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Feliks Audio Elise Impressions Thread – a New Start (please read first post for summary)

Discussion in 'Headphone Amps (full-size)' started by pctazhp, Jul 7, 2016.
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  1. Oskari
    I'm in the bit-perfect is bit-perfect camp. More bit-perfect does not compute.
  2. hypnos1
    Hi O...this is precisely what has had me scratching my head for a very long while now - copying digital 0s and 1s and then transferring them should, in theory, give perfect reproduction. This would appear to undoubtedly be the case with 'ordinary' data, but that which carries sound in digital code - for some really strange reason! - can, according to some, be somehow 'affected' in a way that impinges on the final sound reproduction...albeit only very subtly!

    Pure logic would say this is nonsense...and my life is ruled - most of the time! - by such logic (sad to say lol! :wink:). But the experience I mentioned in my recent post has confused me no end - ie. CD tracks ripped by Windows Media program, thence transferred via USB stick to my Naim server/player do not sound as good as the same tracks ripped by the Naim to its internal SSD drive. So something has happened en route, and I wish someone could give me a definitive answer...it's driving me crazy(ier!)...HELP!!...:ksc75smile:...CHEERS!...CJ
  3. Oskari
    Yep, it's nonsense. Otherwise your external hard drive (etc.) wouldn't work. But not all rippers are created equal, especially with CDs in bad condition. Don't know about Windows Media.
  4. OctavianH
    After I read all the discussions on the other thread, I decided to give a chance to a power conditioner, just to see with my own ears what is all about. Since I need only 2 outputs I decided to try a compact model with a lower price than the big ones, more exactly this one, which was available here in the proximity (in Germany):
    https://www.furmanpower.com/product/10a-two-outlet-power-conditioner-export-AC-210A E
    I plan to compare Elise connected to this one and also to the mains and see if something changes. In the future I might add also a transport or something else to the second output. The PC will not be connected to it since 10A are not enough for both of them but the Qutest has galvanic USB isolation so I expect it has to be fine. We will hear when I will receive it and try it. In the meantime if anyone has any advice for me regarding these Furman filters, let me know.
    Madhyamika likes this.
  5. connieflyer
    Hello O, I am using the Furman Elite 15, and I have a pc,an nas, a gumby, logitech external powered speakers, and a network streamer, and the Euforia all turned on at the same time, which of course normally I would not have on, but to see what I am drawing. The Furman is showing 122 volts, and 2.1 amps current draw. So you should not have a problem with your pc connected. Does not show any strain or undo problems. I really noticed a change for the better, especially when using PlayFi from the nas to my Anthem receiver. It never sounded as good as I thought it should, after the filter network, the Anthem sounds great, just as good as if using the oppo to play music. This is what I am hearing. Hope you get a good experience as well.
    OctavianH likes this.
  6. connieflyer
    Madhyamika likes this.
  7. connieflyer
    Forgot to add the network switch as well to the above equipment.
  8. OctavianH
    Hello cf,

    Thanks for the advice but my PC is a gaming one and sometimes (when playing city builders for example) I use it in parallel with Elise. Last time I checked it was somewhere at 600W. Now, my basic math tells me that if I have 6xxW on a 220V main power this leads me somewhere at 3A. Elise has drivers of 0.6A and powers of 2.4A which lead me to somewhere around max 6A, which, of course, at the volume level I am listening are not reached. Anyway I will double think if I will connect the PC to the Furman since the only common cable is the USB one connected to a galvanic isolated input on the DAC side. The DAC has its own LPS and now Elise will have, when the unit will arive, its own power conditioner.
    Last edited: Jan 23, 2019
    Madhyamika likes this.
  9. Madhyamika
    I’ll be interested to hear of your impressions of the smaller power conditioner, Octavian. I’ve been considering power conditioning options myself but am going to need to wait a while for my finances to recover from last year’s amp shopping :upside_down:
    Last edited: Jan 24, 2019
  10. Madhyamika
    Hello all - I have a “big” question and I’m hoping to tap into the experience and knowledge of the remarkable contributors to this thread to see if I might get some help with a few remedial tube rolling fundamentals questions.

    Some background: With no previous electronics experience to speak of, my recent months of reading bits and snippets from all over the Internet have left me somewhat confused. I got an Electronics for Dummies book and a few others like it, a soldering iron, a multimeter, and some kits to build and I’ve spend dozens of hours exploring all of those along with lots of reading of this and other forums. I’ve picked up a basic understanding of Ohm’s Law and learned a fair bit about the history of tube amplification and hi-fi in general. But there are gaps I’m having a hard time filling in so I’m looking for help.

    Modern basic electronic books neglect any discussion of tubes or relevant aspects of amplifier design. They have told me about the difference between a resistor and a capacitor, but not really why either one helps make my amp work well or what would happen if I, for example, replaced my capacitors with better ones. Meanwhile, supposedly “basic” books specifically on tube amps presuppose a much more thorough understanding of electronics than I have. They assume I already know why we would use particular capacitors and resistors in our circuit designs, but I don’t.

    Neither book tells me what I’m missing. I’m feeling a bit lost in the middle, like I’ve read volume 1 and 3, but volume 2 has what I need to know and I haven’t found a copy of it yet, or even if it’s been written at all. And yet I get the impression that some of you have a good understanding of this missing Vol 2, hence my current post :wink:

    What I’m currently most interested in understanding better is how to determine for myself which tubes could be good candidates for any given amp, especially Elise.

    I’ve got a small collection of octals (mostly 6SN7 and 6AS7 variants), some pentode-types with adapters (EL12, EL32, EL38) and various noval dual triodes as well (12AU7, 12AX7), also with octal adapters, Plus KT120s for my big amp. However, I’ve only ever rolled combinations of these tubes into Elise that I’ve already seen other trailblazers have had good results with here on this thread and on the Euforia thread.

    Other than simply following the successful experiments of others with Elise (octals), with my other preamp (12ax7-based) and my stereo amp (12au7 drivers and KT-88 powers) I have no idea which tubes can be rolled where without risk of damage to the tubes and/or the amps.

    With Elise, I’ve seen triode-strapped pentodes like EL32 and EL38 tubes being used as both powers and drivers which only adds to my confusion. It would never have occurred to me that a pentode could be used in place of a triode, much less in either role. Neat! What else can we do?

    I think I understand this much: by looking at tube data sheets I can determine the current draw that each tube requires and I can compare that to the total current that the amp’s power supply can flow. If the tubes don’t exceed what the amp can flow, that much makes sense.

    I also realize that different tubes have different gain factors - a 6SL7 might be a bad substitute for a 6sn7 because it’s gain is so much higher - I’m guessing this would make the signal distort, but would it damage anything?

    (Please feel free to correct me if I’m off the mark on any of this).

    Are there other factors that would be risky if not accounted for? If I plug a 12au7 into Elise with an adapter instead of a 6sn7, am I asking for trouble? If I understand correctly, they have similar gain but the 12au7 draws less current. Is that fine?

    How did we realize that a supposed power tube like an EL32 can be used as a driver, and vice versa? What about an EL34 or EL37? Does triode-strapping a pentode alter anything on the pentode’s spec sheet? 4 EL38s sound fantastic in my Elise - how do I know if they are safe to use in my monoblocks as preamp and/or power tubes? Can 6SN7s be put in Elise’s power sockets? Can 6AS7Gs or 5998s be drivers for Elise? Why or why not?

    In short, we’ve clearly got a marvelous amount of freedom to roll tubes in this amazing amp beyond what Feliks Audio has officially approved, but I’m not sure what the basic principles are governing the parameters in which we are free to play with relative safety to our amps, tubes, and selves. I welcome any insight anyone feels inspired to share, and if these questions are answered in a comprehensive and accessible way elsewhere, I gladly welcome links for further reading.

    Many thanks to all for this great resource!

    OctavianH likes this.
  11. hypnos1
    Hi M...Yo, a very big question(s!!!). And perhaps I might be able to shed just a tiny bit later, when I have more time lol! Hopefully those with more knowledge of the electronics involved will be able to shine much more...:dt880smile:.

    As for how things came about re. trying triode-strapped pentodes, I first experimented with the C3g in my LittleDot MKIV SE, purely on a passing mention from member Audiofanboy...with no idea whatsoever whether or not it might blow up the amp!! When it not only worked OK, but actually shone, this was the encouragement for me to experiment with Elise, then Euforia.

    I have to admit that apart from scouring the web, and carefully searching the wonderful Radiomuseum site for any info, the only precautions I took were that the heater requirement was 6.3V and that plate output didn't appear too great...crazy or what?!! The same approach was used when trying alternative triodes such as the FDD20 and ECC31, which were less risky because of their similarity to 6SN7 specs. But then came the EL family of pentodes - first spied by @UntilThen (the EL3N), and which I once again risked having a go at, after the success of the C3g. As pentodes, they would probably be much too powerful for our circuits, but as triode-strapping halves their power, I thought the risk may not be too great. Luckily, they worked OK and the rest is history lol! :ksc75smile:.
    At this point, I should stress that to this day, no-one has figured out exactly why/how they work so well in our amps...this has just turned out to be an incredibly lucky find, and a risk worth taking (on my part at least, as guinea pig...ensuring they are at least safe to use!). And so relying purely and strictly on published specs re. 'best' performance according to specific circuit parameters, I'm sure no-one would have even considered using these pentodes in our amps. In fact, when I sent some EL11s to F-A for testing, apparently the bench readings were 'all over the place', and so they couldn't officially recommend them...and yet they performed extremely well, without any untoward effects whatsoever!! And long-term use of these - and following EL tubes - has proved them perfectly safe to use...with the added benefit if running the amps MUCH cooler than stock configuration.

    And so this hints at the great difficulty in knowing just precisely what official specs will ensure success with any particular tube, regardless of depth of electronic knowledge lol! :wink:. The web can be a useful source for info on what others (especially DIY guys) may have tried as alternatives, and the aforementioned Radiomuseum site is great for finding similar tubes that may have preceeded or succeeded a particular one, and give a possible clue (I find it best to Google the tube number first, thence to the site).

    Hope this sheds at least a little light on this massive and yes - confusing subject!...CHEERS!...CJ
    Last edited: Jan 25, 2019
    Madhyamika and DavidA like this.
  12. mordy
    Hi Madhyamika,
    I would like to add just a couple of points to the excellent comments of h1:
    The synergy between tubes is very important. Some tubes don't sound good with certain other tubes, and other combinations are great sounding. I have not come across anything that can predict how things are going to sound or could be measured - it's all trial and error.
    You have to be careful not to exceed the current rating of the amp to avoid damaging it. If the total current draw gets close to the limit, you can check on the amp by touching it, or, using an inexpensive infrared thermometer, make sure that it does not get too hot - heat being enemy #1 of electronics.
    Many times the designer/manufacturer of the amp can tell you what works and what does not, but as you can see from h1's comments, some manufacturers err on the side of caution.
    There is some kind of consensus which tubes are the best sounding, but it is a mistake to think that there is a relationship between price and performance - very often very inexpensive tubes sound absolutely great. Also, a tube that sounds great in one amp may not work as well in a different amp. This is where the advice of forum members becomes invaluable.
    Madhyamika likes this.
  13. Madhyamika
    Thank you @hypnos1 and @mordy for your helpful replies - this gives me a very good philosophical summary of the pioneer spirit that has helped lead us to some of these lovely discoveries that we are already enjoying. I do have an infrared thermometer here that I’ve been using on the big tube amp (a VTA ST-120) so I’ll use it to get a baseline measurement for Elise too with stock tubes and with a quad of EL38s. I’m not inclined to stray too far in experiments since I’m already so pleased with the 38s, but I’m also interested in knowing more about the how and why of how tunes and amp interact electrically and sonically so I’ll be able to make good decisions about possible experimentation with this amp and others in the future.
  14. hypnos1
    Hi again Jay....just another quick note even if not really answering your quest for knowledge!

    I fear you will indeed probably be searching for ever more to find detailed info on the 'hows and whys' of such interactions...there certainly does seem to be very little easily available comprehensive explanation for amateurs and professionals alike. I suspect this is only really geared to specialist electronic teaching establishments, or those who have been in the business a very long time. I suspect also that a good deal of this knowledge is surrounded in secrecy...'trade secrets' if you will. And as a consequence therefore, I would imagine that the best, and most likely source for we amateurs would be the DIY forums. But even many of those seem to have dwindled over recent times re. guys who have both the knowledge and time/desire to actually answer such questions.

    As far as 'possible experimentation' goes, I'm afraid the official line will always (understandably) be 'stick with the tubes specifically configured for'....full stop! Anything outside this will always incur risk, of course. I personally have been happy to indulge such risks, but I don't actually recommend it too much...unless based upon previous findings with something at least similar. I myself have been ridiculed in the past by 'knowledgeable' guys in this hobby, simply because I dared to question 'accepted wisdom'. And I must admit that luck has played a big part also in my end results. So, as Dirty Harry might say...."Do you feel lucky?"!!! I know you would much rather have a solid, scientific basis for experimentation, but I expect you will indeed just have to keep scouring the endless web for clues as to what might be possible/safe if straying off the accepted path, M...:triportsad:

    But re. your power amps and the EL34 etc, I'm sure @Johnnysound could give you a few pointers in that area...he having experience of such tubes (and also loving the EL38 in his own power amp)...

    I wish you all the best in your thirst for deeper insights into the rather mysterious (IMO) world of our glass wonders lol....CHEERS!...CJ
    connieflyer likes this.
  15. OctavianH
    I do not want to interfere in a very interesting discussion, in which I am particularly interested, but I have to come back as promised, with some details and pictures of my new Furman power conditioner. I have to say that I was quite impressed since it arrived at my door in 3 days from Germany. On Black Friday I ordered a SSD for my PC from Amazon and it arrived via local Post Office after 2 months, so it was a surprise to receive it so fast.

    Link: https://www.furmanpower.com/product/10a-two-outlet-power-conditioner-export-AC-210A E

    Ok, but let's see what I found in the box:


    The packaging was very simple. The seller sent me 2 additional cables, which are not normally included by Furman, and provided me the choice to opt for these ones or Schuko ones.
    Inside the box was the unit which looks identical to the pictures:


    The metal enclosure is sturdy and gives a good impression of quality. The included power cable seems also a decent one.
    And to have a size comparison with Elise and my DAC I will put also a picture of the actual configuration of my headphone line.


    And now the opinion regarding the effect on the sound, which I think is what anyone wants to hear. I have to say that I have listened to Elise only 2 hours after I connected it and mostly to the same album, but it was an album I listened yesterday a lot and I can say I know it quite well, it is the latest Evergrey album, The Atlantic. Just to check if everything is fine I tried also my all time favorite progressive rock band (unknown for you, it is a romanian band from 80s), but only for a track. That track is the one I always use to check my audio line, because the production is one of the best I ever heard and for me is a measure of clarity. When that track sounds fine, I can say that everything is in order.

    Ok, now the conclusion: the sound signature is identical, nothing has changed and everything is there as you know it, but the difference is made by clarity. There is exactly the same amount of detail, but every instrument has more edge, instrument separation is better and you have the feeling that Elise sounds the same but you have, somehow, reduced to silence the other noises in the house and you are able to hear it better. I would say that the differences are bigger when the production is better, since the prog rock romanian band just kills Evergrey's production in all aspects and on that track my impression was that the improvement was much more distinguishable. In the past, when I added a LPS to my 2Qute, I had the first feeling that somehow the mids were recessed, especially on the electric guitar, but the reason was, most probably, that the noise was adding a little bit of harshness to the distortion of the electrical guitar which sounded better to my noob ear. In time I got used to that and realized that the LPS was definitely an improvement for the DAC. Now, with this small power conditioner I have the feeling that also Elise is a step higher, and for an investment of approx. 200 EUR I would say, since it provides also protection, that is was a good decision.

    By the way, for others which are using such devices, are you turning off these conditioners when the Elise is OFF or you just leave them ON all the time? Furman is not mentioning anything about this on their support manuals.
    Last edited: Jan 27, 2019
    Scutey and hypnos1 like this.
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