Tuesday, December 20, 2011

Mystery amplifier!

Beyond this being another hot chassis amp with series string AC mains filament, I'm at a loss in terms of identification. That is not to say that it does not have any identifiable or rare qualities, rather, there's no visible mark manufacture, and plugging search terms based on what I do know and conclusions I've drawn based on the object itself, I keep getting flooded with results that do not match.

You can call me captain Run-On-Sentence, thanks.

From left to right, three 6AV6, a 50C5, and a 35W4. Supporting passive components litter the topside of a printed circuit board. I'm forwarding the guess that the caps are not original. The presence of a fuse is a nice touch.

Early printed circuit board.

Three inputs..

..chained together. Some sort of load resistor here may have improved multiple instrument performance. May have... I do not approve of the mechanical ground reference either, but if I'm going to spend time critiquing every last aspect of what was originally a cheap amp we'll be here all day.

A trio of 6AV6. I've seen these in a variety of amplifiers, as the triode section carries similar characteristics to the 12AX7. However these are single triode / dual diode valves, and anyone familiar with building fuzz circuits should already appreciate diodes. I've yet to see a 6AV6 deployed in a stock vintage amplifier that makes use of the diode (for distortion purposes, AGC and detection do not count). I have run signal through these diode stages, and while it takes a healthy level of voltage to make it work, I found it wholly worthwhile.

Of course, I like noise. It is safe to say that this isn't a holy grail of classic popular guitar tone, but it's also safe to say that there are those among you that are not purists. We'll touch upon this tube later on.

Those grey dog bone resistors make me think Japan is the likely candidate of country of origin, but again, it's a mystery.

Another shot of a 35W4 silkscreen. I really have no good reason for the these last two shots, other than it being easier to discern what the tubes were by looking at the pictures than by looking at the tubes themselves.

50 volt filaments, I'll find a spot for you yet.

No comments: