Tag Archives | bass amp repair

About 30-40% of the repairs I do at Ampworks are bass amp repairs. Solid state bass amps are generally quite rugged, but when they go, they aren’t user serviceable, so I see a lot of Trace Elliot, Laney, Ashdown and Fender bass amp repairs. I’ve also had quite a few Ampeg and Mesa Boogie valve bass amp repairs, with truly huge power valve counts and light dimming current draws!

Below are some links to bass amp repair reports from the archive.

Trace Elliot GP12 Repair

Trace Elliot GP12 Repair – Keld Ampworks, Newark

The symptoms exhibited by this Trace Elliot GP12 repair were a loud hum and distortion evident during note decay. Unfortunately I wasn’t able to replicate the customer’s problem which makes repair difficult, so I took a number of steps. I left the amp on soak test for 2 hours, which involves heavily driving the output […]

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Mesa Boogie Bass 400+ Repair

Mesa Boogie Bass amp 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 […]

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Ampeg-repair-svt-ii-bass-amp

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 […]

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Trace-Elliot-repair-AH350-GP7

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 […]

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Laney-Repair-RBH700-Repair

Laney Repair – RBX700

This Laney Repair was an RBX700 with an annoying intermittent problem that I was at first unable to replicate. The customer descibed the fault as a volume drop-out after about 10m or so of playing. On the bench at the repair shop it worked for several hours on several occasions without any issues. When I […]

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Carlsbro Repair

Carlsbro Repair – Cobra 80

Carlsbro Repair – Cobra 80 The owner of this Carlsbro repair complained of an intermittent crackling and occasional dropout. The fault was found to be within the power supply – a not uncommon source of trouble in bass amp repairs. This repair was easily finished within the diagnostic period. When I find a quick fix […]

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Trace Elliot Repair

Trace Elliot Repair – GP7SM 200W

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 […]

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Nottingham

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