Members draines1220 Posted March 10, 2011 Members Share Posted March 10, 2011 i recently acquired a seymour duncan twintube classic pre amp/ pedal...i was wandering if any of you gear gurus had any idea as to how i could go about adding a mid tone control. thanks for any info. Link to comment Share on other sites More sharing options...
Members syscrusher Posted March 10, 2011 Members Share Posted March 10, 2011 Try this link. http://music-electronics-forum.com/t1227/ If that schematic is right, you could change C34 and C35 to 1000pf, then change R34 to 220k. That would pass more mids down to around 600hz. That part of the circuit is a treble pass, and the top half is a bass pass. There is a tone net work right after the last triode and before the masters. Looks like a modified big muff tone circuit. You could pull all the caps, resistors for the tone knobs, ditch that modified big muff circuit, keep all the pots, find a place for a mid control and wire in a traditional fender or marshall tone stack. You won't have much room to work with though. Or you could by pass that whole network. Does it sound mid scooped? Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 10, 2011 Author Members Share Posted March 10, 2011 Not so much on the rythem channel. On the lead channel it is big muff territory for sure. Very scooped. Inside this chassis is a wanderful preamp. It just needs to be brought out. I suppose that there are too many components to remove that would allow a selector switch ( one being origional circuit and another being the mid control circuit) huh Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 10, 2011 Author Members Share Posted March 10, 2011 Or just buy a c-bread dls? Haha...those little petals are to my ears as marshall-esque as you can get from any pedal....ahh the thoughts of having fender cleans and old school marshall dirt from 1 amp is a hard on for me! Haha seriously tghough, c-bread did it right. I really domt know why I don't have one yet. Its amazing that they did marshall tones in pedalform better than marshall did. Link to comment Share on other sites More sharing options...
Members syscrusher Posted March 10, 2011 Members Share Posted March 10, 2011 I'm a little off. What that filter is, is a twin t notch filter. No idea why I thought big muff. It's job is to create a notch, a mid cut. Kind of like a q control on a parametric eq, except it's set in one position and one centered frequency. Basically where the notch is, is where the two filters overlap and cancel each other out creating the notch or frequency cut. http://www.radio-electronics.com/info/circuits/rc_notch_filter/twin_t_notch_filter.php You could change where the notch occurs but I think that would just be a waste of time because making that notch flat would be the same as by passing the filter. If it were me, I would be inclined to bypass that whole filter. You could possibly shift the whole thing to one side of the frequency spectrum but there is no way to change the depth of that notch. The big muff circuit is kind of the same filter. Except, the center frequency is adjustable from high to low; a middle frequency sweep. Bypassing it you would have plenty of mids with no notch but once you turn the treble and bass knobs up, you will have a mid scoop. Turning them down, you would have a fake mid boost if you change the values for the treble and bass so that you're only cutting the very low bass and the very top end. That leaves the middle alone. You could mod that filter to stick a mid knob in there by creating a single T notch with a 250k pot to by pass the t notch. Sort of like framus did in the amps. That would be pretty easy to do. It's not a simple replace this resistor with a pot, unfortunately. Link to comment Share on other sites More sharing options...
Members syscrusher Posted March 10, 2011 Members Share Posted March 10, 2011 Not so much on the rythem channel. On the lead channel it is big muff territory for sure. Very scooped. Inside this chassis is a wanderful preamp. It just needs to be brought out. I suppose that there are too many components to remove that would allow a selector switch ( one being origional circuit and another being the mid control circuit) huh You could do that as well with a switch. Where C33 and R34 meet is ground. Put that ground connection for both of them on a switch and you got a bypass. No notch or mid cut when off, flip the switch and your back to the original circuit. Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 10, 2011 Author Members Share Posted March 10, 2011 Huh, I think I will try this tonight. Could I run one side of the switch to the cap and resistor and the other side to a varistor? Pot whatever....a 250k or 500k? If I did this what exactly would it do? I have some knowlege in electronics and have modded quite a few pedals before but its mostly been trial and error. I dig talking to fellas like you that know about what it will do before you do it. So plz, teach o great teacher. Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 10, 2011 Author Members Share Posted March 10, 2011 Or even use a on-off-on switch to use origional circuit, off to bypass, and the other on to do? Just ideas here. Link to comment Share on other sites More sharing options...
Members syscrusher Posted March 10, 2011 Members Share Posted March 10, 2011 Or even use a on-off-on switch to use origional circuit, off to bypass, and the other on to do? Just ideas here. Yeah, you could do both and I didn't think of it. I don't know how well the pot would act but it could control how much of the notch is in the signal. Where the cap and resistor, C33 and R34, meet at ground, put 500k pot wired as a variable resistor there before ground. Turn the knob to 10, the full effect of the notch would be mixed in the sound,turn it to zero would be no notch. All you can do is try and see what it sounds like. I'm hardly a guru with this stuff. I just pick up stuff from Jack Orman, RG Keen and other great minds out there. I think Jack is a moderator of this DIY forum. Maybe he'll chime in with more or better ideas. Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 11, 2011 Author Members Share Posted March 11, 2011 Awesome man. Kets keep this thread red hot. I'm sure there are others that have the same pedal that would like the same thing done Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 11, 2011 Author Members Share Posted March 11, 2011 well, still have yet to try a pot here, i need a schematic to see if c33 and r34 are in series or parallel with each other.....i hate and am too lazy to try to folow the copper traces....lol...anyone else up for suggestions on some great modds on this already nice pedal? Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 11, 2011 Author Members Share Posted March 11, 2011 found a schematic! printed it off i just need to know now how to copy to here...take a pic and do it like that?please one of you electronic gurus help out here. i want control of the mids! Link to comment Share on other sites More sharing options...
Members syscrusher Posted March 11, 2011 Members Share Posted March 11, 2011 found a schematic! printed it off i just need to know now how to copy to here...take a pic and do it like that?please one of you electronic gurus help out here. i want control of the mids! Go advanced, attach file. Both c33 and r34 should go to ground. Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 12, 2011 Author Members Share Posted March 12, 2011 Yes, they def go to ground. In the morning I will tear into this thing. Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 12, 2011 Author Members Share Posted March 12, 2011 Schematic-check. Soldering iron-check. Now, where the heck did I put that sd twin tube classic? - fail.....I will post this mod when its all said and done. Anyone else done anythhing to this pedal? Link to comment Share on other sites More sharing options...
Members syscrusher Posted March 13, 2011 Members Share Posted March 13, 2011 Any news that it worked? Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 14, 2011 Author Members Share Posted March 14, 2011 man, i totally have gotten sidetracked. a guy brought me a boss odb3 to modd. i experimented with it instead of workin on mine. lol. hey, i got paid. hjahhaha.....will post as soon as i get this puippy modded amd give it a listen. Link to comment Share on other sites More sharing options...
Members draines1220 Posted March 17, 2011 Author Members Share Posted March 17, 2011 well dead thread now boys. i put new tubes in my amp and gave it the life it needed. also got the c-bread dls and i see no need for the twin tube classic anymore. i am going to sell it. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.