how to replace preamp tubes ampeg svt classic

[justbass4]

yep, amp sounds boring hopefully this will fix it. How do I do it? 4 12ax7, tungsol. thanks.

 

[Bent77]

12vx7 you mean?

 

[Killing Floor]

Simple 1 step process if you do t know.

1 - Take to a pro.

 

[GrayGoesBlack]

I have the same amp, the manual covers it. Basically, unplug, unscrew, replace and reverse order of action. I don't think it's very hard, I might give it a try over the holidays. Power tubes need replacing anyways.

 

[Nighttrain1127]

Just pull up gently on the tubes while also gently rocking them back and forth. But I would suggest if there is nothing wrong with them you will not gain much by rolling Pre Tubes. Pre Tubes is not where the tube magic happens.

 

[Wisebass]

How do I do it?

the manual covers it

Ampeg SVT-CL Owner's Manual - Rev A, English

amp sounds boring hopefully this will fix it

Boring is worse than bad! Maybe get a new amp?


greetings

Wise(b)ass

 

[JeezyMcNuggles]

yep, amp sounds boring hopefully this will fix it. How do I do it? 4 12zx7, tungsol. thanks.

Wiggle them out, wiggle the new ones in, turn it on and enjoy

 

[JeezyMcNuggles]

Simple 1 step process if you do t know.

1 - Take to a pro.

Ehh, he'll be a pro as soon he gets the grill off, and gets his wiggle on

 

[byacey]

If you expect to change the sound from "boring" to phenomenal by swapping tubes, you will be disappointed.
How did you determine the output tubes are bad?

 

[JeezyMcNuggles]

yep, amp sounds boring hopefully this will fix it. How do I do it? 4 12zx7, tungsol. thanks.

Oh, it's gonna sound the same though, except maybe brighter. You won't really hear any difference until you drive it. Even then, you play bass. You might not notice much difference there either.

Play a guitar through it. You'll be amazed at how un boring it suddenly sounds.

 

[dbsfgyd1]

I have the same amp, the manual covers it. Basically, unplug, unscrew, replace and reverse order of action. I don't think it's very hard, I might give it a try over the holidays. Power tubes need replacing anyways.

RE: Replacing Power Tubes

Ouch!

 

[toothguy]

I would wait a bit (1 hour?) before touching anything inside the head. The capacitors need time to discharge after you unplug it.
Otherwise very bad things can happen.

 

[agedhorse]

If there’s no real, identified issue with the amp, I suggest leaving it alone.

While changing tubes often goes ok, sometimes it doesn’t and you create entirely new issues. This is especially true of power tubes on SVT’s.

 

[Grinderman]

I estimate there's a 99.90% (±0.10%) likelihood this boring issue has nothing to do with a technical problem inside that amp head.

 

[Wisebass]

amp sounds boring hopefully this will fix it

sometimes it doesn’t and you create entirely new issues

but, but, but, wouldn' t entirely new issues be the opposite of boring?

=> problem solved!

 

[okabass]

yep, amp sounds boring hopefully this will fix it. How do I do it? 4 12zx7, tungsol. thanks.

Show it to a pro. Sometimes even if the amp works, there could be something that your ears notice. Like I had once one of the power tubes off. Or once one speaker had wrong polarity on 4x 10” cab. Show also the cab and cables. And the bass.

 

[GrayGoesBlack]

RE: Replacing Power Tubes

Ouch!

If there’s no real, identified issue with the amp, I suggest leaving it alone.

While changing tubes often goes ok, sometimes it doesn’t and you create entirely new issues. This is especially true of power tubes on SVT’s.

What's so terrible about changing the power tubes? One set won't bias properly no more (bias led won't go green no more), so I'm guessing it needs replacing some time soon. Supposedly the tubes are about ten years old or something. Don't see what's so hard about it, but I'd love to hear any info on it!

 

[agedhorse]

What's so terrible about changing the power tubes? One set won't bias properly no more (bias led won't go green no more), so I'm guessing it needs replacing some time soon. Supposedly the tubes are about ten years old or something. Don't see what's so hard about it, but I'd love to hear any info on it!

It depends on the version of SVT, but the power tubes and the PI/driver tubes all are interactive in the bias process and a failure of one tube can cause a cascading effect. Sometimes, what appears to be a bias issue ends up being a screen resistor, sense resistor or tube socket contact failure.

I see a fair number of players who change tubes like underwear and end up creating new, expensive problems as a result.

 

[JeezyMcNuggles]

RE: Replacing Power Tubes

Ouch!

Same process, $400 more

 

[JeezyMcNuggles]

RE: Replacing Power Tubes

Ouch!

Same process, $400 more