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    A week of listening to my VTA 70 and im hooked!

    Midwestside
    Midwestside

    Posts : 44
    Join date : 2019-03-20

    A week of listening to my VTA 70 and im hooked! Empty A week of listening to my VTA 70 and im hooked!

    Post by Midwestside on Mon Apr 27, 2020 7:01 pm

    I've been quite enjoying my VTA 70 for almost a week now.
    I have it hooked up to a pair of Bozak 302a urbans
    and a XiangSheng 728A chinese tube preamp running JJ 12au7 and 12at7 tubes.
    I upgraded the VTA's rectifier to a NOS Mullard gz34 and the center position preamp driver board tube to a nos mullard 12au7.
    Svetlana el 34 are what im using for power tubes currently.
    It seems like each little upgrade is bringing the magic more and more.
    Decidedly, i seem to like triode mode a lot, esp for jazz and acoustic music.
    The sound is so lifelike and 3d, i feel like 'im there' sometimes.
    I like that i get a lot of lush clarity at lower volumes in triode.

    I still have a lot of hours left on the el34s, but i sort of have the rolling bug and had read some like the KT-66 in this amp.
    What would KT66s bring to the game?
    I would also be interested to hear what some of you would recommend as an upgrade to the JJ 12au7/12at7 in my pre amp.
    I am very new to the world of tubes, but fairly mechanically inclined in other areas, so i may be asking a ton of newbie questions.

    I am so glad i decided to keep this and learned to fix what was ailing my build. I dont think it will ever be easy to go back to SS. lol
    peterh
    peterh

    Posts : 1317
    Join date : 2012-12-25
    Location : gothenburg, sweden

    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

    Post by peterh on Tue Apr 28, 2020 1:17 am

    Midwestside wrote:I've been quite enjoying my VTA 70 for almost a week now.
    I have it hooked up to a pair of Bozak 302a urbans
    and a XiangSheng 728A chinese tube preamp running JJ 12au7 and 12at7 tubes.
    I upgraded the VTA's rectifier to a NOS Mullard gz34 and the center position preamp driver board tube to a nos mullard 12au7.
    Svetlana el 34 are what im using for power tubes currently.
    It seems like each little upgrade is bringing the magic more and more.
    Decidedly, i seem to like triode mode a lot, esp for jazz and acoustic music.
    The sound is so lifelike and 3d, i feel like 'im there' sometimes.
    I like that i get a lot of lush clarity at lower volumes in triode.

    I still have a lot of hours left on the el34s, but i sort of have the rolling bug and had read some like the KT-66 in this amp.
    What would KT66s bring to the game?
    I would also be interested to hear what some of you would recommend as an upgrade to the JJ 12au7/12at7 in my pre amp.
    I am very new to the world of tubes, but fairly mechanically inclined in other areas, so i may be asking a ton of newbie questions.

    I am so glad i decided to keep this and learned to fix what was ailing my build. I dont think it will ever be easy to go back to SS. lol
    KT66 will like KT77 live close to or above it's limits as regards for grid resistors
    VTA70 has 270k grid resistors, KT66 needs 250k at plate loss < 27w 100k
    if the tube is loaded more.
    PeterCapo
    PeterCapo

    Posts : 794
    Join date : 2008-12-05

    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

    Post by PeterCapo on Tue Apr 28, 2020 11:24 am

    KT66 can be used in the Stereo 70, both in the original and with a different circuit installed. But what I do not see discussed very often is that the Stereo 70 optimally functions with EL34 types, while the KT66 and 6L6 family does better seeing a different load at the output transformer primary. As I understand it, distortion will increase using 6L6 and KT66 in the Stereo 70.
    peterh
    peterh

    Posts : 1317
    Join date : 2012-12-25
    Location : gothenburg, sweden

    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

    Post by peterh on Tue Apr 28, 2020 12:02 pm

    PeterCapo wrote:KT66 can be used in the Stereo 70, both in the original and with a different circuit installed.  But what I do not see discussed very often is that the Stereo 70 optimally functions with EL34 types, while the KT66 and 6L6 family does better seeing a different load at the output transformer primary.  As I understand it, distortion will increase using 6L6 and KT66 in the Stereo 70.
    The risk of avalanching grid current exists with KT66 and KT77 as they need a smaller value
    for grid resistor to avoid runaway. This is not an immediate danger but an enhanced risk that
    tube runaway might happen. The fact that both distortion and cost is lower with EL34
    does not stop people to try other tubes.
    MechEngVic
    MechEngVic

    Posts : 58
    Join date : 2019-01-16

    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

    Post by MechEngVic on Fri May 01, 2020 1:07 am

    Midwestside wrote:I still have a lot of hours left on the el34s, but i sort of have the rolling bug and had read some like the KT-66 in this amp.
    What would KT66s bring to the game?
    I would also be interested to hear what some of you would recommend as an upgrade to the JJ 12au7/12at7 in my pre amp.
    I am very new to the world of tubes, but fairly mechanically inclined in other areas, so i may be asking a ton of newbie questions.

    I am so glad i decided to keep this and learned to fix what was ailing my build. I dont think it will ever be easy to go back to SS. lol

    I have not gone back...

    FOR:

    12au7: New production [Gold Lion ECC82 / B749 / 12AU7], [Telefunken Black Diamond ECC82 / 12AU7]
    NOS: Mullard ECC82 (also branded Amperex, look for the "B")
    12at7: New Production [Gold Lion ECC81 / B739 / 12AT7], [Mullard 12AT7 / ECC81 (made in Russia)]
    NOS: German made (RTF, Valvo, Siemens)

    True NOS Telefunken are expensive and hard to get, most out there are Chinese Fakes

    I'd stay with the EL-34. New production Mullards and Tung-Sol are good. NOS Mullard EL-34's are about 150.00 or more each (buy from reputable source)
    peterh
    peterh

    Posts : 1317
    Join date : 2012-12-25
    Location : gothenburg, sweden

    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

    Post by peterh on Fri May 01, 2020 7:17 am

    MechEngVic wrote:
    Midwestside wrote:I still have a lot of hours left on the el34s, but i sort of have the rolling bug and had read some like the KT-66 in this amp.
    What would KT66s bring to the game?
    I would also be interested to hear what some of you would recommend as an upgrade to the JJ 12au7/12at7 in my pre amp.
    I am very new to the world of tubes, but fairly mechanically inclined in other areas, so i may be asking a ton of newbie questions.

    I am so glad i decided to keep this and learned to fix what was ailing my build. I dont think it will ever be easy to go back to SS. lol

    I have not gone back...

    FOR:

    12au7: New production [Gold Lion ECC82 / B749 / 12AU7], [Telefunken Black Diamond ECC82 / 12AU7]
              NOS: Mullard ECC82 (also branded Amperex, look for the "B")
    12at7: New Production [Gold Lion ECC81 / B739 / 12AT7], [Mullard 12AT7 / ECC81 (made in Russia)]
              NOS: German made (RTF, Valvo, Siemens)

    True NOS Telefunken are expensive and hard to get, most out there are Chinese Fakes

    I'd stay with the EL-34. New production Mullards and Tung-Sol are good. NOS Mullard EL-34's are about 150.00 or more each (buy from reputable source)
    Telefunken black diamond are relabeled JJ. Only the best will do !
    Midwestside
    Midwestside

    Posts : 44
    Join date : 2019-03-20

    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

    Post by Midwestside on Fri May 01, 2020 10:50 am

    MechEngVic wrote:
    Midwestside wrote:I still have a lot of hours left on the el34s, but i sort of have the rolling bug and had read some like the KT-66 in this amp.
    What would KT66s bring to the game?
    I would also be interested to hear what some of you would recommend as an upgrade to the JJ 12au7/12at7 in my pre amp.
    I am very new to the world of tubes, but fairly mechanically inclined in other areas, so i may be asking a ton of newbie questions.

    I am so glad i decided to keep this and learned to fix what was ailing my build. I dont think it will ever be easy to go back to SS. lol

    I have not gone back...

    FOR:

    12au7: New production [Gold Lion ECC82 / B749 / 12AU7], [Telefunken Black Diamond ECC82 / 12AU7]
              NOS: Mullard ECC82 (also branded Amperex, look for the "B")
    12at7: New Production [Gold Lion ECC81 / B739 / 12AT7], [Mullard 12AT7 / ECC81 (made in Russia)]
              NOS: German made (RTF, Valvo, Siemens)

    True NOS Telefunken are expensive and hard to get, most out there are Chinese Fakes

    I'd stay with the EL-34. New production Mullards and Tung-Sol are good. NOS Mullard EL-34's are about 150.00 or more each (buy from reputable source)


    Thank you for the recommends.

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    A week of listening to my VTA 70 and im hooked! Empty Re: A week of listening to my VTA 70 and im hooked!

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