madbeanpedals::forum

Projects => General Questions => Topic started by: MIM#1 on January 03, 2013, 11:10:38 PM

Title: EGGHEAD bass trim pot?
Post by: MIM#1 on January 03, 2013, 11:10:38 PM
Hi, just put my EGGHEAD in a 3in1 pedal sandwiched between a RUNT and FATPANTS and I'm loving it [Thanks Mr. Bean for the EGGHEAD!]
I have one question, the 'Barber' version of this circuit has a bass trim pot and I feel that would be a usefull addition. Which resistor would target this so I could swap it out with a trimmer?


By the way, I'm running my RUNT at 18v from the FATPANTS and its the best sounding RAT I've owned!  8)
Title: Re: EGGHEAD bass trim pot?
Post by: MIM#1 on January 04, 2013, 02:36:16 PM
Bumping for a reply. In the mean time heres my 3in1 F.P>EH>RUNT  :)

(http://i748.photobucket.com/albums/xx124/czech-one-2/IMG_5961_zps9d318226.jpg)
Title: Re: EGGHEAD bass trim pot?
Post by: MIM#1 on February 19, 2013, 08:03:43 AM
One more bump as I'd still like to adjust the bass content with a trim pot,is it possible?
Still loving the Egghead BTW! 8)
Title: Re: EGGHEAD bass trim pot?
Post by: madbean on February 19, 2013, 12:40:02 PM
From what I gather from the gut shot I saw, the bass trimmer is done in conjunction with a 68n cap in the second stage of the op-amp. Take a look at the "Sparkplug" schematic and you will see a method to do this. You would need to remove C4 and R6 from the Egghead PCB and wire the pads to a bit of perf or vero, then integrate the bass control on there as well. So, it would be two caps in series and a resistor and trimmer in series, then the junction of the two caps connects to the junction of the resistor and trimmer.
Title: Re: EGGHEAD bass trim pot?
Post by: stevewire on April 24, 2013, 02:17:58 PM
I am trying to wrap my head around this.  Could anyone lay this out?  I am having trouble visualizing it.