DS-1: tone control to mid cut/boost mod?

[benallison]

I did some fairly standard mods on my DS1 and it actually sounds great! I'm surprised. I have it beside an OCD, a Tube Zone, a Metal Muff, and a Silver Kiss, and it's holding it's own!

Now, when I dial back the gain and the tone, the pedal sounds almost identical to the bypassed tone. Great! But the tone control is useless. I keep all the way off (fully counter clockwise). Anyone know how I can turn the tone control into a mid cut/boost?

FWIW, here are the mods I've done so far:

d5 > led
c1, c5, c12 > 0.1uf
c2, c8, c9, c14 > 1uf
c7 > 220pf mica
c3 > 0.033uf
c11 > 0.01uf
r16 > 1k
across diodes > 47pf

[benallison]

I'd be happy with a Baxandall tone control because that should essentially do the same thing (boosting his and lows vs cutting mids). I just don't have a circuit nor do I know exactly how it should integrate into a DS-1 in lieu of the current tone control.

[5thumbs]

What type of tone curve are you looking for?  The DS-1 uses a Big Muff Pi-type tone control, which scoops the mids and see-saws the lows or highs, depending on which way you turn the knob.

This type of tone control doesn't cut the mids by turning the knob...it cuts the mids by virtue of the corner-frequencies of the high-pass and low-pass filters that feed into the #1 and #3 lugs of the TONE pot.  You can eliminate the scoop completely by putting both the high-pass and low-pass corner frequency corners at the same frequency, but this reduces the effectiveness of the tone control.  The passive resistor-capacitor (R-C) high-pass and low-pass filters in use in the BMP tone circuit have a fairly shallow attenuation slope (-12dB per octave), so if you peg the corners at the same frequency, they overlap quite a ways on either side.  This type of mod can be interesting (see my PHLAT Mod on Page 22 of http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf), but I'm not sure if it's what you're looking for.  However, even if you tweak those components differently, you can make your own scoop for the TONE control.

I'd suggest using Jack Orman's 'Simple R-C Filter Cutoff' calculator here: http://www.muzique.com/schem/filter.htm.  It will help you work out the component values for a given corner-frequency.

[benallison]

Actually, I think something like this might work well.



Thoughts?

[5thumbs]

Actually, I think something like this might work well.



Thoughts?

You're going to fit a rotary switch plus inductive transformer inside a DS-1?  Can I please borrow your shrink ray when you're done with this mod? 

OK, seriously, you could use the rotary switch idea to vary the corner frequency of either the TONE LP or HP filter.  You could then vary the width of the mid scoop in a variety of ways.

Another way to do it would be to make the resistor in the R-C filter a variable resistor (a.k.a., pot) so you could sweep them instead.  It's usually easier to make the resistors variable, rather than the caps.

[benallison]

Haha. I wasn't necessarily planning on cramming all that in there... just seeing what's possible (I could always get a bigger enclosure).

I'm intrigued. So, you're saying I could use a pot in place of the resistor in the rc filter. Which resistor would that be?

[5thumbs]

Haha. I wasn't necessarily planning on cramming all that in there... just seeing what's possible (I could always get a bigger enclosure).

I'm intrigued. So, you're saying I could use a pot in place of the resistor in the rc filter. Which resistor would that be?

I think AC30Dirty did this in his DS-1.  He and I had a nice discussion about the resistors/corner frequencies in this thread: http://www.diystompboxes.com/smfforum/index.php?topic=67614.msg539850#msg539850.  He ended up with a sweepable mid scoop sort of arrangement in the end.  It might be an interesting read for you.

That aside, R15 and R16 are the resistors in the LP and HP filters before the TONE control.   R16 is 2k2 and R15 is 6k8.

[benallison]

5thumbs, thanks for all you contribute on this forum. your expertise is greatly valued!

i'm in your debt!

[benallison]

Ok. How's this for an idea:

1) Remove the tone pot and hardwire the tone circuit to be in off position (i'm assuming when the tone pot is fully counter-clockwise it is equivalent to there simply being a jumper in place -- so I'd jumper where terminals 1 and 3 used to be?).

2) Take the now unused tone pot and use it as a variable resistor in place of r17

Will this work?

(* i read on one schem that the tone pot is 20K, and on others that it's 100K. If it is 100K I'll just use a lower value pot or strap a resistor on it to lower the value to something more appropriate)

[5thumbs]

Ok. How's this for an idea:

1) Remove the tone pot and hardwire the tone circuit to be in off position (i'm assuming when the tone pot is fully counter-clockwise it is equivalent to there simply being a jumper in place -- so I'd jumper where terminals 1 and 3 used to be?).

Nope.  When you turn the TONE pot all the way counter-clockwise, you are maximizing the signal coming out of the low-pass filter and minimizing the signal coming out of the high-pass filter.  When you turn the TONE pot all the way clockwise, you are doing the opposite.  There is no position on the stock TONE control that effectively turns either/both of the low-pass and high-pass filters.

If you want to remove the TONE control, remove C11, C12, R15 and R16.  Jumper C11 and R15.  If you pull the TONE pot (or re-purpose it), jumper W8 to W9.  I'm not sure why you'd want to do that, but that' s how to do it.

2) Take the now unused tone pot and use it as a variable resistor in place of r17

Will this work?

I've not played with R17, but I've read others tweaking that resistor to change the highs present in the signal.  You could search this forum for details on that mod, but it wouldn't act like a TONE control as we've been previously discussing.

Will it work?  Well, if you remove the aforementioned components and install jumpers, it will work.  Your DS-1 will have a LOT more mids in it, sound less distorted and have a large volume increase.  If that's what you're after, then you're on the right track with this idea.

(* i read on one schem that the tone pot is 20K, and on others that it's 100K. If it is 100K I'll just use a lower value pot or strap a resistor on it to lower the value to something more appropriate)

The TONE pot on the DS-1 is B20K (linear).

[benallison]

Based on the mods I've done, the pedal sounds killer with the TONE fully counter-clockwise (it almost sounds flat). So that means I'm hearing all low-pass and no high pass?

So would it make more sense to mod the current hi-pass circuit to do mid-scoop duties? Take C11 and R15 out, replace them with a mid-scoop circuit. Then the TONE control will engage the mid scoop as it's turned clockwise?

[benallison]

More thinking:

would I able to just drop this into the DS-1 in lieu of the current TONE circuit?

http://www.muzique.com/lab/tone3.htm

I'm asking about The New AMZ Tone Control. The frequency response looks perfect.

[AC30Dirty]

hey benallison, R17 will reduce the highs!!!! I have a 5.1k resistor in my pedal which seemed to round out the sound the best with all the other mods I've done. I tore this pedal apart before i actually started to get somewhere. If your abel to, I would definitely try the MIJ mods the 5thumbs has. The MIJ mods bring it to Japan made specs and is the best basis to start tweaking in the first place IMHO. R16 will bring out the low mids quite nicely and for what its worth, I personally found R14 to be the best place to effect the tone control. experiment with values all the way up to about 10k. My pedal personally sounds REALLY GOOD with the tone control all the way down. It's cool but, not what i want. I want to be able to use the entire rotation of the pot if possible. Thats why I'm still tweaking!!!

[benallison]

AC30 -- thanks for the pointers! Lots of great info.

[5thumbs]

More thinking:

would I able to just drop this into the DS-1 in lieu of the current TONE circuit?

http://www.muzique.com/lab/tone3.htm

I'm asking about The New AMZ Tone Control. The frequency response looks perfect.

It can't hurt to give it a shot.  I've ended up keeping every one of Jack's ideas I've tried in my DS-1 mods.  He's quite a brilliant chap, IMO.