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

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Aharon
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Post by Aharon »

There seems to be DS-1 mods everywere but opinions are mixed,some people report great results while others say they buggered their pedal and they want it back to stock.
Any of you tone fiends have the definitive mods for the little orange box?
Thanks
Aharon

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modman
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Post by modman »

Aharon wrote:There seems to be DS-1 mods everywere but opinions are mixed,some people report great results while others say they buggered their pedal and they want it back to stock.
I also have an orange fellow on the shelf. Bought it for 22EUR with a broken switch I think it was last summer. Don't have anything in particular to advice, but maybe look at the derivative boutique boxes?

Though I do want to try mosfets for clippers in a box sometime.

i20.photobucket.com/albums/b230/zjokka/Boss%20Pedal%20Clinic/52cee00c.jpg
i20.photobucket.com/albums/b230/zjokka/Boss%20Pedal%20Clinic/5ec036da.jpg
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grolschie
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Post by grolschie »

The Keeley mods sound great.

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Post by modman »

I put in a new switch in my DS-1 yesterday. Now I'm looking at some pages with mods, but pretty sure I'm going to try a mosfet clipper, because everybody just using leds anyway. Not to say the leds don't sound better than the stock diodes.

robertkeeley.com/audio6l6/dstech.html
BOSS DS Keeley 2007.pdf
(185.25 KiB) Downloaded 564 times
erikhansen.net/?page_id=28
erikhansen.net/?page_id=28 wrote: Boss DS-1 Mods
February 15, 2006:
The Boss Distortion is one of the oldest distortion units, dating back to the late 1970’s. This is the second unit I’ve owned. The first one was traded off before I started modding pedals. Good thing they have a good street price ($40 at the time of this writing). There are a few version differences throughout the years. The main change, around 1994, was that the Toshiba TA7136AP opamp was replaced with the Mitsubishi M5223AL.

There are many different mods out there for the DS-1. The two that I have decided to take on are by Robert Keeley and by Bob Melanson (Melanhead in the DIY world). There are some aspects of each that I like so rather than do one over the other, I combined them a little. The dual 3mm LED’s as clippers rather than one was my experiment. Most mods call for one but I like the sound of two for even more crunch, much like the old black Marshall Guv’nor.

C1, C10 - change to 0.047uf
C2, C8, C14 - change to 1uf
C3 - change to 0.068uF
C5, C12, C13 - change to 0.1uf
C9 - 0.47uf
C11 - 0.033uf
D4, D5 - change to Red 3mm LED
R13 - change to 2.2k
R14 - change to 1.5k
R16 - change to 4.7k
R39 - change to 22k
All capacitors are Panasonic metal film although silver mica or poly film would be fine too. Some of the caps are left the same value and just replaced with better quality caps (who knows how much difference it makes but what the heck …).

All resistor changes are 1% metal film but carbon film can be used as well and close-enough values are acceptable (i.e. 2.2k vs. 2.4k; 22k vs. 20k). Since my parts stock is missing some metal film resistors, I opted to use what I had and went with carbon film with little to no noise increase.

Play with the value of R13 as this controls the amount of distortion. Lowering this value increases the distortion. For D4 and D5, the combinations of diodes and LED’s that can be done are endless. Try series LED’s, series LED’s and diodes, series diodes. Let your ears decide.

Thanks to Robert Keeley and Bob Melanson for their mods.

August 29, 2006:
Changed R13 back to stock value of 4.7k. Changed D4 and D5 to 1N4001 and 1N4148 respectively.

May 14, 2007 (updated November 2, 2007):
Changed R14 back to stock value of 2.2k. Changed R39 back to stock value of 4.7k. Put back in stock caps that were replaced with same value. Reverted some other caps back to their stock value. Adjusted parts change list (below) to reflect actual part and value changes.

This is my minimal mod that really changes the sound of the pedal enough that it can be a standalone distortion through a clean channel with a good full sound.

C5 - change to 0.1uf
C11 - change to 0.047uf
C13 - change to 0.1uf
D4 - change to 1N4001
R16 - change to 4.7k
January 23, 2008:
Here is another low parts count mod that I call, Minimal Mod Part II. C5, C11 and C13 are back to their stock values, 0.47uf, 0.022uf and 0.047uf respectively. R14 was raised to increase the lows. R16 was lowered to increase the mids.

D4 - change to 1N4001
R14 - change to 4.7k
R16 - change to 2.2k
These three changes make the DS-1 in to a great sounding distortion. It sounds excellent with both single-coils and humbuckers.

January 25, 2008:
First, I need thank Brian Wampler of indyguitarist.com for this mod. He has a featured article in the February 2008 edition of Premier Guitar magazine and he shares some great info about modding the DS-1. By doing one of those mods, other than all the diode changes, it sounds fantastic. So, starting off with a stock DS-1, make the following changes.

C2 - change to 1uf
C3 - change to 0.033uf
C5 - change to 1uf
C9 - change to 1uf
D4 - change to 1N4001
R16 - change to 2.2k
R17 - change to 15k
Read the full article on premierguitar.com here: Boss DS-1 Mods
If you google for this ds-1 boss mods brings up so many ebay listings and harmoney central reviews, you should add something like 'uF' to the search to get some REAL info.


Has anybody tried using different ICs, I wanted to ask, but instead I ask, how about that 7pin opamp?
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Post by Aharon »

Thanks for the input modman.
I built one with the tonepad layout using a 4558 and it sounded a lot fuller than the original just like that.
A nice thing would be to have the original schemtic so to see what corresponds to what on the tonepad schem and build the ultimate DS-1 from scratch,all the mods etc. although I don't think it would be difficult to sit down and figure them out either.

Aharon

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Post by modman »

Hi Aharon,

Here another nice piece of info making it quite easy to figure out the keeley mods:

http://www.indyguitarist.com/mods_new/keeley-mods.pdf

The schematic and parts layout is even linked to on wikipedia:

http://www.godiksennet.com/images/sch/DS1PG2.jpg

thanks for the great pictures, Brian!
Going to try some of this tonight.

modman
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Post by Aharon »

Wow thanks.......my google skils are seriously lacking.Your kung foo is good.
Aharon
Last edited by Aharon on 24 Oct 2007, 13:01, edited 1 time in total.

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Post by modman »

Aharon wrote:Wow thanks.......my google skils are seriously lacking.Yor kung foo is good.
Aharon
:D still learning every day...

/i20.photobucket.com/albums/b230/zjokka/Boss%20Pedal%20Clinic/DS1mod01.jpg

Already replaced most of the caps in the mod, but on the verge of replacing every capacitor on the board. I used wima 5%.

Never saw a 0,47uF polarized cap before, I must admit. Soldering iron is still hot, so cu later.
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Post by JHS »

There are 2 basic versions of the DS-1.
Before you start you should discover which circuit is used in your box.

I know at least a dozend different mods for the DS-1, so get as much information about this topic as possible before you start modding your FX. Nearly all modders perform the same basic mods on the DS-1 circuit, so comparing the different mods first would be a good idea.

If you want to know what works and what not breadboard the basic circuit, do the different mods and listen to the sound.

IMHO a subtitution of the cheap caps is what you should do first.

JHS

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Post by bajaman »

IMHO a subtitution of the cheap caps is what you should do first.
Absolutely agree with this :wink:
Surprises me how many " top name " pedals use shitty cheap mylar film caps :wink:
bajaman

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Aharon
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Post by Aharon »

JHS wrote:There are 2 basic versions of the DS-1.
Before you start you should discover which circuit is used in your box.

I know at least a dozend different mods for the DS-1, so get as much information about this topic as possible before you start modding your FX. Nearly all modders perform the same basic mods on the DS-1 circuit, so comparing the different mods first would be a good idea.

If you want to know what works and what not breadboard the basic circuit, do the different mods and listen to the sound.

IMHO a subtitution of the cheap caps is what you should do first.

JHS


Yeah,best course of action,build the tonepad from scratch again and do all the mods and see what works.
Aharon
Last edited by Aharon on 24 Oct 2007, 19:18, edited 1 time in total.

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Post by modman »

My experience with these mods, whoever invented them, that they don't change the nature of the circuits, but rather improvements in the rendition of the DS-1 of what it might be.

Will have a look at tonepad still, but could build it from the schematic if I wanted.

Again, what about the orignal Hitashi opamp's 7th leg?
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Post by modman »

As prescribed by Keeley, I changed the first clipping diode to a red led. The second diode in his mods go to a switch that adds an extra red led in series with the second diode.

Wanted something original so I tried out using a mosfet clipper for the second diode: check Jack's article here http://www.muzique.com/lab/zenmos.htm

I used this configuration:
Image

Not turning back now, it sounds interesting to say the least. The original sound sounded so familiar although I never tried this box before. If you want that real 80s flat response distortion, don't mod your DS-1 :wink:
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Post by modman »

DS-1 Part layout and values from a great japanese diy blog, to complete the DS-1 file. The other layout is kind of scruffy, though this might be an younger version? Haven't compared them yet.
Boss DS1 16.gif
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Post by bajaman »

though this might be an younger version? Haven't compared them yet.
Yes - this is the original 1980 DS-1 layout. The more recent one has the dc socket mounted on the board, uses the smaller green pots and an TL072 IC instead of the original Hitachi 7136 chip. I have yet to see the layout for this newer version posted anywhere - all the schematics I have seen and have are for the earlier version, and do not contain R39 or R40.
Cheers
bajaman :wink:

ps: a mod I like to do, is replace the input buffer transistor with an n channel jfet, such as a 2SK117 - much less tone sucking and more clarity on bypass :wink:

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Post by modman »

Baja,

Where do you get your sk117s? Seems to be very scarce and expensive. I mean > $1 . I did find what I think is a K117 on the board somewhere else, will have to check later. Now off to the doctor with an eye infection - new interpretation to the :wink: icon

I checked mine in the boss serial decoder and it said May 1986.

http://www.bossarea.com/serial/sndecoder.aspx

This was added in the links section too :wink:
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Post by bajaman »

Where do you get your sk117s
I get mine from a local television wholesale warehouse - and yes they are not cheap devices here too. :wink:
bajaman

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Post by modman »

Would another, more common, jfet alternative improve matters? I have about anything except that darned (2)sk117 you got me breaking my head over: (2s)k170, j-series, 2n54**
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Post by bajaman »

yes - almost any n channel jfet will work fine as a buffer - try an MPF102, 2N3819, 2N5457,58,59 or even a J201 - they will all improve the input impedance of this pedal.
cheers
bajaman

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Post by Aharon »

Interesting............I have two units....one dates 2002 MIT but the other must be a transition unit.......has the serial in the battery compartment and dates March 1990,the date they stopped using those serial # and although it says MIT outside (black label) it sais MIJ inside.
Good to know.
Aharon

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