Vintage 70’s Ampeg SVT 300W Bass Amplifier Repair

Here’s a rare example of a 70s Ampeg SVT that I had in the workshop.

Introduced in 1969, the SVT has, rightly, gained the reputation as one of the greatest bass amp ever made.

Indeed, even today the SVT is the industry standard bass amp for live work.

However, working on these amps is not for the faint-hearted, with an HT in region of 700 VDC, and their weight stupendous .

Unusually, this was a UK voltage version; most of the 70s SVTs I’ve seen have been US voltage, necessitating a (very large) mains step down transformer.


The massive transformers are a major contributor to the weight.


This amp needed a couple of the 6550 output valves changing. Fortunately, I was able to match a couple of valves with the existing valves in the amp, avoiding the expense of a complete new set of 6.


After repair, this amp achieved well in excess of 300W.

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