Do the four tubes in the Eclipse have to be matched? Any suggestions for NOS tubes?

  • Hello. First question: I have read on the internet that the four tubes put into the Eclipse do not need to be closely matched, as the circuit is self-biasing. Is this correct? Would it be important for the two tubes on the left side (the entry tubes) to be a matched pair, as they are more important than the right hand tubes (exit tubes)?


    I am asking because it is much more difficult to find a matched quad of NOS / vintage tubes. However, it is easier to find either two matched pairs, or four unmatched individual tubes.


    My second question: last year I changed the stock tubes to two Brimar 6067 ECC802S 'T' (the entry tubes), and two Pinnacle 13D5A (the exit tubes). However, I would like to see how much the sonic character of the Eclipse changes with tube rolling. Does the sound of the Eclipse really change very much with different tubes? If so, can anyone suggest which vintage / NOS tubes would be worth trying next? I have read that Amperex 7316 tubes are excellent, but they are very expensive. A less expensive option appears to be the RCA clear top 12AU7A, or the Westinghouse 12AU7 with the carbonised plates from the 1950s.


    Any suggestions would be welcome. Would it be worth moving the two Brimar 6067 ECC802S 'T' tubes to the right hand side (as the exit tubes), and use something different in the left side (entry tubes)?


    Many thanks.

  • Let me please try and address Your first question regarding the Eclipse. First I will clarify the facts for everyone in the forum, Only the Power Amplifiers have the ABR circuit which is also called the Auto Bia Regulator. The preamplifiers do not have this circuit geometry and DO NOT auto Bias.

    Next, you are correct in your statement that the tubes on the left side are most important and that a matched pair would be a very wise investment.

    I myself have no experience withThe Westinghouse 12AU7's but the company has a reputation of as being one of the best in the world. What I can tell you that I have done some good tube rolling with Aperex 7316 out of the Holland factory and the Bugle Boys, RCA clear tops sound very similar to Mallards and the Sylvania triple mica AU7's.

    Everything is a matter of personal taste? My personal taste is the Bugle Boys than the RCA Clear Tops, but I may have different taste than you do.

    I Hope this is of some help. Someone in Florida told me he likes the Sylvania's more

  • Many thanks for your response, particularly the information that the Eclipse does not auto bias.


    After discussing this with audio experts in other forums I've decided not to try other valves in the Eclipse: I do not think it will make any difference to the sound profile.


    In my hi-fi system the sound with the Eclipse is quite mids-focused, and seems to me to lack some precision and definition. In addition, the soundstage is good from left to right, but not so good from top to bottom. This is what I was hoping to fix by trying different valves: a better balanced sound, less mids-centric, a bit more air, an improvement in soundstage, and better placement of vocals. I managed to achieve all of these things when I replaced the Eclipse temporarily with the preamp section of a solid state, neutral signature integrated amp.


    My belief is that if the circuit has been designed correctly around the valve, then it won't matter very much whether you're using a modern production tube or some rare 1950s version with a big price tag. Essentially the circuit as a whole defines the sound signature, and although individual parts do play a role terms of specific characteristics (as they would in a solid state amp), they cannot alter the circuit properties that much. My experience of tube rolling in a headphone amp supports this: there are some very subtle differences between different 6SN7s, for example, but not enough to justify the price that NOS / vintage 6SN7s now sell for. I think there's a lot of hype in some audio forums about the sonic benefits which are claimed for some old production valves: I think a lot of that is just New Toy Syndrome, rather than an actual, significant difference between Tube X and Tube Y.


    Tube rolling comes at a significant cost: a quad of 7316s in the UK will cost at least £300. If they don't give me what I'm looking for then another quad of 5814s (for example) will also be expensive.


    In the last few days I've been trying to weigh up the likelihood of being able to modify the Eclipse signature to what I want by changing valves. But I don't think this will be possible, and perhaps replacing it with a solid state preamp would be a better investment.

  • MP 1968:


    First, I do not know what amplifiers you have teamed up with the Eclipse?

    Every piece of equipment matters! Think of your setup as a multiple windows that you are looking through. If one is dirty than you have compromised the system. A solid State amplifier will sound very much different from a Tube amplifier. The dampening factor of a solid state amp is exceedingly better and will give you more bass control but can't compare to the harmonics of a tube amp. So again we need to know what music you enjoy and what other components are in your setup. I like Nordust Valhalla cable, you may like Cardas or MIT cables. My experience has led me to believe that tube rolling has its merits on the two left tubes. Each manufacture of tubes can differ in materials during manufacturing. I mention the Sylvania Triple Mica 12AU7 and the Bubble Boy from Holland, Both are 12AU7's but the materials are vastly different. The Cathodes will heat at a different rate and temperature releasing thermionic emissions at different rates.

    Think of this in terms of free electrons. A better understand is much easier for you to Google "How Vacuum tube work".

    Again it is all a matter of what you enjoy! If you listen to Bob Marley than the Eclipse is not going to give you that electric bass slam you like. If its jazz or vocals, I love my Eclipse.

    I hope that this has been of some help.

    Enjoy the Music.

  • Hi Martin,


    Many thanks for the information, that's very helpful.


    I have decided to try some tube rolling in the Eclipse. I am going to start with RCA Clear Top 12AU7s. I will also try modern production Psvane 12AU7 TII.


    Can I just clarify one thing? Your post says that 'tube rolling has its merits on the two left tubes'. Hence is it really only the two left tubes which make a difference to the sound quality of the Eclipse? Is there any point at all in changing the two right hand tubes?


    If it's the case that only the two left tubes are worth rolling then that's very important. It means I can put two of the stock Electroharmonix valves (which came with the Eclipse) in the right hand position, and just focus on rolling the two left tubes. This would make it much less expensive, as I will only need to find a matched pair (not a matched quad).


    Incidentally, I collect vintage solid state and valve amplifiers, both integrated and power amps. I have the Sony TA-F7 (V-FET), Sansui AU-111, Sansui AU-907 Alpha Limited, Sansui BA-F1, Pioneer M90a, Sansui AU-X11, Radford STA25 Series 3, Victor JM-S7 (V-FET), Sansui BA1000 (V-FET), and Yamaha B3 (V-FET).


    These are what I use with the Eclipse. The integrated amps can also be used as power amps. Because many of these amps are quite old, they have all been fully serviced and restored (new electrolytics, etc etc) by technical experts in different parts of Europe who I have 'met' through Audiokarma.


    My speakers are Tannoy Eaton Legacy. My DAC is an Aqua La Voce S3 (R2R design).


    I listen to lots of different types of music, but not much classical.


    Best wishes,


    Mark

  • Hello again Mark<


    Nice to hear from you again. I am very interested in your findings with the Psvane 12AU 7's. I have some of the RCA clear tops and have found them to have a similar sound to the mallards with some differences

    Mark, my most succinct answer for you is to think of the left tubes in the Eclipse as your money tubes. Keep the stock tubes on the right and forget about them. I would love to have some of your equipment. I don't have enough room in my flat to own that many Amplifiers and my first real fine speakers were Tannoy's. That was back around 1976. My favorite concert was

    WOODSTOCK8). I had a lot more hair back than.

    Remember the left tubes are the money tubes, I would suggest a match pair whenever possible and please tell us about the Psvane 12AU7's.

    ENJOY THE MUSIC,

    Regards,

    Marty

  • Hello,


    Currently my Eclipse runs with 4 RCA clear top.

    As I read good comments about Telefunken 6211, I'm curious to hear them.

    Please, is this 6211 model compatible withthe Ecplise?

    Is somebody experienced this ones?

    Thanks in advance

    Best regards,

    Gérard

  • Following on from Gérard's question, I'd like to know whether two E80CC valves could be used in the left hand position.


    According to the Brent Jessee website (http://www.audiotubes.com/12au7.htm) they can be used as ECC82 substitutes, but with a couple of factors to consider:


    'Since this tube has a much higher Gm and Mu factor than a 12AU7, the gain is going to be greater and this tube will give a more forward presentation. Awesome in phase splitter applications. If in doubt, check with your amp or preamp manufacturer to see if this tube will work OK in your application. This tube is also about twice as tall as a 12AU7, so installation space in your chassis is a consideration as well'.


    Marty - any thoughts?


    Best wishes


    Mark

  • The AU7 is a great vacuum tube and

    Well known for its a low noise , and part of double triode family. It Is used either in 6.3 V at 300 mg what 12.63 50 mA in a heater circuits for both PreAmps and Amplifiers.

    That said I will address Gerad’s question: You can use the 6211 in the Eclipses. This tube is more like the 12AT7 with a lower gain than both the 12Au7 and the 12AT7. The construction of this tube makes it as as very desirable tube because it tends to be more ridged, robust, and very mellow. Make shure when purchasing that they are tested for Microphonics.

    Gerard, if you can find a matched pair of Telefunken 6211; grab them! Some of my colleagues have claimed better bass response from these tubes.

    Good luck and enjoy the music



    MP1968,

    The ECC80 is a tube I have not come across, As I understand it was primarily made in Europe just like the ECC82 and we have made an equivalent via RCA, GE, Sylvania in our 12AU7. The ECC 80 from Holland would be something I would love to find or our equivalent 6085. I will tell you that I love the ECC82 from Holland and have absolutely enjoyed the sound of the Amperex tubes including the Bugle Boys. I'll try and get a better answer for you regarding the ECC80.

    Until than enjoy the music.

  • Thanks you very much for your answers, a great help for me as I'm new in the tube world.

    I've a matched pair of 6211 Telefunken in my radar. I'll see tomorrow if still available

    In the meantime, today I bought 2 pairs (close for a quad finally) of RTC 6189 and the result is ... wow, wonderfull, well balanced, lot a micro info that appear without being analytic, more natural/neutral sound. Exit/forgot my quad of RCA.

    The Eclipse is a very nice machine, yes enjoy the music.

    Kind regards

    Gérard

  • I have tried two RCA clear top 12AU7 valves in the left hand position, and thought I would post my brief impressions here.


    Certainly the signature is very precise and detailed. My only slight reservation is whether there is perhaps too much treble detail, which is a criticism of these valves on other forums. There is perhaps an emphasis on the higher frequencies with a slight loss of mid range response. Some music tracks can sound quite sibilant.


    Anyway, I'll spend some more time with them. I also have a pair of Siemens 5814A triple mica to try, plus a pair of 6189 tubes which are labelled Philips but which I think were made by RTC. Gerard had good results with these 6189 valves, so I wanted to try them.

  • I used music files through a DAC via the AUX 3 input on the Eclipse. The volume control on the Eclipse was at 50%, i.e. around the 12.00 position.


    I think the AUX3 input has higher gain (24dB), so perhaps I should use the AUX1 input instead? The DAC output is 2.4 V RMS from the RCA outputs.