Bassman one wire "hot wired" mod?

[Lefty Lou]

http://www.ebay.com/itm/Late-1962-Fende ... 4616415%26

I wasn't but a few years ago that I purchased a Fender BF Bassman head from 65'. I needed money immediatelty and had to turn right around and sell the amp which I did w/o losing money. I know the blonde bassmans are more sought after and fetch more than their BF counterparts but from this forum and other forums, apparently there are some minor component tweaks that techs recommended for the blonde bassman heads in order to really "give up the goods".

[Sparky4444]

...sometimes it takes a while for me to get through to my dad on just where I'm going with this lol...so here is the latest...

...I think things are simpler than I thought....even though the original mod my dad did was to feed one channel into the second channel -- no not external jumping -- with some tweaking internally, the mod Chief may be referring could be just activating the second half of the second tube of the Bass Channel..

..In the Bassman, the Bass Instrument Channel has two preamp tubes, but the second tube is only using one half..the second half isn't being used...So when Chief is talking about his old amp still using both channels -- and that the switch was doing "something" -- I think all it was is to activate that V2b of the second tube for the extra gain stage...using the Deep switch, you can switch that in or out...that way both channels remain independent...


...On top of that, you can mod the Bass Instrument Channel to be the same spec as the Normal Channel, which I think you would want to do....Also, you can put in a pot as voltage divider to help tame the gain from activating that second half of the second tube -- this is what I think that other guy was referring to by putting in an extra knob...you don't have to put in a pot, you can wire a voltage divider in there hard-wired, but a pot is handy dandy


...I think adding everything up, this seems to be what is going on...makes sense based on what Chief says, what my dad says and what that other guy said...

...this should be pretty simple to do...

[NY Chief]

Only thing, I remember both channels being "hot", not just the bass channel, Sparky.

[Sparky4444]

Only thing, I remember both channels being "hot", not just the bass channel, Sparky.

Were both channels hot, independently?? Were they hot all the time or did the switch activate the increase in gain??

I'm not sure how both channel's can be hot, independently, without adding another gain stage in there, and that would mean adding another tube -- or cascading somehow where the switch can activate the extra tube stage into either of the two channels

What I am going to do is use the vibrato tube in my Pro Reverb as an extra gain stage for one of the channel's...this, in theory, will be the same kind of idea...

...I think hot-rodding the fenders, be it the Bassman or the Deluxe, or whatever, would involve hijacking the spare tube for extra gain from the vibrato or reverb channel...

[Sparky4444]

I can get my hands on a Silverface 68 Bassman head...I have a 65 Bassman OT/PT that was in the original Bassman head my dad hotrodded back in 1984 when i was a kid...one smart thing he did was pull the trannies before he sold the thing lol

[Lefty Lou]

If anybody here desires to hot rod Fender amps w/o messing with the stock vintage parts, I've got a Hicks "Mender" and an old Groove Tubes "Ice Cube" . The 'Ice Cube" plugs into the send and return RCA jacks for the reverb, and makes the reverb stage a gain stage. The Hicks "Mender" plugs into the first two sockets of the Bright channel on a Fender amp, and the preamp tubes are plugged into the Mender. The "Mender" has a 1/4' guitar jack plug in that allows for on/off switching.

[Sparky4444]

If anybody here desires to hot rod Fender amps w/o messing with the stock vintage parts, I've got a Hicks "Mender" and an old Groove Tubes "Ice Cube" . The 'Ice Cube" plugs into the send and return RCA jacks for the reverb, and makes the reverb stage a gain stage. The Hicks "Mender" plugs into the first two sockets of the Bright channel on a Fender amp, and the preamp tubes are plugged into the Mender. The "Mender" has a 1/4' guitar jack plug in that allows for on/off switching.

ah..funny you mention that because my dad was saying something similar today...I'm going to play around with doing this but with the vibrato stage in my Pro Rever -- tube is just sitting there doing nothing

[Lefty Lou]

For awhile, guys were modifying SF Fender amps by the truckloads because they were considered "less collectible". It's funny how that situation has turned since those particular amps are approaching their half century mark. I've known many guys who have done mods to Fender amps but, they always come back to the stock Fender clean amp sound with outboard effects. It's just a rite of passage I guess.

[NY Chief]

Only thing, I remember both channels being "hot", not just the bass channel, Sparky.

Were both channels hot, independently?? Were they hot all the time or did the switch activate the increase in gain??
..

From what I remember, both hot all the time, independent and boost was NOT switchable, Sparky.

[Sparky4444]

Only thing, I remember both channels being "hot", not just the bass channel, Sparky.

Were both channels hot, independently?? Were they hot all the time or did the switch activate the increase in gain??
..

From what I remember, both hot all the time, independent and boost was NOT switchable, Sparky.

I'm stumped on what they did to your amp back then...the only thing I can think is that both channel's tapped into that V2b that the Bass Instrument channel never used...I mean, at the end of the day, you're just adding another gain stage from that half of that 12ax7 that's just not being used...I can't see how both channel's can't tap into that because you're only using one channel at a time

[mightymike]

Just make a wire with 330k to 470k resister with heat shrink like so, plug it in, and bam! Switchable Overdrive with level control. Your reverb footswitch will turn it on or off, and the reverb level will now control the amount of overdrive.

[Lefty Lou]

Just make a wire with 330k to 470k resister with heat shrink like so, plug it in, and bam! Switchable Overdrive with level control. Your reverb footswitch will turn it on or off, and the reverb level will now control the amount of overdrive.

Mike, no doubt that the JHD Audio Ice Cube (which I mentioned earlier in this thread) that was sold through Groove Tubes, is nothing more than a couple of resistors in a molded epoxy form.

[mightymike]

I finally got to check my mail Friday to get the books I ordered a couple weeks ago. I had just got a chance to skim through a few hours before seeing your post which reminded me of this mod.

It would be interesting to check the resistance across that block to see if it is between 330k and 470k like the book. I bet it is.

I bet if you did this mod, you would notice a huge difference with minimal effort. If I still had an old Fender with Reverb, this is where I would start.


This Hot Rodding Fenders book has a whole chapter on gain mods, and another on things to do with the other channel ( like making it like a Marshall) and how make it foot switchable with their homebrew A/B Y switcher project.

If I read anything else that looks good, , I'll be sure to share it. I think there was another Vibrato channel gain mod I need to investigate further.

[Lefty Lou]

I finally got to check my mail Friday to get the books I ordered a couple weeks ago. I had just got a chance to skim through a few hours before seeing your post which reminded me of this mod.

It would be interesting to check the resistance across that block to see if it is between 330k and 470k like the book. I bet it is.

I bet if you did this mod, and then upped the mid pot to 25k you would notice a huge difference with minimal effort. If I still had an old Fender with Reverb, this is where I would start.


This Hot Rodding Fenders book has a whole chapter on gain mods, and another on things to do with the other channel ( like making it like a Marshall) and how make it foot switchable with their homebrew A/B Y switcher project.

If I read anything else that looks good, , I'll be sure to share it.

Sounds good to me.

[Sparky4444]

This Hot Rodding Fenders book has a whole chapter on gain mods, and another on things to do with the other channel ( like making it like a Marshall) and how make it foot switchable with their homebrew A/B Y switcher project.

If I read anything else that looks good, , I'll be sure to share it. I think there was another Vibrato channel gain mod I need to investigate further.

What is the name of this book??