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Adding a Master Volume to my Bassman

PostPosted: Sun Dec 18, 2011 9:07 pm
by dylanger
How hard is this? I turned up my amp to 7 the other night with my Les Paul and reeeaaaalllyyyy liked it but I would like to be able to do this without turning up so loud. Here's a kit I found online, would it be worth it to get this or could I just pick up that the parts at Munro's?

http://taweber.powweb.com/store/modkits.htm#ef86


Dylan

Re: Adding a Master Volume to my Bassman

PostPosted: Sun Dec 18, 2011 9:52 pm
by Mathieu Benoit
Why not just get a power attenuator?

Re: Adding a Master Volume to my Bassman

PostPosted: Mon Dec 19, 2011 12:39 am
by Malcolm Boyce
Using something like a power soak is going to get you part way to what you want but unfortunately part of what you are loving is the way the cab sounds, and the interaction with the guitar itself at that level.

Re: Adding a Master Volume to my Bassman

PostPosted: Mon Dec 19, 2011 3:47 am
by Mathieu Benoit
Malcolm Boyce wrote:Using something like a power soak is going to get you part way to what you want but unfortunately part of what you are loving is the way the cab sounds, and the interaction with the guitar itself at that level.


Exackery.

Re: Adding a Master Volume to my Bassman

PostPosted: Mon Dec 19, 2011 4:07 am
by Alain Benoit
$8 is pretty cheap for a dual pot, 4 film caps and a knob. Then again add shipping, duty, brokerage, taxes, exchange rate and the fact that Weber has been known to drop orders, also that is kind of a cheap pot, TA Weber is not known for quality parts.
Munro's will not have a dual 1M in stock but you can certainly order one.

Other wise pretty straight forward mod, slam it in between your LTP and your power tubes ahead of your bias feed and Robert is your father's brother. Don't forget your couplers.

Re: Adding a Master Volume to my Bassman

PostPosted: Mon Dec 19, 2011 9:39 am
by dylanger
I undertand that its my cabinet too but if I could just use the master volume to get this to happen a little bit sooner I think I would be happy. roflmao

Re: Adding a Master Volume to my Bassman

PostPosted: Tue Dec 20, 2011 7:15 pm
by Alain Benoit
dylanger wrote:.... if I could just use the master volume to get this to happen a little bit sooner ......


I've lost your logic there, please explain!

Re: Adding a Master Volume to my Bassman

PostPosted: Tue Dec 20, 2011 8:25 pm
by dylanger
Dirt up without having to turn it up to 7

Re: Adding a Master Volume to my Bassman

PostPosted: Tue Dec 20, 2011 8:40 pm
by Alain Benoit
The excitation of your cabinet is fairly independent of the amount of dirt and more due to actual SPL.

Re: Adding a Master Volume to my Bassman

PostPosted: Fri Jun 08, 2012 3:12 pm
by sean.boyer
I did an MV mod to my Bassman 50 which had been converted to Blackface specs.
It was a pre-phase inverter mod. Just a coupling cap from the PI feed to a 1M pot, then to the input of the PI. Pretty simple.

To expand on what Malcolm said, a lot of the greatness of the "turned up" sound doesn't just comes from the preamp. It's a combination of preamp over drive, PI overdrive, power amp overdrive, speaker drive and cabinet/room resonance, etc.
I found with my Bassman that it was worth while to have the MV though, as you do get a good amount of nice sounding dirt from the preamp (especially since for my dirty channel I had added the unused triode section in a Marshall Plexi type configuration in series with the first preamp section to drive the gain up). The way I had it configured, I had split where the two channels meet for the PI input, and had the MV pot only affect the first (dirty) channel.

In conclusion, I'm not really sure how much of a benefit the MV control would be for you on an otherwise stock Bassman, but it wouldn't hurt.

(PS - I had removed the second channels input jacks and that's where I put my MV pot, as well as a mid pot.)

Hope that helps

Re: Adding a Master Volume to my Bassman

PostPosted: Fri Jun 08, 2012 3:17 pm
by Malcolm Boyce
Hey Sean... Good to see you here.

Re: Adding a Master Volume to my Bassman

PostPosted: Fri Jun 08, 2012 3:17 pm
by sean.boyer
Oh, one other thing... That kit would be useless for you, unless you reconfigured the power section to be cathode biased. Which would be stupid IMO.
The parts you'd need for an MV mod you could get at Munro and would only be around $5.

Re: Adding a Master Volume to my Bassman

PostPosted: Fri Jun 08, 2012 3:19 pm
by sean.boyer
Hey Malcolm,
Thanks! I pop in and out here and there.

Haha, just realized that this thread is 6 months old, and if the OP is anything like me, he probably doesn't even have the amp anymore ;) Oh well.

Re: Adding a Master Volume to my Bassman

PostPosted: Fri Jun 08, 2012 4:09 pm
by dylanger
I'll always have my bassman!