[hypnos1]

Hi again guys, I wonder if I should be concerned about possible early burn out from my EL39's? I've noticed the top of the glass has developed a fairly dark 'sun-tan' after being my mainstay powers for a month. I initially burned them in with music overnight for about 3 12-hour sessions, without a fan which may have been the cause because these EL39's actually do get fairly hot - albeit still only around 1/2 as much as those fire-hot 6080's. Since then I've been using a small fan on the tubes to reduce heat buildup in hopes to prolong the life.

Photo 1: before use
Photo 2 & 3 are from today, with #3 showing the top up close revealing the change in color.

Must admit DL, colour change usually happens with the getter flashing...from silver to brown as residual gases are extinguished. I myself have never had a tube that's clear up top change colour. But as @mordy says, perhaps it's just some of the anode coating burning off. I doubt it's use overload, as @Johnnysound has been cooking his own 39s at levels way beyond Euforia's demand lol! And I myself have put far more hours on mine than you have on yours! Mind you, twelve hour sessions are not normally recommended for tubes, although I myself have done so in the past...the usual - as recommended by F-A - is 5 to 8 hrs, with at least an hour cool off in between.

I'm also curious as to why you're using ferrite chokes on the anode wire...I myself have never had any issue whatsoever, even with the teflon tubing actually touching the transformer!...???...

 

[DecentLevi]

The ferrite chokes became necessary to prevent loud hum with some of the multi EL combos with my 6x externally heated power combos and I just keep them on there in case. It doesn't take anything away. In recent months I've been having world class results and splendid synergy with either 2x EL39 + 2x Bendix 6080 + 2x Tung Sol 6BL7 (or) EL39 + 4x EL32 as powers with either Valvo EL11 or RCA 6N7 as drivers.

 

[JazzVinyl]

The ferrite chokes became necessary to prevent loud hum with some of the multi EL combos with my 6x externally heated power combos and I just keep them on there in case. It doesn't take anything away. In recent months I've been having world class results and splendid synergy with either 2x EL39 + 2x Bendix 6080 + 2x Tung Sol 6BL7 (or) EL39 + 4x EL32 as powers with either Valvo EL11 or RCA 6N7 as drivers.

Gotta say, DL this is interesting...mixing such divergent tubes as a set of powers. One wonders if the mu 2 tube can be noticed over it's rack mate with an mu of 15...?

Wish I could hear it

 

[DecentLevi]

Yup it's a very unlikely tube combo and one I would never have dreamt up, save for months and hundreds of pairings going through every mathematically possible tube combination to find which have the best sounding synergy. This combination is sublime, infinite, extraordinary with hard hitting bass, resolving, clear, detailed, visceral, expansive and just the most coherent, ultra performer I have yet to hear in all my years at any home hi-fi setup. Thrills & chills, and more even yet to come as I eventually upgrade my entire chain with even better headphones, DDC (domain digital converter AKA 'decrapifier'), DAC and amp.

PS - what is "mu", is that the gain factor of a tube? Also I didn't post a photo as to not derail the thread much with multi-combos.

 

[JazzVinyl]

Yup it's a very unlikely tube combo and one I would never have dreamt up, save for months and hundreds of pairings going through every mathematically possible tube combination to find which have the best sounding synergy. This combination is sublime, infinite, extraordinary with hard hitting bass, resolving, clear, detailed, visceral, expansive and just the most coherent, ultra performer I have yet to hear in all my years at any home hi-fi setup. Thrills & chills, and more even yet to come as I eventually upgrade my entire chain with even better headphones, DDC (domain digital converter AKA 'decrapifier'), DAC and amp.

PS - what is "mu", is that the gain factor of a tube? Also I didn't post a photo as to not derail the thread much with multi-combos.

Yes, in tube spec sheets the 'mu' is the amplification factor. 6080 = 2 and the 6BL7 has a whopping mu of 15!!

Are you sure it's "visceral, expansive and just the most coherent, ultra performer you have yet to hear"?

LOL

Sorry, you do go on and on in sound description. Kind of fun. Let me ask this...how long to you spend with a combo before changing? Do you write down your 'visceral level' for each combo in a speadsheet or something?

 

[mordy]

I wonder if there is a mathematical formula to figure out the amplification factor (mu) when you mix tubes of different mu - have never found the answer to this question.
If you have one pair of 6BX7 the mu is 10. If you have 4 x 6BX7, does the multiplication factor remain the same?
What happens with the mu if you mix 6BL7 (mu 15) and 6BX7?
Haven't been able to find the answers to these questions.

 

[JazzVinyl]

I wonder if there is a mathematical formula to figure out the amplification factor (mu) when you mix tubes of different mu - have never found the answer to this question.
If you have one pair of 6BX7 the mu is 10. If you have 4 x 6BX7, does the multiplication factor remain the same?
What happens with the mu if you mix 6BL7 (mu 15) and 6BX7?
Haven't been able to find the answers to these questions.

It's my understanding that the mu remains the same in the power position of an cathode follower like the Euphoria.

IE if you ran 2x 6AS7G's per side, the mu stays at 2 buy you have doubled the current avail for moving the P driver cone.

So don't know how to relate that to mixing wildly different mu tubes per side. Guess I assumed that in power position on a cathode follower amp, that mu does not change, that the one with highest mu factor would dominate the sound? But you are adding drive current (or power)...

 

[DecentLevi]

After many, many trials I always found 6BL7 to have the best synergy with 1-2 sets of 6080 tubes (as an externally heated power with combo), then add in the EL39's and everything really opens up and shines brilliantly. Do you folks factor in Mu when rolling different powers on the Glenn amps? I certainly never have and I recommend to disregard the Mu factor and you just might find your best combo ever. The above two mentioned combos are my mainstay tried and true for at least 6-8 weeks and after recently A/B-ing with my former favorite multi-combos they win by a great margin, even over combos including former holy grail tube classes.

 

[hypnos1]

The ferrite chokes became necessary to prevent loud hum with some of the multi EL combos with my 6x externally heated power combos and I just keep them on there in case. It doesn't take anything away. In recent months I've been having world class results and splendid synergy with either 2x EL39 + 2x Bendix 6080 + 2x Tung Sol 6BL7 (or) EL39 + 4x EL32 as powers with either Valvo EL11 or RCA 6N7 as drivers.

OK DL...let's stop here right now. Doesn't this give a clue as to the ill-advisedness of this kind of multi combo in an amp not designed for such use, unlike some of Glenn's? ...This might well also explain the experience of discoloration in one of your EL39s.

I must stress to folks that Feliks-Audio will NOT countenance such use of their amps, and will void the warranty. I also do NOT advise such use, despite the use of an external power supply. And as F-A's voice here on the thread that I personally started, I ask that any further discussion on this practice be taken to another new thread and not continued here.

 

[UntilThen]

DL, I hope you will not bring such extreme tube rolling over to Glenn's thread. In fact no thread will welcome you if this is what you call -

This combination is sublime, infinite, extraordinary with hard hitting bass, resolving, clear, detailed, visceral, expansive and just the most coherent, ultra performer I have yet to hear in all my years at any home hi-fi setup.

from a combination of EL39 + 6BL7 + 6080 and using external power supply. This is what I call tube rolling gone off the rails.

 

[DecentLevi]

No big deal, I won't write about my multi-combos on the Euforia here. I'm moving towards another amp after a bit anyway. If anyone asks me about it I can reply by PM. I was only posting about my experiences which for me have been found without issue over 1 year - but not specifically recommending it, as setting it up takes quite some special steps and is not exactly in spec for the amp. Nevertheless I'm still super impressed with what the Euforia can do, even with setups that it wasn't designed for.

PS - the external heat concept wasn't even my idea, and UT I've seen you do some experimental stuff too recently.

 

[UntilThen]

PS - the external heat concept wasn't even my idea, and UT I've seen you do some experimental stuff too recently.

What I did was purely to get an idea of how EL11 and EL12 spez sound like before I commit to a custom build from Glenn. Go back to the thread and see my warning to others that I do not endorsed this as a common practice.

Knowing you, I have explicitly state that, in case you think I endorsed it.

If you like a certain combination of tubes, get it custom build but no amp builder will build you an amp using EL39 + 6BL7 + 6080 and what nots.

 

[DecentLevi]

You're right UT I haven't had a chance to catch up on the 'other' thread except for browsing the photos. Thanks for your reasonable response and I really enjoyed some of your contributions over there too. And I really don't think I will have any need at all for experimental tube rolling with the new one.

 

[hypnos1]

DL, I hope you will not bring such extreme tube rolling over to Glenn's thread. In fact no thread will welcome you if this is what you call -

This combination is sublime, infinite, extraordinary with hard hitting bass, resolving, clear, detailed, visceral, expansive and just the most coherent, ultra performer I have yet to hear in all my years at any home hi-fi setup.

from a combination of EL39 + 6BL7 + 6080 and using external power supply. This is what I call tube rolling gone off the rails.

WELL SAID UT!

 

[UntilThen]

You're right UT I haven't had a chance to catch up on the 'other' thread except for browsing the photos. Thanks for your reasonable response and I really enjoyed some of your contributions over there too. And I really don't think I will have any need at all for experimental tube rolling with the new one.

No problem DL. I'm not an unreasonable man. Look forward to the new custom amp. You'll enjoy it without resorting to such combination.