Classic Low Plate PAB

[Krinkle]

I am super happy with my modified SF Bassman to SSS002 specs, except for the PAB, which of course wasn't on the SSS002 schematic.

I have a killer SRV tone set up with my Bass and Treble on about 5 and my Mids at about 3. When I switch in the 2 x 22Meg PAB just about all of the Bass gets dumped and the sound is nowhere near as nice as it was pre-PAB.

Even if I short the 22M for the Treble pot and only boost the Bass, the Bass still gets dumped. Does that even make sense? I tried it vice versa just to see, pretty much the same result. I double checked my connections, I'm using the AN PCB which is great so it's not like I have a lot of opportunities for error.

I searched the site top to bottom and tried 2 x 4M7, and also added the 500pF cap across the treble caps as per YeahYeah's suggestion, still pretty much the same.

I keep watching the Welagen Muzz video on YT and even though I can't tell 100% if they are using PAB, if they are, it sure sounds a lot better then what I have as every tone on that video is kickass.

Is it common knowledge whether or not Jelle uses PAB and if so, what he is doing?

I tried the Skyliner tonestack and the PAB works a lot better with it but my SRV tone suffers, so I would prefer to find a nice Low Plate Classic PAB.

Anybody know of something better than the 2 x 22M or 2 x 4M7 methods?

[mojotom]

I like the dual pot lift (500k), between mid pot and ground and bass tail R to gnd.

Nice to be able to tweak boost bass content that way and could be set to a more smooth boost than tha PAB.

[Krinkle]

Thanks for the reply, that sounds promising. I'll use resistors to test it out.

[mojotom]

I liked the PAB on 50/100W amps but for the OD mainly (gain boost) but depending on the tonestack could be too much for me, 10M could be an option, didn't like 4M7.

I read about the dual pot stack lift option here and it's a very good way to add a mild boost. It is less noticeable than the PAB (more of the same but tweakable), easier to use at lower volume too.

An easier solution would be to lift the two grounds with a single trimmer but you'll loose the ability to tweak the bass boost content. I have to try the simplified one with a mid boost on one relay but I didn't find a value I like for the mid boost cap yet. Could be an option too if the dual trim boost sounds too much like the unboosted amp.

I guess Mr D like a Huge boost option. The Bluesmaster PAB is exactly what it's name implied, Megaboost, with 22m mid lift, a 100k would be plenty (for the clean). Hotel Hog boost is huge too.

[Krinkle]

I'm excited to try this. I guess I should also add that I'm using single coil pickups, even though the SRV reference should be a hint.

[norburybrook]

Remember SRV used a tube screamer in front of his amp so I would hazard a guess the PAB wasn't used at all.

Sent from my Nexus 6 using Tapatalk

[Krinkle]

Thanks for the reply. That is most likely correct. If there was one place I would have even guessed SRV used PAB, it would have been Voodoo Chile, as I don't think it was a single TS, there seems to be something extra going on in that one. But it's more likely that it could be 2 TS's, or even a fuzz (along with the TS).

I should have clarified that I don't want an SRV PAB, I just want to keep my classic low plate tone stack and add a useful PAB to that circuit. The typical 22M one sounds terrible to me when used with single coils.

[dimitris]

(Edit:just saw that mojotom has already suggested the same thing)
You can try the bluesmaster pab padded with a resistor,i find it usefull especially with a strat and it will not alter your tonestack in any way.
It's easy to implement it too.You have to disconnect the bass tail resistor from ground and solder it to the
mid pot's lug that connects to ground.
Replace mid pot's ground connection with a resistor (try a value between 68k-220k or a trimmer) and use the pab relay to short-unshort this resistor.

[splgeo]

heres a skyline with a bluesmaster pab

[Krinkle]

(Edit:just saw that mojotom has already suggested the same thing)
You can try the bluesmaster pab padded with a resistor,i find it usefull especially with a strat and it will not alter your tonestack in any way.
It's easy to implement it too.You have to disconnect the bass tail resistor from ground and solder it to the
mid pot's lug that connects to ground.
Replace mid pot's ground connection with a resistor (try a value between 68k-220k or a trimmer) and use the pab relay to sort-unsort this resistor.

That sounds even better, I can easily desolder those grounds and clip a pot in and try that out. Is that the PAB they call the Megaboost? I've been meaning to search for that one here and it keeps slipping my mind.

I'll be away from my bench for the next few days but I'm happy that I have a bunch of different things to try. I'm especially hopeful after your comment about the strat/single coils. Thx

[Krinkle]

heres a skyline with a bluesmaster pab

That looks very clean, great job. Any chance you have the part number for that trim pot? If not, don't worry about it, I'm sure Mouser has something suitable.

[splgeo]

That pic is from the 50watts thread that was up a few weeks ago