First Time Bassman Ten Mods

[joetad]

Hey guys. Fantastic forum here.

I've recently been bitten by the gear/tinkering bug after a 15 year hiatus. I found a 1976 Bassman Ten for next to nothing and I'm wanting to mod it out a bit.

It's in rough shape on the outside, but appears to be stock and in perfect working order. I know its not the most sought after amp, so I figured it would be a great one to play around with.

The speakers were shot, so I replaced them with Celestion G10C30's wired to 4 ohms. I have been told a 4 ohm load won't be too low as long as I don't ever try and run an additional cabinet off the other output jack. Being a 1976 50 watter it was originally wired for 8ohms. I also plugged to ports on the cabinet.

I'm wondering what mods would be a good start to get a little more grit out of it? I'm not looking for a gain monster, and I love the clean sound, I'm just wondering if I can boost the gain in one of the channels for a little more grit.

Could I possibly use a clean channel, mod one channel for more grit, then use my stompboxes for any additional gain/fuzz and effects or am I going to ruin what is already a great clean sounding amp?

Thanks and I look forward to reading any suggestions.

[Ronsonic]

Good speakers? Check.

Plugged the Ports? Yep.

Those are the first two things on my list. You are probably safe on the impedance match. You may get more tube wear - that's what tubes are for.

My BM10 had a 5V transformer winding and a rectifier socket half-punched in the chassis. I took that as a guidance and went with a tube rectifier.

I also converted the bias to an overall adjustment (instead of balance) to accomodate a Post PI MV, in place of the original master.

I'm wondering what mods would be a good start to get a little more grit out of it? I'm not looking for a gain monster, and I love the clean sound, I'm just wondering if I can boost the gain in one of the channels for a little more grit.

Could I possibly use a clean channel, mod one channel for more grit, then use my stompboxes for any additional gain/fuzz and effects or am I going to ruin what is already a great clean sounding amp?

This is where things can get interesting. You can certainly do the sort of mod you're talking about. My approach to this was to look at historical Fender amps and rebuild the channels according to those. I have one channel of brown era Concert and one of tweed. I forget just which tweed, but one of them. If you use a simple Vol and Tone tweed circuit in Ch1 you can use the other knob as a "master" for that channel.

[joetad]

Thanks

Thanks so much for the reply.

I think changing to a tube rectifier, a PPIMV, and the volume/tone Tweed circuit would be perfect.

I have a schematic handy. Would you possibly have a link for a little more detail on these mods? I think the tube rectifier should be easy enough, but I'm a little unclear on what ther PPIMV would take, and I haven't been able to find any diagrams/instructions for it or the tweed tone/volume circuit.

A also think I may go with the "Super Reverb" mods found here in the 2nd channel...

Souping Up a Bassman 10 - Premier Guitar

Thanks so much for the help Ronsonic. I haven't been this excited about tinkering/modding in a long long time.

[Ronsonic]

I pretty much did all my stuff on the fly, without instructions or a whole lot of planning. Just a schematic on the bench.

The link you've got all looks good.

You won't find the PPIMV among traditional Fender mods. Basically, it's a dual pot installed after the PI with the wiper going to the grid, the cold lugs to bias and the hot lugs at the coupling caps.

[The Kirbster]

I wrote a letter to "Ask Amp Man" of Premier Guitar magazine, asking basically the same questions of him (Jeff Bober). His reply is in the December issue, which can be read online for free. He also added a short paragraph that was accidentally left out in (I think) the February issue. He has good tips, his suggested mods should turn your studio channel into a close replica of a Super Reverb.

[joetad]

Bassman 10 mods

Thanks for the reply.

So far I have followed the recommendations in the article (converting the studio channel to those similar to Super Reverb specs), wired the amp to 4 ohms with new Celestion speakers, and plugged the speaker ports.

I've got 2 more tricks I want to try.

I'm going to try the pot in series with the 820 ohm NFB circuit.

I would also like to get as close as I can to a Tweed circuit with the Normal Channel. If anyone has any suggestions for cap/resistor values to start with for wiring up a Treble/Bass/Volume Tweed channel the feedback would be much appreciated.

Thanks.