Ampeg SVT (old school) amp help - 60s/70s

[agedhorse]

Whatever you do, don’t power it up. You said that you have electronics experience. Make sure that the electrolytic capacitors are fully discharged and have zero voltage across them. If you feel comfortable doing so, before sending it out, it would help to carefully clean it up. Use pharmacy isopropyl alcohol (IPA) with Q-tips and cotton makeup removing pads. This is a time consuming process and can save on tech time.

Or add to the cost… I know most protects don’t want to mop up other people’s work, no matter how well intentioned.

 

[agedhorse]

If you had (real) electronics experience, you wouldn’t be asking the questions you are asking.

That’s a pretty messed up amp that appears to have had a repair attempt made and then aborted or abandoned.

The danger is that there is more hidden (and costly) damage. A bad transformer, correcting improperly done work, a set of pots/switches that have been ruined by “miracle cure-all spray” can push the cost of repair to beyond what the amp is worth.

If you were my customer, I would advise you to run away as fast as you can. Is it worth putting $500-$1000 into it?

 

[BassicJazzy]

Or add to the cost… I know most protects don’t want to mop up other people’s work, no matter how well intentioned.

Yeah, don't touch it. I didn't listen and probably messed my old amp with tube pre-amp up. I'll never know for sure, but it got lots worse after I went about "cleaning it up."

 

[/\/\3phist0]

If you had (real) electronics experience, you wouldn’t be asking the questions you are asking.

That’s a pretty messed up amp that appears to have had a repair attempt made and then aborted or abandoned.

The danger is that there is more hidden (and costly) damage. A bad transformer, correcting improperly done work, a set of pots/switches that have been ruined by “miracle cure-all spray” can push the cost of repair to beyond what the amp is worth.

If you were my customer, I would advise you to run away as fast as you can. Is it worth putting $500-$1000 into it?

Not worth it unless you really want “that amp” for the same money you can get a functioning unit. Or a modern amp that may serve your purposes better.

 

[BassicJazzy]

Sad to see a legendary amp like that die, but that thing does look pretty screwed up. Trash it. It was a flashback for me just seeing pics of it, even as sick as it is. I let a less significant, semi-legendary amp die that was in far, far better condition. For the same money you could get a GK Fusion or something equally modern and really good. With a warranty.

 

[/\/\3phist0]

Sad to see a legendary amp like that die, but that thing does look pretty screwed up. Trash it. It was a flashback for me just seeing pics of it, even as sick as it is. I let a less significant, semi-legendary amp die that was in far, far better condition. For the same money you could get a GK Fusion or something equally modern and really good. With a warranty.

Don’t trash it!!!! Post an ad for “parts only” as-is local sale: sell it for a pittance and let it live on with someone with the skill to repair it or as a doner so that another amp can live on.

Call a couple local techs, and see if they have a use for it, and perhaps they have something else in their shop that you can use its value towards in trade.

It’s not landfill, YET!!!

 

[Podgorny]

Years ago, I bought my blue-line SVT from a pro audio dealer who listed it as having been refurbished. I got it into the studio and turned it on. First it hummed, then it buzzed, and then there was a brilliant flash of light from the back of the thing and it went silent. I brought it to Bob Dixon, and spent nearly as much making it right as I had spent on the head itself. And thankfully I did, as a previous "repair" had routed 600V in such a way that was allowing it to arc to the chassis. Not the sort of thing you want to be messing with. Anyway, it sounds great now. Best of luck with yours!

 

[/\/\3phist0]

On that note, the drivers in that cab are really messed up, and at least one is an inappropriate replacement.

You got a stack of equipment that deserves to be restored, but needs to be executed PROPERLY with respect to what it once was.

That, will take funds. The whole “get it running” on the cheap is a fools errand.

Both are far enough gone that it will take much effort, research, luck and knowledge to achieve any sort of desirable result.

 

[J Wilson]

Take it to Todd Sharpe in Nashville. A couple hours drive, but his shop is as good as it gets for nice amps.

Seriously good advice. Sharpe is THE guy for all the touring and recording musicians here in town. He more than knows what he's doing. Very respected here in Nashville.

 

[rickdog]

Don't junk it until you know it's junk

If I had it in my hands, I'd pay a tech with appropriate skills to see what's up with it. (Well, actually, I have some appropriate skills, so I'd probably do some basic checking myself first.)

 

[Aidenn7]

bubba here the basics that $2000 rebuild. Parts are prolly $900.00 you want a vintage ampeg sound try this Super Three Hundred | Ampeg SVT in a box for Bass | Master Effects

into this

🎸 Harley Benton GPA-100

Compact power amplifier for electric guitar Power amplifier in pedalboard format, Designed for direct use with a preamp or effect pedal, Power: 100 W into 8 ohms or 190 watts into 4 ohms, Class-D technology, Controls for master volume, bass, mid...

www.thomannmusic.com

Keep the cab.. if you like the head keep it for the look.
but the pedals will do all the work. the power amp runs on 230v but you can do a step up adapter. buy the amp used if possible. the amp is like 100watts but your at home any way so it's going to be loud enough. I think you can make the rig for like $300.00
ish

 

[BassicJazzy]

Years ago, I bought my blue-line SVT from a pro audio dealer who listed it as having been refurbished. I got it into the studio and turned it on. First it hummed, then it buzzed, and then there was a brilliant flash of light from the back of the thing and it went silent. I brought it to Bob Dixon, and spent nearly as much making it right as I had spent on the head itself. And thankfully I did, as a previous "repair" had routed 600V in such a way that was allowing it to arc to the chassis. Not the sort of thing you want to be messing with. Anyway, it sounds great now. Best of luck with yours!

You mean it's not supposed to do that? Like Crocodile Dundee would say, "That's not an overdrive, now this, This is an Overdrive!"

 

[Wasnex]

Thanks…should I do the burned in??

IMHO the burn in is pretty important. Whether you pay extra or not varies by vendor. Some vendors do a burn in for all of their tubes.

AFAIK, Vendors can buy different QC levels. If they buy the lowest tier of QC, they may receive untested tubes or possibly tubes that were rejected from other vendors. The best vendors will likely buy higher levels of QC and also do their own burn in, testing, and matching.

What the burn in does.

• The first thing burn in does is give weak and faulty tubes an opportunity to reveal themselves. AFAIK the infant mortality rate for new tubes is fairly high.
• The vacuum in new tubes is not perfect and there may be various impurities inside the tube. Tubes have something called a getter. When the tube is operated, it heats up the getter causing it to absorb remaining gases inside the glass envelope.
  • During the burn in, the tube's operating characteristics will change. Tubes matched before burn in are more likely to fail and/or drift apart
  • Tubes matched after burn in tend to be more reliable and more stable.

 

[Wasnex]

Sad to see a legendary amp like that die, but that thing does look pretty screwed up. Trash it.

I don't see any reason to trash it. Better to find someone who has the skill and interest to repair the amp and either donate it or sell it cheap for parts.

 

[Wasnex]

I don't think there is really much point in buying a set of 6550s for the amp just yet.

Before committing to the work, you typically pay the repair facility a bench fee. This is basically a flat fee that is non-refundable so a tech can develop an initial estimate for repair cost. Before proceeding the tech will get your approval. Any residual value remaining in the bench fee goes towards repair.

Before installing the tubes, a tech should go through the amp and make it right...or at least do the best he/she can. The amp does not need tubes to check the transformers, power supplies, and grid networks. The idea is to make sure required operating voltages are properly distributed to the tube sockets, before tubes are installed. In an SVT, the output tube sockets get ground for the cathodes, about -47V for the controls grids, about 350V for the screens, and just under 700V for the plates.

 

[sleepy_monkey]

I don't think there is really much point in buying a set of 6550s for the amp just yet.

Before committing to the work, you typically pay the repair facility a bench fee. This is basically a flat fee that is non-refundable so a tech can develop and initial estimate for repair cost. Before proceeding the tech will get your approval to proceed. Any residual value remaining in the bench fee goes towards repair.

Before installing the tubes, a tech should go through the amp and make it right...or at least do the best he/she can. The amp does not need tubes to check the transformers, power supplies, and grid networks. The idea is to make sure required operating voltages are properly distributed to the tube sockets, before tubes are installed. In an SVT, the output tube sockets get ground for the cathodes, about -47V for the controls grids, about 350V for the screens, and just under 700V for the plates.

This seems to be the best way forward. I’ve reached out to a few amp techs and hopefully one of them is up for the challenge. I’m into this whole setup for a very minimal amount. It was actually being sold as an empty headshell and then he ended up throwing in the power section…so no loss on my end.

 

[agedhorse]

This seems to be the best way forward. I’ve reached out to a few amp techs and hopefully one of them is up for the challenge. I’m into this whole setup for a very minimal amount. It was actually being sold as an empty headshell and then he ended up throwing in the power section…so no loss on my end.

Maybe he knew something that he didn't communicate to you?

 

[sleepy_monkey]

Maybe he knew something that he didn't communicate to you?

He bought the cab and head with a purchase of a lot of gear. He didn’t know anything about the condition….but he said he remembered when he got it the guy told him it didn’t work. Wish it was going to be an easier fix….but doesn’t sound like that is the case.

 

[jmpiwonka]

I would definitely find a legit tech and pay the bench fee to see if it’s worth fixing.

 

[sleepy_monkey]

Anyone want me to send them the power section so they can document this adventure?? ;-)