The AMZ 2-resistor mod for the Boss DS-1 Distortion pedal.
The DS-1 is a classic distortion pedal and is widely used by pros and amateurs alike. However, if it has any flaws, it is that the distortion is too extreme and the tone can be a bit harsh. This mod can fix both problems by merely changing two resistors.
The schematic at the top of this article is the input transistor gain stage in the DS-1, which is built around the Q2 bipolar transistor. It offers a lot of voltage gain and an extreme treble boost, which can make the distorted tone sound thin.
The two resistors that are changed in this mod will be R9, which controls gain, and then R6 to bring the bias back into the proper range. We want to decrease gain of the Q2 booster so the value of R9 is increased. Remove the 22 ohm original R9 and replace it with a 1k resistor. Next, take out R6 (100k) and put a 150k resistor in its place. That’s it!
I measured the collector voltage of Q2 after the mod and it was 4.72v, which is close to ideal. The lower gain of Q2 will give more control over the DS-1 boost, and will take it out of fuzz territory and solidly into the distortion range.
When R9 was increased, the input impedance also went up. This improves low end response and takes away some of the harshness. The drawing below illustrates the final configuration of the pedal after completing the mod.
If you don’t like the sound, the mod is easily reversed by replacing the original resistors. Give it a try and tell me how you like the improved fat DS-1 sound!
The Boss DS-1 is currently selling for $39 in our online store. It is a great pedal whether you mod it or not!
If this mod reduces the treble too much for your rig or taste, you can decrease the value of C3 to bring some of it back.
Start by changing C3 to 0.022uF or 0.01uF. The smaller the value, the more the low freqs will be rolled off.
regards, Jack
Very, very nice, and no, I wopn’t be changing it back.
Mr Orman, you’ve done it again! I also think this one tips the balance to having more changed components on my ds1 PCB than original!
Hi Jack. Thanks for sharing this mod. I just did this change last week and used my DS-1 on stage last Friday with pleasing results.
My DS-1 also has other mods done to it and C3 is 0.033uf right how. It’s a little dark so I’m going to try 0.022uf in there next.
I need to get another one and make just these changes for kicks.
perfect sound.. very similar to session man II IBANEZ .. SS20..BUT THIS ONE HAS A DELAY SECTION UN USEFUL.. I’LL TRY TO RAISE THE SCHEMATIC EXCEPT THE DELAY PART.. JUST LOOK ON E BAY.. THERE IS ONE FOR SALE THERE .. NOBODY KNOWS THAT IT HAS A VERY SIMILAR DISTORSION..FORGET ABOUT THE FOURTH KNOB..THE DELAY KNOB.
I have simulated the circuit in spice and this mod does not change the low-end frequency response. The frequency response becomes flat with a gain of approx. 8 between 100-10kHz which might give the impression of boosted low-end.
I tried your mod and a peculiar thing happened. When I replace R6 with the new value the pedal produces no sound when the pedal is switched on.
Any idea what is going on? It works fine once I put the old resistor back in.
Check the value of your new R6 resistor with a meter and make sure that it is 150k ohms.
Have you changed R9 as well? That is necessary.
Numerous people have successfully made this mod so it is definitely confirmed by modders other than me.
I’ll try this mod tomorrow, but there’s a mod to give more mids to the pedal ?
I was thinking about modding my DS-1 to make it good for bass guitar. Is this mod the deal? Have you tried this on bass guitar?
Thanks.
Modded mine tonight, and used it at a show. I can confirm that it is awesome for bass guitar. I play an Ibanez gs205 through a Peavey TNT 115. Put my DS-1 in chain after my KMD Phaser aand with the tone straight up, volume about 1/4 up and dist cranked to about a 9, was able to bust out a sweet cover of Beastie Boys’ “Gratitude”.
This mod will cut your distirtion down quite a bit, but it is a raspier, meaner distortion. It also overdrives pretty niceley for a bluesy grumble. If you want full-on distortion, you can crank the dist all the way up, but I found my sweet spot for the night around 8.5-9. Gonna try a couple other mods though to try to get a bit of the distortion back. I play in a punk/alternative band, but I like my rig to sound metal. A bit more distortion back would be nice, just for that little bit of headroom.
BTW, the tone knob works sweet for the bass. You can tune it in along with the level and set it like a guitar, where you hear the bass still with the distortion added in a layer on top.
I modded mine a few days ago. Sounds great!
Thanks Jack. I did many other changes to it
(caps, asymmetrical clipping) but this one
really cleans the sound.
I must say that the clone of DS1 I built from tonepad.com layout sounds still better with JRC4558!
hi i´m new here, i ´ve been looking for the “hi Z input low Z output” issue that every body talks about… i read the pete cornish web page and he is got a point!
is that the reason why my DS1 is a tone sucker? not enough HI Z input? or what?
thanks for this forum!!! is great!
Hi, how can in corporate this mod to the tonepad ds1?
the r6 100k in your schem is connected to the ground while the 100k is connected from the vb?
are they the same?
Hi guys, I am new here and I will greatly appreciate your help on the following matter.
I did the Keeley SEM/Ultra-mode mod a couple of weeks ago and although I was initially happy with it, now I feel that:
1) the sound is quite distorted even when the distortion knob is at 0 (actually increasing gradually from 0 to 10 has a very small effect on distortion level, whereas from about 12 onwards distortion increase becomes more apparent)
2) The sound sounds compressed,…I don’t know if its the actual pedal or the fact that I have high output pups (or a combination of the two).
Anyway, what I wanted to ask you is that given that I have done the keeley mod, is there an additional change that I can do to correct those 2 things? i.e. the extreme distortion and the deeply compressed sound? I am asking this question because maybe Jack’s mod works as a charm provided that one hasn’t already changed anything else…and I have done a lot of changes already for the keeley mod..
Thank you
Great Mod. I am a DS1 fan I did the Keeley mod, It helped but it compressed the tone a lot and ended up with squeeshy distortion. I think that this Mod by it self its a great deal.I would only change the Clipping diodes to LEDs and tame the tone control with a 10nf cap across the tone Pot. Cheers Fron Los Angeles
If you’re into classic sound. This mod is for you. I tried this mod and to my ear my DS turnned like less gain “muff.” But this is a very good a idea. W/ some experiment you can add the principle on making the DS1 less fuzz. Great work Mr. Orman
hi! I will be happy if you replied me on this one. I did a keeley mod to a DS1 but didn’t replace the R39, R14 and R35 becaue I left a 3mm power led in it. the pedal works great but with 100% on the gain nob I would like to increase that for some 10-15% percent to make some room on it. should I replace R6 with a lower value like 50 or 60k?
thanks!!!
any suggestions to where i can find the parts for this mod? i guess there are websites for ordering parts or local stores that sell them.
But is it possible to recycle parts from some old electronic equipment? like a pager, a busted up Rocktron Rampage amp or tv remote controlls?
Try mouser.com or smallbearelec.com for the parts needed to build pedals or make mods
>>>any suggestions to where i can find the parts for this mod?<<<
Hi,
I tried the mod and I screwed up somehow. After I thought the two resistors were in place I connected the jacks and the only thing I got was an awful hiss and squeaks while I was touching the strings. I removed the resistors and it sounded the same, off or on.
Could it be possible that I shorted the circuit some place or broke it? In some place the thin conductive layer came off a bit but I think there is still contact there.
The good part is that I am receiving a radio station
Thanks.
Never mind, I did the test with all the guts out. I went to bed and then it hit me: the metal case is used for grounding. Now it sounds OK. Thanks!
sweet sister mary….. 2 resistors….. 5 cents 20 minutes muckin` about….negotatable…..the sound…..priceless nice tip jack….you`re the man
Well nice to know the mods I use the ds1 and Hm2 for swedish death metal on the ds1 it makes this swrill sound don’t know why turn the gain down it goes awaybut will try some mods to perfect it its an old style but i still like the old analog stuff besides tube tone
Will this mod also work on the Super Feedbacker Distortion?
i think i went a little to far;
http://i488.photobucket.com/albums/rr243/alfalfasprout69/Boss%20DS1%20-%20Distortion%20Pedal/BossDS-1MetalFilmRst.jpg
Great mod, thanks for sharing! Just enough gain, when maxed, for bluesy leads on my strat with Kinman Woodstocks. But now the tone is smooth and chunky and still has the bite which I love the DS-1 for.
Hahaha! Damn alfalfa….how does it sound with all those resistor and cap improvements?
I did this mod after buying another ds-1, I had a ds-1 before and had done the keeyley/brent mason mod and those @indyguitarist&premierguitar sites, and I wish I could have read this forum beforehand, which is better in my opinion.
The tone is more upfront with boosted presence & body, but the volume is compromised a bit, but overall it’s the best mod i have done to the ds-1. Yes the distortion is meanier! almost like a speaker-ripping like tone but still on the distortion color.the good point in this mod is that the clipping diodes are preserved and thats what i like about the stock ds1 .All you need is to bring up your presence and tone and this mod is the one we’re looking for!
thanks to the one who discovered this!
excellent contribution!
for those who want back a little more gain, you can lower r6/r9 .I trimmed it to my taste and made R6(150k) to 120k and R9(1k) to 680ohms
now it sounds almost the same but is sweeter sounding this time