DS-1..... almost where I want it..... info please

[AC30Dirty]

I've had this happen a few times, but usually with long cables with rather cheesy shield wire coverage.  Does it happen with different/shorter cables? 

It happens with any cables i use. It happens in my pedalboad chain and by itself. none of the other pedals on the board pick it up.

[5thumbs]

im picking up a radio station from the pedal now. Even when the pedal is off. I know its the pedal cause i ran my guitar straight to the amp and the station is not there. Have any of you guys experienced this when modding your DS-1?

From searching other posts on this topic, it might be a case capacitance/grounding issue.  Suggestions range from putting a 22-47pF cap from the PCB input (not input jack) to ground, as well as checking all the grounds for continuity and possibly even using shielded wire from the input jack to the PCB.

Here's the info from the 'DIY FAQ' (http://www.diystompboxes.com/wiki/index.php?title=DIY_FAQ) on this site:

"misc - I am picking up radio stations, how can I stop this?

From Eric Hensel: A 47pf cap to,ground, after the input cap will probably do it --you can adjust this up or down --higher values will start to cut treble. use the lowest value that works.

From Zachary Vex:

Mount the pc board as close as you can physically to the metal box. this will serve as a ground plane to reduce the heterodyning that can pick up rf. don't let the input and output wires cross... make sure the layout doesn't allow input and output connections to get too close to each other. if you can, solder in ground connections around (near) the sensitive input circuitry. if rf is being picked up by rectification, these fixes won't help, but if it is being picked up due to beat frequencies generated by heterodyning (internal rf oscillation in the circuit beating against rf from radio stations) you can get rid of it through the use of careful layout and grounding to reduce oscillation.

You might try using miniature shielded cable inside of the enclosure for the input to the board too."


Here are some other threads that discuss this problem and potential solutions:

http://www.diystompboxes.com/smfforum/index.php?topic=38267.0
http://www.diystompboxes.com/smfforum/index.php?topic=62829.0

And a short blurb on GEOFEX on the topic:

http://www.geofex.com/fxdebug/picksupradio.htm

[erikm5150]

This mod looks interesting:

http://www.muzique.com/news/?p=95

[AC30Dirty]

Thanx guys, for the link hook up!!!!! I had gigs this past friday and saturday so, I haven't really been abel to mess around with the pedal. I'll get around to it this week for sure though. I'm definetely gonna try that DS-1 fat mod. If it does what it says it does it just might be the icing on my cake for this pedal!!!!

[5thumbs]

This mod looks interesting:

http://www.muzique.com/news/?p=95

Thanks for the link, Erik!  I've not heard of that one before, but it looks too simple and too good not to try at least once.  If you put the resistors on a DPDT and you can A/B then with a flick of a switch...and if you like that switch thing, mount the switch and keep that feature around for good.

[AC30Dirty]

well..... i tried out the mod to that link posted by erikm5150 and the pedal wouldn't work, so I went back to stock values. it was weird.... maybe it to a different DS-1 version or something...

[5thumbs]

well..... i tried out the mod to that link posted by erikm5150 and the pedal wouldn't work, so I went back to stock values. it was weird.... maybe it to a different DS-1 version or something...

In the section of the circuit cited by Jack Orman, the only difference between the pre-1994 "vintage" DS-1 and the post-1994 variants is C5 (other than Jack's changes to R6 and R9, of course.)  Jack has the pre-1994 value of 0.47μF in C5, where the post-1994 pedals have 0.068μF in C5.  That difference in itself shouldn't make a huge difference, so there might be something else causing Dead Pedal Syndrome here.

I have a DS-1 that is in-progress on the "Mondo-MIJ" mod, but hasn't gotten the updated clipping network yet.  (Given that, you can think of it as a hi-fi version of a 'MIJ-Mod'-ed DS-1.)  I'll try the resistor swap on that pedal tonight and report back with my results.  FWIW, all of the MIJ-type mods have 0.47μF in C5, so on paper, they should match up with the diagram Jack provided.

Thanks,

Brett

[AC30Dirty]

hey 5thumbs, what is this MIJ modded DS-1 your talking about??? I've never heard of that. By the way, on my pedal C5 is an electrolytic cap that read 47uf not .47uf or 4.7uf  That seems REALLY BIG!!!!

[AC30Dirty]

ok.... so here is what i tweaked with tonight..... i changed C3 to .033uf and this caused the pedal to open up consideralby. No really noticeable compression but, theres still some there. Next I C12 with a .047uf cap to go along with the 5k pot.... now the pedal can really be tweaked on the fly quite nicely. I also increased R13 from 2.2K to 3.3K for a little bit less drive. The pedal doesn't feedback now at MAX GAIN and I still have plenty of drive to work with and the sustain is still there. I did notice however, since i chaged C3 to .033uf it seems the pedal has lost a little punch. What spot on the pedal could I alter to bring the punch back up??? I was thinking C9. Would this be the way to go???

[5thumbs]

hey 5thumbs, what is this MIJ modded DS-1 your talking about??? I've never heard of that.

The 'MIJ Mod' is a mod I developed to make the post-1994 DS-1 pedals sound like the pre-1994 DS-1 pedals by changing critical soundpath components back to the values in the pre-1994 DS-1 pedals.  The MIJ-Mod is discussed on Page 16 of the 'Build Your Own DS-1 Distortion' doc I co-wrote with miqbal: http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf.  (If you want to know why I selected the components in the MIJ-Mod, read Pages 24-26 and I try to explain all the component differences between pre- and post-1994 DS-1 pedals.  It was my way of "showing my work.")

The 'MIJ-Plus' mod (Page 17) is basically the MIJ-Mod with a tweak to the D4/D5 clipping diodes, done largely to reduce fizz that was more apparent with the later op amps than it was with the TA7136P op amp in the pre-1994 DS-1.

I A/B tested my MIJ-Mod and MIJ-Plus against my pre-1994, M.I.J. DS-1 and they sound very similar.  I know it might be heretical to say this, but I think the post-1994 DS-1 pedals with any of the MIJ mods sound better than the original.  I'm keeping the pre-1994 for its historical value (plus I got it for $75 in good condition.)  It's also useful for settling arguments with folks who insist the pre-1994 DS-1 pedals can't be beat.

The 'Mondo-MIJ' (Pages 18-21) is basically the hi-fi version of the MIJ-Mod with a rather complex clipping network installed in place of D4/D5.  It's the best-sounding of the lot, but the Mondo-MIJ is a bit of a pain in the tuchus to build.  So one of these days, I'll get around to finishing the 'EZ-Mondo' mod, which will get the best parts of the Mondo-MIJ sound in a mod one can do in under an hour.

All that and more is in the doc (http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf), so give it a read when you get the chance.

[5thumbs]

I have a DS-1 that is in-progress on the "Mondo-MIJ" mod, but hasn't gotten the updated clipping network yet.  (Given that, you can think of it as a hi-fi version of a 'MIJ-Mod'-ed DS-1.)  I'll try the resistor swap on that pedal tonight and report back with my results.  FWIW, all of the MIJ-type mods have 0.47μF in C5, so on paper, they should match up with the diagram Jack provided.

OK, I tried out Jack's DS-1 "Fat" mod this morning.  (It doesn't kill the pedal, BTW.)  If I had to characterize this mod by another name, I'd call it the "mud" mod.  It reduces the highs considerably, which can be useful.  It also causes a boost in perceived bass and mids, due to the aforementioned treble cut.  Unfortunately for my ears, it cuts them a bit too much, causing a loss of articulation.  If you're going for more of a fuzz-type sound, then Jack's "Fat" mod would be pretty groovy.

I personally prefer more note articulation when going for a flat, non-scooped DS-1.  Given that, I'll stick with my PHLAT Mod (Page 22 in the http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf doc) to bump up the mids (actually, remove the mid-scoop in the TONE control) and keep the highs crisp.

Either way, Jack's "Fat" mod is interesting and very easy to do.  I'd encourage the curious to give it a shot...if you're going for fuzz tones with your DS-1, then this mod could meet your need.

Good luck!

[AC30Dirty]

hey 5thumbs, I can't seem to open up your pdf. file on the MIJ mods. I really wanna read up on it. Even if I download it, it'll tell me that the file is incomplete or corrupted.  

By the way..... The DS-1 im working on right now has an IC chip that reads

NJM3404AL
JRC  G008A

[5thumbs]

hey 5thumbs, I can't seem to open up your pdf. file on the MIJ mods. I really wanna read up on it. Even if I download it, it'll tell me that the file is incomplete or corrupted.  

I just downloaded the doc from http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf and it worked OK for me.  Curious...can someone else here try downloading it and see if it works for them?

AC30Dirty, if you PM me with your e-mail address, I'll send you the latest PDF copy of the doc.

By the way..... The DS-1 im working on right now has an IC chip that reads

NJM3404AL
JRC  G008A

That's the latest op amp in the DS-1.  I've never had the chance to try the BA728N (the ROHM op amp first used when they redesigned the DS-1 in 1994) in a DS-1, so I can't offer an opinion on it.  However, I've played a bunch of DS-1 pedals with the M5223AL op amp in it and a handful of ones with the NJM3404AL in them.  The NJM3404AL isn't as good as some replacements (e.g., OPA2134PA, LM358N, etc.), but it is better than the M5223AL.   The sample 'MIJ-Plus' pedal I keep around has the NJM3404AL because I liked it better than the M5223AL -and- the NJM3404AL is technically a stock op amp (which is important for testing purposes.)

BOSS used the M5223AL from around 2000 until 2007, when they switched to the NJM3404AL.  Fortunately, the replacement op amp sounds better, so it's a win-win for BOSS.

[Melanhead]

I just downloaded the pdf and it worked fine ...

[5thumbs]

I just downloaded the pdf and it worked fine ...

Cool. Thanks for checking for me, Bob.

I e-mailed the doc to AC30Dirty.  If anyone else can't download it, PM me with your e-mail address and I'll send it to you directly.  FYI for those of you getting the doc via e-mail...when I update the doc, I'll post it in the same location, but drop an update into this thread: http://www.diystompboxes.com/smfforum/index.php?topic=64731.0.

[5thumbs]

OK, I tried out Jack's DS-1 "Fat" mod this morning.  (It doesn't kill the pedal, BTW.)  If I had to characterize this mod by another name, I'd call it the "mud" mod.  It reduces the highs considerably, which can be useful.  It also causes a boost in perceived bass and mids, due to the aforementioned treble cut.  Unfortunately for my ears, it cuts them a bit too much, causing a loss of articulation.  If you're going for more of a fuzz-type sound, then Jack's "Fat" mod would be pretty groovy.

I personally prefer more note articulation when going for a flat, non-scooped DS-1.  Given that, I'll stick with my PHLAT Mod (Page 22 in the http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf doc) to bump up the mids (actually, remove the mid-scoop in the TONE control) and keep the highs crisp.

Either way, Jack's "Fat" mod is interesting and very easy to do.  I'd encourage the curious to give it a shot...if you're going for fuzz tones with your DS-1, then this mod could meet your need.

(Boy it's weird quoting myself in a response.)

I think I owe Jack Orman an apology for the "mud mod" comment above.  I took one of my lesser-used DS-1 pedals and reworked it today to combine Jack's "Fat" mod, the components from the Mondo-MIJ (minus the clipping network) and added in a BS170 MOSFET clipping arrangement and ended up with a killer sounding mod!

The pedal ended up being identical to the one I tested with before, but by increasing the proximity-to-clip from the stock 1N4148-type diodes to the MOSFETs really cleared up the mud/fuzz and produced a distortion that reminds me of the few odd Plexis I've played in my lifetime.  (My ToneLabSE models the '68 Plexi, but it's not quite the same as the real thing.)  I've tried other "plexi" mods for the DS-1, but was never very happy with the loss of note articulation that those mods ended up with.  They all seem to get the growling bottom end right, but I was never happy with the top end.  That's why I started with the Mondo-MIJ components...good note articulation with lots of detail and sustain.

I'm going to add this setup as a new mod (the 'VR-MIJ') in the BYODD doc tonight.  Jack was right (as usual), so I've got to give yet more kudos to the man.

[AC30Dirty]

Thanks for sending the doc. to my email!!!! I was able to download it and open it up. VERY INTERSTING AND INFORMATIVE stuff you got there 5thumbs. After reading the entire document I converted my pedal back to stock and performed the MIJ MONDO mod (leaving the cliiping mods out because I don't have that type of transistor) and the pedal sounds pretty good. I'm messing again with the high and low pass filters and getting some great results. I'm gonna be tweaking most of the night tonite and see what I end up liking. What other type of transistors can I substitute in the clipping section? I'm not to familiar with transistors so some different models would help. Thanks

[AC30Dirty]

ok.... this maybe a dumb question for some of you guys but, I need to ask it.....what does the whole corner frequency term mean??? The higher the number the more lows or highs are introduced depending on what you pluging in to the frequecy calculator? If R16 and C12 make the low pass filter and R15 and C11 make the high pass filter what do C10 and R14 control?? Does the higher the total number for the combination of R16 and C12 mean it will result in more bass or is it the opposite? I'm really trying to understand this stuff but, I feel a bit lost!!!!!!

[5thumbs]

ok.... this maybe a dumb question for some of you guys but, I need to ask it.....what does the whole corner frequency term mean??? The higher the number the more lows or highs are introduced depending on what you pluging in to the frequecy calculator? If R16 and C12 make the low pass filter and R15 and C11 make the high pass filter what do C10 and R14 control?? Does the higher the total number for the combination of R16 and C12 mean it will result in more bass or is it the opposite? I'm really trying to understand this stuff but, I feel a bit lost!!!!!!

Not a dumb question to me, as I don't know the answer myself.  I suspect R14 is working with C9 (the DC decoupling cap after the op amp) to reduce RFI pickup.  (I read R.G. talking about that somewhere on this board recently, but I can't recall where.)  As for C10, I always figured was a cap shunt to darken the tone a bit after all the boost stages and the diode clipping.

Hopefully others wiser than I can provide a more technically-grounded explanation as to what R14 and C10 do in this circuit, but those are my S.W.A.G.s.

As for more light reading on low/high pass filters and corner frequencies, you might check out: http://en.wikipedia.org/wiki/Cutoff_frequency, http://en.wikipedia.org/wiki/Low-pass_filter, http://en.wikipedia.org/wiki/High-pass_filter and I'm sure R.G. has some good stuff on it over at GEOFEX.

[AC30Dirty]

Thanks 5thumbs..... I can't begin to tell you how much you've helped me with this pedal!!!!! So.... after about an hour or two of tweaking and reading this is what I have my pedal modded to.....

C1, C11, C12, C13- .1uf
C2- 1uf
C3, C10- .047uf
C4- 330pf
C7- 220pf
C5, C8, C9- .47uf
R16- 4.7k
R17- 5.1k
R14- 6.8k
R13- 2.2k

The diodes are stock right now but, i need to experiment with that. Even with stock diodes this pedal is very useful now. I able to achieve tones ranging from Rush, Iron Maiden, Pink Floyd, to Alice In Chains, Weezer, other Marshally type stuff. I do however like it for more vintage rock type stuff but, thats what I was going for.

MORE STILL TO COME!!!!!!!!