3 Tubes?
Chito said:
Need some advice, does anyone have any experience, ideas on how these amps sound? I'm thinking of making it some sort of a "hobby" amp and have it modded, etc. From what I know about the amp, its a Kent Model 20A with 3 KT66 power tubes.
Just finished a '57 Kent amp for a mandolin player. Pair of 6V6's, tremolo - the head snapped onto a speaker cab with an old 15". Really vintage!
Kent was an old Canadian manufacturer. It was never a well-known name so it's not surprising I searched the main schematic websites and found nothing on a model 20A. If the tech knows his stuff a schematic is not absolutely necessary, it just makes things go faster. Unfortunately, it means I have no way of knowing how your amp is wired up from the info you've given.
Using 3 KT66's is rather bizarre! It's like finding a 5 cylinder car engine. More likely there's a mistake somewhere. Usually an amp will use one output tube, a pair of tubes or multiple pairs of tubes. Except for a small one output tube amp you would never see an odd number of output tubes.
Sometimes an amp will run in what's known as Class AB2 or Class B. It may use a large tube as a driver so it's possible that would account for an extra KT66. Still, that would be strange because a much smaller and less expensive output tube like a 6V6 would easily drive a pair of KT66's in this type of amp.
Maybe that 3rd tube is not a KT66 at all? It might be a rectifier tube like a 5Y3 or a 5U4. The shape might be the same or similar.
Many amps glue a schematic somewhere inside. If you could find it and scan it you could post it or email it to me and I'd be able to offer more specific advice.
If the amp indeed runs a pair of KT66's then if you tell me the preamp tube lineup I could make some suggestions. You can change an amp into any type you want, depending on what you have to work with. It would mean you have to have some experience working with hundreds of volts without zapping or killing yourself, of course!
Give us some more info!
