Star IsoNode plus 50 duro sorbothane sheet, I was already getting improved sound in several areas but the size was so small it was getting squished under the Ultrasonic amp. So here's what I went with:

Bright Star IsoNode size extra large +
70 duro sorbothane damping film

After a few hours experimenting with combinations of either sorbothane type or either feet size alone or in combinations, I got immediately noticeable differences in sound ranging from dull to bright, flabby, etc. But (to me), my hunch was right on the above pairing of isolation feet and damping film. The result could very well be different for you but for me it's bringing all around improvements most notably depth of realism and dynamics handling.