Boss - DS-1 Distortion mods (what works, what doesn't?)

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matt239
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Post by matt239 »

I have changed R6 to 150k & R9 to 300k (Jack's AMZ Fat mod, with R9 closer to 5Thumbs value..)
- changed D4 & D5 each to a single 1N34 germanium.
Sounds good to me so far!

I am thinking of changing R14 to 1k & R18 to 1k? to increase output. Is this a good/bad idea? ??

- maybe change R2 to 680k or even 1M? ??

Will increasing the value of R16 give more lows through bass side of tone control? - maybe 10k?

Would increasing value of C13 have any effect? or is it only coupling, & not really filtering in audible range anyway?
?? :D ??

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Post by matt239 »

I have changed R6 to 150k & R9 to 300k (Jack's AMZ Fat mod, with R9 closer to 5Thumbs value..)
Correction: changed R9 to 300 Ohm, not 300k

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Post by tasteless »

Matt, I have a clone That I did just a couple of mods to ( virtually what You have described ! ).
After the Fat mod I too, was looking for more volume .
Just off the top of My head I think I halved the resistor off the Vol. control ( that may be R18 ? ).
I think You would want to DE-crease R16 for more bottom end.
Umm...I suppose I best go and have a look at it.

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Post by matt239 »

I think You would want to DE-crease R16 for more bottom end.
I think you are correct. :D :slap:
R18 follows the volume pot as you said. It's 10k stock, I just have to decide whether to make it 1k or 4.7k.
1/2 value worked well for you?

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Post by tasteless »

Oh, sorry Matt ,Not paying attention , Yeah I used 4.7K for both ( R16 and R18 ).
Also , consider that any other mods may add to the overall volume as well , actually R16 will add a bit.
I remember thinking one day that I would do more to My pedal But , After plugging it in decided it was Ok .

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Post by HTH »

if anyone fancies trying a tone control mod to their DS-1, heres one I simulated in TSC. at halfway setting its flat, above halfway you get a simultaneous treble boost/bass cut around 800Hz-1kHz, below halfway you get treble rolling off at around 800Hz-1kHz. should work a treat with the DS-1 in adding meat and getting rid of the scooped tone. also put a 20k resistor across the tone pot to give a working pot value of 10k.

R15, shorted out
R16, 39k
R17, 33k
C11, 0.022uF
C12, 0.1uF

not promising anything, but this should work pretty well.

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Post by matt239 »

Tried a few values @ R18, ended up replacing it with a jumper!
Sounds good.

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Post by Cannibal »

Since cctsim has already tried a MOSFET in place of Q2, would a JFET work? I have some 2n5458, are they suitable for something like Analogguru FET booster?
Probably i'll have to solder some components on the trace side, but i think that this isn't a huge problem
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Post by cctsim »

Cannibal wrote:Since cctsim has already tried a MOSFET in place of Q2, would a JFET work? I have some 2n5458, are they suitable for something like Analogguru FET booster?
Probably i'll have to solder some components on the trace side, but i think that this isn't a huge problem

Yes, that's possible but JFETs typically have less gain than MOSFETs.

If you use the 2N5458 try the following biasing circuit which I found to work well:

-Change R6 to 1Meg Ohm
-Remove R7 and C4 completely.
-Change R8 to 680 Ohms
-Remove R9 and replace it with a short.

I personally change C5 to 22 nF but you can leave them to the original value.

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Post by GuitarlCarl »

Whatever clipper mods ya do... use a switch with center off... I like mine best with no diodes!
It cranks that way, really open and airy... [smilie=a_holycrap.gif] yeah its an overdrive now....
I want it to sound like bees buzzing around in a 55 gallon drum...

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Post by cctsim »

5thumbs wrote:
5thumbs wrote:The first is the '5thumbs HMG Mod', which adds switchable soft-clippers, Crackle-NOT-Okay! (CNO) replacement of Q2, active tone booster to the HG Mod. The objective is additional clarity and bass while maintaining saturation.

The second is similar to the '5thumbs HMG', except that I wanted to use a CNO to drive the hell out of the NPN booster in Q2. (That combo produces a nasty, metallic, splatty fuzz as you get increased clarity out of the CNO, then use the gain of the CNO to overdrive the merde out of the Q2 NPN. This mod will be almost the same as the '5thumbs HMG' mod, except Q2 stays stock as an NPN transistor and I replace/mod Q1 and Q3 with two CNOs.) This mod is weird in that it removes the ability of the DS-1 to be bypassed in the conventional sense and makes it an always-on sort of pedal. Why? This mod will allow you to switch the distortion circuit on/off with the footswitch, but when the distortion is off, the dual CNOs are still in the signal, kind of like a ZVex Super-Duper 2-in-1. The objective of this mod is to add the clarity/boost of the CNO as the input stage, but then use that gain to overdrive the Q2 transistor. The name of this mod will be "CNO-EV1L".

I've got parts ordered for the final '5thumbs HMG' build and need to do the same for the CNO-EV1L, plus finish daughterboard layouts and doc text for the latter. I hope to get these done in the next few weeks (certainly before June 1), so you might want to wait and see if the new mods tickle your fancy.
I knew I was forgetting something when I described the new mods. I've also upgraded all the DS-1 mods in the doc (except Mr. Keeley's, of course) to allow +18V or +9V operation of your DS-1.
Hi Brett

I noticed that in the "Build Your Own DS-1 Distortion" document, C7 for the post 94 DS1 is referred to as 100pF. The actual value is 10pF (code 101). Several pages/mods/schematics have this value wrong.

Best Regards
cctsim

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Post by HTH »

cctsim wrote:
5thumbs wrote:
5thumbs wrote:The first is the '5thumbs HMG Mod', which adds switchable soft-clippers, Crackle-NOT-Okay! (CNO) replacement of Q2, active tone booster to the HG Mod. The objective is additional clarity and bass while maintaining saturation.

The second is similar to the '5thumbs HMG', except that I wanted to use a CNO to drive the hell out of the NPN booster in Q2. (That combo produces a nasty, metallic, splatty fuzz as you get increased clarity out of the CNO, then use the gain of the CNO to overdrive the merde out of the Q2 NPN. This mod will be almost the same as the '5thumbs HMG' mod, except Q2 stays stock as an NPN transistor and I replace/mod Q1 and Q3 with two CNOs.) This mod is weird in that it removes the ability of the DS-1 to be bypassed in the conventional sense and makes it an always-on sort of pedal. Why? This mod will allow you to switch the distortion circuit on/off with the footswitch, but when the distortion is off, the dual CNOs are still in the signal, kind of like a ZVex Super-Duper 2-in-1. The objective of this mod is to add the clarity/boost of the CNO as the input stage, but then use that gain to overdrive the Q2 transistor. The name of this mod will be "CNO-EV1L".

I've got parts ordered for the final '5thumbs HMG' build and need to do the same for the CNO-EV1L, plus finish daughterboard layouts and doc text for the latter. I hope to get these done in the next few weeks (certainly before June 1), so you might want to wait and see if the new mods tickle your fancy.
I knew I was forgetting something when I described the new mods. I've also upgraded all the DS-1 mods in the doc (except Mr. Keeley's, of course) to allow +18V or +9V operation of your DS-1.
Hi Brett

I noticed that in the "Build Your Own DS-1 Distortion" document, C7 for the post 94 DS1 is referred to as 100pF. The actual value is 10pF (code 101). Several pages/mods/schematics have this value wrong.

Best Regards
cctsim
101 = 100pF
102 = 1000pF
103 = 10,000pF

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Post by cctsim »

My mistake , thanks.

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Post by matt239 »

I've got a DS-1 with the 7-pin SIP, but it's cooked. I'm getting a TA7136P IC from Small Bear.
Does anybody know how the pins line up? What pin is removed to make the 8 pins fit the 7 holes?

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Post by blackbunny »

I'm not sure what you're asking here. The TA7136P has 7 pins; it is a single op-amp in a SIP package, and it was used in the MIJ and MIT DS-1's up until 1993. The T7136P from Small Bear should fit right into a pre-1994 DS-1.

Recent DS-1's use a different circuit design and either BA728N, M5223AL or the NJM3404AL used in current DS-1's.
These are all dual op-amps in a SIP8 8-pin package.

Are you trying to fit a TA7136 (single op-amp) to a newer DS-1 which had an 8-pin (dual op-amp) IC?

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Post by thyx »

FWIW, I just converted a post '93 DS-1 from 8-pin to 7-pin operation. It involved cutting one trace and drilling one hole, and fooling around with some alternate routing of a few different components...TA7136P from Small Bear. Then I did the Monte Allums "Rectifier" mod on it. I test-run all my pedals through the normal side of a Twin Reverb with the bright switch off, just to get a feel for how they're going to sound. In comparison to an original MIJ DS-1, my "new" DS-1 has bolder and more clear lows and highs...but still seemed scooped in the mids a bit more than I like. Allums uses a pair of 1N4002 diodes for clipping in that mod...my solution was to add a 1N34 in series with each of them. This raised the clipping voltage to be closer to that of the original MIJ DS-1, and softened the clipping just enough to fatten up the tone. It really is all a matter of taste, though. Try it...you may like it!

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Post by matt239 »

I'm not sure what you're asking here. The TA7136P has 7 pins; it is a single op-amp in a SIP package, and it was used in the MIJ and MIT DS-1's up until 1993. The T7136P from Small Bear should fit right into a pre-1994 DS-1.
You are right of course! :)
When I first posted, I had ordered the chip, but didn't have it in-hand yet. - For some reason, (No idea why..) I was thinking it was a work-alike with 8 pins, one of which wold not be used..
In reality, it's the exact part; 7 pins for 7 holes. :D - making my question, um, - meaningless.. :slap: - :oops:

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Post by Audiowonderland »

Complete rookie here. Having read through a mind numbing number of mods for a DS-1 I put together this combination of mods to try out. The first section is from the AMZ mod and the rest I believe are from a premier guitar article. The goal is to lower the gain a bit, lose the bright/fizziness and lose a little bit of the compressed quality. Any thoughts on this combo? Happy to experiment but don;t want to waste time on something that can't possibly work either

Lower input transistor gain stage distortion
R9 from 22ohm to 1k resistor
R6 from 100k to 150k resistor
Modify other gain stages
C3 .033µF
R17 15k
C2 1µF
D4 Red LED
D5 Blue LED
C5, C9 1µF

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Post by Audiowonderland »

Audiowonderland wrote:Complete rookie here. Having read through a mind numbing number of mods for a DS-1 I put together this combination of mods to try out. The first section is from the AMZ mod and the rest I believe are from a premier guitar article. The goal is to lower the gain a bit, lose the bright/fizziness and lose a little bit of the compressed quality. Any thoughts on this combo? Happy to experiment but don;t want to waste time on something that can't possibly work either

Lower input transistor gain stage distortion
R9 from 22ohm to 1k resistor
R6 from 100k to 150k resistor
Modify other gain stages
C3 .033µF
R17 15k
C2 1µF
D4 Red LED
D5 Blue LED
C5, C9 1µF

While I was ordering parts I ordered a few germanium diodes as well. Planning to stick with the LED's I think but I am tempted to try these. I like the idea of smoother but I think the LED's extra output would be useful.

To refresh my memory, the black band represents the neg end of a silicon diode correct?

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Post by ballfire »

hello..

i build this ds-1 distortion pedal, i dont add any mods..i leave it the way it should be..

for me i think..I advice you not to add mods...the pedal itself its already good sounding..


thank you..

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