Author Topic: How could I add more gain and bass response to a DOD 250 while staying true  (Read 1565 times)

Belanger

How would I add more more gain and bass response to a DOD 250 while trying to stay as true as possible to the original sound

It's not a mod I'd be building it from scratch so I have the ability to use a larger enclosure or just about anything else so please feel free to throw any ideas out there. 
I'm really just after making it the best it can be.  I have a ton of on-off and on off on toggle switches I can use as well for multiple clipping or capacitor mods.  So if there's a few values that would perhaps give me the original as well as more/less bass.and or more or less mids

Any help is appreciated as I've only built a few tube screamers on vero.  I'm just starting to get a better idea of how and why we use certain components in certain places as to make A loss pass filter or something basic like that.  But I haven't the experience yet to truly understand why the circuit is built the way it is all the time.   Anyone who could better explain the DOD 250 circuit to me would be heaven sent lol.  Thanks your time guys and gals
« Last Edit: April 24, 2016, 01:56:29 PM by Belanger »
The best substitute for intelligence is silence

Mark Hammer

"Gain" gets misused nd confised, when it comes to overdrive pedals.  Sometimes people use it to mean more distortion.  Sometimes, people use it to mean just greater output level.  Given that the DOD250 is not an especially high-output pedal, you can understand how your request can have several meanings.

As with the Distortion+, and the TS-9, more bass can be added by increasing the value of the ground-leg cap (normally .047uf).  Doubling its value (0.1uf) will lower the bass rolloff point by an octave, which will provide more audible bassat higher gains, without changing the character of the sound too much.  Since adding more bass will  result in mre crunch, you may want to raise the clipping threshold by putting another pair of diodes in series with the existing ones.  A pair of germanium or schottky-type will raise the threshold enough, and also result in a hotter output.

ashcat_lt

Adding bass at the amp stage does more than just more crunch.  It changes the balance of harmonics that come out of the distortion.  It starts to go from OD/distortion more toward fuzz.  Maybe that's what we're looking for, but maybe we would do better boosting bass after the clipping diodes.  This will leave the overall character of the distortion alone, and just give more low end output.  Because that low end hasn't been crushed so much, it'll actually be more dynamic and (hopefully) sound more like weight and punch than mud.

There are a couple of ways you might accomplish that, but I'm not up to sorting it out right now.  Course, if this thing is smashing into an overdriven amp, more bass from the pedal will change the way that responds...

Mark Hammer

That's sort of why I recommended raising the clipping threshold; so the added bass wouldn't change the tone too much.

Note that the bass rolloff at max gain is still only 340hz or so(with the cap-value I recommended), which gives a little more substance to the resulting sound, but not so much bass that the character changes drastically.  Keep in mind that at lower gains, one would normally have pretty much full bandwidth anyway.  The sharp bass rolloff only occurs at highest gains.  So if one raises the clipping threshold with a pair of schottkys in series with the 1N4148s, that should keep the added bass from having a drastic impact.

But you're right to be attentive to what having extra bass does to the overall signal amplitude hitting those diodes.
« Last Edit: April 25, 2016, 10:40:39 AM by Mark Hammer »

Belanger

Great advice.  I'm going to build one each way on a breadboard and see which one works better for my friend.  He wants a pedal that sounds like a marriage of zeta drive and DOD 250.   I know the zeta has a almost sagged fuzz feel and sound from what I've been told about it. I really really do appreciate the help, it's really nice to have people who know more then you do. Also it's always nice to learn how to truly say what it is I'm looking to accomplish.   As you said gain can mean so many thing.  I really do want it to have more output  and kinda a sagged fuzz od tone with a decent amount of bass.   I'll probably do a 3 way switch for the bass so he can choose between stock DOD 250 bass response and then more/less bass.

 
« Last Edit: April 24, 2016, 07:52:55 PM by Belanger »
The best substitute for intelligence is silence

Belanger

I did a boost not long ago where there was a high pass filter in the input and one in the output and the one at the input deffenitly cuts far more bass.  I really didn't understand how much difference there was between that until then. I did how ever just start building a few months ago so I expect to be ignorant to a lot of things now. Hopefully with a ton of reading and being able to ask questions I'll be able to move past that
The best substitute for intelligence is silence