[triod750]

 

[OctavianH]

I’m curious about your impressions of el39 vs el38 and e3375. I’m still not sure I can run the el38 properly in my amp. I will go back to them eventually. I have 3 el39 tubes kicking around but I am unsure when I bought them or what kind of shape they are in.

I will let those run for a few days. The problem is that those are not exactly EL39, even if electrically compatible, and I do not have anymore my Philips EL38. For me those are extremely resolving, quite neutral sounding. EL38 and E3375 are warmer than those, at least judging about how those sound at the moment.

 

[Isaacc7]

I will let those run for a few days. The problem is that those are not exactly EL39, even if electrically compatible, and I do not have anymore my Philips EL38. For me those are extremely resolving, quite neutral sounding. EL38 and E3375 are warmer than those, at least judging about how those sound at the moment.

Whenever I run el38 tubes they tend to be very (overly?) clear and bright. That holds in both my Odyssey and my single ended amp. I frequently hear people echoing your impression of them being warmer or darker than some other tubes. Do you happen to know what impedance your output transformers are? Mine are 8k.

 

[OctavianH]

Whenever I run el38 tubes they tend to be very (overly?) clear and bright. That holds in both my Odyssey and my single ended amp. I frequently hear people echoing your impression of them being warmer or darker than some other tubes. Do you happen to know what impedance your output transformers are? Mine are 8k.

I have no idea, but those are, for sure, warmer. These 4654K are not like that, but I'll wait around 100 hrs on them to be sure about this. Maybe they need some time because they were not used.

 

[Isaacc7]

I assume this thread is going to dry up due to the sad situation with Tomas. Will probably post my impressions on the pentode, 6sn7, and 6j5 threads from here on out. Once upon a time there was a chance someone else could order an amp like mine. Now that my amp will forever be a unique one, not sure how useful my thoughts on tubes will be in this thread.

 

[Thaddy]

For those that might be interested, I will most likely be selling some of the power tubes I've accumulated in anticipation of my Odyssey that was scheduled to be built last month. I've got Mullard xf2 EL34's, RFT EL34's, La Radiotechnique EL39's (w. adapters), GEC KT66's, and Tung-Sol 6550's. All are NOS and never installed.

 

[Isaacc7]

For those that might be interested, I will most likely be selling some of the power tubes I've accumulated in anticipation of my Odyssey that was scheduled to be built last month. I've got Mullard xf2 EL34's, RFT EL34's, La Radiotechnique EL39's (w. adapters), GEC KT66's, and Tung-Sol 6550's. All are NOS and never installed.

Wow! That’s quite a collection! Are you sure you wouldn’t use those in another amp? Would be difficult and expensive to replicate that group if you sold them. On the other hand they’re bound to fetch some good money so I understand the desire to move them.

 

[OctavianH]

I assume this thread is going to dry up due to the sad situation with Tomas. Will probably post my impressions on the pentode, 6sn7, and 6j5 threads from here on out.

I follow you wherever you go, as I do with 2-3 other users, because you are making things which I consider interesting: explore tube types I never heard of, which are cheap and might sound better than the ones everyone are using. So I have no problem. In my case, I learned that my impression on specific tube types is influenced by the design of my amplifier. When I received Eternity I observed that tube types I have previously used on another amplifiers were sounding different on this one, so I prefer to post my impression in this specific thread, they are not relevant outside it. I start to wonder what I will do when Eternity will stop functioning, because honestly I am not interested in any other tube amp existing at the moment on the market. I was interested in a possible future Citadel build, but I did not want to renounce on Eternity, so my crazy mind went to a kind of dual Eternity-Citadel amp on the same chasis. My last message to Tomas, the one he never got to answer, was:

Hi!

I have a very crazy question for you. I do not remember to ask this, and it is just a question, do not be scarred.
Have you ever thought to build on the big Telemachus chasis an amp which combinates 2 of your designs?
So for example, with a front switch to have a Citadel and also an Oblivion or Eternity? I know, sounds crazy. LOL
(of course, reusing tube socket, so each amp inside to use all or a part of the ones already wired).
I expect something like this is not possible, but this would be a game changer, in my view (of course, for a crazy person like me). LOL

I guess this will remain a fun fact in the history of UltraSonic amplifiers.

 

[hpamdr]

I assume this thread is going to dry up due to the sad situation with Tomas. Will probably post my impressions on the pentode, 6sn7, and 6j5 threads from here on out. Once upon a time there was a chance someone else could order an amp like mine. Now that my amp will forever be a unique one, not sure how useful my thoughts on tubes will be in this thread.

In Fact for the one using Eternity the input tubes does not act like drivers in many amp an this is by design. The 6j5, 6sn7 thread is not the most useful for lucky one who got an Eternity or citadel with rolling options. This thread can still be a good place to share about tube combination for the few one who run with Ultra Sonic Amp.

I'm very sad about the latest news on Tomas... But the amps remain and happy users also.

So yes the thread will not grow but it is a valuable source for the one who run or get used amp.

 

[OctavianH]

So yes the thread will not grow but it is a valuable source for the one who run or get used amp.

I think besides our 2 Eternity's and Isaac's Push-Pull Odyssey (which is a different animal than normal Odyssey) there are 3-4 Odyssey builds (including the Infinity which was adapted to Odyssey later) which can benefit from tube rolling. The only problem is that Odyssey is a classic design, dependant on expensive transformer and capacitors, and it does not sound in the same way as our amps. So what we experience on Eternity is not always valid for Odyssey. Besides these amps, I recently learned that Oblivion can have a small tube rolling capability on output tubes (there are 4-5 types of EL81 which sound different and all of them very nice, so Oblivion users can, up to a point, experiment). Unfortunately there is no Citadel built with tube rolling capabilities, I had in plan to ask for one but now my plans are not relevant anymore. I guess we will remain with these amps we have and use them as much as possible. Time will tell how much we will experiement or not because I start to realize I tried almost everything I had in mind.

One thing Tomas has done was to give the power to the end user. He build an amplifier which is not dependant on expensive internals and can use almost anything as long as you can bias it and you match the heater's voltage. Many tube amplifier manufacturers are building upon their own choice of tubes and then you are stucked in those tube types which, based on the success of the model, become more and more expensive. So you start to pay more and more on those tubes in the benefit of the manufacturer and greedy Ebay sellers. Tomas freed us from that, so we can experience top class sound with a 5 EUR tube, and for this I will be eternally grateful to him. He was not the first trying to make amplifiers which sound good with cheap tubes, before I discussed to Tomas I was in the Glenn queue for that 9 socket OTL (Super OTL or how he was calling it). But I renounced and went for the modern design of UltraSonic. And here I am.

 

[Thaddy]

Wow! That’s quite a collection! Are you sure you wouldn’t use those in another amp? Would be difficult and expensive to replicate that group if you sold them. On the other hand they’re bound to fetch some good money so I understand the desire to move them.

Hard to imagine another amp out there that could compete with Odyssey! I’m told Cayin HA-6 takes EL34’s but I’m not sure what else.

 

[Isaacc7]

Hard to imagine another amp out there that could compete with Odyssey! I’m told Cayin HA-6 takes EL34’s but I’m not sure what else.

I too have some tubes I was saving for another amp from Tomas though nothing as valuable as what you have. I am going to ask around and see if there are any other amp builders willing to build my wacky idea.

My amps aren’t complex circuits but they have unusual features. At its heart, my Odyssey is a push pull amp with direct coupling of input to output tubes. Pretty standard stuff. I wanted specific transformers, external heating supplies, etc. but those things are just odd not difficult.

For the amps I want, Tomas was the perfect builder. He was willing to build what I wanted and he had amazing case work already done. I’m sure others could build the circuit I want but few make such beautiful amps. I’m going to take my time and see if I can still have my amp.

 

[triod750]

I start to realize I tried almost everything I had in mind.

You just have to roll your mind and start over. Keeping the thread going is a nice thing to do.

 

[Thaddy]

For the amps I want, Tomas was the perfect builder. He was willing to build what I wanted and he had amazing case work already done. I’m sure others could build the circuit I want but few make such beautiful amps. I’m going to take my time and see if I can still have my amp.

This sums up my Odyssey as well. The whole package was fairly simple, but beautiful. Probably won't happen now, so I hate to hold on to such rare and valuable tubes when someone else can use them for enjoyment.

 

[UntilThen]

The only problem is that Odyssey is a classic design, dependant on expensive transformer and capacitors, and it does not sound in the same way as our amps. So what we experience on Eternity is not always valid for Odyssey.

You will be surprised. If I didn't have Oblivion and Odyssey I wouldn't be able to compare but I have them and I know how they sound.

Odyssey has the clarity and details of Oblivion. And bass and texture. Only in the area of soundstage, Oblivion has a slight advantage but that said Odyssey already have a wide soundstage.

Eternity and Infinity would be in between those 2 amps. I don't there's a bad Ultrasonic amp.