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DIY Stompboxes => Building your own stompbox => Topic started by: Wagster on March 18, 2008, 02:36:34 AM

Title: ToneBender MkII/1k Attack Pot Vs 2K
Post by: Wagster on March 18, 2008, 02:36:34 AM
What tonal differences do you guys hear between a 1kB and a 2KB pot in the MKII Circuit?
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: yeeshkul on March 18, 2008, 02:56:02 AM
when attack is fully up there should be no difference, i guess the only difference is that you can reach less fuzz ...
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: Wagster on March 18, 2008, 11:49:15 AM
Thanks Jan ;D
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: mac on March 18, 2008, 10:32:05 PM
If you add a 2k pot you need to increase the collector resistor by 2x, so final gain would be the same when pot is at min, since Rc/Re would be constant. Maybe the transistion from dirt to clean would be smoother. Also the new resistor could interact with the output cap changing the output freq response.

mac
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: yeeshkul on March 19, 2008, 03:25:33 PM
Mac i am just curious, if this was a common voltage divider where you get half voltage by 2 resistors of the same value then yes, you have to increase Rc 2x to get 4.5V on collector .. but in this case ... pot is 1k and Rc is roughly 10k to get 4.5V in the middle. I mean do you really have to increase the Rc 2x in this case?
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: mac on March 21, 2008, 01:20:34 PM
The base of q2 is set by q1 collector and it is almost fixed at 0.6v or so no matter the size of the fuzz pot. So the emiter of q2 should be also almost constant. If the voltage is fixed then ie=ic will be reduced by 2x.
You now need to increase Rc to keep 4.5v at q2 collector.

mac
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: yeeshkul on March 22, 2008, 03:14:09 AM
thanks Mac, i see now (i suppose you were talking about Q2 and Q3).
Title: Re: ToneBender MkII/1k Attack Pot Vs 2K
Post by: mac on March 22, 2008, 01:45:01 PM
Quotethanks Mac, i see now (i suppose you were talking about Q2 and Q3).

Yes, q2 and q3.

mac