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

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
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lexluthier72
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Post by lexluthier72 »

Hey Guys,
I recently did the Wampler "modern distortion" mod on a MIT ds-1. I also did the "more gain" step from the vintage mod. I like the "tightened up distortion, but now the tone control is way too dark. (too much bass when rolled all the way down, and not enough treble all the way up) Im assuming changing the values of C5,C9 control this function. Im at a loss as to what value to change them to.
-Erin

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Post by matt239 »

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. ...
If you want the sound of the germanium diodes with a higher clipping threshold, (Like the LEDs) try just replacing each diode with 2 or 3 germaniums in series, or 2 germaniums & a resistor etc..

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_olarlite
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Post by _olarlite »

Hey people, I just got myself a stock DS-1 with the intention of modding it. Not because I think it sounds bad, but I think this should be a good starter project as I'm just getting into butchering.

My question is, what are the worst offending components? I'd really just like to do the bare minimum to start with, then progressively transform it to a Keely mod (or any other recommended great sounding mod).

Cheers for any help.

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Post by MoonWatcher »

_olarlite wrote:My question is, what are the worst offending components? I'd really just like to do the bare minimum to start with

Cheers for any help.
While it is all subjective as to what equals good or bad sound in a stock DS-1, I think that generically there are a few that many users don't favor:

- stock clipping diodes compress too much (especially compared to the old MIJ's, which the MIT's are frequently compared against)

- tone stack sucks out too much midrange

- too much harsh treble content at higher distortion settings, which is primarily due to the first gain stage - it's a transistor that most people miss, and they go right to op amp replacements that can be avoided over 80% of the time.

So what to do? Increase the forward voltage of the clipping diodes to open up the threshold a bit. No need to look for grail diodes or a specific type - grab a multimeter that lets you measure them, and use series combinations until you get up to around 850mV or so, maybe topping out at 1100mV. I've found that combining a stock one in series with a BAT42 is great, but you can use a 1N34A for just a bit more air. You can also use a pair of 1N4001's in series, but the thick leads can be a problem with the PCB (you can end up gouging it up or tearing traces).

For the tone stack, try increasing either the treble cap or treble resistor, or decreasing the bass cap or bass resistor. I don't have component numbers in front of me, but both resistors are 6.8K, and the treble cap is 22nF and the bass cap is 100nF - all are in proximity to the op amp chip at the rear of the pedal.

The first gain stage is an ordinary bipolar transistor that is biased for lots of gain and is the true culprit for much of the buzz. Lots of people replace the op amp thinking this will improve the tone, but if you don't address the transistor (I think it is Q2) then it's kind of like trying to put on the brakes while you are still slamming down the gas pedal. There is a 22 ohm resistor from the transistor's emmiter that can be increased to decrease all of the buzzsaw clipping. Since you lose gain by modding at this point, modding the clipping diodes almost becomes necessary.

I loathe LED's in the DS-1 since they make the clipping threshold too big, but lots of other people seem to like them. I also hate adding a mid pot as it makes a nice simple distortion pedal a bit less intuitive or "automatic." I just temporarily sub in different diodes and caps until I get it where I want it. I know that Brett Miller has resistor values for adjusting the gain and character of the bipolar transistor, but my opinion is that they tend to "cool it off" a little too much. IIRC, the base-to-ground resistor is 100K stock, and if used with a 100 ohm emitter resistor, it works pretty well. But bipolars are flexible in their biasing, so you can experiment (within reason) at this point, too.

Lots of people shotgun out all of the stock caps and the op amp. I wouldn't bother, or at least save it for later. Just a few tweaks (starting with a modest adjustment at the clipping diodes) are usually sufficient for lots of DS-1 users.

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_olarlite
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Post by _olarlite »

Thanks for that, MoonWatcher.

I really am just beginning, so this is quite a lot for me to take in, but I'm certainly keen to have a go.
For the tone stack, try increasing either the treble cap or treble resistor, or decreasing the bass cap or bass resistor. I don't have component numbers in front of me, but both resistors are 6.8K, and the treble cap is 22nF and the bass cap is 100nF - all are in proximity to the op amp chip at the rear of the pedal.
This seems like a good starting point. Is this a case of trial and error, or could you give a rough guide as to what values I should be aiming for?

So out of bass resistor or cap, or treble resistor or cap (C11, C12, R16, R17?), which would you recommend? Any one of them or all four?

Also,
No need to look for grail diodes or a specific type - grab a multimeter that lets you measure them, and use series combinations until you get up to around 850mV or so, maybe topping out at 1100mV.
Daft question, I know, but how do you solder in series on a PCB?

Thanks for the help.

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Post by MoonWatcher »

_olarlite wrote:Thanks for that, MoonWatcher.

I really am just beginning, so this is quite a lot for me to take in, but I'm certainly keen to have a go.
For the tone stack, try increasing either the treble cap or treble resistor, or decreasing the bass cap or bass resistor. I don't have component numbers in front of me, but both resistors are 6.8K, and the treble cap is 22nF and the bass cap is 100nF - all are in proximity to the op amp chip at the rear of the pedal.
This seems like a good starting point. Is this a case of trial and error, or could you give a rough guide as to what values I should be aiming for?

So out of bass resistor or cap, or treble resistor or cap (C11, C12, R16, R17?), which would you recommend? Any one of them or all four?

Also,
No need to look for grail diodes or a specific type - grab a multimeter that lets you measure them, and use series combinations until you get up to around 850mV or so, maybe topping out at 1100mV.
Daft question, I know, but how do you solder in series on a PCB?

Thanks for the help.
With the bass and treble cap and resistor pairs, you can reach the same high pass and low pass filter rolloff points by just changing either the resistor or the cap in the R/C pair. That said, I guess it really comes down to what you want, and what components you have available.

...If you want less bass, just decreasing the 100nF cap will do it, but the common size of 47nF might reduce it too much. That means having access to a 56nF, 68nF, etc. cap to get a low pass filter at an in-between value. So instead you may wish to reduce the 6.8K resistor. Again, a common size like 4.7K might reduce things too much. If your parts stash is limited, it means you will have to experiment more with both the resistor and capacitor.

If you want more midrange, you make either the treble cap or resistor (or both) bigger, too. I've seen people take the stock 22nF cap as big as 100nF. I tend to increase the 6.8K resistor upwards to either 10K for a mild change, or more likely take it up to something like 15K. Again, some people will push the resistor up to 22K (because it is a common size), but I personally think it is a bit much.

The truth be told, I think the stock bass R/C pair are fine. I would only recommend playing with them if you want less bass or tighter bass. So I just end up replacing the treble resistor, and leave the other 3 components stock. That's just my tastes, though.

As far as diodes in series, there's really two ways that I know of to do it. The first is to join the two as an "upside down V" with the other ends in the stock PCB holes. Just watch the polarity, obviously. You want cathode to anode orientation with your diodes, just like flashlight batteries. I will sometimes orient a pair of diodes so that they create a rectangle, with their leads bent 90 degrees, and soldered together the length of the space between the diode holes in the PCB. That way, I can cut out that middle area and add a THIRD diode in series if I want. I also recommend heat shrink over the exposed solder junctions so that nothing shorts out.

Some people also put transistor or chip sockets (cut up parts of them) in place of the stock diodes, so that you can swap stuff without having to unsolder and resolder as you experiment with diodes. I usually just run a pair of wires out of the pedal and temporarily swap stuff until I get a combination that I like. I will usually wait about a week and a half before settling on something. Just one or two auditions usually doesn't personally work for me. I don't like switches that much personally, either, as I won't end up using the other diode settings. But again, it's a personal thing - no real right or wrong.

Whatever you do, just try to keep it fun and simple as you are starting out. I recommend not changing too much at once. Most DS-1 tweakers that I personally know had to go back in and un-do a bunch of overzealous changes. Either that or they didn't know which specific ones got them the sounds they were looking for.

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Post by Shiny_Beast »

I always thought limited the input capacitor to get rid of some low end at high gain was a good idea but I've never tried it.

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Post by theblackman »

back when i started playing with stompboxes i bought wampler/indyguitarist sd1 and ds1 mods, i just dug out my "evil" modded ds1 to lend to a friend and had a little bash. WHOA it was really good. I was wondering if anyone has the mods available I can download I'd like to look at those mods again? are they still for sale or open sourced now??

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Post by matt239 »

theblackman wrote:back when i started playing with stompboxes i bought wampler/indyguitarist sd1 and ds1 mods, i just dug out my "evil" modded ds1 to lend to a friend and had a little bash. WHOA it was really good. I was wondering if anyone has the mods available I can download I'd like to look at those mods again? are they still for sale or open sourced now??
Brian/indyguitarist has a book for sale that includes that, several other DS1 mods, & mods for a bunch of other pedals, pics, schems, & explanations of the circuits, not super heavy on maths/theory. - I liked it.

Also, everybody have a look @ 5Thumbs DS-1 document (referenced earlier in this thread)(find with search function :D ) ; TONS of info on DS-1 models, history & mods! Free!! 8)
_olarlite wrote: ...could you give a rough guide as to what values I should be aiming for?
Check out Jack Orman's AMZ-website's R-C-filter calculator,& Duncan's Tone Stack Calculator.
MoonWatcher wrote: ...The first gain stage is an ordinary bipolar transistor that is biased for lots of gain and is the true culprit for much of the buzz. Lots of people replace the op amp thinking this will improve the tone, but if you don't address the transistor (I think it is Q2) then it's kind of like trying to put on the brakes while you are still slamming down the gas pedal. ...

+1 :) - Check out Jack's AMZ-blog DS-1 mod.
Shiny_Beast wrote:I always thought limited the input capacitor to get rid of some low end at high gain was a good idea but I've never tried it.
+1 :) (smaller value input capacitor = higher high-pass frequency (or consider it a low freq cut @ input) = less sputter/splatter/roughness/uneven decay..)

& then I like to add bass through the tone section. :twisted:

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Post by Marshallmaniac »

Hi all, great forum!

I really hope someone can answer this one for me. I've tried Keeley, Boss, another electronics guy and no-one can answer the question..

I bought a current production DS-1 and liked it, except I notcied the standars stuff like fizzy highs, lack of mids and general buzziness. I figured, I do like the underlying tone of the pedal so I ordered the Keeley ULTRA mod and now it sounds GREAT! But.. The pedal has always had this fault: Even in stock form, the volume/level pot is as loud as amp volume at just 1/4 of the way up. Thats at 9 o'clock.. Whearas any other pedal I've ever owned is usually somewhere arounf noon.

I even took it in to a music store and tried it against the one they had there and same story.. Is this a new thing? And most importantly (Pleaaaase!!) Is there a way I can get less volume without changing the tome of the pedal? I wouldn't mind so much except if it's a tiny bit lower than it is then I get the 'blanket' effect and highs start to go missing.
It's just crazy loud.

Thanks all, I'll be checking up with anticipation cause' I really want to get this sorted and find out whats going on
Cheers!

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Post by allesz »

Ok, I found a ds1 used for 25 euros.... sadly I had 25 euros in my pocket so.... I went home with a used ds1 (MIT).

Well, I think that stock the unit has got a fizziness that is really terrible (a real pity, because all in all the effect is built really good and the gain range is just perfect).

So I read all this tread and surf the net in search of some inspiration and simple ideas, by the way 5thumbs did a stunning work :shock: :hug:

Since I did non want to swap components I planned to just solder components in parallel (from the trace side of the pcb), so it would be easy get back to stock.

long story short:
C4: added 1nF
C10: added 10nF
C11: added 10nF this is the most important mod to lower the work frequency of the tone (sizzle) pot.

Components numbers are the ones in the 5thumbs schem on the "build your own ds-1" document.

Before a proper road test is hard to tell, but now the unit seems more useable, less noisy, a good all around dirt box.

Actually it as a lot of output, even with the gain at zero you can have a huge volume boost... but since I like to work in the low gain region of the drive pot I don't think it will be a problem 8)

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Post by matt239 »

Marshallmaniac wrote:Hi all, great forum!
I really hope someone can answer this one for me. I've tried Keeley, Boss, another electronics guy and no-one can answer the question..
I bought a current production DS-1 and liked it, except I notcied the standars stuff like fizzy highs, lack of mids and general buzziness. I figured, I do like the underlying tone of the pedal so I ordered the Keeley ULTRA mod and now it sounds GREAT! But.. The pedal has always had this fault: Even in stock form, the volume/level pot is as loud as amp volume at just 1/4 of the way up. Thats at 9 o'clock.. Whearas any other pedal I've ever owned is usually somewhere arounf noon.
I even took it in to a music store and tried it against the one they had there and same story.. Is this a new thing? And most importantly (Pleaaaase!!) Is there a way I can get less volume without changing the tome of the pedal? I wouldn't mind so much except if it's a tiny bit lower than it is then I get the 'blanket' effect and highs start to go missing.
It's just crazy loud.
Thanks all, I'll be checking up with anticipation cause' I really want to get this sorted and find out whats going on
Cheers!
I would try Jack's Phatt mod: http://www.muzique.com/news/fat-mod-for-the-boss-ds-1/ -Make R9 1k, & R6 150k. This will change the tone slightly, but most folks like it; less "fuzzy" and a bit quieter. You should be able to turn the Vol control up a bit w/o it becoming too loud. If it's not bright enough you could change C3 to 0.022uF.

If it's too much change, you could try 470 Ohm for R9, & 125k for R6, but try the first thing first. (I haven't tested those values)

If none of that gets you there, you could try a treble bypass on the volume control; Place a 4.7k resistor in parallel with a 0.001uF cap across the "input" lug of the vol control to the wiper lug.
(I haven't tested this either..) :)

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Post by allesz »

The mod goes on :lol:
I was quite happy with the tone of my modded ds-1, but even at low gain I percieved some annoing sizzle going on.

I re read this tread and 5thumbs document, and spent some time staring at the stock ds-1 schematic :scratch:

I decided to eliminate C7: maybe I misunderstand the schemo but it seems to let pass very high frequencies even at zero gain.... :scratch: :hmmm: who designed this unit really likes sizzle, or they play a super dark amp with an incredible dark and dull sounding guitar.

Since I had to reopen the pedal I decided to put on proper caps (instead of the ones soldered in parallel on the solder side of the board) and so, since I de-soldered the old caps, I had a chance to re-listen to the stock sound....
MoonWatcher wrote:- tone stack sucks out too much midrange

- too much harsh treble content at higher distortion settings, which is primarily due to the first gain stage - it's a transistor that most people miss, and they go right to op amp replacements that can be avoided over 80% of the time.
I totally agree and I did not spent a lot of time with the stock unit (it is nearly useless for me).

Right now:

C4: 1nF
C7: absent
C10: 22nF
C11: 33nF
D4: 1N4007

I used better caps this time, first ones I put on where ceramic type, so the tolerance was probably very high.
I could not resist to try and swap une of the clipping diodes, the difference between 1N4007 and 1N4148 is not so big, but clipping seems a little..... I like it more than stock for shure (but maybe it is just the result of the combinations of the others mods).

The change of C11 really lowers the frequency of work of the tone pot, right now it seems quite a presence control, at max gain you still got too much sizzle, but now it is possible to eq out almost all of it.

I did a comparison between the modded Ds-1 and a stock Sd-1: I really like them both as a generic everiday overdrive - distortion, SD-1 has got more (and beautifully selected) mids; DS-1 has less mids, highs are more pronounced and the bass frequencies too (V shaped eq). The bass are very beautifull and the highs can be controlled somehow. DS-1 has got some more gain, SD-1 is better as a (middy) clean boost.
DS-1 needs to be modded, SD-1 is good stock and is (almost) foolproof (like the good old TS, right now I happen to just prefer the SD-1).

Right now I plan to use the DS-1 because of the better bass and gain (it is more flexible in the end).... probably it would be even easier to add a little bit of basses on the SD-1.... but I think I would miss the stock sound wich is a classic :hmmm:

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Post by Groovenut »

I just finished messing with a DS-1 I got bored with. I posted it's own thread but thought I would reference here as well.

https://www.freestompboxes.org/viewtopic ... 11&t=16692

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Post by allesz »

The quest goes on, but maybe thanks to inspiration from Jack Orman, I will enjoy a new pedal for some time:

Mi previous mods are explained just two or three posts before, but I still heard some nasty sounds expecially wen playing hard, and the tone pot was still working on too high frequencies.

Probably the biggest responsabilty for ds1 nasty sounds is Q2..... I did not change both r6 and r9 as did Mr. Orman, but I just changed r9 with good results (hey, my unit was not a stock one anyway). First I used a 1K resistor, but the sound got too clean and the output was very low.
After some swaps I settled for 280 Ohm for r9 and most of the annoing distortion seems gone wile leaving some gain and volume boost, even with the drive at zero.

Then I put a 47 nF cap in C11's place.

Beware, you will loose some gain (now gain is just an air more than a standard sd1), but the sounds gets musical and useable. Compared with the stock sd1 my modded ds1 sounds very similar but with more basses and less mids (sd1 feels muddy in comparison); the raise in gain and distortion is very progressive within the rotation of the drive pot, on the sd1 you get severe clipping even with gain at 10 or 11 o'clok.

So in summary:
R9: 280 Ohm
C4: 1nF
C7: absent
C10: 22nF
C11: 47nF
D4: 1N4007

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Post by Seven64 »

I just picked up another ds1 to play with and by some string of luck it is a MIJ pedal with the TA whatever chip that is 7 pins. It sounds pretty good except it can only take the aca adaptor. Every other pedal I just remove the diode and resistor closest to the 9v source on the pcb (which are hunkered on all modern pcbs) but this pcb does not have that setup on it. Is there any way to concert it to accept the psa adaptor? I know I had this problem with my hm2 and modding out drastically helped.

I'm on my phone so it is hard for me to search for the difference between the aca and psa adapters

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Post by jorgezorro »

Basically the same mod as the ACA/PSA fix for the HM-2. You short out the resistor that's in series with the DC supply.

On the DS-1 this can be done at the connections numbered 10 and 11 on the PCB. These are usually a blue and a yellow wire. I just used a piece of wire lead from a component. If you want to get fancy you could put in a SPST switch to select ACA or a PSA power supply (more useful on a HM-2 if you want to starve the pedal and make it sound nasty).

Image

Image

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Post by ianjd »

What Ds1 mod do you guys think would be best for a Satriani/Vai tone? I'm considering having the analogman or keeley mod done.

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Post by euronymous0001 »

hi all!

modded my ds1 with brian's modern distortion tone. changed R16, R14, C10, C5, C9 and D4. i wanted more distortion so i also changed R13 to 1k and C8 to 1uF.

if i want more distortion, should 1 change R13 and C8 to 510R and 2u2 to increase distortion. thanks in advance. :applause:

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Post by Shiny_Beast »

I've tried muching around with the input buffer tranny on my MIJ, I didn't like the change, overdriving that first transistor is probably what separates the ds=1 from a lot of other "clip to ground" pedals.

I'd like to build a

mu-amp -> 741 -> GE diodes to ground

as kind of a ds-1 killer. Put some eq trimming in the feedback path like a lot of the booteek pedals do these days. I think a lot of the charm of the ds-1 is the pick attack and dynamics you get and I suspect having that buffer there is responsible for a lot of it. If it wasn't for that rediculous tonestack I'd still keep it in my case as a problem solver.

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