4x10 Bassman clone down to deluxe volumes?

Figaro

Supporting Member
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12,424
What would I need to change in a tweed Bassman 4x10 clone to get it down to Deluxe volumes? 6V6 power tubes and a Deluxe size output transformer, power transformer?
 

slegros

Member
Messages
499
Check the B+ voltage. I just did a direct swap of JJ 6V6S into a Marshall Bluesbreaker Reissue (similar circuit to a Bassman). My B+ was around 415V, and my amp biased perfectly within the range of the bias pot - no other changes needed except the tubes.

The JJ 6V6S are rated to 500V in AB operation (fairly high for a 6V6). If your B+ is safely below 500V (Say 470V or less just to be on the safe side), and you have the range on your bias pot, you may be able to swap in the JJs directly with no other changes, and not have to change the transformers.
 

drgonzoguitar

Member
Messages
4,707
I guess I'll preface this with the warning that this is my opinion. :D

The joy of the Bassman is the grunty goodness that it kicks out. If you are wanting that edge of breakup goodness at lower volumes, you might need a different amp. It's not worth modding.
 

pdf64

Member
Messages
6,916
I just did a direct swap of JJ 6V6S into a Marshall Bluesbreaker Reissue (similar circuit to a Bassman)
The BBRI OT has an 8k primary, which is a good match for 6V6, whereas the Bassman 5F6A has an OT with a ~4k primary, which is on the low side for 6V6 (though may not be an issue, especially for JJ).
A DR OT would be unsuitable for a 2 ohm cab (though the 4x10 could be re-wired to 8 ohms).
Also 4x10 is probably louder than 1x12, all else being equal.

A DR PT is smaller than a bassman type, so an adaptor plate would be needed to mounted it on to a bassman chassis.
An alternative may be to try a saggier rectifier, eg 5R4.
Pete
 

zenas

Member
Messages
8,228
What speakers are you running?

On the 6v6s I tried them in a 1987 and it was still loud. Sure it cut some volume but not a heck of a lot. (like pulling two power tubes in a TR)
In the end I use the 1987 for cleans and built a 5E7 Bandmaster with the most inefficient speakers I could find Weber SigS alnicos (also cheap) and use that for the dirty stuff.
 

Prattacaster

Member
Messages
1,369
Running a 1x12 as compared to a 4x10 will give you the greatest change in volume.

For instance, just worked on a showman 100w amp fitted into a 1x12 combo, using a less efficient altec it was not much louder than a normal deluxe, so much so I had re-test to make sure it was still putting out at least 100w,

Also worked on a super reverb fitted with two JJ 6v6's(not the greatest idea IMO). It was still quite loud even with the mismatched reflected impedance.

Super was "louder".
 

Billm

Member
Messages
574
Two thoughts: A tweed Deluxe (5E3) or a modded Blues Junior.

Both are 15 watts, both break up easily at tolerable volume. The 5E3 has its idiosyncrasies--the interactive volume controls and the decidedly tweed tone control, plus some extra natural compression from the cathode-biased 6V6s. It breaks up at reasonably low levels, certainly a lot faster than the Bassman.

With proper modifications, the Blues Junior can be a pretty decent baby Bassman. It has the same two stages of gain before the tone stack. There's an unused 12AX7 stage that converts to a cathode follower very easily. Once you add the cathode follower, the Blues Junior schematic looks just like a single-channel Bassman, except for some coupling cap and resistor values. The TMB tone stack is easily modified with a couple of capacitor swaps (or just change the slope resistor) to operate like the Bassman stack. A presence control is likewise a very easy addition. You can stick with the EL84s or do a socket conversion to 6V6s with no other changes.

The voltages are low, so the amp is a little saggy, easy to break up, even without a tube rectifier. The master volume is your friend. You can back off to conversational level and still get sustaining distortion from the preamp, or just good, guitar-driven crunch.

I'll grant you that 4x10 moves air differently than other setups, but you could use either amp to drive your Bassman's speakers. Or, for the sake of quiet and ease of use, just live with the difference in tone and sound stage.
 

Figaro

Supporting Member
Messages
12,424
Two thoughts: A tweed Deluxe (5E3) or a modded Blues Junior.

Both are 15 watts, both break up easily at tolerable volume. The 5E3 has its idiosyncrasies--the interactive volume controls and the decidedly tweed tone control, plus some extra natural compression from the cathode-biased 6V6s. It breaks up at reasonably low levels, certainly a lot faster than the Bassman.

With proper modifications, the Blues Junior can be a pretty decent baby Bassman. It has the same two stages of gain before the tone stack. There's an unused 12AX7 stage that converts to a cathode follower very easily. Once you add the cathode follower, the Blues Junior schematic looks just like a single-channel Bassman, except for some coupling cap and resistor values. The TMB tone stack is easily modified with a couple of capacitor swaps (or just change the slope resistor) to operate like the Bassman stack. A presence control is likewise a very easy addition. You can stick with the EL84s or do a socket conversion to 6V6s with no other changes.

The voltages are low, so the amp is a little saggy, easy to break up, even without a tube rectifier. The master volume is your friend. You can back off to conversational level and still get sustaining distortion from the preamp, or just good, guitar-driven crunch.

I'll grant you that 4x10 moves air differently than other setups, but you could use either amp to drive your Bassman's speakers. Or, for the sake of quiet and ease of use, just live with the difference in tone and sound stage.
A tweed Deluxe circuit has almost no clean, that's why I want a Bassman circuit. And sorry, but I had a Blues Jr, did all the mods to it, and I just don't like EL84s, I like 6V6s.
 

Billm

Member
Messages
574
I like the idea of a master volume. A ganged-pot post-PI MV would retain the tone and character best.

I just don't like EL84s, I like 6V6s.
Yep. That's why I came up with a conversion kit. :)
 

mrface2112

Member
Messages
2,029
A tweed Deluxe circuit has almost no clean
Not to pick nits, but I completely disagree with this. Some of my favorite cleans are those from a 5E3. I record clean tones out of my 5E3 all the time. Just roll the guitar's volume back a bit and don't jumper the channels and maybe use a 5751 instead of 12ax7 in V1.

Anyway......I love the cleans I get out of my tweed deluxe.
 

Speedy East

Member
Messages
120
The simplest mod is to put a pair of Yellow Jackets in the tube sockets where the 6L6/5881 power tubes go. The Yellow Jackets accept a pair of EL84 power tubes. These would yield about 15 watts (cathode biased, instead of fixed biased). This would change both the volume and the touch and tone of your amp, some.
 




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