analogman ds-1 mod

[chizkop]

Hello all.   Does anyone have any information on the analogman ds-1?  Cap and resistor values etc...

[gmaslin]

I know I'm resurrecting this old thread but I'm not as thrilled with any of the other mods on this pedal. Which op-amp and supporting parts got this circuit right?

[ElectricDruid]

Link? Values? Schematic? Go on, give us *something* we can work with!

What did you start with? What have you done so far? What have you got now?

Tom

[gmaslin]

Hey Tom, nice to see you here

I have an early 2000's Boss DS-1 in its original state. It sounds noisy, thin and anemic on my single coils. I got a chance to play on the Analogman DS-1 with the same rig and it's all I could have asked for in a distortion pedal. The output increased, the clarity improved, it had more authority and the EQ became more pleasing overall. I'd rather mod than build from scratch so like the OP here, I just want to know if anyone has the formula.

[ElectricDruid]

Hey Tom, nice to see you here

I'm often caught hanging out here. More fun than the synthy forums somehow, although I frequent Muffwigglers a bit.

I have an early 2000's Boss DS-1 in its original state. It sounds noisy, thin and anemic on my single coils. I got a chance to play on the Analogman DS-1 with the same rig and it's all I could have asked for in a distortion pedal. The output increased, the clarity improved, it had more authority and the EQ became more pleasing overall. I'd rather mod than build from scratch so like the OP here, I just want to know if anyone has the formula.

Aaah, sorry. Can't help there. But it's a simple enough circuit - can't we develop some of our own? The "DIYSB mods"?

Tom

[gmaslin]

Electric Druid
You're ever the cheerful optimist aren't you
Okay, I told you what I hate about this pedal. Job one? It needs to quiet down, then, I'd like all the knobs to have a greater range. The clipping should start at 8 o'clock on the distortion knob and it should clean up nicely when I roll down my guitar volume. Here are some cure possibilities:
1. remove D4 and D5 - This lowers the EQ and tames the distortion some but moving the tone pot past 12 o'clock kills the volume. You also lose easy pinch harmonics.
2. increase value of C12 - This lowers the EQ, fattens the sound and removes the fizziness. It allows finer adjustments of tone but it reduces the total tonal adjustment range.
3. reduce value of R5 - This cuts the fizz and allows a faster cleanup when you rollback the volume on the guitar but doesn't do much else.

[ElectricDruid]

You're ever the cheerful optimist aren't you

Hey, no point getting down before we've even got started, right? We can save that for the inevitable moment when it all goes hopelessly tits up

Okay, I told you what I hate about this pedal. Job one? It needs to quiet down, then, I'd like all the knobs to have a greater range. The clipping should start at 8 o'clock on the distortion knob and it should clean up nicely when I roll down my guitar volume. Here are some cure possibilities:
1. remove D4 and D5 - This lowers the EQ and tames the distortion some but moving the tone pot past 12 o'clock kills the volume. You also lose easy pinch harmonics.
2. increase value of C12 - This lowers the EQ, fattens the sound and removes the fizziness. It allows finer adjustments of tone but it reduces the total tonal adjustment range.
3. reduce value of R5 - This cuts the fizz and allows a faster cleanup when you rollback the volume on the guitar but doesn't do much else.

All seems like a good place to start. But first...I need to do the required background reading:

https://www.electrosmash.com/boss-ds1-analysis

And not forgetting this, of course:

http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf

Lawds, it's Sunday already. Druid out.

[Fancy Lime]

Why mod? The DS-1 is a very simple circuit, building it from scratch is fairly easy. Many people start with more complicated stuff for their first build. Modding a Boss pedal on the other hand is pretty difficult if you need to change more than just some component values. Since you are going for a pretty profound change in sound, you would probably need to change many parts and maybe add some, too. When you build from the ground up you can do whatever you want, modding is always restricted. Plus, there are simpler, less noisy ways to get exactly the same sound as the DS-1. Commercial designs are usually guided by what is cheap to produce in mass, not what sounds best. Often these two do not conflict but sometimes they do.

Andy

[gmaslin]

Fancy Lime
You make a good point. I can probably cut a breadboard to fit in the DS-1 case but the appeal of the mod is cost. A few bucks worth of parts and I might have exactly what I want in a dirt pedal. That is:
1. distortion that goes from a little crunch to full plexi without getting fizzy but also maintaining its pinch harmonics
2. a tone knob with a proper EQ that cleans up the distortion when you roll off the guitar volume input
3. a level knob that actually increases the level
A new build will probably cost ~10x that if I have to buy the parts.

[Fancy Lime]

Hi gmaslin,

the main costs of a pedal with no special parts (like specialty ICs and optocouplers or mojo artifacts like Ge-transistors) is the hardware. Box+pots+knobs+jacks+footswitch cost about 15-25€ or USD. The innards with all the resistors, caps, op-amp and transistors (for a good DIY distortion design, not an exact replica of the DS-1) together will set you back little more than 2 bucks (at least where I buy my stuff), maybe even less. So if you use the box you have but rebuild everything within, you will spend about one side order of fries at Mc D.'s worth on parts. Just to put that in perspective. Sure, if you only replace a handful of resistors and caps you can get away with under 50 Cents.

And since you basically want a completely different pedal from what you describe (all the pots are supposed to work differently, which requires major changes to the rest of the circuit if you want to keep using the existing pots or a change of pots, which would cost more than replacing the whole circuit board), I don't see the point of modding, considering the cost/effect relation. Now if you want to mod because you want to mod, thats a different story. That can be fun, which is a good enough reason for me. Just don't fool yourself into thinking it is easier or significantly cheaper than building from scratch (at lease if you use the existing hardware and only replace the circuitry). I don't mean to kill your buzz, just trying to help you identify what it is you really want.

If you decide to go custom and build your own distortion circuit to replace the old one, there are many people here who have extensive experience with exactly this kind of circuit. And we are always glad to help. Modders on the other hand are a bit scarce here. If you decide to mod, other forums may be more help with that (unfortunately I don't know which ones, not my field as you can probably tell).

Hope that helps a little,
Andy

[gmaslin]

Andy,
I don't think the AnalogMan mod gives me a completely different pedal and that's why I prefer mimicking that result instead of making something new. From what I've read, he achieves that remarkable improvement without changing pot values. If we approach this from an electrical design standpoint, how are we likely to address the excessive noise? One way would be to reduce the first gain stage so the noise is less amplified. Another would be to address the input path (check the path length, grounding and shielding) and a third involves looking for the noisy parts. Depending on how successful we are at addressing the noise, we will make a decision about true bypass switch wiring. The board layout on my DS-1 looks okay on first glance so component replacement should be sufficient to get me what I want:
1. a quieter pedal in the chain
2. distortion that goes from little crunch to full plexitone
3. an overall lower EQ with a well balanced tone knob that doesn't lower the level much
4. a level knob that works properly all the way through its rotation (9 o'clock position begins increase)
5. all the above while maintaining a proper cleanup when you roll down your guitar volume
Does anyone know why this isn't achievable with component swaps alone?

[ElectricDruid]

From the guts shots I've seen of the pedal (I don't have one) it looks like they used carbon film resistors and cheap polyester and ceramic caps. To get the noise down, I'd build the circuit with decent quality metal film resistors and polypropylene film caps. And maybe a better op-amp too. At that point, you've replaced more than half the parts in the pedal, and you haven't even changed anything yet.

In terms of mods, I'd definitely look at changing R9 to a larger value - 1K is suggested. This reduces the gain on the transistor booster stage and prevents it from clipping the op-amp. That gives you more scope to go from clean to dirty on the distortion control.



The overall effect of that is to reduce the pedal's total gain, so you could also tweak the op-amp stage to get more range out of the distortion pot there instead. R13 gives a gain range from x2 to x42. Reducing it to 3K3 boosts that to x60. I would imagine this opens the pedal up a bit and gives it a more dynamic sound.

I'd also swap one of the hard clipping diodes for either an LED or a series pair of diodes. This gives an asymmetrical clipping (like the Plexi you mentioned) for more even harmonics and also helps boost the level a little bit, which helps with the passive tone stage where we get a 12dB loss. It might even be enough to be able to provide a level boost overall.

If you just want the tone less fizzy overall, you could bump up the values of C7 and C10 a little bit. C10 tames the edges of the clipping, so it'll have the biggest effect.

The tone stage is the classic Big Muff scooped-mid design. You can mess about with the values of that on the Duncan Amps tone stack calculator to find something more to your taste. It might be possible with some tweaking to reduce the losses in the tone stack which again would help with the level.

It *is* possible with component swaps, but a rebuild from scratch is almost as easy - an "inspired by the DS-1" pedal rather than a DS-1 clone.
If I was modding one, I'd definitely do the gain changes and look at the tone stack.
If I was building one, I'd go for full boutique components and I'd probably do the boost stage with the other half of a dual op-amp.

HTH,
Tom

EDIT: Also worth pointing out that the original Made-in-japan pedal used diodes with Vf=1V rather than the typical silicon VF=0.65. So the original pedal probably didn't have the level problems that the modern ones do. Again, boosting the level from that clipping stage would help. Maybe all the way to a pair of silicon diodes one side and an LED on the other.

[Fancy Lime]

Yeah, what Tom said!

I didn't mean to imply that modding was impossible. But unless you know exactly what you have to change I think it is easier to build from scratch. But since you seem hell bent on modding (not that I don't respect that, it's just not for me), let's review some options:

If you can find the correct change for exactly the AnalogMan mod, just use those. However, I could not find them quickly (meaning AnalogMan does not seem to publish details) and if I had them I would not post them or use in a commercial pedal because I find that somewhat unethical since it interferes with AnalogMans business model. You could just ask AnalogMan directly. Maybe He/They will answer your questions, maybe not, but there is no risk involved in asking.

If you end up having to figure out what to change by yourself (with help from the forum) you can either swap components in the pedal and hope that does what we think it does to exactly the extent you want it to, or you can bread board the whole thing to figure out what needs changing and how before you start messing with the actual pedal. I would strongly recommend the second option, but that may just be me being a control freak. Be aware that repeatedly  swapping a certain component by soldering it in and out to test what effect that has takes it's toll on the board and it may fail at some point.

Either way, an important part of the AnalogMan mods seems to be changing chips, transistors and caps for "audio grade parts", which is just marketing-speak for "normal quality, not completely terrible" and will improve the sound and more importantly the noise quite a bit. I trust you have read the DS-1 section here:
https://www.buyanalogman.com/Boss_DS_1_Pro_p/am-boss-ds-1-pro.htm
So you know there are different versions with differing "mod friendliness".

Changing all ceramic caps to film is almost always good idea. For C4 and C7 you can go with silver mica for extra mojo points (may or may not make a difference to film but definitely wont be worse but will be physically bigger).

I would leave the 2SC2240 transistors alone, these are pretty good as they are.

The M5223AL does not have the best of reps, although I have no personal experience with it. I find a plain old NE5532AP to be the best sounding op-amp in distortion and overdrive pedals of this sort to my ears. It is also very low noise. The JRC4558 aka NJM4558 is also a popular choice.

+1 for Toms suggestion to make the clipping diodes C4 and C5 asymmetric by changing one of them to a red LED or two Si-diodes in series. Using slower Si-diodes of the 1N400x series instead of the fast 1N4148 may also reduce the sharpness of the clipping a bit but that effect will be subtle. Using the body diode(s) of MOSFET transistors is also a very mojolicious option but return on investment may not be great.

+1 for Toms suggestions to cap and resistor changes.

The tone stack is of the Muff variety. Major wars have been fought about what the best Muff tone stack is. Explore the options and compare to the stock values using Duncans Tone Stack Calculator:
http://www.duncanamps.com/tsc/
Adjusting the cap and resistor values of the tone stack for less mid scoop seems to be what you are looking for.

The interaction between Tone and Volume comes from the lack of buffer between the two and is a basic design flaw of the DS-1. Not much you can do about that one in terms of modding other than increasing the value of the Volume knob to 500k or 1M or add a little daughter board with an extra buffer that goes between the two pots (if there is space in the box for that).

Hope that helps,
Andy

[gmaslin]

Andy and Tom
I think with you guys looking over my shoulder, I might be able to do this without much headache
What we agree on:
Yes, the lower gain in the first stage is a good idea but it looks like this circuit is biased and increasing the R9 value might destabilize the circuit. Yes, ceramic caps are generally noisy but durable and cheap. I've discovered from my experience with hi-fi amps that only the caps directly in the signal chain contribute to the noise.
What needs more clarification:
Carbon resistors are not a noise problem if they're big enough (ie: rated over power). Depending on how they're laid out, their inductance and endcaps could introduce noise. The devil is always in the details. Color LEDs typically clip >1.5V and that's three times the voltage of my silly diodes. IR diodes typically clip closer to the Japanese 1V spec. Such a dramatic change will probably require more cap and resistor tweaking. This means more parts, more expense and more chances to screw up. Also, there are diodes that bounce less noise (soft recovery) into the circuit. Yes, I noted the three DS-1 circuit board types and I have the worst sounding one (Mitsubishi 5223). I've looked at the chip spec and it isn't so bad, not as quiet as a NE5532 but acceptable.

[ElectricDruid]

I largely agree about the resistor and capacitor changes. While better components will *help* with noise, and would be what I'd use if I was building one, I don't think I'd go to the trouble of changing them all on an existing pedal.

Altering R9 might alter the bias on the transistor a bit, but currently the output from that transistor slams into the rails anyway, so where exactly it's biased isn't a big deal. By reducing the gain, you're going to reduce the distortion it produces, and that's the general idea. If it still produces a bit because it clips slightly at one end or the other, I don't much mind - considering what we're about to do to the poor waveform, that's the least of it's worries.

With the diodes/LEDs, changing them only really changes the level at which the signal is clipped (and hence the level going to the next stage). That'll change the amount of gain from the distortion control thats required to hit clipping, but it won't alter much else. Vf=0.65V silicon diodes will clip easily, so hardly any gain is required to make them crunch. LEDs that have Vf=3.0V (like some blue ones for example) will need a lot of gain to get the same amount of clipping, so the crunch will start further around on the distortion control. The diode choice will alter the sound a bit, but it's not a huge effect compared to some of the other things you could do (like change C10 or mess with the tone control circuit).

Tom

[Fancy Lime]

Hi gmaslin,

you're right, not all caps and resistors that are "not good" are equally bad, it depends on where they are. A ceramic cap in the power supply filtering or for shunting radio frequencies for example is perfectly fine. So what I would do if I were you is to go through the whole board and identify all components. Write down which caps are ceramic, which are film (+ part number if they have any), which resistors are carbon, which metal, what the exact part number and packaging of the IC and transistors are etc. Compare to the existing schematic and see if the values are the same. There are different versions as you know and even within the same version there can be differences in values and sometimes just plain production errors in "Monday units". If we know what type the components are we can probably do a better job at identifying which should be replaced and which may not be critical. The Boss circuit boards are usually quite nicely labeled so identifying the components should not be too hard if you can find the factory schematic with the same component numbering. You only need to look at the audio path, the switching circuit is pretty inconsequential for your mod purposes.


Andy

[BetterOffShred]

You know I've been reading about DS-1 mods for years, literally since I figured out people modified guitar pedals, but I've never owned one.   I think I'm going to buy a used one off E-bay and tinker.  I modded a Dano FabTone and I really ended up liking the results.   Is there a preferred year range of the DS-1  or "generation" that lends itself to these modifications more easily?  gmaslin indicates he has at least 3.. certain only is preferable ?

Thanks guys
-Brett

[gmaslin]

BetterOffShred
Have a look at the last post in this thread. It should answer your question

Fancy Lime
You are suggesting that I map all the components. That is sensible to do but too much work for this project. I'm looking for a 20 minute solution and I'm already over my time budget

Electric Druid
We all agree that the most good is likely to come from reducing the first gain stage. I get your point about the bias effect but one of the things I prize in a pedal (maximum functional range of the pots) might be sacrificed by letting it go uneven. It also might cause some circuit/chain destabilization. Changing R9 to 680 ohms seems like a painless and safe way to reduce the first stage gain. It shouldn't change the bias much and reduce gain significantly where going higher might have some negative effects. It should also give me more range on the tone control but I might lose some level, we'll see. If the R9 tweak doesn't make me happy, I'll hit the D4/D5 diodes and look at C10.

[ElectricDruid]

Why not pull out R9 and then stick a 2K pot in there for a few minutes and do some experiments? You can try it at full 2K, in the middle 1K, quarter way around 560R(ish), between those two 680Rish etc etc.
You'll soon find a point on the pot that makes you happy, and then all you have to do is get it out without altering it so you can measure it accurately!! (I snip the wires I used to attach it, and then desolder the stubs of wire from the board later).

HTH,
Tom

[gmaslin]

Tom
Thanks for the tip on leaving the leads in when using a test (range) pot but I don't want a false indicator. I've been burned ranging in a value on audio circuits before. I don't want the pot characteristics to fool me into believing it's what I'll hear from the resistor.