Help me calculate this bass control

[lars-musik]

Dear Friends,

I built a 1590a Triple Wreck for a friend of mine (horrible experience) and I swore to never open that enclosure up again. However, said Friend would like to have more bass at full rotation of the pot on that beast. I gather from several forums that this is a rather unusual wish as this thing seems to have a bucket full of bass on tap. But I'd like to do him the favour. Could you explain how I'd calculate that bass control?



Or maybe just tell me which value is the best one to change? I tried to engage that tonestack calculator and came up with the idea of raising the pot's value. But it doesn't sound right.



Any suggestions?

Thanks!

[GibsonGM]

Hang on, I will play around with it in TSC....why did you change the original values?  The original 1meg bass pot had more of a bass bump...

I'd use a 1Meg pot and play with R4...values like 68k, 47k, perhaps.  I don't know how that will change the real world interaction of the controls, though.  Does look bass-heavy as it comes 

[Kipper4]

Maybe breadboard it and change out the caps rather than the pots or resistors.
Although I love to experiment with the calculator, I find my ears are mostly a better judge.
Buffer>tonestack>booster (for making up loss from the tonestack)
I feel sure there are pages on tinternet that explain calcs need to reconfigure the James ts.
Is it James?

[lars-musik]

...why did you change the original values?  The original 1meg bass pot had more of a bass bump...

Mike, the schematic of the TripleWreck calls for a 100K-rev log pot... I tried to re-built the bass part in the tonestack, so that I could play with it.... Right now I am half way to a 1Meg pot (500K-C at the moment) but I am still unhappy.

Is it James?

Hi Rich,

thanks for your help - again!

The playing around with caps is what made me post my message. I doubled the 100nF cap and *think* I lost bass. So this tonestack seems not to work like input/output caps. I was hoping for someone to tell me something like "well, the James TS is like that, because....."

Still learning.

[Kipper4]

Lower value caps?

[GibsonGM]

If you increase the pot to 1M, the bass bumps up (try it in Tone Stack Calculator, that is the value it 'comes with' for the James...).  Then, R4 has a notable effect if you play with it.    LOWERING C2 (Kipper) will move the knee out in frequency, and should give you a sense that the bass/low mids went up.

All you can do is try things.  They did when they designed it, and now you want something different, so you need to change stuff   You will not load anything down by increasing the pot...other way around...

Calculating the response is ungainly, LOL....using TSC is much easier, as well as your ears.  You're always affecting more than just one "band" when you do this stuff - they interact, so you need to use your sense of (musical) taste as you adjust things.

Definitely breadboard it first, and try those things.   

[PRR]

The ratio (in TSC) C2:C1 should be 10:1 (like all the other parts-pairs), not 2:1.

I'm not sure which you would change. I'm not sure 10:1 throughout, which can give "flat" response, is best for guitar. Or this guitarist. But I'd start from that thought.

The insight answer is that you can not get "more bass", only "less midrange" (so bass stands-out more). The 10:1 pair-values gives 20dB overall, with +/-18dB variation possible in bass and treble.

[lars-musik]

Thank you all for your answers. I had to do this without a breadboard because I already built it and it was all a bit tight.




But nevertheless I tried some values that I previously checked in the Tonestack-Calculator and finally I resorted to a 500K pot and another switch to dial in 100nF or 22nF for C15.



Now the whole pedal sounds like something musical and not like metal from a can.