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Feliks-Audio EUFORIA - A Wolf in "Sheep's" Clothing...

Discussion in 'Headphone Amps (full-size)' started by hypnos1, Jan 9, 2017.
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  1. Johnnysound
    Yes indeed, $ 99 for a single RFT EL11 is absurd, specially when NOS Valvos appear regularly at about $ 90 or so for a pair. I think prices of RFTs will go way down as soon as a new batch appears...as far as I know RFT produced a lot of EL11s, under their own brand and later mostly for Telefunken (and maybe also for Siemens and Valvo, who knows ?) after TFK ceased producing this line (in the late sixties ?) For example, it is well known that all Siemens branded EL34s, and a lot of TFKs of this and other types were in fact made by RFT in East Germany.

    I first learned about the sound quality of RFT tubes with the EL12N, an excellent power in Euforia. Later on, I needed an “ultra neutral” driver to balance the warmth of the EL38s in my power amp, and while the famous TFKs and Siemens ECC81 more or less did the job, the cheap (and strongly built) RFTs ECC81 were a revelation in terms of transparency and sonic accuracy...precisely controlling the exhuberance (and specially the bass) of the “wild horses” as I call the 38s as powers. Anyway, the RFT EL11s are great drivers in Euforia, but not at that ridiculous prices !
    Last edited: Jul 19, 2019
    teknorob23 and hypnos1 like this.
  2. DecentLevi
    As far as I remember the Telefunken & similar RFT EL11 I got two years ago were closer to $15 for 1-2. They have quite good bass definition, detail, dynamics and transparency but don't come quite close to the valvo 11s in terms of organic lifelike and holographic sound and 'natural' bass so not worth $90 each
    Last edited: Jul 19, 2019
  3. Johnnysound
    Hi DL, after all that rave about the Valvos you (and H1) left me with no other choice than to try to get some. Not that easy to find, but finally located a nice trio in Germany...and one of them is a forties vintage “black glass”. The unobtainable “mesh plates”, maybe...?
    Last edited: Jul 19, 2019
    DecentLevi likes this.
  4. Scutey
    Wow $99 for a single RFT?, that makes the £40 I paid for NOS pair a few months ago seem like a bargain!.
    hypnos1 likes this.
  5. connieflyer
    That old supply and demand kicking in to high gear. Johnnysound, if one is a black glass mesh plate, you will be a lucky fellow to be sure.
  6. hypnos1
    Oh dear, J...at this rate, you could well be citing me as prime cause of financial penury lol! :astonished::wink:...but hey, join the club!! :beyersmile:

    However, well done on bagging those Valvos, and who knows, you just might have struck gold with that oldie black glass - I do hope you've been lucky, after my and @connieflyer 's teasing!...CHEERS!...CJ
  7. hypnos1
    By the way @Dobrescu George , as you mentioned you're curious to put Euforia through her paces, you might also be interested in what led to its development post-Elise : ie. in my first post on this thread. And the birth of what was to become Elise itself is covered in the first post of the original 'previously prototype' thread.

    You have the Kennerton Thror and Empyrean? I will be especially keen to hear your impressions/comparison of the two...in my own system, with mesh plated Valvo EL11s driving EL39 powers, the Empys are performing extremely well indeed (couldn't ask for anything more in fact!! :L3000:).

    Hope you don't have to wait too long for your curiosity to be satisfied :wink:...CHEERS!...CJ

    ps. I'm sure you're already au fait with the need for decent burn-in of both amp and tubes, but some of us have found Euforia to keep improving even up to 150+ hours (often also depending upon the actual tubes used...).
    Dobrescu George likes this.
  8. mordy
    Hi h1,
    Could you elaborate on how different tubes affect the burn in?
  9. hypnos1
    Hi mordy.

    Although hard to actually prove incontrovertibly, of course, given one would need several amps side by side for real time comparison!, I myself have come to suspect this anomaly from the reports of those with new amps, and the apparent differing lengths of time before burn-in 'changes' cease to be noticed. Given that the amp itself should pretty well be a constant, compared to other similar models, the only other variable within the amp will be the tubes themselves. As many have gone quickly from the stock tubes to others in the same family, as opposed to 'alternative', non configured-for tubes, this would point to these different tubes somehow possibly contributing to the variance in burn-in time. I have also noticed this on occasion when some folks have actually gone quickly to 'alternative' tubes similar to other users, but from a different manufacturer.

    Just as with the amp obviously needing longer to 'adjust' to tubes not actually configured for, so I propose that although the spec sheet may look identical from different makes of the 'same' tube family, the sometimes quite marked differences in actual construction - especially internal component size/design and placement/metallurgy/coatings etc. must react differently to the amp's input and output circuitry, thereby affecting/determining the length of burn-in required by the amp itself, in addition to that of the tubes.

    To me, at least, this seems to indicate there may well be some truth in my conjecture...but would welcome any other possible explanations...except that "everyone's different"...please!...CJ
    Last edited: Jul 19, 2019
    teknorob23 and connieflyer like this.
  10. mordy
    Another one of the mysteries of tube amps......But your explanation seems plausible.
    Another thing I don't understand is why an amp that hums may stop humming just by switching the positions of the tubes.....
    Johnnysound and barontan2418 like this.
  11. barontan2418
    This is now my first IA, usually driver tubes but on occasion powers also. No idea why but it very often works.
  12. Johnnysound
    Yes indeed CF, in the last few months the offer of nice old tubes (specially european) at reasonable prices seems to have shrink alarmingly, and the prices have went way up...hope this is only momentary. Regarding the “black” Valvo, I am full of faith...this one MUST be a mesh plate !!

    Another matter is whether the mesh plates by themselves are the key factor in the sound of the tube....or it is the better general construction/materials, and build quality of the older tube ? The EL38s are a good case in point: the older balloon “black glass” sound kind of sweeter than the newer “clear glass”...with similar plates, but the old one looks more carefully built all around, including welded black plates and gold grids...may be the same with the Valvos ?
    Last edited: Jul 20, 2019
  13. hypnos1
    Hi J. Yep, it is indeed rather alarming to see the fairly recent change (for the worse!) in availability and price of many old tubes...particularly the ones we like in our amps lol! :triportsad:. I know that supplies wax and wane, but I've a horrible feeling that finally, stocks of these are few and far between - the likely owners now undoubtedly getting on in years!! :wink:

    Re. the mesh-plated versions, it's quite possible that sometimes they reflect better overall tube quality, but I must admit that of my various black glass Valvo EL11s of the same (old) age, only a very few had the mesh plates, even though otherwise the tubes looked absolutely identical... even down to very similar numbering (which caused me disappointment, to say the least...could have sworn I'd struck gold when buying lol!). So my fingers are still crossed for you...:ksc75smile:

    And re. the differences in performance between the older EL38s and later clear glass Mullards, they do look quite a bit differently constructed, in different bottles - especially between the black plates of the older versions and the grey of the later ones. Also, the wire to the top cap runs directly from the anode plate in the earlies, but from a spur in the later, which might just have a bearing?...(I always believe in the least possible connections, as you well know! :L3000:).

    Something else I've noticed when working on the various types of EL38, the (also early) silver-banded Philips (France)/Dario/RT 38s have the most pristine looking wires that go to the pins of any tube I've come across. Not even the slightest hint of corrosion, which is miraculous given their age! Most also have the black plate of the early 'balloon' Mullard, and look identical to the EL39 apart from base size and getter(s). And there are even occasionally some that have dual getters, as does the 39...another lucky find for the fortunate, as they also sound pretty well the same as the 39! :smile_phones::smile_phones:...CJ
    Johnnysound and connieflyer like this.
  14. hypnos1
    Yo mordy...these wonderfully 'exotic' glass marvels - along with what drives them - certainly can be fickle, and sometimes very frustrating (no wonder I often refer to our amps, including tubes, as "She"..."Who must be obeyed?" lol :wink:). The way different tubes interact with the amp itself - as in my last post on this subject - seems to be a topic on which there's scant information about unfortunately. Surely there's still a few 'old timers' around who became redundant with the rise of transistors, but who retain intimate knowledge of such things? Never seem to hear much about/from them alas...:triportsad:

    That humming anomaly you mentioned certainly is one of the stranger head scratchers, as opposed to tubes that like to scare you for a while before deciding to settle down lol!!:smile_phones: Perhaps once again it's related to the interaction between differences in both the tube in question and those in the amp...especially when, like ours, you have dual runs of resistors and capacitors, no two ever likely to be absolutely identical (unless made from the finest materials/primed/exhaustively tested, measured and matched...and priced accordingly!! :astonished:)...CHEERS!...CJ
    Last edited: Jul 21, 2019
    DecentLevi likes this.
  15. Mh996
    A week-and-a-half (25-30hr) update. Euforia is breaking in very nicely. At first she was VERY dynamic, which was especially compounded by how dynamic my Focal Clears are, but this has mellowed out nicely to fit my selection of classical music. I also initially found the soundstage, while incredibly wide, to be fairly shallow, which made imaging rather un-precise for large orchestral pieces. This too has begun to improve as the Sylvania power tubes have begun breaking in. This may still be the only point of comparison where the advantage goes to Mojo, though my reading through this thread suggests this may be fixed through aftermarket tubes. Speaking of which, it sounds like the EL39's are the premier choice in upgraded power tubes. This may be the second think I upgrade in my system, behind maybe acquiring a linear PSU. The gold PSVanes seem to be of superior quality in the new-stock tube market, so I may well wait to upgrade the drivers. My new questions are: does anyone have experience w/ the 2018 model and upgrading from the gold PSVanes to, say, the EL11s which are highly-acclaimed here. Also, it looks like an adapter would be necessary use EL39s as a power tube. It looks like some people here got some Chinese lemons for converters. Does anyone have a reference for reliable adapters? This may still be out a ways, as I'd like to finish burn-in before moving up in tubes (plus I've only come across a single Philips EL39 on eBay). Thanks for the help and terrific advice on this thread.
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