The sound you are going for will have very little to do with the opamp used and everything to do with the curcuit used ......
I personally like to use a multi-stage tube preamp with a multi-band active EQ ....
I have never been able to get that nice low end crunch with high end definition useing an opamp preamp and a passive tone controll though I do use a TS9 type curcuit to overdrive my tube peramp ......
I personally like to use a multi-stage tube preamp with a multi-band active EQ ....
I have never been able to get that nice low end crunch with high end definition useing an opamp preamp and a passive tone controll though I do use a TS9 type curcuit to overdrive my tube peramp ......
Like I said it isn"t the components that are going to give you the sound you want , it is the Curcuit , Once you come up with the curcuit then you can think about what opamp , diodes ect would sound best but till then you are putting a cart before the horse ......
Try looking here for curcuits :
General Guitar Gadgets
DIYstompboxes.com - Index
Cheers
Try looking here for curcuits :
General Guitar Gadgets
DIYstompboxes.com - Index
Cheers
Inverting, like this one:
In place of Rf I put a pot to adjust the gain. For a dual stage I used a dual-gang pot that would adjust the gain of both stages at the same time. This allowed me to have a huge range of gain, anywhere from classic rock overdrive to full on shred metal. I made mine very simple, with just a passive tone control (cap and pot to ground after the final stage, right beside the clipping diodes), and relied on the amp for final EQ. On the input I just used a capacitor to block any DC offset from going out the input. I did have a later version that used a single transistor as a buffer before the first op-amp.
In place of Rf I put a pot to adjust the gain. For a dual stage I used a dual-gang pot that would adjust the gain of both stages at the same time. This allowed me to have a huge range of gain, anywhere from classic rock overdrive to full on shred metal. I made mine very simple, with just a passive tone control (cap and pot to ground after the final stage, right beside the clipping diodes), and relied on the amp for final EQ. On the input I just used a capacitor to block any DC offset from going out the input. I did have a later version that used a single transistor as a buffer before the first op-amp.
Silicon diodes (1N914, 1N4148 etc) clip "harder" (= more harsh) than germanium.
If you choose your supply voltage carefully in your pedal, you could also try to clip against the rail voltages....
YMMV
I only experimented with a few types, standard silicon (1n4001, etc) and some germanium diodes (don't have the part number handy). With dual stage you'll be getting a lot of your clipping from inside the op-amps, which is partly why the JFET based op-amps are better IMO. The tone of the overdrive and distortion is less harsh. For metal you may be thinking that harder clipping would be better but what I found is that smoother clipping gives a more consistent crunch and better tone. I would recommend that you build using DIP sockets for the op-amps so you can swap out different types and experiment with it until you find the balance of tone that works for you.
Oh yeah, and speaking of power supplies, I always used 9V with a 4.5V DC offset at the op-amp input. This low voltage made it very easy to clip at the rails internal to the op-amps. Then of course you need the input and output caps to block the DC component.
why is it easier to clip the 4.5?? your saying the 9v goes to the V and 4.5 into the input then feed it back into the inverted op ?? what does tieing a resistor to 4.5v before the + on the op amp do if my feed back is coming to the - ??
"This low voltage made it very easy to clip at the rails internal to the op-amps" WHAT do you mean by clip the internal rails?
"This low voltage made it very easy to clip at the rails internal to the op-amps" WHAT do you mean by clip the internal rails?
"With dual stage you'll be getting a lot of your clipping from inside the op-amps, which is partly why the JFET based op-amps are better IMO" can you clarify this a lil ? Imo? BTW thank you alot for the help its exACTLY THe the information im looking for. its hard to find answers so indepth.
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