DS-1...UGLY distortion with NO diodes

[vcamargo99]

First, I would like to apologize for posting yet another DS-1 question. I used the forums search function and viewed sooooo many entries and came up empty.

I'm trying to fix a Boss DS-1 that was given to me. It has a real "farty" distortion. Only when the drive is maxxed out can it be remotely usable. It had the infamous Keely SE mod done to it. I replaced all of the caps and resistors the normally are used in the mod. I  also tried replacing them to their original values (I got those off this site somewhere). Here's where I'm having the problem. It has NO diodes, LED's, germs, etc and it still is producing that Farty distortion. Shouldn't it be a "clean boost" without the diodes? I have played a DS-1 with no diodes before and it had ZERO distortion. It was actually (with the new Keely value caps and resistors) a "REALLY nice" clean boost. I also looked for solder problems, but can't see any. Anyone have a clue?

[smnm]

I don't know the DS1 in detail, but I know it's a LM741 /TL071 type op-amp distortion.
I had a Morley distortion along similar lines - it was quiet, and distorting but in a horrible farty way - I changed the op-amp, and all was well. I put in a socket and tried a few diff op-amps.

[Mark Abbott]

I'm having a similar problem where the distortion doesn't sound so hot, and the pedal is distorting when the distortion control is set to minimum. I am using humbucking pickups and I can't remember if this sort of thing is normal or not?

How did your pedal use to work?

I think if the diodes are removed the pedal should work as a clean boost up to a point. I tried removing the diodes from a Tubescreamer and I found that it was cleaner for longer, but it did eventually distort, though it was much louder than a regular Tubescreamer.

What IC are you using?

I would check out the DS-1 clone at Tonepad, it will have a circuit there which will show you how to use a garden variety TLO72 in place of the inline IC that was used in some pedals. I did have an IC go bad in a RAT pedal which caused ugly distortion. I wouldn't have picked it as it all happened gradually , but the RAT stopped working totally so I had to replace the IC.

Anyway let us know what cures the problem.

Yours Sincerely

Mark Abbott

[wampcat1]

I don't recall the exact mods keeley does these days but looks look at the schem:
http://www.indyguitarist.com/schematics/boss/DS1PG2.jpg

Q2 is distorting by itself. Lower R7 if you don't want this.

Also, raise the value of r13 and lower the value of C8 if you want it to clean up better as well.

bw

[Mark Abbott]

Dear Brian

Thanks for the reply and the link to the circuit. I'm not sure what the best plan for attack is with this pedal. I dare I will have to hear another second hand pedal to see what it does and then see what mine is doing differently. I think I may start off by shooting a signal down the guts and see what happens. Then I might try lifting diodes out and try doing a TLO72 substitution and then take it from there.

Thanks for the help by the way, much appreciated.

Yours Sincerely

Mark Abbott

[MartyMart]

Mark, I dont want this to be a double thread thing but I'm 99% sure that a stock DS-1 only "just" gets
clean and that a Keeley modded one is dirty even at zero gain, I had a mate who got me to reverse a mod
for him, for that exact reason, he wanted his DS-1 to have less gain at zero.

MM

[Mark Abbott]

Dear Marty

Thanks for your reply. I don't doubt what you say, though I am after responses from other DS-1 users who can give me some idea on how this thing is suppose to sound, as i have forgotten. I'm thinking something must be wrong with this pedal as the tones in higher frequencies (C on the E string on the 8th fret and notes of a higher frequency do sound terrible.

I think I will have to reverse some of the mod to do the test on the DS-1 data sheet where you input 22mV sine wave and 200mV sine wave is present at the output.

My attitude towards all of this is to take it all in and see what works. I jumped on to this thread as it seemed similar to my thread and perhaps we could get where we both want to be.

Yours Sincerely

Mark Abbott

[vcamargo99]

wampcat1 - Thank you VERY much! I will try  raising and lowering those components.


Mark Abbott - I had a stock pedal not too long ago (and gave it away). Even at minimun gain, it had PLENTY of gain. I removed the diodes and it was VERY, VERY clean. I play my clean amps at the verge of breakup, so it did push the amps preamp a tiny (and I mean tiny) bit, but so little that it was almost negliable. It effectively became a clean boost.



I'll report back soon!!

[theblueark]

Mark Abbott, I have extensively played around with the DS-1's clipping diode section and on my own mod and rehouse:

I have allowed one of my 5 settings to have no diodes in there at all. It's very very clean, even with distortion past 12oclock. Turning the distortion all the way up will give some distortion, very much in the flavor of the crunchbox on lower gain settings.

Must be something else that's wrong with yours 

[Mark Abbott]

Dear the blueark

Does your DS-1 (when the diodes are switched in) remain clean or does it distort?

Marty thinks the pedal (with the Keeley mod in it) will distort even when the distortion control is set to minimum. Marty could well be correct, though the information that I am trying find from users is the characteristics of a good fully functioning DS-1 and even better if the user has the Keeley mod implemented.

I'm finding that the pedal sounds best when the tone control is set from 12 o'clock to 2 o'clock and when the tone control is set at 9 o'clock the bassier notes sound okay though the higher frequencies around the 8th and 10th fret sound terrible. An octave like distortion is present and there is a lack of sustain. I know it isn't the guitar as it all works out with the RAT pedal.

Basically, I don't want to trust my memory on this one, it has a tendency to be rose coloured.

Thanks for your help.

Yours Sincerely

Mark Abbott

[MartyMart]

Mark, my memory is correct just checked two brand new DS-1's that have a similar Keeley type mod done
to them ( ready for my local music shop ) and they are distorting a little on minimum gain, subtle but enough
to be like an overdrive ie : NOT clean  !!
This is using a strat with vintage pups so not very high output.
I'm therefore 99% sure that a stock unit will be cleaner, having no additional gain structure adjustments, even though
this one of course has LED's for clippers ( higher clipping onset threashold )
Hope this helps ?
MM.

[Steben]

Don't take this the wrong way, but what's the point in wanting a distortion box to sound clean?
Isn't it normal finding difficulties if you want to make it into a booster?

Lowering the gain by swapping some resistors is quite normal mojo I guess.

[Mark Abbott]

Dear Steben

I don't take your point the wrong way, but wouldn't it be cool if I could use the pedal to boost the signal of the guitar up to overdrive the input of the amp, and when I wanted to hear the colouration that the pedal has to offer I could take advantage of that as well.

Yours Sincerely

Mark Abbott

[theblueark]

Mark, I'll do a demo vid later tonight showing you how it sounds when I turn the knobs, on all the different clipping pairs.
Germs clip the earliest, so with germs there is very little volume and it clips at lower settings on the distortion knob.
Silicon is next. To my memory with silicon there is distortion even at the lowest setting.
Then LEDs. Keeley's seeing eye mod and Ultra mod uses LEDs, among other changes in the circuit. LEDs clip a little at the lowest setting. Can be clean if you pick lightly or roll off the volume. Marty, which Keeley mod did you try? Was there a toggle switch on it, and if so, what setting was it on?
I have starved 12AX7s running at 6.5V used as a clipping pair on my DS1 as well. Sounds almost exactly like if it's open. I perceive a slight rounding off the top end, which takes out the ice pick which I sometimes hear with the open setting.

Anyway, I'll do the video and you can see and hear for yourself from there 

[MartyMart]

Marty, which Keeley mod did you try? Was there a toggle switch on it, and if so, what setting was it on?

It's not a Keeley mod but a combination of my ideas/melonheads and keeley.
It's probably close to the SEM without the switch for the extra LED, so it's assym clipping/tone changes
and gain changes on the board.
I dont want a "clean" tone with the DS-1 so I'm fine about it clipping at zero gain, if the gain setup on the board
was left "stock' and LED's used I'm pretty sure that the zero gain setting would be clean.

MM

[Steben]

Dear Steben

I don't take your point the wrong way, but wouldn't it be cool if I could use the pedal to boost the signal of the guitar up to overdrive the input of the amp, and when I wanted to hear the colouration that the pedal has to offer I could take advantage of that as well.

Yours Sincerely

Mark Abbott

Ok, I understand. What I make up out of it is that you actually want "some kind" of distortion, without real deformation.
Still, lowering the gain is the only solid solution (maybe with a trim pot set by ear). It ensures no distortion at low settings and being able to go the point of max colour/min distortion rate.
It is the "level" setting that will make your amp clip. The "dist" knob falls to the background.

[theblueark]

Got it up 

Sorry about the poor quality, I'm doing the recording with whatever I could find lying around and in as short a period as I could.

http://www.youtube.com/watch?v=TbEgkIMbQ7A

Hope this answers some questions