PAB mode, adding bass

[Bob-I]

I have an HRM 100 watt in a Brandon chassis. Sounds great in clean and OD modes but the PAB is thin, no bottom end.

Suggestions for adding bottom end to PAB mode?

Also, I find OD mode to be much louder than clean. Typically I have the clean on 12:00 and OD on 8:00 to get a balance between the 2. Suggestions?

Thx.

[tubedogsmith]

The couple I've built looked pretty close to this schematic. Not exact but nothing that would change the bass in boost mode and mine have all the bass you would ever want. My R/J and PAB were wired just like the schematic. I initially had a 5uf on V2b and it was way too much bass. In fact now with the PAB and Mid boost on it can be too bassy with some speaker cabs.

[Bob-I]

Yea, that's almost exactly what mine looks like.

Again, the non-PAB sounds great, plenty of bottom end, very balanced, but kick int he PAB and all the bottom goes away.

[glasman]

If you reduce the resistor between the bottom of the treble control and the top of the bass control (normally 22M when you hit the boost) you can dial in bass. I bought (a few years ago) 5M piher trimmers and installed them on my boost board so that I could make that exact adjustment.

Another trick is to tie the ground end of the mid control to the ground side of 10K resistor on the bass control and float these on a 100K to 1M resistor to increase the bass. Place the switch that normally opens the bass control across this new resistor.

There are a LOT of ways to thicken the skyliner boost, just have to find that one you like .

Gary

[bluesfendermanblues]

Here's another one....I can't remember who on this forum developted this mod, but here it is.

It combines Glaswerks 'reducing the 22m'-idea, showing two 4M7 instead.
AND a capacitor is added to the vacant connector on the realy.

500p is mid boostish, but try 1n or 2n and you'll be fine

Have fun!

[Bob-I]

Thx guys, that gives me some things to try.

[Bob-I]

Cool...

I tried Gary's suggestion on the resistors. I paralleled 4.7M across the 22M, not much difference, then down to 1M and it was a tad better but still not what I was looking for.

Next I tried the cap on the relay to the slope resistor like bluesfendermanblues suggested. 500pF was very midrangy, .001uF fatter, .002uF, perfect. Then I noticed that I'd removed the parallel resistor and was running 22M again, turns out to be a decent combination.

Since I already put the relay board back in, I'm gonna leave it like this for awhile and listen again later.

Thx

[talbany]

Bob
Any reason why you just don't try the BM lift w/the right value resistor in the bottom of the mid pot?..Is that to much bass..

Tony

[Bob-I]

Bob
Any reason why you just don't try the BM lift w/the right value resistor in the bottom of the mid pot?..Is that to much bass..

Tony

I'd try it ... if I knew what it was

[talbany]

Bob
Any reason why you just don't try the BM lift w/the right value resistor in the bottom of the mid pot?..Is that to much bass..

Tony

I'd try it ... if I knew what it was :oops:

Sorry thought it was common knowledge.. Real simple.. You can experiment around with the value resistor hanging on the bottom of the Mid pot.. Since the mid cap is in parallel with the bass cap on the stack by lifting the mid pot also lifts lows as well.. You can even install a switch that lets you choose between a subtle 470k or mega lift no resistor...You can also put the resistor across the COM NC right on the relay is what I do... Good Luck!!

Tony VVT

[Bob-I]

Thx for the idea. I haven't seen that circuit before, interesting.

I'm pretty happy with the added cap right now. I may wait a bit before changing anything else, this one goes into the bag of tricks for later.

[mcinku]

I implemented BM style PAB in my OTS. I have no resistor in there and strangely enough my boost is not that big at all. Actually if I max the mid pot, I can't even notice the boost at all.

[dimitris]

Mcinku have you disconected the tail resistor of the bass pot from ground and connected it to the left lug of middle pot?It's not shown in this diagram and you have to do that in order to implement the bm boost.

[mcinku]

Mcinku have you disconected the tail resistor of the bass pot from ground and connected it to the left lug of middle pot?It's not shown in this diagram and you have to do that in order to implement the bm boost.

Damn, I think that resistor is still there

Thanks a lot

[Joost]

So you're changing the two 22m resistors to 4m7 and adding a 500 pf cap. Will these changes affect the unboosted clean tone of a #124 100k plate skyliner?

Here's another one....I can't remember who on this forum developted this mod, but here it is.

It combines Glaswerks 'reducing the 22m'-idea, showing two 4M7 instead.
AND a capacitor is added to the vacant connector on the realy.

500p is mid boostish, but try 1n or 2n and you'll be fine

Have fun!