Westinghouse model 604 radio

[Colas LeGrippa]

Hi, I have got this radio from a friend who wants to use it as a small guitar amp. I plugged an electric guitar into the ''phono in'' but the sound is very weak ( 1/4 watt or so). What can I do to increase the volume ? The guy doesn't care about permanent modifications. The circuit is very complicated for me, as I don't know much about old tubes and transfo. coupling stages. (I don't know much about my old person neither, hey hey, though my coupling stage works fine ).
Any help apreciated thanx


Colas

[sluckey]

There is not enough audio amp stages to boost a guitar signal very much. The easiest thing to do is use a boost pedal between the guitar and phono jack.

[Colas LeGrippa]

what about adding a 12ax7 ?

[PRR]

This may be a VERY good AM radio. I have a similar Zenith with RF stage. All modern radios, in this area, pick up mostly buzz (weak stations and nasty power lines). The Zenith will pull WCBS-AM from 500 miles away with listenable quality.

6K6 will need 20V peak drive. 6SQ7 is like 12AX7, will give gain like 60 in this circuit. 20V/60 is 300mV needed at "phono" for full output.

Guitar amps generally drive to full output with 20mV.

So you need another gain of like 15.

There's no more gain to squeeze in the original audio path.

Agree: boost pedal is by far the best quick fix.

If you want to get radical: rip G1 G2 and P wires from the IF amp socket. Strap G2 to P. Try stock Fender input network to G1, use 100K plate resistor and 0.2uFd coupling cap to Phono.

[PRR]

> what about adding a 12ax7 ?

9-pin mini in an all-Octal chassis?? So out-of-style.

Anyway even a half 12AX7, or another 6SQ7, is more than you need, unless you want to bang holes for more tone knobs.

[Colas LeGrippa]

Job done, oval speaker sounds great. Inserted a homemade tube preamp between guitar and radio.

Good volume now.

Thanks buddies.

Colas