How to boost bass on input DS-1?

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Cluckhold
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Post by Cluckhold »

Good afternoon,

I was modding an unrelated Bad Monkey overdrive and one of the mods adjusted the intensity of the bass knob. I reverted it because it was too much for my liking, but it worked really well into my DS-1.

My question is, are there any ways to add a pre-distortion bass boost on the pedal? Hopefully one that wouldn't require I add my own little circuit board into the pedal?

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CheapPedalCollector
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Post by CheapPedalCollector »

If you check the service manual, there is one cap that is larger in the original DS-1, I modded one of mine to have this larger cap and now it sounds better. At least as well as a DS-1 can sound.

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Cluckhold
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Post by Cluckhold »

I'm looking at the service manual and all I can see are a few component changes that don't affect the audio path as well as a few changes to the opamp.

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Post by CheapPedalCollector »

C5 makes a lot of difference. C8 makes a slight difference.

So do the roll off caps in the feedback loop. 100p vs 250p , and the two 150p the way it's connected in the circuit. These are probably to prevent oscillation but will also roll off some highs.

D8 is hooked up to limit the voltage on the input in a certain way, probably the chip is sensitive to large differences between the the +/- inputs, but they should just strap a couple of diodes across them instead. This chip fails a lot in DS-1A.

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Cluckhold
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Post by Cluckhold »

Interesting. How exactly does C5 affect the circuit? From what I can see all it does is make a low pass filter around ~23hz, that shouldn't be too audible right?

As for the feedback loop, I more interested in boosting bass rather than cutting highs.

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Post by CheapPedalCollector »

Math and what happens in a real circuit often can be different due to other factors in play. In the original circuit there is a .47uf driving a divider of 100K and 47K, which is essentially a 150K pot turned up 2/3rds, which will roll off a lot of highs. The original DS-1 is bassier because of that too. The DS-1A has less filtering after the gain stage which sounds different and "fizzier" while not having the same low end response either. The preceding gain stage also has high negative feedback with the 250p cap and a bit of current feedback the way the base is biased which gives a bit of compression.

You could also lower R13 for more bass gain or do something like the klon or rat to change the curve to your liking.

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Cluckhold
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Post by Cluckhold »

Interesting, this has been very helpful. I'll update you guys as I fiddle around with my circuit.

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Cluckhold
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Post by Cluckhold »

Also, does anyone know offhand how to "split" the tone control? I'd assume it's as simple as a concentric 20k B-taper pot, one pot would recieve a wire from R17 and output to the level pot and the other pot would recieve a wire from C12 and output to the level pot?

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Cluckhold
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Post by Cluckhold »

Aw, I may have to put this one on the back burner seeing how I'd need a B20k concentric mini pot and those aren't too easy to come by. I'm not sure how much space I have to shove 4 resistors in there to alter the taper either

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Post by CheapPedalCollector »

Small Bear has them.

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Cluckhold
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Post by Cluckhold »

On Small Bear I see a 10k audio and a 50k audio. How big of a difference will it make if I change to either of these values from 20k?

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Post by CheapPedalCollector »

Not sure, just have to try it.

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Cluckhold
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Post by Cluckhold »

Imma try the 50k then I'll report back with my findings.

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Cluckhold
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Post by Cluckhold »

50k works, does exactly what I want

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Post by CheapPedalCollector »

Right on.

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Post by indyguitarist »

Just bumped into this. I'm looking at an older schematic for reference, but the cap right before the npn boost will do it. C3 on the schematic I'm looking at. Stock is .047u, make larger for more pre-clipping bass. I did a video on this recently where I stuck a 1u right there to show that by increasing the bass there drastically you can get it to have some fuzz characteristics.

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Post by CheapPedalCollector »

That's what I did, I increased this cap to the pre revision value on my newer one and I like how it sounds better.

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