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  1. #1
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    Tube questions....again

    I don't think I ever got a good answer to my question as to which set of tubes in my pre-amp have the most effect on the sound output. My VAC uses 2 12AU7s (input I believe) and 2 12AX7s for the output-gain.

    When I took ownership of this pre, the previous owner had 4 12AX7s in it, which will play but not correctly. One could also use 4 12AU7s but again without good results.

    I had several pairs (triplets) of Sovtek 12ax7lps and wxt+ from my previous Sound Valves 101i so I used a set of those along with purchasing a set of JJ Tesla ECC82s. I think they were under $15 a piece.

    I recently had some AX7s go bad and am looking to replace them but still have questions.

    Is it always best to have both sets of matching quality-price range and MFG?

    Would I be best off leaving the AU7s alone and focusing on the AX7s? The PSVane tubes have a pretty good rep so far but I don't want to spend $200 right now.

    So I'm trying to decide do I go with 1 set of PSVane 12AX7s or get a set of each JJ Tesla Gold Pin or similar keeping my budget somewhere near $100?

  2. #2
    Forum Regular blackraven's Avatar
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    Choice of tubes is definitely a personal choice. It all boils down to what sounds best to you. For example, my gear uses 6CG7 or 6N1P tubes. People rave about how great the 6CG7 RCA Clear Tops sound. To me they sound just ok and I prefer my Tong Sol's along with Aprex, Mazda-Brimars and RCA Black Plates.

    When rolling tubes there is always a trade off in some part of the sound. You can absolutely go nuts trying to find that right combination. But to answer your question, there is no written rule that you have to have matching price tubes. One of the benefits about tube gear is tube rolling to taylor the sound to your liking.

    I hope this helps some.

    Larry
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  3. #3
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    Quote Originally Posted by blackraven View Post
    Choice of tubes is definitely a personal choice. It all boils down to what sounds best to you. For example, my gear uses 6CG7 or 6N1P tubes. People rave about how great the 6CG7 RCA Clear Tops sound. To me they sound just ok and I prefer my Tong Sol's along with Aprex, Mazda-Brimars and RCA Black Plates.

    When rolling tubes there is always a trade off in some part of the sound. You can absolutely go nuts trying to find that right combination. But to answer your question, there is no written rule that you have to have matching price tubes. One of the benefits about tube gear is tube rolling to taylor the sound to your liking.

    I hope this helps some.

    Larry
    Thanks BR, but I guess my main question is, will I get a better change in sound by changing the AU7s or the AX7s. I don't understand enough as to what the AU7s do. I do understand the AX7s are the output and add gain.

  4. #4
    frenchmon frenchmon's Avatar
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    Quote Originally Posted by Hyfi View Post
    I don't think I ever got a good answer to my question as to which set of tubes in my pre-amp have the most effect on the sound output. My VAC uses 2 12AU7s (input I believe) and 2 12AX7s for the output-gain.

    When I took ownership of this pre, the previous owner had 4 12AX7s in it, which will play but not correctly. One could also use 4 12AU7s but again without good results.

    I had several pairs (triplets) of Sovtek 12ax7lps and wxt+ from my previous Sound Valves 101i so I used a set of those along with purchasing a set of JJ Tesla ECC82s. I think they were under $15 a piece.

    I recently had some AX7s go bad and am looking to replace them but still have questions.

    Is it always best to have both sets of matching quality-price range and MFG?

    Would I be best off leaving the AU7s alone and focusing on the AX7s? The PSVane tubes have a pretty good rep so far but I don't want to spend $200 right now.

    So I'm trying to decide do I go with 1 set of PSVane 12AX7s or get a set of each JJ Tesla Gold Pin or similar keeping my budget somewhere near $100?
    Here's a good site that Raven sent me some time ago. If you go towards teh middle of the page you will see a chart with a list of tubes and the characteristis of each tube. It may be of some help to you.

    12AX7 Tube Type Review


    Also I to thought about the PSVane. Another good choice would be the Golden Lion tubes...
    Music...let it into your soul and be moved....with Canton...Pure Music


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  5. #5
    frenchmon frenchmon's Avatar
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    Quote Originally Posted by Hyfi View Post
    Thanks BR, but I guess my main question is, will I get a better change in sound by changing the AU7s or the AX7s. I don't understand enough as to what the AU7s do. I do understand the AX7s are the output and add gain.
    In my preamp I have a pair AX7's which are the left and right gain. I have a pair of Au7 with one not going through the signal becasue it some how is for the power supply. The other Au7 has both AX7's signal going through it. So I assume the Au7 in your has the gain stage going through your Au7's.

    I changed out my stock Au7 for a Tulefunken Au7 and it gave me a better presentation. I think the Au7 would change the sound more...but I have yet to change the AX7's.
    Music...let it into your soul and be moved....with Canton...Pure Music


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  6. #6
    frenchmon frenchmon's Avatar
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    This is what Poppachubby sent me some time ago

    "Frenchy lots of preamps wil have a final stage which the signal will go through. My EICO has a pair for each channel and then a fifth tube which it all filters through. What it means is that you can have more fun manipulating the tone. I often switch out this fifth tube between a Mullard and a Psvane. I am done rolling for now, so enjoy and hopefully you will find the perfect combo."
    Music...let it into your soul and be moved....with Canton...Pure Music


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  7. #7
    frenchmon frenchmon's Avatar
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    He it is again just in case you did not see it.

    "Frenchy lots of preamps wil have a final stage which the signal will go through. My EICO has a pair for each channel and then a fifth tube which it all filters through. What it means is that you can have more fun manipulating the tone. I often switch out this fifth tube between a Mullard and a Psvane. I am done rolling for now, so enjoy and hopefully you will find the perfect combo. "
    Music...let it into your soul and be moved....with Canton...Pure Music


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  8. #8
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    Quote Originally Posted by frenchmon View Post
    Here's a good site that Raven sent me some time ago. If you go towards teh middle of the page you will see a chart with a list of tubes and the characteristis of each tube. It may be of some help to you.

    12AX7 Tube Type Review


    Also I to thought about the PSVane. Another good choice would be the Golden Lion tubes...
    Thanks Frenchy. I have been going over the previous threads and suggestions. Seems like everyone agrees the Sovtek LPS to be good tubes but I think I can get better sound. I can't afford to buy multiple sets of tubes to experiment but would rather just spring for the best option.

    I would really like to know what the 12AU7s do before the signal gets to the 12AX7s. And, which ones have the most effect on the sound output.

  9. #9
    frenchmon frenchmon's Avatar
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    "I would really like to know what the 12AU7s do before the signal gets to the 12AX7s. And, which ones have the most effect on the sound output. "

    I would imagine its only job is to manipulate the sound according to which tube is in the soket, and then output that sound to amp. I dont know that it does anything before the signal gets to it. But thats just my guess. I got my little knowledge for PoppaC, E-Stat, and Poultrygeist.

    Did you see my post above of what PoppaChubby said?
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    Quote Originally Posted by frenchmon View Post
    "I would really like to know what the 12AU7s do before the signal gets to the 12AX7s. And, which ones have the most effect on the sound output. "

    I would imagine its only job is to manipulate the sound according to which tube is in the soket, and then output that sound to amp. I dont know that it does anything before the signal gets to it. But thats just my guess. I got my little knowledge for PoppaC, E-Stat, and Poultrygeist.

    Did you see my post above of what PoppaChubby said?
    Yeah, thanks for the info and reposts. I'm going to try emailing VAC and see what they tell me.

  11. #11
    frenchmon frenchmon's Avatar
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    Yeah..I agree.
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    I just talked to Kevin at VAC and he gave me one hell of an education I will probably never understand. By the time we were done and he took the time to answer my many questions, I am considering ordering tubes from them. The 12AU7s are NOS American, Phillips I think he said and the 12AX7s are from one of 3 Chinese MFGs.

    He said the JJ tubes have what he describes as a Bark, along with the signature Sovtek sound of being up front and sharp. With their recommendation of tubes, I would have a more linear sound with some more air, mellower highs and more detailed bass.

    He also said that if I upgraded my unit to a MK3, do not run Sovtek tubes in it at all. Also, for my pre-amp, I do not need to worry about spending extra for Low Noise but he does suggest matched pairs.

    Each tube they sell is $22 so I can do all 4 for under my $100 mark and get a real good baseline sound that the VAC engineers are familiar with and if I am unsatisfied, he can point me in specific directions to alter the sound any way I want.

    Other info he gave was that the AU7s are the more critical tube and should be the higher quality if going that route. But, he also said that with a given set of AUs with another given set of AXs that it will sound just great, and by swapping the AXs, the preferred sound from the AUs would change also. It's all pretty confusing to the layman for sure but I think going with the tubes that they put in their new gear today will put me on the road I am looking for without having to experiment and spend too much money playing around.

    Who better to suggest the correct tubes as a good start but the people who created my pre amp.

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    I just ordered 2 matched sets from VAC. $88 plus shipping and they should make it to me by Monday or Tuesday so I can update this thread after that before break in time and then after another 50-100 hours.

    Looking forward to some better sound from my VAC after using the cheapest Au7s I could buy along with the old run down Sovteks.

    I will also update as to exactly what makes and models they send me when I get them.

  14. #14
    frenchmon frenchmon's Avatar
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    Very good Hyfi! Thanks a lots....I think you did the right thing. Peabody's Conrad-Johnson came with some great tubes as well and Conrad Johnson does specify the tubes he should use. I think I will give a call to the USA distributor of Vincent to see what they recommend.
    Music...let it into your soul and be moved....with Canton...Pure Music


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  15. #15
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Hyfi View Post
    I don't think I ever got a good answer to my question as to which set of tubes in my pre-amp have the most effect on the sound output. My VAC uses 2 12AU7s (input I believe) and 2 12AX7s for the output-gain.
    If you look on their website, you'll find the manual for the CPA-1 which adds a phono stage to the line stage of the CLA-1. The 12AU7s are used for gain and the 12AX7s are unity gain buffers. For that reason, the 12AU7s will have a more profound effect on the sound quality - unless you choose the passive buffered mode. The Manley DAC I use in the vintage system also uses 12AU7s where I have experimented a bit. I really like the sound of 60s vintage RCA Cleartops.

    Quote Originally Posted by Hyfi View Post
    Is it always best to have both sets of matching quality-price range and MFG?
    For the gain stage, yes. For the buffer stage, no.

    rw

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    Quote Originally Posted by E-Stat View Post
    If you look on their website, you'll find the manual for the CPA-1 which adds a phono stage to the line stage of the CLA-1. The 12AU7s are used for gain and the 12AX7s are unity gain buffers. For that reason, the 12AU7s will have a more profound effect on the sound quality - unless you choose the passive buffered mode. The Manley DAC I use in the vintage system also uses 12AU7s where I have experimented a bit. I really like the sound of 60s vintage RCA Cleartops.


    For the gain stage, yes. For the buffer stage, no.

    rw
    Thanks E.
    While I had seen the manual, just didn't quite understand it. I'm googling my butt off but electronics was never my strength.

    So in gain mode, it's more about the AU7s and in Passive its all about the AX7s. There lies another rolling expedition. The trick is putting together 2 pairs that compliment each together and in passive. That is why I am hoping that the VAC suggested tubes gets me to that place.

    They go on to say
    "The Active modes add a Class A amplifying triode tube to each channel, and causes the main
    outputs to have inverted absolute polarity with respect to the line inputs. To correct for this you may
    invert the polarity between your power amplifier and loudspeakers."

    Should I be reversing one end of my speaker cables? And, are they saying only in active mode, which would mean flipping the cables along with switching from gain to passive?

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    Both the 12au7 and 12ax7s will affect the sound. The JJ's and Sovtek's are entry level tubes at best and can't compete with vintage NOS tubes. You won't go wrong with tubes like RCA clear tops/black plates, Amperex orange globes/bugleboys, Mullards, Tungsols, Telefunkens etc. NOS Mullards took my Paramours to another level. Had the guy who sold me the Bottlehead Paramours heard them with the Mullards he would never have sold them.

    Look for relabled organ tubes such as Conn, Lowery, Baldwin etc as they are built to higher standards. Good testing used tubes will save lots of money over NOS. Preamp tubes can last forever.

  18. #18
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Hyfi View Post
    Should I be reversing one end of my speaker cables? And, are they saying only in active mode, which would mean flipping the cables along with switching from gain to passive?
    That would seem to be the case. Conrad-Johnson preamps also invert phase. Not a problem, but definitely a detail.

    rw

  19. #19
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    I recently replaced stock 12ax7 preamp tubes with Genelex golden lions. Definitely pleased with the decision. Warm and very very quiet.

  20. #20
    frenchmon frenchmon's Avatar
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    Quote Originally Posted by TheHills44060 View Post
    I recently replaced stock 12ax7 preamp tubes with Genelex golden lions. Definitely pleased with the decision. Warm and very very quiet.
    thanks for that information.
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    Just looking at some new products on the VAC website and within one of the descriptions, there was a mention of the VAC President, Kevin Hayes.

    So when I called yesterday to ask questions, thats who I talked to but had no idea I was speaking to the Pres.

    Where do you get that kind of service to a nobody calling to ask dumb questions?

  22. #22
    frenchmon frenchmon's Avatar
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    Sounds like great customer service.
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  23. #23
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Poultrygeist View Post
    Look for relabled organ tubes such as Conn, Lowery, Baldwin etc as they are built to higher standards. Good testing used tubes will save lots of money over NOS. Preamp tubes can last forever.
    Most of my collection is Conn branded. I also have some Sylvanias which are pretty nice, too.

    rw

  24. #24
    Charm Thai™
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    Quote Originally Posted by Hyfi View Post
    Just looking at some new products on the VAC website and within one of the descriptions, there was a mention of the VAC President, Kevin Hayes.

    So when I called yesterday to ask questions, thats who I talked to but had no idea I was speaking to the Pres.

    Where do you get that kind of service to a nobody calling to ask dumb questions?
    Sounds like my experience with Richard Gray Power Company. Great customer service is so refreshing.

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    Quote Originally Posted by Hyfi View Post
    They go on to say
    "The Active modes add a Class A amplifying triode tube to each channel, and causes the main
    outputs to have inverted absolute polarity with respect to the line inputs. To correct for this you may
    invert the polarity between your power amplifier and loudspeakers."

    Should I be reversing one end of my speaker cables? And, are they saying only in active mode, which would mean flipping the cables along with switching from gain to passive?
    Well that was a little more than a subtle change. I only had a chance to spin one comp at low levels and could clearly hear a difference.

    Hard to explain but it was as if the system took a decongestant. Clearer separation, more air and detail. Looking forward to spinning a few of my reference tracks at higher volume later today.

    With this change and some new tubes, I should hit another level of performance I have yet to experience in my system.

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