Volume boost mod on a Tonebender MKI

[MordechaiBenZev]

I'm trying to get a touch more volume out of my MKI.  I already lowered the 2.2M on the output down to 1M and it sounds good...a bit more would be great but I understand that lowering it further would introduce more high end shrill. 

If I brought it down to 820K but strapped a 100pF across it, would that sufficiently tame those shrilly bits?  Maybe a 220pF?  I'd appreciate thoughts before I dismantle my build and mess with the circuitboard.

[antonis]

Raise 47k (or 56k) output to GND resistor value and lower output cap value by the same amount..
(e.g. make it 100k and halve 100nF to 47nF..)

[MordechaiBenZev]

I have actually removed the 47K at the tail end of the circuit (I built the Hurst version) and reduced the vol pot to 50K to keep the same frequency response.  Did removing that 47K actually lower the output, then??

[antonis]

Could you plz post a schematic of your particular MKI..??

[Wavelength]

What most people do is dump the 2.2M and the 500K pot and replace the 47K with a 50K pot to the output.

The 47K is there to lower the output z of the circuit. The 2.2M into 500K provides like -15dB pad.

Maybe me, but I prefer the 1.5 over the other ones. Get a set of hfe OC140/950 Mullard NPN at 80 (Q1) and 120 (Q2) and that makes an excellent sounding Tonebender.

Thanks,
Gordon

[MordechaiBenZev]

I've read build reports with those components removed and it seems that the already-inherent volatility of the circuit periodically works against this resulting in a ton of noise and chirping in some builds (I guess the Hfe/leakage of Q1-3 becomes even more crucial with those mods, so success becomes very hit and miss).

I really like the sound of the MKI for the application I have in mind, but I'll eventually build up a 1.5 because...well, we all have to at some point, right?

[MordechaiBenZev]

Could you plz post a schematic of your particular MKI..??

Sure, here it is.  The only changes I made were that I reduced the 2.2M to 1M, removed the 47K at the output, and exchanged the 500K vol pot for a 50K pot.

[antonis]

Make 56k resistor 100k one..

P.S.
I shouldn't go for less than 100k OUT pot, in case of 2M2 resistor damped due to Q3 15k Collector resistor loading..