Mesa Boogie Bass amp Repair

Mesa Boogie Bass 400+ Repair

This mesa boogie bass amp repair had the highest power valve count I’ve seen. The amp uses no less than twelve 5881 6L6 valves!

Like the recent fender amp repair this valve amp was blowing fuses. Also like the fender repair, the failure was down to a damaged power tube. Two in fact.

Much is made of Mesa Boogie’s insistence upon the use of mesa branded valves on guitar forums and these guys come in for quite a lot of stick. You can read Randall Smith’s defence of the idea here. My opinion is that the principle is reasonable for the majority of non technical users.

In this case, the amp had been fitted with Sovtek valves. Aside from the two failures many of the valves no longer matched well.

By testing mesa boogie valves in my valve tester I know what non mesa valves are within mesa parameters for use in their amps. I could tell that 4 of the sovteks were out of spec, meaning that 6 of the 12 needed replacing. After completing this simple task the amp was fixed.

If you have a mesa boogie bass amp repair please contact me via the contact page.

Ampeg Repair – SVT pro ii


What a huge beast this Ampeg repair is! Weighing in at an incredibly heavy 32kg I wasn’t sure that my workbench would take the strain!

It’s an SVT ii powered by 6 KT88 output valves meaning two massive transformers, owner for three mains and one for the output stage. When both must be capable of 300W continuous, that’s a lot of iron!

The owner was finding that the amp would drop in volume after a few minutes of running. It’s a common problem that I was quickly able to trace back to an oxidation issue, meaning a nice low cost repair for the customer.

If you have an Ampeg repair that needs attention, please get in touch , but you’re carrying it in!

Trace Elliot GP7SM Repair


A recent Trace Elliot GP7SM Repair, a amp service actually.

The owner brought the amp in for a check over before sale. This is a really beautiful Trace Elliot!

This particular AH350 (from the early 90s) uses the Trace MOSFET output stage, with Lateral type audio FETs. These are expensive, but worth it – the other Trace Elliot Bipolar output stage has some reliability issues that I’ve seen in the past.

This GP7SM was fine though. No problems.

It’s got a really cool optional UV light at the front. I haven’t seen one like this before. Makes the green front panel glow nicely. Great, if you like it!

Available to buy (as of Nov ’14). If you’re interested I’m obviously not going to publish customer’s details, but I can put you in touch.

Peavey Repair – 6505

Peavey Repair

Sadly I forgot to photograph the amp so here’s the stock Peavey repair image! I’m not the most djenty/hardcore kind of musician, but it’s hard not to admire the level of filth before feedback that the Peavey engineers have got out of this fiery monster. This amp is a 6505, which I believe is a progression from Peavey’s 5150 amp.

As part of a service, I diss-assemble the amplifier, check output power, check all the valves in my valve tester, test all the potentiometers, soak test the unit and generally do any preventative maintenance required.

Just in for a service. No need for a Peavey repair on this day!

If you need a Peavey repair, please contact me.

Trace Elliot Repair – GP7SM 200W

Trace Elliot Repair

Trace Elliot Repair – GP7SM 200W

This Trace Elliot repair is actually a service. My solid state service procedure involves the following steps:

  • Cleaning of all pots and connectors
  • Re-soldering dry or suspect joints
  • Any preventative maintenance required
  • Replacement of out of tolerance or defective components
  • Output power test.


I’ve seen a couple of Trace Elliot repairs in a pretty sorry state. The main cause of trouble is normally the ‘bipolar bear’ (bad electronics joke by the designer) output stage. This unit uses a lateral MOSFET output stage that is more reliable, so the customer has little to worry about. I’d recommend that owners of a Trace Elliot amp with the original stage have the output stage replaced at some point if the amp gets really heavy use.

Here’s the owner’s feedback, taken from the now extinct review site ‘’ before it merged into ‘’ and deleted all old reviews!
“ Rowan at Ampworks very kindly serviced my Trace Elliot GSM200 solid state head at extremely short notice. He did a thorough job of making sure everything was as it should be inside, re-soldered any suspect connections, checked the electronics and pots. I can’t recommend Rowan and Ampworks enough. John (Leicester) “(pigbobman, 28-03-2013)
Thanks for the kind words John. I’m glad you were happy with your service.

If you have a Trace Elliot Repair job that needs doing please, get in touch.