1959 Tweed Bassman – Part VI

Part 6, Tweaks

Well peeps, I finally had some extra time to finish some more tweeks on the ’59 Bassman clone.

First up I replaced the “orange drop” signal capacitors with SoZo units. These are closely modeled after the Yellow Astron and Blue Molded series of vintage capacitors. Listening before and after the SoZo units was quite revealing. The sound, after putting in the SoZo units became higher in fidelity. The high-end was nicer, more articulate. The bottom-end was tighter and a bit more beefier. Amazing!

SoZo caps

Next up, I modified the bias circuit making it adjustable. I removed the 56k resistor and replaced it with a 50k linear potentiometer wired as a rheostat. I also replaced the ground wire from pin 8 to chassis with a 1 ohm resistor to ground. This will assist you in taking readings with a voltmeter to bias the power tubes. Once you have an adjustable bias control you can really dial in your sound. I started out low in bias voltage and ended up higher than what Fender traditionally has it set at.

At about 18 static dissipation watts per tube, the sound really opened up. The player can no be very expressive in their playing. Using a lite touch sounds nice and clean while a more aggressive touch makes the amp break up just wonderfully. Find out what your output tubes can handle in wattage. The 5881’s max out at 24.

New Cap

1ohm resistors

. Record . Mix . Master . Music .

1959 Tweed Bassman – Part V

Part 5, Assembly of chassis and speakers into cabinet and final listen:

If you use the MojoTone kit w/cab you will need to have them drill the mounting holes in the 4-10 cabinet to install the chassis. Minor additional charge. Install the 4) 10” Jensen speakers so that the speaker terminals are towards the center of the cab. This will help in wiring and servicing. When installing the chassis turn the cabinet on its side for easier line up of the chassis mounting holes.

There is a time element for the speakers to break-in and loosen up a bit. About 40 hrs. But still, this 4-10 cabinet sounds GREAT! Guitar or bass, this is tone HEAVEN!

If you have found this blog fun and interesting let me know. I had a lot of fun doing it. If you know any guitarists looking for an amp like this I am open to building one out for them.

Great Mix Recording
Great Mix Recording
Great Mix Recording
Great Mix Recording

The previous posts have been opinions from Jacques Sewrey re: the building of a ’59 Fender Bassman clone kit.

Coming up in future blogs will be the modding of and minor circuit changes of the aforementioned Bassman. This will improve the tone options and make biasing for the power tubes easier.

. Record . Mix . Master . Music .
Related Posts Plugin for WordPress, Blogger...