Fender Musicmaster Bass Amp Maintenance

[dbishopbliss]

A friend asked me to look over his Musicmaster Bass amp (6V6 model). Its a little buzzy so was thinking of swapping the filter caps. The original used a firecracker style 20uF/20uF 300V capacitor. Those aren't produced any more so I think I have a couple of options:

• 2 Illinois 500V 22uF caps.
• 1 F&T 450V 33/33uF cap
• ???

I noticed this has a 0.0047 capacitor after the 68K input resistors BEFORE the grid in V1. Is this because this was supposed to be a bass amp? I have read some unfavorable comparisons between this amp and a deluxe. Sure its a lot simpler, but are some of the tone complaints because of this cap?


Also, it has a transformer for the phase inverter. I haven't seen that before. Curious what are the benefits/drawbacks of this.

[shooter]

Curious

I was too!  so I built a couple using an inter-stage transformer (PI). both were well liked, even sold them!!
I'm no musician, but the cleans were crispy clean, the OD was a kinda different animal, best to play side-by-side with a non tranny PI for tonal interpretation.

I wouldn't worry about the cap, looks like part of input signal "conditioning"??
make it quiet, then tweak with owner

[PRR]

> some unfavorable comparisons between this amp and a deluxe.

It's not intended to "be a Deluxe".

Not really intended to be a serious bass amp (Fender would sell you a Real Bass Amp, but not this price).

That input cap rolls-off below 70Hz. This probably saves the low-price speaker from early death. (And a real bass player would move up the bass-amp aisle to find a more-$ box with more ballz.) It would have little effect when (mis)using this amp on guitar. And Marshall made some money selling even higher bass-cut to guitarists. But IAC, put a jumper across and see how it changes.

[st]

I liked mine (6aq5) a lot, for guitar. Speaker is the weak spot in these things. I replaced it.

Here's what I have archived:
http://hasserl.com/musicmaster_bass
(I did not perform these mods, but they do make sense)