Boss DS-1 "Midrange Knob" question

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souped_up
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Post by souped_up »

I found this pic of a Midrange knob for ye ole Boss DS-1.It doesn't say what kind of pot their using.Linear maybe? :hmmm:
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MoonWatcher
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Post by MoonWatcher »

I'd actually start with a log taper, but I don't think either choice would really be awful one way or the other.

Since you know it's a lowpass filter, you could map out what frequency would be cut at the mid point for each, or at least know the following:

- mid point with linear taper will be about 400 hertz

- mid point with log taper will be a bit lower than 400 hertz

And a linear taper will probably sound more like it's topping out at around 80% clockwise rotation. Conversely, the log taper will have a lot more of a frequency change going all the way to max from roughly 65% upwards.

But the log taper could possibly sound too close to stock for a good bit of its anti-clockwise settings. This is why I suggest starting with it - an assumption of somewhat sticking to the original sound more than deviating from it.

So it could really be a matter of preference, as well.

Maybe it would be better to visualize what happens with a linear taper pot at min / mid point / max as follows:

240 hz / 400 hz / 1 khz

Then you can visualize that those frequencies (in between) are going to happen at lower points of the pot's rotation with a switch to log taper.

If you wanted to push things in the direction of midrange emphasis with the pot at a mid point setting, then I guess a reverse-log taper pot might even be worth considering.

There is no right or wrong here, and that may be why the taper of the pot was omitted from the illustration.

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souped_up
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Post by souped_up »

MoonWatcher wrote:I'd actually start with a log taper, but I don't think either choice would really be awful one way or the other.

Since you know it's a lowpass filter, you could map out what frequency would be cut at the mid point for each, or at least know the following:

- mid point with linear taper will be about 400 hertz

- mid point with log taper will be a bit lower than 400 hertz

And a linear taper will probably sound more like it's topping out at around 80% clockwise rotation. Conversely, the log taper will have a lot more of a frequency change going all the way to max from roughly 65% upwards.

But the log taper could possibly sound too close to stock for a good bit of its anti-clockwise settings. This is why I suggest starting with it - an assumption of somewhat sticking to the original sound more than deviating from it.

So it could really be a matter of preference, as well.

Maybe it would be better to visualize what happens with a linear taper pot at min / mid point / max as follows:

240 hz / 400 hz / 1 khz

Then you can visualize that those frequencies (in between) are going to happen at lower points of the pot's rotation with a switch to log taper.

If you wanted to push things in the direction of midrange emphasis with the pot at a mid point setting, then I guess a reverse-log taper pot might even be worth considering.

There is no right or wrong here, and that may be why the taper of the pot was omitted from the illustration.
Thanks Moonwatcher!I might ditch this idea :?: and go with changing C12 to a .022uf and put it on a switch with the stock cap?I would like a "Mid-Hump" like a Tube Screamer,but be able to go back to the "Mid-Scoop" as well.Any suggestions?Thanks again,-soup

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Post by MoonWatcher »

That's one alternative.

If you're going to add a switch, you might want to get a DPDT and change the treble cap to something bigger as well. I think the caps for the "phat mod" are 22nF for the bass like you're thinking of trying, and 68nF for the treble. I'd think 47nF would probably work equally as well and is a more common size.

The truth be told, I also like just a pair of 47nF's in both slots.

There's so many things to try that it's really up to you.

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Post by souped_up »

MoonWatcher wrote:That's one alternative.

If you're going to add a switch, you might want to get a DPDT and change the treble cap to something bigger as well. I think the caps for the "phat mod" are 22nF for the bass like you're thinking of trying, and 68nF for the treble. I'd think 47nF would probably work equally as well and is a more common size.

The truth be told, I also like just a pair of 47nF's in both slots.

There's so many things to try that it's really up to you.
Hey Moonwatcher.I can't remember what the treble and bass resistors were?Is it R16,R17?How would you implement them on a dpdt switch?On you're post do mean maybe having one-side of the cap+resistor pair on a dpdt switch?(one pair on one-side,and the other pair on the other side of the dpdt switch).If i remember correctly,the bass and treble caps were,C11,C12?What values can i try for these res.+cap. pair's to get what i'm looking for?Thanks for your help!-soup

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Post by 1oldsidewinder »

Try changing R16 and R17 (6k8) to 4k7 along with changing both C11 and C12 to .047uf. This will set both sides of the tone control at 720hz and give the pedal more of a TS mid humped sound.

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Post by soupbone »

1oldsidewinder wrote:Try changing R16 and R17 (6k8) to 4k7 along with changing both C11 and C12 to .047uf. This will set both sides of the tone control at 720hz and give the pedal more of a TS mid humped sound.
Awesome!Thanks!

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Post by Bouncingbuddha »

Would a dual concentric pot wired up to R16 the same way the diagram shows and the other bottom lugs wired to C12 the same way effectively work? Or would C12 have to be reversed so as R16 increases, C12 decreases in value? Orrrrrrrrr am I just talking absolute rubbish?? Any help would be great if it’s a possible idea. Thanks guys and girls.

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