Tube Amp Archive

Yes, I would also suggest checking the filter caps, sounds like ghosting.

See link for a picture. https://www.lelandlittle.com/items/3503 ... -tube-amp/

The Bronco is identical to the vibro champ circuit, with some red/orange decorative appointments. It was marketed as a set with the Bronco guitar, an entry level guitar-amp combo.

I have a basketcase bronco amp somewhere in my basement.

solderhead wrote: ↑Tue Feb 25, 2025 4:41 pm
HEY! You gotta remove that JBL tag and replace it with an EV tag!

It’s like seeing a 340 Duster, but it actually has a Hemi in it.

Smitty wrote: ↑Mon Feb 24, 2025 3:25 pm But changing out the white Mallorys? Wow! Instant tone upgrade.

How would you describe the tone change?

I have a 1971 SuperSix reverb that is 99% original (other than the bias and power supply caps), and it is a great sounding amp, white Mallory’s and all.

Since were doing show and tell, here’s my ‘68… These were factory recones from the early 90s (Mark IV industries) that sat unused in their shipping boxes until last year.

Maybe a good reason to get an ultra linear silverface Twin Reverb….with JBLs…Tele with 1M volume pot, and out of tune strings. Play my version of Van Halen I with a long chord set up in the shed. Or maybe a wireless, and a webcam set up underneath so I know when to bang out some noise.

Looking to dyi a relatively cheap but powerful >20KHz tone setup to mount under the floor of my shed in the backyard. Something like 1000W, or more. Bonus if I can generate 2 dissonant sweep tones on demand.

No schematic available yet?

My feedback resistor was too high, >1.2k, so over 40% high. The tail-ground resistor was in spec at 104. Quite an enlightening experiment…a parallel 1k to the now 1.2k (550) gave it a Twin Reverb like tightness. Paralleled a 3.3k for now to get it closer to spec while I await a replacement resistor....

I think linear is stock, but audio taper may give you better control of the lower part of the reverb ( never tried it myself).

I prefer 470 for fenders, but if you will be cranking it a lot and/or with pedals, 1k might work better.

The other experiment I want to try is plugging the amp into my QR speakers. In theory they are the same oxfords, other than the Swiss cheese basket and 16ohm impedance, but the QR sounds great with them.

He doesn't have an AB165 Bassman. He has an AA165 Pro Reverb. [/quote] Yes! Since the Pro reverb was new in 1965, this is the reason for the AA165 schematic for it, though it is identical (?) to the AB763 amp schematics, I believe. I’m going to recap the PS, and check the one old electrolytic cap a...

From what I can tell, the Pro Reverb was only the AA165, a different amp than an AA or AB165 bassman. Pretty much the same as a AB763 ____reverb amps.

https://schematicheaven.net/fenderamps/ ... _schem.pdf