Bass man transformer in Pro Reverb

[Ephi82]

i have a BF Pro Reverb. I love it except for what I think is a flabby low end. I have heard that the Bassman amp shares a similar circuit but has a beefier transformer for more low end. Anyone know what needs to be done to replace the transformer? Does it require re biasing etc, or is it just the swap?

 

[zenas]

Yeah bigger OT will stiffen up the low end on the small OT BF Fenders, Bandmaster, Pro, Vibrolux and so forth. With today's volume I don't think it's as popular as it used to be to do that.
So my first question is what condition is the amp in? Unless you play pretty loud I'm thinking there's something else going on.

 

[Ephi82]

Thanks for the reply. There is nothing necessarily wrong with my amp, it actually sounds very good. My only complaint is a lack of stiff low end. It’s kind of flabby. ( yes, 40 watt amps sure are loud!)

I’ve done the non destructive mods to get it to sound great at lower volumes ( pull the v1 tube, disconnect one speaker, etc)

 

[woof*]

Swap the baffle for 1x15 and put a 15” EVM in it.
I did that with my 66.
Your flubby mush bass will be gone. That speaker just screams in a Pro Reverb.

 

[Ephi82]

Swap the baffle for 1x15 and put a 15” EVM in it.
I did that with my 66.
Your flubby mush bass will be gone. That speaker just screams in a Pro Reverb.

Interesting idea! Is it louder?

 

[woof*]

Interesting idea! Is it louder?

It’s more everything. It’s really a great sound. I was considering changing to a bigger output transformer too, but it’s the speakers.
It’s non invasive. If you didn’t like it you can put everything back. But you’ll like it! I bought the Evm off eBay and Rogers made the baffle (Rip). I think you can find the baffle at mojo possibly

 

[zenas]

If you go the 1-15" route then you could use a Twin Reverb OT, with two 6L6s it's 8 ohms impedance and big. Of course there's a bunch of after market transformers to choose from.

As far as flabby bass goes on a blackface ( or any older amp) fresh filter caps are very important. Some people don't change them if they look good and test ok with whatever 9 volt meter they think works. If that describes the tech you use at all, well you can guess the rest.
Tubes and bias can do it.
Speakers can do it, but I've seen speakers get blamed when it wasn't speakers.
Also with a BF you might try turning down the bass as you go louder.

Real easy to see if it's the speakers. Get it to where it's farting out, then plug into some other speakers, preferably "tighter" ones (EV, JBL type things) with 4 ohms impedance. DON'T CHANGE AMP SETTINGS and play it.
Often times guys miss the "don't change settings" part and because they're often using more efficient speakers (louder) they simply turn the amp down to the level they're used to. And that can be enough to mask the real problem.
Speaking of speakers, what's in it now?

 

[Rumble5]

The looser bass response along with the tube rectifier in the Pro is what gives it a tweed-like, early Marshall feel that's unlike any other BF amp. I love it. With a couple mid-focused speakers I can totally cop Neil Young and LZ tones without the need for pedals (though I do use an attenuator so I can keep the amp volume on "9" and control the amount of grit with my guitar volume).

A BF Bassman OT should give you more low end oomph but will also make the amp louder I think. It may require changes to other parts as well, though. Personally, I'd try a speaker swap first which is a lot cheaper and less obtrusive than swapping major components on a vintage amp.

 

[Ephi82]

Thanks for all the suggestions!

 

[The Dirty Tube]

Thanks for the reply. There is nothing necessarily wrong with my amp, it actually sounds very good. My only complaint is a lack of stiff low end. It’s kind of flabby. ( yes, 40 watt amps sure are loud!)

I’ve done the non destructive mods to get it to sound great at lower volumes ( pull the v1 tube, disconnect one speaker, etc)

Have you tried a solid state rectifier?

I experimented with a solid state rectifier in my 66 Pro Reverb.

To my ears, it made bass response significantly tighter, and made the amp as a whole a good bit punchier.

 

[Mickey Shane]

I have a '65 Pro Reverb. I played though the original re-coned Oxford speakers for over a decade. It sounded good to me. The pair of Eminence Red Fang speakers that are in there now sound a lot better to me. The bass is probably tighter with the Redcoats.