Boss SD-1 Diode Clipping

Howdy,

I have a boss sd1 and heard a lot of people saying it does sound a lot better with the c16 diode clipped.

Can anyone tell me in what direction the sound of the pedal is shaped afterwards? I heard some people saying that it does sound a lot less compressed and saturated. Is this true? I'm putting together my first pedalboard at the moment and appreciate any input. Also I'm looking into the joyo/harley benton vintage overdrive tubescreamer clone. Any opinions there?
:roll: Just too many pedals out there.

David

Its the C6 (capacitor). It just makes it less muffled sounding. Opens it up. I like the mod.

I am not a sd-1 hotrodder (yet--picking one up this afternoon). Are you sure you don't mean C6 clipping mod. Also, c6 is a capacitor not a diode.

Its the C6 (capacitor). It just makes it less muffled sounding. Opens it up. I like the mod.

+1 its an amazing mod!

Yeah, your title 'diode clipping' threw me.
Clipping the .01 C6 capacitor makes the pedal more 'transparent', clear and brighter.
A lower value cap works for me but my rig is bright already.

Sorry for the confusion regarding the diode clipping thread title, of course i meant the c6 cap. Brain fart.

Thanks for the input everyone. I understand that it will sound less compressed and brighter afterwards, but will it sweeten up without sounding muffled when you turn down the tone knob on the pedal?

It doesn't make it less compressed, just brighter
and more open sounding.

The stock value of C6 in the SD-1 is .01uF.

The role of the capacitor is to roll off treble.

In its location in the circuit, a very small value cap of 100pF or even smaller is typically standard. Also, such a cap is really only needed if there is significant clipping occurring at that part of the circuit. In this particular case, it is merely a tone circuit with a relatively small "gain factor."

Also, the part of the circuit in question is essentially equivalent to a Tube Screamer, and there is no capacitor at all in that pedal.

If anything, it is an odd sort of "redundancy" on Boss' part, because there is already treble being removed by another capacitor. I think they "messed up" with that part of the design because the SD-1 was based off the OD-1. The problem seems to be that the OD-1 had no tone control, so a capacitor to remove treble would actually be helpful. But once the tone control was implemented, Boss made the mistake of leaving the capacitor in (and I think they made its value even larger!).

Here's another way to look at it - a pedal like the OCD is capable of creating much more distortion than the SD-1, and it only uses relatively tiny 220pF capacitors in the same location. Also, the tone circuit falls after those capacitors. And something like a Big Muff uses a huge 470pF cap at each clipping stage, and it has an insane amount of distortion and clipped treble in comparison...

So even if Boss went with a .001uF cap (or what is considered 1000pF), that would still be "ten times too big" the average size of 100pF. And - something like a TS actually uses a 47pF or 51pF cap, only where the distortion/clipping occurs (in the main drive stage, NOT the tone circuit).

The bottom line is that it was primarily a design mistake on Boss' part. It's easy to forget that the OD-1 predates the TS, and when Boss rolled out the SD-1, a tone control was still a fairly new concept with many pedals.

So that's the reason why C6 presents the problem that it does.

The stock value of C6 in the SD-1 is .01uF.

The role of the capacitor is to roll off treble.

In its location in the circuit, a very small value cap of 100pF or even smaller is typically standard. Also, such a cap is really only needed if there is significant clipping occurring at that part of the circuit. In this particular case, it is merely a tone circuit with a relatively small "gain factor."

Also, the part of the circuit in question is essentially equivalent to a Tube Screamer, and there is no capacitor at all in that pedal.

If anything, it is an odd sort of "redundancy" on Boss' part, because there is already treble being removed by another capacitor. I think they "messed up" with that part of the design because the SD-1 was based off the OD-1. The problem seems to be that the OD-1 had no tone control, so a capacitor to remove treble would actually be helpful. But once the tone control was implemented, Boss made the mistake of leaving the capacitor in (and I think they made its value even larger!).

Here's another way to look at it - a pedal like the OCD is capable of creating much more distortion than the SD-1, and it only uses relatively tiny 220pF capacitors in the same location. Also, the tone circuit falls after those capacitors. And something like a Big Muff uses a huge 470pF cap at each clipping stage, and it has an insane amount of distortion and clipped treble in comparison...

So even if Boss went with a .001uF cap (or what is considered 1000pF), that would still be "ten times too big" the average size of 100pF. And - something like a TS actually uses a 47pF or 51pF cap, only where the distortion/clipping occurs (in the main drive stage, NOT the tone circuit).

The bottom line is that it was primarily a design mistake on Boss' part. It's easy to forget that the OD-1 predates the TS, and when Boss rolled out the SD-1, a tone control was still a fairly new concept with many pedals.

So that's the reason why C6 presents the problem that it does.

Yeah. Just like I said. LOL! ; )

simple but effective mod, and it doesnt cost one penny!!

Sorry to sound like a real nerd, - but what, exactly, does "clipping out" mean here? Assuming I can locate the actual component, (advice on this welcome) do I simply snip the wire bit on one or other of the sides of the component, thus breaking the circuit its part of, or does "clipping" actually mean "jumpering" i.e soldering a bit of wire from one side of the component to the other to take it out of circuit. And where, exactly, is it, and what does it look like?

(I'm not actually that stupid, I do know what caps look like in general, I've soldered enough in and out of the control plate loom. But in this case I don't want to screw up what is already a decent enough pedal. My other reason for wanting some help in id'ing the bit is that I bought the pedal used, so its possible that the C6 cap has already been clipped, given the popularity of the mod).

Thanks in anticipation,

(the electronically challenged) Rick J

Sorry to sound like a real nerd, - but what, exactly, does "clipping out" mean here? Assuming I can locate the actual component, (advice on this welcome) do I simply snip the wire bit on one or other of the sides of the component, thus breaking the circuit its part of, or does "clipping" actually mean "jumpering" i.e soldering a bit of wire from one side of the component to the other to take it out of circuit. And where, exactly, is it, and what does it look like?

(I'm not actually that stupid, I do know what caps look like in general, I've soldered enough in and out of the control plate loom. But in this case I don't want to screw up what is already a decent enough pedal. My other reason for wanting some help in id'ing the bit is that I bought the pedal used, so its possible that the C6 cap has already been clipped, given the popularity of the mod).

Thanks in anticipation,

(the electronically challenged) Rick J
You can desolder it or just clip it out. Or just yank it I suppose. If I remember right its near the top of the board. It is clearly marked C6.

Sorry to sound like a real nerd, - but what, exactly, does "clipping out" mean here? Assuming I can locate the actual component, (advice on this welcome) do I simply snip the wire bit on one or other of the sides of the component, thus breaking the circuit its part of, or does "clipping" actually mean "jumpering" i.e soldering a bit of wire from one side of the component to the other to take it out of circuit. And where, exactly, is it, and what does it look like?

(I'm not actually that stupid, I do know what caps look like in general, I've soldered enough in and out of the control plate loom. But in this case I don't want to screw up what is already a decent enough pedal. My other reason for wanting some help in id'ing the bit is that I bought the pedal used, so its possible that the C6 cap has already been clipped, given the popularity of the mod).

Thanks in anticipation,

(the electronically challenged) Rick J

You'd just clip one side of the component with a snipper. [ remainder edited for being wrong I think ]

You'd just clip one side of the component with a snipper. [ remainder edited for being wrong I think ]

Does it matter which side you clip?

Haha it's humorous that you would ask me for more info given the last bit of my post above, but if I'm not mistaken here is the schematic

http://www.hobby-hour.com/electronics/s/schematics/boss-sd1-super-overdrive.gif

and you can see that it doesn't matter, clipping either or both sides out.

Haha, yes funny!

Better to snip both ends than to desolder and cause accidental overheating that area and ruin the whole pedal.

Looking at the circuit, am I right in saying that jumpering would also work? I'm thinking of ease of reversal if required, also I could take a wire from each end and make/break to hear better what the mod actually does, before making the mod permanent.

Rick J

Looking at the circuit, am I right in saying that jumpering would also work? I'm thinking of ease of reversal if required, also I could take a wire from each end and make/break to hear better what the mod actually does, before making the mod permanent.

Rick J

Seems to me jumpering would cancel out R9 (10k)

Seems to me jumpering would cancel out R9 (10k)

R9 essentially sets the gain at the op amp stage used for the tone circuit. So a jumper would basically make it like a unity gain buffer, and you would disable the tone circuit.

Better to snip both ends than to desolder and cause accidental overheating that area and ruin the whole pedal.

You wouldn't ruin the pedal even if you messed up the circuitboard where C6 resides. After all, it will function without it.

C6 is conveniently sort of "out on its own" on the SD-1 circuitboard - pretty decent space around it compared to many other components.

Boss usually mounts the caps with lots of lead length, so it's easy to snip out many caps. It also makes it easy to unsolder them, since you can get a decent pair of pliers down on the leads.

It's also why Boss went to using that nasty "super snot" stuff some years back, to hold stuff in place. It's cheaper to build them with the caps having a bit of wiggle room, and just pour some of that goop on them. But they put it on the ends of the ribbon cables in the BD-2, and other "strategic" locations in some of their pedals.

C6 is VERY easy to snip out. I don't think I've heard of a single person wanting it re-installed after hearing the pedal with it removed.

C6 is VERY easy to snip out. I don't think I've heard of a single person wanting it re-installed after hearing the pedal with it removed.

Well...it was a little too bright for me removed completely :oops:
Sounds good stock,removed or with a smaller cap though,hard to make an SD-1 sound bad!

Well...it was a little too bright for me removed completely :oops:


While it would necessitate an "extra step to do correctly," you could correct the brightness by making either C4 (.018uF) or C5 (.027uF) larger in value.

If you make C4 larger, it is the equivalent of having something in C6's place, because the treble attenuated is fixed. If you make C5 larger, it is tied to the tone pot, so you can "dial it out to taste."

Generally speaking, just tweaking C5 if a TS/SD-1-type tone circuit is too bright or too dark will do the trick.

If it's not too inconvenient, try replacing C5 with a .033uF cap and give it a listen.

FWIW, simply changing both C4 and C5 to .022uF will make it equivalent to a TS, since the TS has a 1K instead of the 10K @ the SD-1's R7. That means that the TS needs those .22uF caps instead. If you make the resistor bigger (as Boss did), you can make the caps smaller and get the same low pass filter.

...To tweak it just a bit more with the pair of .022uF caps, you might also try changing R8 from 470 ohms to the value of 220 ohms in the TS.

********************

Almost forgot - the MAIN reason why things can get a little hairy tone-wise after pulling C6 is that Boss didn't put a small cap across the clipping diodes! After fiddling with that a bunch, I think that 33pF works better than the TS value of 47pF/51pF. If you really crank up the drive, upwards of 100uF might work, but I think it kills "something special."

So how to install a cap where there is no provision for one? You basically have two choices:

1. Locate D4 on the circuitboard. Carefully solder a small ceramic cap between the two terminals on the solder side.
There are very small multilayer ceramics that are nice for this. You could even try a SMT cap for this purpose. A disk cap will work fine, too. You just have to make sure that its leads don't touch any other solder connections. And, the cap must lay flat on the circuitboard so that you can get the plastic cover and bottom plate back on.

2. Locate D4 on the circuitboard, and unsolder it. Either get a new diode to replace it (any 1N4148 or 1N419 will work), or take the stock one, and pull the leads out straight. Take your small ceramic cap and "piggyback" the diode. What you want to do is "loop" the leads of the cap around the very ends of the diode body, and then put just a dab of solder on each. You then trim off either the excess cap leads, or the excess diode leads. Now reinstall the entire thing back in D4's slot, taking care to have the piggybacked cap positioned so that it doesn't contact anything else (you basically want it oriented "straight up"). Make sure the diode is oriented with the polarity the correct way when reinstalling it.

Putting a cap across the clipping diodes really takes the remove C6 thing all the way. And for those of you who are skeptical about pedal mods, it should allow you to witness how wonderful the well thought out mods can be.

Given a choice between a TS or SD-1 with "just the warts removed," I would pick the SD-1 every time, no question. Boss got there first - they just stumbled when they added the tone control. That's alright, because it keeps the cost/value of the SD-1 lower.

Almost forgot - the MAIN reason why things can get a little hairy tone-wise after pulling C6 is that Boss didn't put a small cap across the clipping diodes! After fiddling with that a bunch, I think that 33pF works better than the TS value of 47pF/51pF. If you really crank up the drive, upwards of 100uF might work, but I think it kills "something special."

Aha, thats what Fuller does to the Fulldrive 2 right?

Would C6 clipping work on the OS-2 as well?

Aha, thats what Fuller does to the Fulldrive 2 right?

No - he used the stock 51pF TS value. IIRC, it has a 33K minimum drive resistor like the SD-1, and it obviously has asymmetric clipping.

But the vast majority of component values in the FDII are kind of closer to the TS - same in and out cap values, same .22uF caps for the TS tone circuit.

...The two things that seem to set the original FDII apart from other TS clones are the asymmetric clipping, and that it doesn't kill bass like a TS does - Fuller set his high pass filter @ ~400Hz instead of ~700Hz in a TS (or SD-1).

Now, the FDII has the other settings, but they just do things like increase the gain at the clipping stage, bypass the clipping diodes in comp cut, or use different diodes in the mosfet setting of the FDII Mosfet. But it still comes back to less bass cut and asymmetrical clipping - that is what makes the FDII the specific TS-derivative that it is. I know some folks like the flat mids setting too, but that can be modded into any TS-like pedal.

11,

What would be the repurcussions of clipping C6 on my OS-2? It looks like similar tone circuitry to the SD-1. Would it effect the DS-1 side?

11,

What would be the repurcussions of clipping C6 on my OS-2? It looks like similar tone circuitry to the SD-1. Would it effect the DS-1 side?

k tone, I'm just guessing here but most probably your c6 is NOT the same c6 as found in the SD-1 circuit.Different pedal,different layout etc...

k tone, I'm just guessing here but most probably your c6 is NOT the same c6 as found in the SD-1 circuit.Different pedal,different layout etc...

I have looked at the cct and to my eyes it is just about the exact tone cct as the SD-1 including C6 being the same (the whole OD side of this pedal is an SD-1 cct). I just wonder how clipping it would effect the DS-1 side.

(the whole OD side of this pedal is an SD-1 cct).

I must have not seen a schem of that pedal. If what you say is true, then it will obviously work the same for it.

Bottom line is when a cap is added in that spot on what is considered to be a TS tone control at this point, that it takes most of the treble away. You really only see caps like that in another separate stage for boosting mids and bass, like with the LTD and its pair of trimpots, but in those instances, it is never tied to a tone control, and it almost always falls after the tone control.

hard to make an SD-1 sound bad!

+1

Now, can someone post a picture of the actual PCB with C6 clearly marked on it? I can't find it.
I can only see D's, Q's, and a whole ballsload of numbers

135503

Here you go. It's clearly marked. When you remove the back, you'll notice that there is plastic sheet between the back and the circuit board. Make sure you put that back in or the metal back will touch the circuits and it won't work. I made that mistake and thought I had screwed up the mod.

135504

Here's a picture. It's the square silver diode right below R10 at the top of the picture and to the left of what looks like R9.

Mine is a japa from 1985, which could explain why the PCB was labelled differently.
Thankfully, the mod is reversable.

Sounds blimmin' good though. Not that a tele needs to be any more bright, but it's always better to have way too much than not enough ;)

Let me jump in with a followup question for the SD-1 users. Is the SD-1 considered a 'touch sensative' pedal? Meaning, does it respond to pick attack like the OCD or Honeybee (for comparative example)?

Let me jump in with a followup question for the SD-1 users. Is the SD-1 considered a 'touch sensative' pedal? Meaning, does it respond to pick attack like the OCD or Honeybee (for comparative example)?

Not so much IMHO

Let me jump in with a followup question for the SD-1 users. Is the SD-1 considered a 'touch sensative' pedal? Meaning, does it respond to pick attack like the OCD or Honeybee (for comparative example)?

It can be equally as touch responsive, but will require more mods than just clipping out C6.

It's easy to forget that the bulk of its design comes from the late 70's. so once you add the OCD/HB/Zendrive/etc. elements, the SD-1 can be as touch sensitive as you like.

AAMOF, it really isn't that hard (to me) to mod a SD-1 into an OCD. And conversion to a ZD takes a little more work (and you have to be creative about where to stick the 4th control), but it's not really a complex mod.

The SD-1 can be molded into almost any dual op amp OD design out there. I'm not saying that based on the modding potential - I'm saying it because I've actually done it!

11 Gauge is spot on with this, I bought a Boss SD-1 quite cheap on ebay to replace a Joyo Sweet Baby overdrive which I felt was a bit flimsy to me and it also has a bit of a midrange bump to it, Boss pedals are more robust and I didn't think the Joyo would hold up well under battle conditions. Well when I A/B 'd the 2 together the Boss SD-1 had even more colouration to the tone. I have it in front of my Tech 21 Trademark 60 to get just a bit of early breakup, something in between clean and real crunch. Well I was majorly disappointed and was about to sell the SD-1 when I came across this mod (it's not really much of a mod but hey) anyway I de-soldered the C6 capacitor from the PCB (gwjensens pic above is perfect) plugged in and A/B'd them again and et viola , the Boss is now better than the Joyo and it's back on the board. You will NOT be disappointed with this alteration. There is far less colouration to the tone, it's almost identical to the clean tone I have dialed in just with a bit of dirt. There is still a smidge of bottom end loss as before but it is SO much better now.

I started out with this C6 mod when I first got my SD-1. Then I wanted to improve its sound some more. I now have two modded SD-1 - one is set as my 'boost' and the other as my overdrive (with double the gain and volume of the stock pedal.) I have done a variety of mods with ideas plucked from other modders (Keeley, Wampler book etc.) and molded it for my own usage. I think it is a very versatile pedal and great for first-time modders to get stuck into!

I'm now currently working on one for a friend to use with analogue synths, adjusting the tone control so that it cuts much more treble and makes the tone control useable over the full spectrum while smoothing out the gain with resistor changes and placing OA95 and 1N34A germanium diodes in the clipping section.