Damned Fender output transformers.

[Mark]

I'm rebuilding a Fender Bassman 100 and the original output transformer (P/N: 021667) has been replaced by Schumaker 022889, which was used in Twin Reverb amps.

It's obvious that the 021667 txer was larger than the current 022889 transformer. I'm assuming the 021667 transformer has a superior bass response due to it's larger core size.

Do you think it is worth getting a replacement 021667 output transformer and where would you find one?

Thanks for your assistance.

Note: I just found out transformer part number 021657 is also a suitable output transformer the difference in it having an 4 ohm secondary impedance.

https://ampgarage.com/forum/viewtopic.p ... 33#p409733

[pdf64]

Do you need a super deep bass response? eg is it to be used with bass or guitar etc?
If bass, is the cab to be used likely to cope with deep bass at full power?

[Mark]

Thanks for your reply, the amp is to be a gift to my brother who plays bass. He has a number of different speaker cab, and uses them with his SVT. So I don't doubt he has a few 15" and 10" speakers that will handle the output from the Bassman 100.

[Stevem]

You could make up for the OT mass difference a fair amount by upping the two main filters in the PS to 220 uf up from the shock 100 uf.

[Mark]

Steve increasing the power supply values was part of the plan. I want to increase the screen grid cap from 22uF to 47uF to minimise sag in the output stage.

I think the Hammond 1650TA should be the right output transformer.

https://www.hammfg.com/part/1650TA?referer=1047

[M Fowler]

The last BM100 I worked on the OT is 021657A

Mark in my message I noted the number incorrectly it definitely is 021657A and very large.

Mark

[Stevem]

The 14lb mass of that 1650TA should even handle the low B string of a five string bass ok for rehearsal usage.