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    6CA7EH in the VTA70

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    Bigron865

    Posts : 45
    Join date : 2013-03-15
    Age : 48
    Location : Birmingham Alabama

    6CA7EH in the VTA70

    Post by Bigron865 on Fri Mar 22, 2013 7:25 pm

    Well Guys...Just got a new matched set of these and I'm so amazed!!! I usually listen to vinyl exclusively but I just put in Diana Krall on CD and I've never enjoyed the sound of a CD until today! Air, Soundtage, buttery but present vocals and highs to die for! I have 2 JAN RCA 5814A's on each side of the board and a military GE 5814A in the center right now. Sweet sweet sweet! I can't imagine how good this combo will sound when the tubes burn in. The vocals are DEAD CENTER. I'm so glad I upgraded this amp! The test numbers on the tube boxes were all the same. How much do you think the exact matching of the 6CA7's has to do with this great sound? I wasn't getting anywhere near this sound with the Sovtek EL84 tubes and who know if they were even matched? Please excuse my rame but I'm sure that you guys understand what I'm experiencing right now and can appreciate the joy!
    Bigron

    Bigron865

    Posts : 45
    Join date : 2013-03-15
    Age : 48
    Location : Birmingham Alabama

    Re: 6CA7EH in the VTA70

    Post by Bigron865 on Fri Mar 22, 2013 7:30 pm

    Btw all of the 6CA7 tubes biased at .40 and rechecked after 30 min very little drift. Should I check again? If so when?

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: 6CA7EH in the VTA70

    Post by peterh on Sat Mar 23, 2013 4:57 am

    Bigron865 wrote:Btw all of the 6CA7 tubes biased at .40 and rechecked after 30 min very little drift. Should I check again? If so when?
    each full moon is enough :-)

    Bigron865

    Posts : 45
    Join date : 2013-03-15
    Age : 48
    Location : Birmingham Alabama

    Re: 6CA7EH in the VTA70

    Post by Bigron865 on Mon Mar 25, 2013 2:26 am

    Im really enjoying the new vta classic mod with the 6CA7EH tubes. but can it be better?I still have the 30-20-20-20 can cap. What can I expect by upgrading to the 80-40-30-20? And what would upgrading the std vta board capacitance do? I noticed on the tubes4hifi site that I could have gotten the 400uF total cap upgrade when I ordered. Thoughts/benefits?

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: 6CA7EH in the VTA70

    Post by peterh on Mon Mar 25, 2013 2:52 am

    Bigron865 wrote:Im really enjoying the new vta classic mod with the 6CA7EH tubes. but can it be better?I still have the 30-20-20-20 can cap. What can I expect by upgrading to the 80-40-30-20? And what would upgrading the std vta board capacitance do? I noticed on the tubes4hifi site that I could have gotten the 400uF total cap upgrade when I ordered. Thoughts/benefits?
    If you don't have audiable hum there is no point replacing capacitors.

    The speakers are the most likley place where to find next improvement.

    Bigron865

    Posts : 45
    Join date : 2013-03-15
    Age : 48
    Location : Birmingham Alabama

    Re: 6CA7EH in the VTA70

    Post by Bigron865 on Mon Mar 25, 2013 3:08 am

    Ok. But why is it called an upgrade? Don't larger capacitors pass larger frequencies and speed attack?

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: 6CA7EH in the VTA70

    Post by hawaii.ken on Mon Mar 25, 2013 7:41 am

    Bigron865 wrote:Ok. But why is it called an upgrade? Don't larger capacitors pass larger frequencies and speed attack?
    Bigger is NOT always better. Depends on the circuit design. Sometimes you can get a noticeable improvement by bypassing
    (in parallel) your electrolytic caps with film caps.


    peterh wrote:The speakers are the most likley place where to find next improvement.
    Totally agree with that!

    Bigron865

    Posts : 45
    Join date : 2013-03-15
    Age : 48
    Location : Birmingham Alabama

    Re: 6CA7EH in the VTA70

    Post by Bigron865 on Mon Mar 25, 2013 8:12 am

    Thanks. I have some really efficient Klipsch refrence series speakers and I know what they are capable of from using them with other amps/ combos. Just wondering if I'm at the end of my upgrading with the vta 70 or will I just be throwing money away? Next ill get a tube preamp.

    sailor

    Posts : 269
    Join date : 2011-04-04

    Re: 6CA7EH in the VTA70

    Post by sailor on Mon Mar 25, 2013 11:02 am

    Personally I don't like the EL34 including NOS. I think the 6ca7EH is a huge improvement in sound quality.
    As far as power supply. The main purpose of the caps and choke is to lower ripple. Because Dynaco used a choke in stead of a resistor less capacitance is necessary. Plug in different values into the LC calculator below then go to the RC ripple filter calculator and use the same cap value but use different resistor values. You will be surprised how big the resistor must be to get the same ripple attenuation. Check DC voltage drop.
    http://www.ampbooks.com/home/amplifier-calculators/LC-ripple-filter/
    http://www.ampbooks.com/home/amplifier-calculators/RC-ripple-filter/

    Bigron865

    Posts : 45
    Join date : 2013-03-15
    Age : 48
    Location : Birmingham Alabama

    Re: 6CA7EH in the VTA70

    Post by Bigron865 on Mon Mar 25, 2013 1:00 pm

    I agree about the EL's. with the 6ca7 tubes its a whole different amp. What about the PIO cap upgrade? Worth it?

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