Hd 130 power tube brand mismatch

Marin Teddy

Hi everyone! First post here ! Sorry if my english not perfect iam just a frenchie ... I am a new and proud owner of an HD 130 with tube inverter which I use for bass. Today I open it for a big cleaning and I just discover that my power tubes are brand mismatched... two EH at the center and two sovtek at the sides ....
Is it a problem ?? The seller told me that a tech checked it and replaced some caps. Also it already blown some fuse but i think it work well . Thanks for the help !

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mm210 Fri, 06/23/2023 - 15:29

Tube brand means nothing. It's al about the current they draw and how they are biased. If they pull the same current, they're fine. Mike.

Marin Teddy Sat, 06/24/2023 - 09:44

Hi Mike! Thanks for your answer! I am quite newbie in tubes amp so was afraid that my amp didn't perform as it should or it could be a potential issue that could damage the amp! So great to have such a forum !

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mm210 Mon, 06/26/2023 - 07:26

ALL amps suffer from old age. The power filter caps will blow fuses and they all dry out and go bad. If he replaced them ALL, you should be good to go for a long time. MM's are no more common to blow fuses than any other tube amp. If it's still doing it, I would have it looked at. Maybe he didn't replace ALL the power supply caps. Mike.

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bill_moore Mon, 06/26/2023 - 14:57

When I serviced my RD100, the low voltage power supply section was in worse shape than the high voltage! Also pay attention to the resistors, the board showed signs of heat, I used larger metal film, and raised them farther from the board.

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mm210 Thu, 06/29/2023 - 07:04

I would also advise having the amp bias checked properly and NOT that crap about 1/2 volt at point "Y" crap. Get it biased and crank it down to 20-22mA on EACH TUBE. You'll last longer.

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