Author Topic: you guys might like this  (Read 7555 times)

sickbend

you guys might like this
« on: November 17, 2008, 03:37:35 PM »
I'm working on the dod 250 clone but I'm tweaking it like mad I'm using a slightly diffrent schematic though but it's about 90 percent the same though 500k is huge and  it sqeeled like mad and i thought i had something wired wrong seems 50 k fits the bill nicely

here is the one I'm working with  http://www.rabbathrecordings.com/DOD250Schematic.JPG

 ok so what I've done so far is take the main clipping diodes  d1 and d2 and changed them to germanium and put a switch which disconnects ground then I threw in a zenier diode in the feedback loop and I need to add a small pf capacitor to control the high end or maybe a simple filter? have to look at that but what I want to do is put a trim pot on the main volume 100k pot that engages and disengages when I flip the switch that kills ground on the main diodes thinking maybe like a reverse boost so you can kick the switch and get diffrent volumes from clean and dirty like a ts 9 I think that would work or a foot switch and another pot to have a tuby boost with the ziner and then the bigger high gain distortion anyway try that out and see what you guys think of the zenier but one thing I noticed is when i back of the gain the tone gets darker and when i increase the gain it gets bright so id like a way to use the pedal for a natural sounding tuby boost then a bright lead so any advice on the filter would be awesome thanks     

ZiggyZipgun

Re: you guys might like this
« Reply #1 on: January 17, 2009, 01:58:24 PM »
That is one crazy run-on sentence.  A question mark popped up and it was as if you ran it over without blinking.

sickbend

Re: you guys might like this
« Reply #2 on: January 17, 2009, 03:44:44 PM »
I'm working on the dod 250 clone, but I'm tweaking it like mad. I'm using a slightly diffrent schematic though, but it's about 90 percent the same.  500k is huge and  it sqeeled like mad and i thought i had something wired wrong seems 50 k fits the bill nicely.

here is the one I'm working with  http://www.rabbathrecordings.com/DOD250Schematic.JPG

 ok so what I've done so far is take the main clipping diodes  d1 and d2 and changed them to germanium. Put a switch which disconnects ground then I threw in a zenier diode in the feedback loop. I need to add a small pf capacitor to control the high end or maybe a simple filter? Have to look at that, but what I want to do is put a trim pot on the main volume 100k pot that engages and disengages when I flip the switch that kills ground on the main diodes. I'm thinking maybe like a reverse boost so you can kick the switch and get diffrent volumes from clean and dirty like a ts 9. I think that would work or a foot switch and another pot to have a tuby boost with the ziner and then the bigger high gain distortion. Try that out and see what you guys think of the zenier. One thing I noticed is when i back of the gain the tone gets darker and when i increase the gain it gets bright so I'd like a way to use the pedal for a natural sounding tuby boost then a bright lead. Any advice on the filter would be awesome thanks     

ZiggyZipgun

Re: you guys might like this
« Reply #3 on: January 24, 2009, 11:54:19 AM »
That's some nice penmanship, sickbend.

MattXIV

Re: you guys might like this
« Reply #4 on: March 17, 2009, 04:26:21 PM »
I think I know what's causing the bass loss as you up the gain.  The capacitor in series with the gain pot makes it a low-pass filter on the feedback.  The amount of signal going to the - input of the op amp is determined by the ratio of the 1 M resistor to the impedance of that shunt to ground with the cap and the gain pot.    When the gain pot is at a lower resistance, less of the signal goes to the - input (ie higher gain) and the impedance to ground is determined primarily by the capacitor, sending the highs to go to ground and the lows to the - input.  Increasing the resistance on the pot both sends more signal to the - input and makes the capacitor less significant in the circuit so the distribution of the highs and lows going to the - input is closer to that in the output.

You may want to play around with different values for the cap (larger ones will increase the bass response as well as increase the overall gain - a large enough value should pass everything in the audio range without any noticeable filtering), putting a pot in the position of the 1 M resistor to control the gain without altering the filter, and putting a small cap in parallel with the 1 M to send more highs to the - input like you mentioned.  Putting a pot in series with that cap will give you an adjustable high-pass filter on the feedback.