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When changing the .47 cap to a .22 or .1 for added bass in the screamer circuit, does that also affect the bass fequencies that are passed. I.E. lower frequencies also being clipped now, or does the low pass stay the same?

The following is likely to not be very helpful... but I'll try.

I made the swap you describe when I built mine. I've not heard a BYOC with the .47 cap, so I can't compare. I have compared it to my newish Ibanez tube screamer (TS9). The BYOC is definitely more bassy, with the tone knob cranked all the way it approximates the tube screamer with it's tone at about 12 o'clock. I happen to like more bass and more mid on the guitar, plus, I reasoned the mod would make the peddle work better on actual bass (I've tried it, it sounds great).

I don't know if the BYOC is "clipping" more of the lower frequencies. Hopefully my less than perfect description helps.

exactly. It does clip off some of the top, but you seem to be able to compensate with the tone knob.

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I much appreciate your attempt to help guys! BUt i am really looking to fing out specifically if the low pass frequencies are affected by the mid hump mods.

Actually, you'd be changing a 0.047uf cap (720Hz bass rolloff) to 0.1uf (339Hz) or 0.22uf (154Hz) to add bass. And by the term "adding bass", it means that these lower frequencies will be processed through the pedal's gain/clipping circuitry. So, yes, these lower frequencies will be amplified and clipped, the same way the higher ones are.

Personally, I found that 0.22uf made the bass too muddy, especially for humbuckers. That's why I went with a switchable cap set-up on my Screamer clone. If you plan to lock into a single cap, I'd suggest 0.1uf as a good compromise.

There's a bit of misconception regarding the so called "mid hump" or "pushed mids" of the Tube Screamer circuit. It doesn't push the mids. It rolls off the lows. Increasing the capacitor size moves the corner frequency towards the low end of the frequency response. The larger the cap value the more mids and lows will be allowed to pass. Let too much pass and the sound will get muddy and sound like crap.

So if I were to create the eq curve of a tube screamer, it would simply be to cut all the frequencies below 720, and leave everything else level? Is this true?

Depends on whether or not any highs are being attenuated as well. I don't know myself. Since it's often referred to as "pushed mids" having attenuated high and lows would account for that.

Ok, thanks guys! Now i am led to another question! Is there any way to increase the amount of bass coming out of the Screamer whitout affecting the bass pass frequencies? IE the frequecies allowed to pass remain unclipped but reducing the amount of bass cut?

....

the only way that i know of to do that, is to do kinda what voodoo labs did with their sparkle drive. process the bass separately along a completely separate signal path, making sure to amplify the bass (high value cap in RC feedback path to ground ensures that more bass gets amplified) without clipping (gain of 12 or so). then you would have to mix that signal back into the other signal line. that's the cleanest way to do what youre wanting. but it's also the most complex.

I have a sparkel drive and that pedal has a clean boost on the other side, a full range clean boost, so thats not what im looking for either. I just want to lessen the "mid hump" without changing the frequencies being clipped.

i see.

well the tone control of the screamer is basically setup for a "mid hump" around 3.2kHz. Actually, at the bass end of the pot, it's a combo bass cut / treble cutoff. At the treble end, its a combo bass cut / treble pass. but the 3.2kHz point seems to be pretty static at all pot positions.

because the tone control is configured this way, there isnt a good way to flatten this. what i would recommend is to bypass the tone control with a DPDT switch, and add a simple rat-style LPF or a BMP mid cut style tone control. oops i meant to say a RODENT LPF and a BEAVER tone stack.

go to http://www.geofex.com/ and clock on FX TECHNOLOGY OF.... at the top left. Then click TUBESCREAMER.

Now, you can still set up the clean mix control like the sparkledrive, but add a LPF in the RC before the amp stage for the clean. so youll mix just a bassy clean sound with your clipped signal.

ok now i understand. thank you. next question is changing the tone pot to the 2k has what effect on that taper situation? also the .18uf tone caps, what can i expect to happen there?

2k? i thought the stock pot was a 20k? are you wanting to swap the 20k with a 2k? could you clarify? this kind of change would dramatically alter your tone stage response in less than desirable ways.

and which 0.18 uF tone caps are you referring to? i'm used to seeing 0.22uF. if you are talking about the R and C to ground in the tone section, then changing the C will result in a shifting of the 3.2kHz "hump" lower or higher in frequency (but it will not change the bass cut stage that is present at the very front of the gain stage, so you're not gaining any bass by doing that, only losing/gaining highs). changing the R will do the same thing, BUT you will change the gain structure of the tone stage. i dont recommend that.

the 2k pot puts the sweep in a more useable curve, than the stock 25k pot. try it. you'll like it.

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