Mailliw
Well-known member
Hi,
I was given this working but very noisy tube guitar amp head. The can-caps on the top are stamped JUL '67. There is basically no info about it on the internet. It was made in Canada.
I drew up the circuit, it is very similar to a Fender Champ, but it has two 12AX7As whereas most champs only have one.
large schematic
small schematic
physical pictures:
top full
top 800x ...
bottom full
bottom 800x ...
bottom right full
bottom right 800x ...
bottom left full
bottom left 800x ...
I read that a lot of people replace 40-450s in Fender amps with spraque atoms, but they are ~5 each bucks at mouser. Would panaonic ecgs be fine? (~2.35 at digikey)
The blue/yellow 0.1uFs are Dubiliers, are those oil/paper?
I had some 220-25 panasonics laying around so I swapped them in for the 25-25 cathode decoupling caps and the amp didn't work. I put the originals back in. Reading Morgan Jones' Valve Amplifiers, I was lead to believe a higher capacitance would only lower the low-filter knee. Whats the deal?
I don't know what speaker load it was designed for, does it even matter if its 8 or 4? If I measure the resistance of the output transformer, will that tell me?
Thanks!
I was given this working but very noisy tube guitar amp head. The can-caps on the top are stamped JUL '67. There is basically no info about it on the internet. It was made in Canada.
I drew up the circuit, it is very similar to a Fender Champ, but it has two 12AX7As whereas most champs only have one.
large schematic
small schematic
physical pictures:
top full
top 800x ...
bottom full
bottom 800x ...
bottom right full
bottom right 800x ...
bottom left full
bottom left 800x ...
I read that a lot of people replace 40-450s in Fender amps with spraque atoms, but they are ~5 each bucks at mouser. Would panaonic ecgs be fine? (~2.35 at digikey)
The blue/yellow 0.1uFs are Dubiliers, are those oil/paper?
I had some 220-25 panasonics laying around so I swapped them in for the 25-25 cathode decoupling caps and the amp didn't work. I put the originals back in. Reading Morgan Jones' Valve Amplifiers, I was lead to believe a higher capacitance would only lower the low-filter knee. Whats the deal?
I don't know what speaker load it was designed for, does it even matter if its 8 or 4? If I measure the resistance of the output transformer, will that tell me?
Thanks!