DS-1 mod question

[jonathansuhr]

What exactly is R17's purpose? I see it in a lot of mods, but can't seem to figure out what exactly it does to the sound.

[biggy boy]

Hi there!
Do you have a link to a schematic or the site you are talking about?


Glen

[jonathansuhr]

http://www.godiksennet.com/images/sch/DS1PG2.jpg

[BAARON]

It's part of the tone control.  Making it smaller cuts more bass when you turn the tone control higher, while making it bigger reduces the amount of bass the control cuts when you turn it up.

[jonathansuhr]

Ok, that's as I suspected.

I adjusted the hi and lo pass filter frequency cutoffs to about 1200 for more mids, and I upped C8 on the drive network's lo-pass to about 1uf for a lower cutoff frequency. Also, I did change C3 to 0.033uf which might be the inherent problem..

Did I do something wrong? I would expect more bass and less treble, but apparently my math was not correct.

Any mods to keep the mid frequencies I modded for, but maybe darken the tone and take up the bass? I will probably change C3 to .1uf later, but until then..

oh, and I will probably up R17 to about 22k and see how that turns out.

[5thumbs]

I adjusted the hi and lo pass filter frequency cutoffs to about 1200 for more mids, and I upped C8 on the drive network's lo-pass to about 1uf for a lower cutoff frequency. Also, I did change C3 to 0.033uf which might be the inherent problem..

Did I do something wrong? I would expect more bass and less treble, but apparently my math was not correct.

Don't forget the role Q2 plays in the tone of the DS-1.  In its stock configuration, the "mis-biasing" of Q2 (in the opinion of some) gives a big volume -and- treble boost before the dual op amp.  In Jack Orman's Fat Mod for DS-1 (http://www.muzique.com/news/fat-mod-for-the-boss-ds-1/), he re-biases Q2 to get less treble boost and more bass (via higher input impedance).  In my Huevos Grandes Mod for DS-1 (Pages 25-26 of the 'Build Your Own DS-1 Distortion' doc from http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf), I tweaked Jack's Q2 re-biasing to keep the flatter EQ in the gain increase, but reduced the input impedance to keep the bass from getting flabby.

You can experiment with Q2's biasing further if you like, but if you want less treble and more bass than the stock Q2 biasing, try changing R2 from 22-ohm to 220ohm.  This will replicate the Q2 biasing in the Huevos Grandes mod and should help cut some of the treble.