[UntilThen]

The headphones are Final Audio D8000 Pro. These are my end game, I have sold all my headphones since I have bought these. I am fully convinced I might find something better, but at a much higher price (Susvara or maybe 1266 TC) but I do not need more. These are the ones I was looking for since I was born

You don't need more. I heard the Final D8000 Pro is good. I stop lusting for the Abyss 1266 TC because I remember I didn't like the Abyss 1266 Phi which I heard several years ago with Ragnarok and Woo Wa5le.

 

[OctavianH]

You don't need more. I heard the Final D8000 Pro is good. I stop lusting for the Abyss 1266 TC because I remember I didn't like the Abyss 1266 Phi which I heard several years ago with Ragnarok and Woo Wa5le.

Well I guess I'll never listen to it. For me the D8000 Pro is enough and I do the rest with tubes. They are very transparent and lively, so I can tweak them a lot with tubes. Perfect for me and what I do.

 

[OctavianH]

It is very hard to change something in the phase 3 of my experiments. All the combos are good enough to let you forget about the equipment and listen to music. And when you listen to music you do not really care about equipment, if it sounds right. This is why my activities are delayed. One of the plans was to revisit all my EL34 collection and assess it based on my new discovieries, the novals. Today I found some energy to switch my outputs from GEC ATS25 I was praising last evening to Mullard EL34 xf2. If you start with EL34, these are always the first choice. In my opinion these are the best, but they are followed close by old Tesla EL34 production. So here we are, Mullard EL34 xf2 with Telefunken ECC801S.

Soundwise these are clearly more relaxed that 807 and are somehow towards the KT77. But the good thing is that the Mullard EL34 xf2 is creamy, laid back, and masks some imperfections from the recording era. On this very clean sounding amplifier this is a quality, because you can go more towards that "analogue" sound many praise and mask a little bit from the imperfections of a pure solid state reproduction. Nothing is dry here, nothing scratches the surface, Mullard EL34 xf2 remains one of the best outputs for UltraSonic amplifiers because it provides what we need here, a laid back and solid sound.

So here starts my journey of reassessing EL34. I have a lot of tubes of this kind and I am fully convinced I'll have very interesting results with these tiny 12A*7 but the real challenge is to change something. Everything is so good you just want to open a new beer or work on something.

Later edit: I called EL34 a kind of KT77. Well, many consider KT77 a premium version of EL34 but for me these tubes are in their own category. I will explain. KT77 is for me the best I have ever heard on Eternity, and even if maybe electrically can be related to EL34, I keep them as a separate tube. I should do the same for ATS25 because it is not quite 807, it is much more even if it derives from it. It is the same like Mullard ECC35, all call it a premium 6SL7, but for me it is in a different league, it even biases differently, much stronger than the casual 6SL7. I am sold to british tubes, these are the sound of music for me and ECC35, ATS25 or KT77 are for me reference. Maybe because I was born and followed the british heavy metal from 80s and I am a huge fan of older stuff like Black Sabbath? For me everything started from Black Sabbath, Led Zeppelin or Iron Maiden, maybe this is biasing my assessment and this is the reason I praise these british tubes. I will let you decide.

 

[OctavianH]

The dark brown base of the Mullard EL34 xf2 is incredibly beautiful. No picture can make it justice, but I have tried.

I am very pleased about EL34 and I consider it a very good option for Eternity. Being able to use so many types of tubes natively (EL34, 6V6, 6L6, KT** and so on) is a strong point of this amplifier and if we look on the market, more and more vendors are releasing amplifiers wired for these. If we just look on the Cayin HA-3A or the rumors that the future Feliks Euforia amps will be wired to use KT88 in the output stage it is a clear point that these tubes are the future. I was lucky enough to understand this before the point when people start to buy these types and raise the prices and I have a good stock of EL34 and 807. I was also lucky that I got in contact with Tomas when UltraSonic was almost unknown and he was able to build me this wonder of an amplifier. His vision of the modern design of tube amps is also the future, and more and more people start to realize this and go into this path. I really think these amplifiers are the future and that UltraSonic will become a very big brand soon. I do hope I will also find time and enough reason to build the "ultimate Citadel" I was writing about on several topics. Why Citadel? Well, I always wanted to experiment different things and Citadel is for me the most appealing model. But not the common build, a Citadel wired to use the tubes I have mentioned (6V6 family with 6SL7 as input) and which will be able to find an operating point and accomodate the whole family. A tube rolling fully balanced amp with 12.6/6.3V heaters. But about it we have plenty of time to talk.

 

[UntilThen]

The dark brown base of the Mullard EL34 xf2 is incredibly beautiful. No picture can make it justice, but I have tried.

Is that double O or double D getters? They are both good but D is just a bit more special sounding. My fav.

 

[OctavianH]

Is that double O or double D getters? They are both good but D is just a bit more special sounding. My fav.

Mine are double O getters. I have some Philips xf5 double D getter but are more towards neutral sound (like Telefunkens). These are thicker and warmer sounding, I like these a lot but I will revisit the other types as well soon.

Later edit: I found a picture of the Philips double-D getter near this pair of Mullard (branded Valvo) xf2 double-O getter.

 

[UntilThen]

I have some Philips xf5 double D getter but are more towards neutral sound (like Telefunkens).

Unless we're talking about different tubes, my Philips Miniwatt EL34 xf4 double D getters have the best tube tone. Definitely not neutral.

Anyway, I'm rolling in these metal base now for a listen - again. I don't find Philips tubes neutral leaning like Telefunkens. Not even these Philips Miniwatt metal base. It's just tighter than the D or O getters but still a very good tube tone.

 

[OctavianH]

Unless we're talking about different tubes, my Philips Miniwatt EL34 xf4 double D getters have the best tube tone. Definitely not neutral

Yes, you have the Philips metal base ones, the most rare and expensive. Mine are these:

There is a website which describes types, very useful for me. Here.

 

[UntilThen]

Yes, you have the Philips metal base ones, the most rare and expensive. Mine are these:



There is a website which describes types, very useful for me. Here.

I know because I posted this link before. These double D getters are the ones I have and they are definitely not neutral leaning. I put them on the same standing as the metal base in terms of euphony.

 

[OctavianH]

This means I will have to take a look on them again. They are stored in my tube boxes but I will bring out all my EL34 tubes to try. I find a very good synergy with 12AT7 and I am really enjoying them. This is much more above 6SN7 or 6SL7. It seems EL34 loves 12AT7 on UltraSonic amplifiers.

 

[DecentLevi]

Incoming yesterday was the 12BH7A by Philco, a miniature tube that uses an E80CC / 12A*7 adapter. It worked as expected with the manual bias settings I plotted for it. I was getting a vivid, dynamic and and quite transparent sound, possibly bright. Later the brightness gradually became more apparent, so I switched to another tube I'm more familiar with, and it hit me how much low end and overall body I was missing. Chalked it up to being a first listen of my system for the day, maybe I should've started a fresh listening session with a familiar point of reference. I hope to not discriminate (LOL), but I'm not sure the 12BH7's in general have what it takes. There's a lot of other brands and designs of these, but overall miniature tubes have their place - namely in dynamics, sweet tone, vividness and clarity, but usually seem to fall short on the likes of soundstage and presence or instrument separation - save for select rare holy grail gems.

This tube was part of the journey I'm on testing a theory that lower gain tubes are able to reduce the amps' background hum. Much testing with both this and 6BL7 has confirmed to me that while that is possible with a quiet enough tube and on low gain settings, the tendency is to increase the gain knobs to make up for the lower gain of the tube - thereby achieving equal performance with perhaps 3rd (of 4) gain setting of what I would have achieved on 2nd gain setting with a normal gain tube - so any benefits of having a quieter tube now cancelled out by increasing the gain which also equally increases the hum.

 

[OctavianH]

This tube was part of the journey I'm on testing a theory that lower gain tubes are able to reduce the amps' background hum.

It is sad to hear you are still facing hum issues. My amp is dead silent regardless of the headphones I use or the tube types I try. I've had headphones in range of 20-600 Ohm and I never heard anything more than music.

 

[UntilThen]

It is sad to hear you are still facing hum issues. My amp is dead silent regardless of the headphones I use or the tube types I try. I've had headphones in range of 20-600 Ohm and I never heard anything more than music.

Likewise both my Oblivion and Odyssey are quiet with no music playing. I don’t understand Levi’s amp. I think he has ground loop problems in his home.

 

[OctavianH]

A little bit of blue in the morning. But for a short period of time because I never got to like these Sophia Electric EL34. Besides the build quality which for me is under the NOS variants (light plastic bases, overall feeling fragile in hand), the sound is also under my expectation for EL34. I will try to explain, these are thin sounding for me, detailed but somehow sterile. I can compare them somehow to the Psvanes CV181T2 which are sold with Euforia. If you like those you can imagine these in the same direction. On my amp definitely not a good pairing, and I am unsure if someone searches for this type of sound from EL34, usually we want a more holographic and warm presentation.

So I went to some brown towards afternoon and chose the Philips EL34 xf5 (date code L1L, double-D getter). These are indeed exceptional and my task is to decypher them when used with some 12AT7. Clearly more detailed and less sweet than Mullards xf2, but still nice and full sounding. I was lucky to get these because they are quite rare.

On input there is another special one for me, a Philips 12AT7 (date code Tk1 Δ7F - Heerlen).

 

[DecentLevi]

So, people think the hum on my amp is my fault. It's not, and here's why. Innumerable trials and troubleshooting have shown the issue is internal. After reading the below list you will see I have likely tried everything that is known and even into the unknown.
TLDR: My amp is a unique build I requested (probably erroneously), and I do not recommend this specific design I call Finyssey. Go for auto-bias instead.

Hum reduction remedies I have tried:

• Touching the ground connection, RCA jacks, outside of transformer and chassis with my bare hands. Normally for a ground loop issue, the hum would have been momentarily quelled or reduced by this way
• Power conditioner: My system goes through a Furman IT Ref-15i. This is a heavyweight TOTL performer is in great shape and is worth over $3k
• Aftermarket AC cables. Tried 2 different types with thick gauge, and even combined it with an additional inline power filter
• Faraday cage: created a makeshift faraday cage with tin foil that fully wrapped around the Sowter transformers with a non-conductive inner shielding to not touch any metal
• Tube rolling: Tried many dozens of combinations, including brand new factory sealed & tested KT88s paired with multiple trials of perfectly matched and tested input tube combos. Some were the same combos that were silent on previous amps. There is some variance of hum/buzz level depending on the tubes but only around 1/4th of the noise coming from the tubes, with the remaining approx. 3/4th of the noise 100% constant from the amp regardless of configuration
• Fuses: cleaned all internal/external and AC power supply fuses (5x) with isopropyl alcohol applied a thin layer of contact enhancer
• Ferrite clamps: tried them on: Tubes with top cap wires, around a dozen on key wires internally on the power section, and elsewhere on my chain (fidelity improved in many areas, but not hum)
• External inline headphone volume limiter: had to reduce the volume by 50% to not hear it, and by then everything good about the sound had been squished / compressed
• 2x external ground loop noise isolator units connected to my 'dummy' sockets that are connected to the ground signal of the amp
• Vibration absorption feet under the amp + stacked with sorbothane sheet. Reduced the hum by a bit, and improved the sound performance! Alas, not enough reduction by a longshot
• Headphones: tried 6 different pairs with sensitivity hovering around 95db and 32-600 ohms
• Tried the amp with 0 tubes towards when I first got it. The same background hum was still present that was always there. I have not tried the amp this way again since.
• Tried a Klein Tools RT110 Outlet AC Tester, which shows this house is wired properly

Throughout all of the above, the lion's share of the hum was constant and unchanged; the same background sound I heard the once I tried without any tubes. Designer Tomas mentioned my new amp does have some noisefloor and mentioned he heard a very modest hum when building it, but his headphones are less sensitive. I've definitely got plans for less sensitive headphones when funds permit, such as the HEDDphone at 87db. With a recommended max. 90db sensitivity to reduce the hum on this build however, my choices are quite limited. The entire Senn. line of headphones is out, along with most ZMF, Hifiman Susvara, most Audeze, etc., as most all are around 100db. The hum is just loud enough to hear during semi-quiet passages of music and bothersome during silence - only on the most ideal setup with my very few tube combos that are the quietest. Anything more than 2 (of 4 max.) gain position it becomes ridiculously obvious; along with many of my favorite tube combos, many of which I'm unable to use for this reason. This amp design is prone to highlighting any minute hum of a tube, and I've learned that the gain factor of input tubes can increase / decrease the main source of hum of which originates from the Sowter transformer on mine. Alas, input tubes with lower gain made it quieter but I needed a higher gain knob position to get the best sound, cancelling out this effect.

Environmental considerations

• My exact same power supply & AC cables were dead silent with about 6 former SS and tube amps of differing types, including with the initial version of this very same amp
• After the revision which included addition of hefty 15 watt Sowter transformers, I started hearing the hum (this was after my requesting auto-bias output tubes)
• My "Finyssey" amp is a custom build. It is the only one that has a combination of auto bias output, manual bias input, and user selectable 4 gain settings. These along with other possible design elements may have something to do with the noisefloor on mine

Input tube circuit issue

Making things even worse for me, is that for the last couple months I've been dealing with a seriously disruptive issue with the input tubes! For most dual input tube combos (using the 2x 6J5 sockets), starting the amp will cause an intolerably LOUD hiss on the left channel, with the left mA meter dedicated to the left input channel not moving. In every iteration of this issue, I am able to switch the input tubes from R to L side, and the issue is only on the left channel regardless of tube condition or tube class (6J5 and 3-4 other types with adapters all do the same thing, around 8 pairs of good tubes). To make it weirder, about 1 of 10 times the amp will STILL WORK with the precise same combination smoothly without flaw, and that the single input tube socket (6SN7 class) still works 100% of the time, even though it is said to be wired in parallel to the dual tubes.

It is thought a pair of Valvo EL11 that may not have been tested could've caused a short-out of some sort. Since then I've discarded said tubes right away and only been using tubes that are well tested. Troubleshooting has included my replacing / soldering in a resistor in the input tube circuit that was found to be partially fried / dark, but that tested stable on a my Voltometer at about 90% efficiency. Also I cleaned all tube socket pins as instructed on the main thread with a fine metal scraper and slightly nudging them back into an optimal grip. But problem still persists. The fact that my amp does still work exceptionally with the single input socket, and with dual (2x) tubes at odd random times (such as after a 12+ hour cool down period) means that operation is not necessarily causing further damage to the amp, but what's been done has been done.

I have found a few local audio service technicians experienced with tube amps and I am saving up a few hundred $$ so I can take this thing in for local repairs so I don't have to return for a 2nd time to Poland.

What? My amp still sounds good?
Yes!! Ironically I am listening to this gem of an amp as I type! I am getting an absolutely immense sonic experience from the Finyssey! Outstanding sense of real-life touch, huge soundstage, vivid, true sound unlike anything I've ever experienced at home and better than many top setups at CanJams, with dynamics in droves and ability to dial in a change of signature - that is, with tubes that don't A: amplify the hum too much or B: cause a frightening white noise hiss on the left channel. As you can see my experience is very limited at present. But nevertheless, Tomas has done such an impeccable job and this amp still has so much potential that I am in it to win with a new fix!

With my unique amp build involving manual cathode bias adjustment, there are highly exacting usage instructions (bias settings with a Voltometer according to the tube type), and other functional instructions like a 5-min. warm-up / cool-down period and checking the mA meters for certain levels, which were explained to me. One bad pair of tubes may have been the culprit, but alas my take-home is to go with auto bias. The main sonic difference I heard while manually fine tuning the bias was merely a change of volume, so no, I would say manual bias is not worth it. OTOH auto bias is said to allow for a somewhat higher tolerance level for less than perfect tubes, so that would be my recommendation for other users. Until I may potentially find the cause and solution, I do not recommend my design "Finyssey". I would imagine Odyssey would be the ideal option, the one UT has.