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HarryY
Dogstar
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    ST-120: KT88’s in front KT120’s in back

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    Dogstar


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    Post by Dogstar Wed Sep 04, 2019 9:14 pm

    Can that be done?
    HarryY
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    Post by HarryY Wed Sep 04, 2019 10:09 pm

    I would say No because it will be unbalanced
    Roy Mottram
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    Post by Roy Mottram Thu Sep 05, 2019 1:04 pm

    anything can be done . . . . but does that make it better, or just different, or just a bad idea, or maybe a great idea
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    Dogstar


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    Post by Dogstar Fri Sep 06, 2019 3:54 pm

    I’d be willing to experiment if it won’t cause resistors to pop or caps to fry. I have Sovtek KT88’s and TungSol KT120’s. But I want a guarantee that it won’t freak out my amp.
    deepee99
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    Post by deepee99 Fri Sep 06, 2019 8:39 pm

    Why?
    Bob Latino
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    Post by Bob Latino Sat Sep 07, 2019 7:19 am

    Dogstar wrote:I’d be willing to experiment if it won’t cause resistors to pop or caps to fry. I have Sovtek KT88’s and TungSol KT120’s. But I want a guarantee that it won’t freak out my amp.

    This won't hurt the amp BUT it is not an optimal situation for running the amp. If you had TWO Sovtek KT88's and TWO Tung-Sol KT120's, what I would do is run the two Sovtek KT88's in ONE CHANNEL and the two Tung-Sol KT120's in the other channel of your amp. It is better to match up a tube in a pair with one of the same type. Just a note here > Sovtek stopped making KT88's about 3 years ago. The Sovtek 6550 (WE version) will work in the same situations as the old Sovtek KT88 and IMHO is more rugged that the old Sovtek KT88.

    Bob
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    Post by Dogstar Sat Sep 07, 2019 5:55 pm

    I have 2 Sovtek KT88’s that got very little amp time one I got the KT120’s and then the GL KT88’s. I had no intention of investing more Sovtek tubes...just using up the ones I had.
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    audiobill


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    Post by audiobill Sun Sep 08, 2019 8:47 am

    Your amp is push-pull; your suggestion is like having Laurel on one end of a seesaw, and Hardy on the other. It should work, but.....
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    Post by Dogstar Sun Sep 08, 2019 6:59 pm

    So what if I have two GL KT88's and two Sovtek KT88's? Would it be better to put the 'matched' pairs in separate channels? Or as I asked originally?
    Bob Latino
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    Post by Bob Latino Sun Sep 08, 2019 7:05 pm

    Dogstar wrote:So what if I have two GL KT88's and two Sovtek KT88's? Would it be better to put the 'matched' pairs in separate channels? Or  as I asked originally?

    I would put the two GL KT88's in one channel and the two Sovtek KT88's in the other channel. You always want one tube of a push-pull pair to be matched with one of similar characteristics.

    Bob
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    Post by Dogstar Tue Sep 10, 2019 3:09 pm

    Thank you ..
    deepee99
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    Post by deepee99 Tue Sep 10, 2019 5:03 pm

    Again I ask. Why?
    I see no happy ending.
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    Post by Dogstar Tue Sep 10, 2019 5:46 pm

    Just curious...without having the innate understanding of electronics that most of you probably have I perceive things differently. Is the biggest problem with doing something like that the sonic weirdness it would do? Bob did say it isn’t harmful to the amp which is key to trying things like that. Not that I actually would just that I think strange stuff like that.
    Bob Latino
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    Post by Bob Latino Tue Sep 10, 2019 5:53 pm

    Dogstar wrote:Just curious...without having the innate understanding of electronics that most of you probably have I perceive things differently. Is the biggest problem with doing something like that the sonic weirdness it would do? Bob did say it isn’t harmful to the amp which is key to trying things like that. Not that I actually would just that I think strange stuff like that.

    Think of a pair of output tubes in a push-pull configuration on one stereo channel like two horses pulling a wagon. You don't want the two horses to have different physical characteristics. (an old horse and a young horse, a strong horse and an old tired horse etc.) For best performance in pulling your wagon, you want two similar horses.

    Bob

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