[OctavianH]

Forgot to mention an unpleasant episode which happened last week, related to Eternity. One of my brave soldiers, Tung-Sol 6SL7 grey glass decided to leave me while being on the amplifier. I have observed that a "big light" was coming from the tube. Now, being a grey glass tube is not quite helping on this problem. Anyway I stopped imediately the amplifier and felt an idea of "burnt" smell. Not being sure what happened I unplugged all and tried to open the bottom plate which is fixed on 4 screws. Very small ones. The chasis of Eternity is a Galaxy case several amp builders are using. When I tried to open it I observed that 2 screws, on diagonal, were blocked. I tried to force a little bit but without success. What went wrong was that the screw head was also damaged a bit, even if I have used the proper screwdriver. Anyway, I decided to stop here and try if the amp still works properly. Surprisingly the amp works as before, but I was not able to check inside what happened.

This is the bloody tube who caused this:

I haven't tried to measure it or inspect if it still works or not, I will do this one day. If I remember correctly I have somewhere 2 more pieces of 6SU7 grey glass which has to be very close sounding to this one. Sad is that I was linking this tube, good sound.

So what to say, until I will be able to properly inspect what happened, I am very reluctant to another amplifier in the same case as this one. I will never buy another one with these Galaxy cases. Just look at this tiny screw, and this one was never touched by me. I never touched the top plate, I only opened it several times on the bottom to resize some fuses inside which were blowing, in the first week of usage, because my "experimental" feature which was the tube rolling add-on was not finalized.

I would definitely prefer a more solid case with better screws in the future. I do not care if they are looking more industrial, I like that kind of design.

The future plan is to force open it if the amplifier will stop working, which might happen sooner or later due to the big listening hours I put on it and also extremely high number of tubes I have tried, some of them being experiments. But this is not a problem, the purpose of this amp was to let me explore and understand as many families of tubes as possible. So its job is done, now it is just a collectible piece I use more to listen to my favourite combos. Other more powerful amps will come, built around what I learned on this one.

 

[OctavianH]

@Isaacc7 found you a nice small new amp. LOL Check this out. This guy sells a handmade 12V heaters small speaker amp. I see there 1626 which is a triode and 12SL7. Not sure if these are headphone outputs:

But it might be, 2 switches? Headphone/Speaker out and on/off maybe? I think it also has a rectifier, how cool!

I'll gladly buy this for fun but honestly I do not want to go on 12V tubes. Enough headache already. But who has a box of 12V tubes might have some fun with this. I think I saw this amp a while back and now saw it again.

PS. Damn how close is the pinout of 1626 to 6V6, basically only G2 is missing. So this triode could work natively in a 6V6 wired amp if you can bias it. I see there some 250V plate with -70V grid for 25mA.

 

[Isaacc7]

You have made the right choice because they will not be at this price forever. I know about GU50 in triode for a long time and you are not the only one praising them.

It seems tubes with "50" have something. I am also not really interested in anything else than the tubes I already acquired. I buy from time to time, at very low prices, tubes which might be interesting from construction point of view, usually bulk boxes. I am not really sure I have something more to discover, at least on this amp. But I think about future amps and made some plans to expand my experience. A part of them was the new headphone. Not really that I needed it, I just wanted to explore 2 headphone signatures on EL50 and my current amplifier, then sell it, most probably.

I stopped buying tubes because I still have tube pairs I never got the energy to try because I already know how they will sound and why I will be bored about them. Who knows, maybe winter mood. EL38 still sits in a box, prepared. Csf 5933S is really good but I miss my EL50. I also have some "surprises" on the P8A and a pair of Mullard EL86 I always wanted to try, EL86 fascinated me at some point. No real energy, so I put it also in the box.

Regarding 6J7 and 6SK/SJ7, all these types have lower screen voltage rating and quite low plate dissipation:



But I guess if 6SL7 works and you strap them triode should work. There was a time I wanted to go towards this path but renounced because these were already too expensive. With amplification factor around 20 I guess strapping them you obtain a 6J5. LOL

Exactly, the triode strapped 6j7 is a 6c5 which is essentially the same as a 6j5. They are great input and preamp tubes. Going this way allows me to get some of the more exotic marques cheap. Mind you, Svetlana isn’t exactly expensive in any case. Those are just coming along for the ride

 

[Isaacc7]

@Isaacc7 found you a nice small new amp. LOL Check this out. This guy sells a handmade 12V heaters small speaker amp. I see there 1626 which is a triode and 12SL7. Not sure if these are headphone outputs:



But it might be, 2 switches? Headphone/Speaker out and on/off maybe? I think it also has a rectifier, how cool!



I'll gladly buy this for fun but honestly I do not want to go on 12V tubes. Enough headache already. But who has a box of 12V tubes might have some fun with this. I think I saw this amp a while back and now saw it again.

PS. Damn how close is the pinout of 1626 to 6V6, basically only G2 is missing. So this triode could work natively in a 6V6 wired amp if you can bias it. I see there some 250V plate with -70V grid for 25mA.

That is a cute amp. Luckily I’m not tempted by it. The last amp I was sorely tempted by was a custom 2e26 amp. It has massive chokes and I’ve always wanted a 2e26 amp. I have yet to try them in my amp even though I have the adapters. My gut feeling is that an amp designed with them in mind are bound to sound better.

If I were to have another amp made it would be specifically for lower voltage tubes like the el90, kt61, 6f6, etc. Plus of course the weird voltage ones like the n34, n43, etc. I am getting such good sound out of my current amps that thought no longer really comes up very often.

 

[ARCXENOS]

Forgot to mention an unpleasant episode which happened last week, related to Eternity. One of my brave soldiers, Tung-Sol 6SL7 grey glass decided to leave me while being on the amplifier. I have observed that a "big light" was coming from the tube. Now, being a grey glass tube is not quite helping on this problem. Anyway I stopped imediately the amplifier and felt an idea of "burnt" smell. Not being sure what happened I unplugged all and tried to open the bottom plate which is fixed on 4 screws. Very small ones. The chasis of Eternity is a Galaxy case several amp builders are using. When I tried to open it I observed that 2 screws, on diagonal, were blocked. I tried to force a little bit but without success. What went wrong was that the screw head was also damaged a bit, even if I have used the proper screwdriver. Anyway, I decided to stop here and try if the amp still works properly. Surprisingly the amp works as before, but I was not able to check inside what happened.

This is the bloody tube who caused this:



I haven't tried to measure it or inspect if it still works or not, I will do this one day. If I remember correctly I have somewhere 2 more pieces of 6SU7 grey glass which has to be very close sounding to this one. Sad is that I was linking this tube, good sound.

So what to say, until I will be able to properly inspect what happened, I am very reluctant to another amplifier in the same case as this one. I will never buy another one with these Galaxy cases. Just look at this tiny screw, and this one was never touched by me. I never touched the top plate, I only opened it several times on the bottom to resize some fuses inside which were blowing, in the first week of usage, because my "experimental" feature which was the tube rolling add-on was not finalized.



I would definitely prefer a more solid case with better screws in the future. I do not care if they are looking more industrial, I like that kind of design.

The future plan is to force open it if the amplifier will stop working, which might happen sooner or later due to the big listening hours I put on it and also extremely high number of tubes I have tried, some of them being experiments. But this is not a problem, the purpose of this amp was to let me explore and understand as many families of tubes as possible. So its job is done, now it is just a collectible piece I use more to listen to my favourite combos. Other more powerful amps will come, built around what I learned on this one.

Any ideas what could have caused it? Was it just a bad tube after many years of usage or something else?

Amplitrex (and other modern stuff) is very expensive, but I am gonna play with tubes for decades, I think its a good investment...I haven't crossed that bridge yet though

 

[OctavianH]

Any ideas what could have caused it? Was it just a bad tube after many years of usage or something else?

Honestly not. The tube was in good condition, measuring more or less like the others. I have it for some time, played it for hundreds of hours but nothing made me think it will start to create problems. I did not have energy and time to inspect it closely, I will do it, put it on my tube tester and maybe I will know more. In my view, this is the normal hazard happening when using tubes. I have to search in my archives and notes, maybe I find initial measurements when receiving it and compare with what will be now. That could give me a clue.

Amplitrex is very expensive, but I am gonna play with tubes for decades, I think its a good investment...I haven't crossed that bridge yet though

I have a very basic tube tester, nothing compared to Amplitrex, but I saw the advantages. But in this particular case, I doubt the tube tester will save you.

 

[ARCXENOS]

Honestly not. The tube was in good condition, measuring more or less like the others. I have it for some time, played it for hundreds of hours but nothing made me think it will start to create problems. I did not have energy and time to inspect it closely, I will do it, put it on my tube tester and maybe I will know more. In my view, this is the normal hazard happening when using tubes. I have to search in my archives and notes, maybe I find initial measurements when receiving it and compare with what will be now. That could give me a clue.

I have a very basic tube tester, nothing compared to Amplitrex, but I saw the advantages. But in this particular case, I doubt the tube tester will save you.

I would definitely like to know what happened when you find out!

 

[OctavianH]

I would definitely like to know what happened when you find out!

If I find out I will definitely share. A big light inside, at the base of the place near the base of the tube. That was the "symptom". Maybe something related to heaters?

 

[Designsfx]

If I find out I will definitely share. A big light inside, at the base of the place near the base of the tube. That was the "symptom". Maybe something related to heaters?

Did It look similar to this?

 

[OctavianH]

Did It look similar to this?

Nope, only towards the base. Some heater failure in my view.

 

[OctavianH]

I made today a short 1:1 test of the Csf 5933S and the RCA 807.

Same song, same input, same warmup time to be relevant. The only weak point is my memory. Surprisingly both sounded quite close, with a slight preference to Csf because it had an idea more forward mids and an idea sweeter, RCA being an idea smoother on that area. I was expecting bigger differences, but well... both are excellent tubes.

Next in line: Mullard EL38!

 

[OctavianH]

Grid voltage set to -10.5V and we are ready to go. Mullard EL38 after around 2 years on Eternity. I said from the beginning that I never liked this tube. I felt it's always between EL39 and EL32, trying to be half delicate, half thick sounding but failing at both. LOL But 2 years ago I had much less input tubes or experience with the amplifier. Will this make me change my mind? I have no idea.

This is just a short functional test, these tubes were never used before by me and I doubt that others used them, but you know, NOS tubes are a mistery. I am also taking into consideration that I am nowhere near a "sweet spot" for this tube with my small low power amplifier. 200V/20mA are peanuts for these tubes and others tried them at different voltages and detected a change in tone.

How does this sound for me now? Well, the same as always. Fuzzy, in the middle of a dreamy sound but also trying to be a "power" tube. I am not quite pleased about separation and rendering, tries to be sweet in the british style but fails in the bass and I have the feeling I need to increase volume to hear something. Mullard 807 is better, has some ingredients from this sound but the bass and overall presentation is better. At least for me, at least on this amp. Most probably RCA 6N7 does not help either, but the fight here would be to sharpen this sound while not making it shouty.

Anyway, the interesting things started to happen while writing this post. Because thinking about the -10.5V of Mullard EL38 for 200V/20mA made me realize these could work in input in Eternity. Lowering the plate voltage to 180V as the input stage, and putting a little bit more negative grid bias might bring these to 4mA. Quite high transconductance so it might work. And why not, who else besides me puts 1.4A EL38 on input. LOL

So here we are, Mullard EL38 around -12.8V on input with Philips PE06/40N in output. Why I have chose them? Well, my problem with EL38 is that these are fuzzy while with PE06/40N that they are speedy and sharp. So, Captain Planet, let's combine these maybe both types will sound normal. And voila, honestly this combo sounds better than the previous one. Very low gain for my taste, I had to go towards 2-3 o'clock to keep my usual listening level which rarely goes above 12. But soundwise not that bad. I always prefer high gain, I have the feeling that lowering gain I let the "amplifier" amplify more than the tubes and the sound is less tasteful. Of course, maybe it is all in my head but for me there are some sweet spots related to gain for this amplifier and I always try to follow them.

Anyway, EL38 on input, never thought of that. I will, of course, not keep this combo, but it was a nice demonstration. Eternity does not have any heater limitation, all up to 14A as a sum are fine, regardless of the stage.

Now, I need a beer! Friday Beerday!

 

[OctavianH]

Honestly, if EL50 and the old Philips pentodes never existed this combo would win the beauty contest. They look incredible. I'll try to show this.

 

[OctavianH]

Time for me to listen to a CD after a long time. Now we have streaming services, ultra expensive gear and so on... But music sounds worse than on my old cassette line I had in my parents house. Old full analogue setup. Honestly, if I think about those times for me it was better, now we try to imitate it with a lot of tips and tricks. Most probably only nostalgia.

We had analogue setups when we were kids, now we buy tube amps to recover that sound. I wonder if kids which never had analogue setups want tube amps. LOL

 

[OctavianH]

One more thing I had to do today, to be pleased. Later we return to EL50 and EBL1. To try my pair of EL86 from Mullard, Blackburn.

I liked a lot my Mazda France EL86, listened to it a few months ago and realized the potential of EL86, but well, Mazda France is an idea too neutral for this amplifier. EL86 remained on my radar and luckily now I have the chance to listen to a Mullard B-code EL86 pair. Excellent sound, more linear and less melodic than EL84 but powerful sounding. Bias is low, around -22V, strong tube type. EL86 is a very nice tube for those who like a more technical sound from these small pentodes. Same adapter for EL82/84/86.

I also find it beautiful, well, as long as Lilliput kingdom allows.

And some detail:

They came in some plain Philips boxes, but "Made in England" written on them: