[JazzVinyl]

I have also a question: I remember that I read somewhere that it makes sense on Euforia/Elise to switch the tubes from Left/Right channels between themselves in order to prolongue their life. This is not very clear to me why, does anyone know a scientific explanation? Maybe the circuitry inside or how the sockets are wired?

Should be identical circuitry on L/R and not matter at all. Both sides use both of tubes' triode sections,

 

[hypnos1]

From what I know and tried, yes, looking from the volume knob to the tube sockets, the left pair of driver/power is the left channel and the right one is the right channel. I had tubes with problems and this was the way for me to identify the problematic one and fix or replace it.

I have also a question: I remember that I read somewhere that it makes sense on Euforia/Elise to switch the tubes from Left/Right channels between themselves in order to prolongue their life. This is not very clear to me why, does anyone know a scientific explanation? Maybe the circuitry inside or how the sockets are wired?

Hi OH...re. your own question, the only reason I can think of would possibly be down to the different transconductance, gain and plate dissipation figures that are bound to exist between each tube, regardless of so-called 'matching' (which might actually only be with reference to just one of several working measurements lol!). And as @mordy says, there are indeed 'acceptable' variations from '100%' that will hardly affect the final sound...as if by magic, a good amp circuit will take such differences in its stride. But IMO there will still therefore be slight differences in signal load/quality from driver tubes to corresponding powers that once again, may not be very noticeable to the listener. And perhaps switching tubes will even out things a bit more...just my own take on it lol! ...

 

[hypnos1]

Allow me to pose a question that may be self-evident to some, but I'd rather learn than maintain a false facade of knowing. The question is whether for an amp like our FA's (Elise, Euforia) configured with 2 power tubes and 2 driver tubes, does each of the power pair and each of the driver pair correspond to the left or right stereo channel? In other words, does one driver tube map to left channel, other driver to right channel and same with power tubes or is their output "pooled" before going to each channel of the headphone (or preamp) output?
The reasons this seems pertinent to me are two-fold:

1. If one tube of a driver or power pair goes bad / underperforms will that be reflected in difference in one channel's output specifically or produce a more global sound impact across channels?
2. Some suggest mixing 2 different driver 6SN7 types can produce good results, but from 1st principles this seems like a strange idea if each tube is responsible for one of the stereo channels, but could be interesting to try if not.

I appreciate this community for the opportunity to ask perhaps dumb questions on my journey to get the most out of my FA amp. Thanks!

All queries are welcomed LW...very often, as in all spheres of life, 'dumb' questions can in fact shed a very pertinent light on matters...so ask away lol!

Enough folks have answered the general principle, but there are also further aspects involved here :
1. Given the 1 set of tubes per channel circuitry, and one channel underperforming, this could also have a slight global impact if more recent Euforias' 'Cross Feed' function is engaged (due to the slight mixing of both channels and which, if Hugo2's CF is anything to go by, I personally don't rate very highly at all I'm afraid! ).

2. Mixing 2 different driver tubes - or power even - from similar families can indeed sometimes bring positive results...the one compensating for shortcomings in the other principle. But very sharp ears can also sometimes notice certain anomalies if some aspects of delivery are too different from each other. The only real way to tell is, as usual, try it and see!! I first experimented with this (then) rather contentious practice way back in my Elise days, when I partnered an FDD20 (20V tube, needing external transformer) with an ECC31 - both only distantly related! - and the whole was definitely 'greater than the sum of the parts'. Ever since, this practice seems to have become rather more accepted and appreciated lol . Currently, I'm finding the same is happening with an EL39 power in partnership with the slightly different from normal Mazda/Dario EL38. So 'mixing and matching' can definitely bring its own rewards lol...

ps. Even more surprising such 'm and m' to follow......CJ

 

[hypnos1]

OK @LoryWiv and for those who may be interested in the Tung Sol (reissue) 7581A trials, I have today asked xulingmrs to make an adapter for this (6L6) family of tubes to work in our amps, and have given precise details of the pin configuration I myself am using...and hopefully this time, as opposed to their EL38 adapter, they will stick rigidly to my instructions lol!

Also, this time I shall be getting one for myself, just to make sure it works fine in my Euforia (and have a good look at its construction! ). To this end, they will be listing it on ebay tomorrow for me, even though it seems it'll be 10 days or so before a batch is ready...(with the hundreds of adapters sold based on my various tube experiments over the years, I thought they might have just sent me one gratis...but c'est-la-vie, I suppose ).

Anyway LW, I can honestly say that your purchase of 4 tubes will not be money wasted...far from it! With over 40 hours on my first 7581A, including important generous cooling down periods, it is already performing brilliantly as partner to an EL39. Bass is now a match for the 'special' Mazda EL38 in this role, if not going even deeper! The EL family's trademark clarity within a deathly silent background is repeated here just as magnificently, as is the sweetest treble. And if anything, mids are slightly more pronounced...but not to the often described as 'sugary' degree in the famous EL34, and certainly not in any way upsetting this tube's enviable overall balance and cohesion. All of which is extremely encouraging, given other users' recommendation for the long burn-in we've also come to expect from all the EL family (possibly a trait of the pentode tube type?...).

And so, after a quick comparison with another EL39 tomorrow (I've got a pretty good handle on the 38/39 now), I hope to see how two 7581As sound. But I'll wait 'til the second has at least got 24 hours on it before any critical listening of course. But whatever, as a partner to an EL39 - and also an EL38, no doubt - I would rate this tube already as superior to the EL12 Spezial, which is no mean feat. And for the price...no contest/no-brainer!!...watch this space ...CJ

 

[LoryWiv]

All queries are welcomed LW...very often, as in all spheres of life, 'dumb' questions can in fact shed a very pertinent light on matters...so ask away lol!

Enough folks have answered the general principle, but there are also further aspects involved here :
1. Given the 1 set of tubes per channel circuitry, and one channel underperforming, this could also have a slight global impact if more recent Euforias' 'Cross Feed' function is engaged (due to the slight mixing of both channels and which, if Hugo2's CF is anything to go by, I personally don't rate very highly at all I'm afraid! ).

2. Mixing 2 different driver tubes - or power even - from similar families can indeed sometimes bring positive results...the one compensating for shortcomings in the other principle. But very sharp ears can also sometimes notice certain anomalies if some aspects of delivery are too different from each other. The only real way to tell is, as usual, try it and see!! I first experimented with this (then) rather contentious practice way back in my Elise days, when I partnered an FDD20 (20V tube, needing external transformer) with an ECC31 - both only distantly related! - and the whole was definitely 'greater than the sum of the parts'. Ever since, this practice seems to have become rather more accepted and appreciated lol . Currently, I'm finding the same is happening with an EL39 power in partnership with the slightly different from normal Mazda/Dario EL38. So 'mixing and matching' can definitely bring its own rewards lol...

ps. Even more surprising such 'm and m' to follow......CJ

Thank you @hypnos1 and others who responded...really helpful and also rather fascinating. The more I learn the more questions arise, and I am grateful for this gracious community's collective experience and willingness to share ideas. Thank you!

 

[connieflyer]

Went back and rolled in some old favorites. Sylvania Jan vt231's and RCA 6AS7's my opinion is of all the various 6AS7's I have tried I like these the best. Bass and mids are powerful and the Sylvania's have the treble covered in spades. With some drivers the Sylvania's are a little bright, but with these RCA 6AS7's a very nice spread to the music spectrum. Using this as a pre amp out , that is why the volume is so high.

 

[Johnnysound]

YE GODS, guys...especially @ZRW0 , @Johnnysound and my chief fellow pioneer risk-taker @connieflyer ...this time I cannot take credit for what looks like (at the moment!) could well be a power tube that's by far the best value-for-money I personally have ever had the pleasure to experiment with. And that, from initial performance at least, may well be easily the equal of the silver-banded EL38 and close on the heels of the EL39/'special' Mazda/Dario EL38!

To be precise, my Tung Sol reissue (Russian) 7581As arrived today; popped one in Euforia (using my EL39 adapter with a simple wire link between socket pins #3 and #4), and with trembling hand remaining glued to the power switch, went for bust...

Well, the first surprise was deathly silence, and with no signal yet, even with the vol knob at max! The second came with signal volume gradually increased...beautiful sound already from a brand new tube not 50 to 60 years old lol!! And still not the slightest hint of any untoward noise/distortion...in fact, when pushing the tubes to ear-busting levels, the partnering EL39 would go into distortion, but the 7581A stayed totally in control, even at impossibly high volume level...WOW!...

Although still very early days - just a few hours in fact! - this tube is holding its own against the EL39, albeit with not quite the bass mastery of the special Mazda EL38. But hey, it can only develop more with time. It is delivering a very impressive balance right across the FR, and with a treble I've seldom heard this good, and without sibilance, right from the off. Stage is not yet quite as wide either, but this can definitely only get better.

And so if things develop as I'm sure they will, this 7581A is going to prove a no-brainer power tube for our amps...especially at just an average of $42 a pair (in the USA)...crazy (cheap) money!!!

Once again, I'm confounded by our F-A amps' ability to shine so brightly with tubes not configured for...quite amazing...

A couple of photos of this extremely well made and good-looking tube in situ :




ps. Unfortunately, as I and cf suspected, Euforia doesn't push this tube anywhere near hard enough to create the lovely blue glow triportsad:)...big sigh...but once again, as recompense, it has our amp running cool as a cucumber . And will also, of course, mean much longer life for both the amp and tube lol...consider me super impressed.

So a big THANKS and MERCI BIEN! to Erwan for suggesting I try this tube...you were spot on!

pps. I shall ask cf to check once more precisely how Mrsx's EL38 adapter is configured, to see if this time a simple wire link can also make it work for the 7581A. And if not, it may well be worth my asking Mrsx to make one specifically for this tube...if anyone is interested, that is! Naturally, however, I will need to trial this tube for a good while yet before I personally can recommend it as perfectly safe to use...but after over 5 hours' continuous use, everything is still performing 100%, and the amp still just lukewarm!!...CHEERS!...CJ

ppps. Anyone with my EL39 adapter will be able to use it for this new tube, using the wire link I mentioned earlier...and I shall show once again just where it goes on the adapter's socket...

Hey H1, the 7581A has exactly the same pinout as my KT150 dinosaurs !! A wire between socket pins #3 and #4 using your EL39 adaptor ? Won’t fry the amp ?(LOL)
At 1.7- 2 amp each may be suitable in Euforia...

 

[OctavianH]

Went back and rolled in some old favorites. Sylvania Jan vt231's and RCA 6AS7's my opinion is of all the various 6AS7's I have tried I like these the best. Bass and mids are powerful and the Sylvania's have the treble covered in spades. With some drivers the Sylvania's are a little bright, but with these RCA 6AS7's a very nice spread to the music spectrum. Using this as a pre amp out , that is why the volume is so high.

I have a pair of RCA 6AS7 and as far as I remember these had the biggest bass from all my powers. But I tried them only once. I guess I need to try them again. Now I have to thank you for reminding me about these.

 

[connieflyer]

That has been my results as well. These don't have many hours on them so should perform even better.

 

[teknorob23]

Back in the room and keen to catch up. Others might have already seen these but if you're UK who dont want to wait or pay the import duties, Hotrox have the 7581A's in stock. The listing on their website is missing the "A" but i've spoken to them and they assured me they the tube in question @ £24 each.
http://www.hotroxuk.com/tungsol-7581-6l6-matched-valves.html

 

[ZRW0]

Looks like I've contributed to create a new trend
If one "dares", I'd been interested in knowing what a quad 7581A could do on an Euforia.

Cheers,

Erwan

 

[connieflyer]

I know I said "no more tube trials" well, what I meant to say was, no more tube trials after the 7581A's! Just ordered a pair. Checked ebay but MrsX has not posted adapters for sale as of yet. I sent a message asking when. Good luck folks. Here we go again CJ!

 

[ZRW0]

At least, this time the tubes are quite easy to find and quite affordable as well.

 

[connieflyer]

For those ordering from MrsX adapters.. Just got email back......New message from: xulingmrs Top Rated Seller(9,261Green Star)
Yes my old friend.item number is ‭202792462994‬.
Because this week is China holidays,please order 06.Oct.
Thanks!

发自我的 iPhone

 

[Deyan]

For those ordering from MrsX adapters.. Just got email back......New message from: xulingmrs Top Rated Seller(9,261Green Star)
Yes my old friend.item number is ‭202792462994‬.
Because this week is China holidays,please order 06.Oct.
Thanks!

发自我的 iPhone

I could be of help