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    7581A Power Tubes in VTA-70

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    fedoragent

    Posts : 35
    Join date : 2013-09-14

    7581A Power Tubes in VTA-70

    Post by fedoragent on March 11th 2016, 7:54 pm

    Folks,

    It is about that time of year when I buy power tubes. I'm currently running some 6L6GCs as an experiment. A Chinese tube experiment that is. I've run them for about 6 months with little or no problem and they sound great. However, I think it might be time to get back to the NOS or Russian tubes. I'm thinking about the Tung-Sol 7581A. I hear they are interchangable with the 6L6GC and I assume they'd bias at about 0.40/0.45VDC. Has anyone used the 7581, from any manufacturer in their VTA-70 gear? They are supposed to provide more headroom apparently.

    Any opinions would be welcome. Even smart alec ones.

    Cheers,

    FG.

    peterh

    Posts : 641
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: 7581A Power Tubes in VTA-70

    Post by peterh on March 12th 2016, 3:20 am

    I have used JJ 6550 for 2 years, still keeping bias, still sounds excellent

    Dave_in_Va

    Posts : 128
    Join date : 2013-04-02

    Re: 7581A Power Tubes in VTA-70

    Post by Dave_in_Va on March 12th 2016, 3:13 pm

    I've used 7581A's in guitar amps where 6L6GC's were stock. They're fine.
    I can't imagine new production 7581A's being the same as NOS tubes (which are expensive). They're just too close to 6L6GC's, it seems to me, to justify any manufacturing differences. Just my opinion.

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: 7581A Power Tubes in VTA-70

    Post by tubes4hifi on March 13th 2016, 5:54 pm

    7581s are equivilent to KT66, which is a better quality 6L6GC.
    Just make sure you dont' confuse those with 7591s which are TOTALLY different pinout !!

    fedoragent

    Posts : 35
    Join date : 2013-09-14

    Re: 7581A Power Tubes in VTA-70

    Post by fedoragent on March 19th 2016, 1:59 am

    tubes4hifi/Ray,

    Thank you for pointing that out. And I ALMOST made the 7591 mistake and then remembered...yeah no different pin out. Sold them to my neighbor so I wouldn't forget and make a mistake. Smile I have GL KT66s right now and I love them. As variety is the spice of life, I'm just looking for a change of power tube. I also have experimented with some 6L6GC Shuguangs out of curiosity. They're cheap and cheerful. But I thought the 7581 Tung Sol Reissue might be something to try, which is why I had asked.

    Thanks again folks!

    FG.

    dodeca

    Posts : 5
    Join date : 2009-02-18
    Age : 64
    Location : Butte, Montana

    Re: 7581A Power Tubes in VTA-70

    Post by dodeca on March 19th 2016, 2:49 pm

    Just put a quad of the TS 7581As in my VTA-70 Monday, love this tube. The bottom sounded a little lean at first, but 50-60 hours of break-in cured that. Top to bottom the best power tube I've heard in my amp. I have the older 12at7 board, and in my system like both the Sylvania and RCA black plates for the front end.
     Found these on Ebay for 84.95 (includes shipping) for a matched quad. The 7581A has a different plate than the 7581 and 6l6GC. Highly recommended.
    Richard

    fedoragent

    Posts : 35
    Join date : 2013-09-14

    Re: 7581A Power Tubes in VTA-70

    Post by fedoragent on March 26th 2016, 8:16 pm

    dodeca wrote:Just put a quad of the TS 7581As in my VTA-70 Monday, love this tube. The bottom sounded a little lean at first, but 50-60 hours of break-in cured that. Top to bottom the best power tube I've heard in my amp. I have the older 12at7 board, and in my system like both the Sylvania and RCA black plates for the front end.
     Found these on Ebay for 84.95 (includes shipping) for a matched quad. The 7581A has a different plate than the 7581 and 6l6GC. Highly recommended.
    Richard

    I have been between the Tung-Sol 6L6G (Ahhhh, Coke Bottle) and the Tung-Sol 7581A.  Part of me is thinking that the soundstage characteristics will be the same.  I figure that the headroom is equal if not proportionate to what the OT is putting out. That is a theory...

    However, I am trying to differentiate if in OUR VTA gear the full 35W for the newish 7581A can be fully utilized for the 70.  I suppose only tubes4hifi and Bob can really tell us.  Part of me thinks that the 35W and the new larger cooling 'fins' are marketing rubbish..  However, at 84.00 a quad, that's pretty good.  I've bought from the wpc dude before.  Upstanding dude.

    FG.

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