BOSS DS-1?

[JohnnyCrash]

Originally Posted by 11 Gauge

If you don't mind fiddling with it a bit more, try reverting R6 to the stock 100K, but change R9 to 220 ohms. If it still needs just a touch more push, drop R9 to 100 ohms.

I don't mind at all. In fact, all night I was thinking my DS-1 needs just a little more push.

As it is now, it is not very DS-1. It's sorta neutered and not as hardcore. The fizz is less and the mids are better, but the crunch and drive are severely lower. A slight tweek towards more crunch and I think I'll find a happy medium between drive and fizz.

Originally Posted by 11 Gauge

I now forsee a monogamous relationship with me and the R9 swap to 100 ohms. All these years of building Big Muffs, and it's boost stage is exactly that (10K/470K/100K/100 ohms).

And with the R9 mod only, I'm able to drive my DS-1 reasonably hard, and I'm using a 3.3K for R13. My diode arrangement is around 1100mV for each "side." I think that I'm going to drop one side to about 800mV, and it should be a done deal.

...Then I'll have to finish up my other DS-1 guinea pig, and resist the temptation to get any more.

I don't have the caps to go lower than 2.7k on R13 and keep bottom end, so I'll simply play with Q2 again. I was thinking of leaving the 150k as-is and going with a 500 ohm (I figured it was sort of between the stock 22 ohm and the new 1k), but if you think 100k/220 ohm is good, maybe I'll start there and work my way up or down.

It seems curing the fizz at Q2 also changes how much crunch, drive, and harmonics you get. Its more like an organic overdrive and less like an extreme distortion.

The clippers seem OK enough to keep for now. Stock it seems hard, tight, and crunchy. With the switch in the other mode - an LED on one side and the stock diode on the other, it seems a little more 2 dimensional and breathy. For me to get their flavor I have to play it at low, medium, and high Dist settings... its subtle, but different enough to notice with time. Note decay seems another area where the differences can be heard a little more.

[11 Gauge]

Originally Posted by JohnnyCrash

I don't have the caps to go lower than 2.7k on R13 and keep bottom end, so I'll simply play with Q2 again. I was thinking of leaving the 150k as-is and going with a 500 ohm (I figured it was sort of between the stock 22 ohm and the new 1k), but if you think 100k/220 ohm is good, maybe I'll start there and work my way up or down.

If you keep R6 at 150K, then 470 to 680 ohms is probably the most optimal range of choices for R9. I just don't think that you'll get back sufficient drive to un-neuter the pedal to your tastes.

100K/220 ohms are the values for the Huevos Grande mod. It makes Q2 have a basically flat freq response. Gain is pretty good, but I find myself pushing the Dist knob just a bit higher than I would like.

100K/100 ohms really seems to bring the balls back, but drop just enough treble to balance things sufficiently (IMO). And your diodes are not that far off from mine - yours s/b approx 600mV/1600mV (w/the LED), while mine are 1100/1100.

If you need just a bit more punch than 100 ohms provides, 47 ohms may be your perfect value. Luckily it's only R9 that you have to play with.

[pchilson]

11 Guage,

Can you build a list of mods to your liking?

This thread is great but the mods are getting rather "distributed".

[JCSIFU]

Originally Posted by 11 Gauge

...The MOST CLEVER thing that I've witnessed done with Q2 is to replace it with a MOSFET, which basically converts it into a SHO boost. There's a guy who goes by cctsim on a few other boards who seems to have mastered this. Do some googling, and his techniques should pop up.

I want to do cctsim's DS-1 SHO173 MOSFET MOD and I'm not sure which pins go when using the BS170 MOSFET substitution at Q2. Is it that D = C, G = B, and S = E? I have been trying to search for the answer, but I am not familiar with MOSFETS and all the datasheets just list pin outs and not functions. Any help is greatly appreciated.

[JohnnyCrash]

Originally Posted by 11 Gauge

100K/100 ohms really seems to bring the balls back, but drop just enough treble to balance things sufficiently (IMO). And your diodes are not that far off from mine - yours s/b approx 600mV/1600mV (w/the LED), while mine are 1100/1100.

This is what I'll be doing in 10 minutes.

As far as my clippers, they're actually closer to 600mV and 1000mV (D4 is a 1N4148 and D5 is an LED --or-- I flip the switch to go back stock stock two 1N4148's).

I did NOT do the real "Seeing Eye Mod" (which adds the LED in-series) since I wanted assymetrical, but still a bit more clipping.

[11 Gauge]

Originally Posted by JCSIFU

I want to do cctsim's DS-1 SHO173 MOSFET MOD and I'm not sure which pins go when using the BS170 MOSFET substitution at Q2. Is it that D = C, G = B, and S = E? I have been trying to search for the answer, but I am not familiar with MOSFETS and all the datasheets just list pin outs and not functions. Any help is greatly appreciated.

It appears that cctsim has already at least fundamentally answered your question:

http://www.bossarea.com/forum/forum.asp?FORUM_ID=10

...with his last response.

I'll paste it here:

"This is a mod I did for me and a few friends. It replaces the the CE stage of the DS-1 with a ZVEX SHO MOSFET booster. I posted the mod originally on freestompboxes.org.

The mapping of the electrodes is as follows:

C -> D
B -> G
E -> S

(so you've guessed correctly)

However, check the datasheet from the manufacturer of your BS170 device for the order of the electrodes. Some bending might be required."


Every BS170 that I've used has the same DGS pinout. Download a datasheet and it will give you a little illustration of which pin is which.

I've actually been using 2N7000's myself - they are a little crisper and more raw, and seem to work better in pedals like the DS-1. Their pinout is the same as the 170, but it's inverted to SGD, so you just flip it around 180°.

The big issue with the stock BJT transistor in the DS-1 is that it does NOT have the standard CBE order. I believe that it is CEB (the C and B locations are clearly labeled on the underside of the pcb).

...This basically means that the center pin of the MOSFET must go into the appropriate outer hole in the pcb. In essence, two pins will be "crossing over," so you must be sure that they don't touch each other.

The easiest thing to do would be to replace the stock transistor with part of a chip socket, and then fiddle around with getting the MOSFET leads in the right holes, until you've got it right. Once you've got it working, dab a little hot glue on it to hold it fast.

[11 Gauge]

Originally Posted by pchilson

Can you build a list of mods to your liking?

Do you mean complete mods that I like?

Or specific parts of the circuit and how I like them modified?

I can comment on one or both, and elaborate with my subjective thoughts on what I like about them.

[franchelB]

I have a friend that modded my DS-1. I believed he used Wampler's version. And it sounds great!

[pchilson]

Originally Posted by 11 Gauge

Do you mean complete mods that I like?

Or specific parts of the circuit and how I like them modified?

I can comment on one or both, and elaborate with my subjective thoughts on what I like about them.

Well, kind of on the order of what Wampler did here. But substituting values of how you would mod it.

Just something a bit eaiser to see what and why.

[11 Gauge]

Originally Posted by pchilson

But substituting values of how you would mod it.

Just something a bit eaiser to see what and why.

Gotcha. Since I don't mod the DS-1 to sound like any particular amp, I'll just give a blow-by-blow on component tweaks that I like, and how they affect the sound.

C3 - Reduce to .027uF or .033uF, possibly .039uF. This cap is your "true" input cap, since C1 and C2 are actually couplers for the buffered bypass circuit, which only passes unity gain. By pinching down C3, things typically get much tighter and punchier, and the midrange tends to get accentuated in a nice way.

R9 - Enlarge to 100 ohms or 220 ohms. This will bias Q2 into more of a linear range with a flatter frequency response, smoothing out the highs. A very dramatic difference. Q2 is the first gain stage in the DS-1. Many folks are not aware of that!

C7 - Enlarge to 220pF. Shaves off a little more brightness, allows the op amp to behave just a bit more.

R13 - Reduce to compensate for gain lost at Q2, if tweaking R9. If R9 is 100 ohms, I prefer 2.7K to 3.3K in this slot. If R9 is 220 ohms, I prefer 1.2K to 1.5K in this spot.

C8 - Must be changed to keep the high pass filter the same IF R13 is altered. For 1.2K, it should become 2.2uF. For 2.7K, it should become 1uF. The EXACT high pass frequency is not critical. For instance, you could use a pair of 1uF caps in parallel w/the 1.2K value for R13, and you won't notice a difference. C8 MUST be a good quality cap if more gain is added to the op amp. While I don't like poo pooing mojo components, I speak from experience regarding C8 swaps. Anything polarized is a huge no-no, and I don't even like nonpolarized electrolytics in this slot, either. The best film cap that you can fit in that spot should be used. I prefer metal films, but mainly because they fit easily.

R14 - Often overlooked, this resistor actually alters the clipping behavior of D4 and D5. Increasing it will exaggerate the effect, while decreasing it will lessen it. I actually tend to leave it stock, but it is a valid component for tweaking what happens with the diodes.

D4, D5 - This is very subjective. Personally, I don't like how much the stock diodes compress and limit, but not by much. And I don't care for anything as severe as LED's either - too much compression is lost. I basically chain different diodes in series to get roughly 700mV for one "side," and 900mV for the other (these are values that the diodes conduct at). It isn't so much a matter of asymmetrical clipping as it just seems to create the best "balance."

C11 - Cut down this cap to .015uF to get a similar upper midrange response like a Rat. I don't do it much any more, but it's got a lot of appeal.

C12 - Cut down this cap to make the tonal balance a little less boomy. My favorite is .068uF, but .047uF to .082uF will all reduce the stock bass at the tone control by different amounts. IIRC, reducing it to .056uF will give the pedal the same bass response as a Big Muff (low pass filter frequency of ~400 Hz).

R17 - Increase this resistor to anwhere from 12K up to 18K, but LEAVE C11 STOCK if you do. This will make the treble response much less overt at the tone control. Translation: you can really crank it clockwise and it won't sound too bright. It really works great with single coils.

C14 - Replace with either a nonpolarized cap (electrolytics are okay here), or increase to 10uF if sticking with a polarized E. While the effect is subtle, it is noticeable. For some reason, the crummy ESR of a polarized cap on the output can make it sound a little hinky - the frequency response can be nonlinear, and you want a fairly flat response here. Not a deal breaker, but just a little icing on the cake.

Components that I think can be left as is:

- C1
- C2
- C4
- C5 (in most instances)
- R39 (NEVER alter this)
- C9
- C10 (I actually remove it sometimes)
- C13

If you're convinced that metal film caps sound better, any value from .22uF up to 1uF for C2 and C9 are fine. I typically go with whatever cap fits best, which usually means the smaller value.

C1 and C13 have more to do with the bypassed signal. If you don't like your bypassed tone, try replacing them. I rarely bother.

C5 can be bumped up if you're dropping down C3 significantly (I sometimes go as low as .01uF for C3).

Anyone who decreases R39 doesn't know what they are doing (IMO), and should give their pedal to me, or get rid of it. Boss carefully chose this value as the optimal "stopper" for the op amp. And they also were kind enough to add D8 as protection against voltage spikes on the op amp's input.

Folks get all goofy about tweaking C10, and I just don't see the fuss. If you tweak the gainstaging and diodes properly, you can actually lose C10 altogether. Why? The tone circuit immediately follows. By tweaking that, you don't cut down the highs until you have to. And they can be much more dynamic. Actually, the stock value is typically fine in most circumstances.

That's my basic thoughts on the circuit as a whole, and how each component that I tweak will alter it in a given direction. I don't like referring to my tweaks as something like "the vintage stack mod," or the "cranked tweed bassman mod," because the DS-1's circuit is too crude to truly allow for such. If you think that you're hearing an actual amp sound coming from the pedal, it's because you have a good amp that is filling in the blanks, IMO. Or your hearing is very forgiving.

[pchilson]

Wow!
Fantastic 11 Guage.
Saved and printed.
Thanks

[pchilson]

I bought a new DS-1 last weekend. This one actually sounds pretty good compared to the first one I had which was new a year ago. Most likely just me that thinks this new one sounds better but who knows there could be differences. Same amp different guitars...

I'm gonna stop by the electronics shop today and grab up a bunch of caps/resistors/diodes/leds so I'll have stuff on hand to use. Taking 11 Gauges list with me...

[11 Gauge]

Originally Posted by pchilson

Taking 11 Gauges list with me...

Some of the values of components on "the list" may not be stocked at your local store. It's more the given range that's important, as opposed to the stock value.

And you can always add caps in parallel to get a sum equivalent of what you want, i.e. .01uF + .0047uF = .015uF. Or .022uF + .0047uF = .027uF.

And resistors in series give you the sum equivalent. So if you want 1.2K, 1K + 220 ohm = 1.2K.

And resistors in parallel provide a fraction of the resistance. For instance, 33K and 22K in parallel will give you ~13.2K.

The only critical material composition is for C8, which might pose a problem. Either they may not have a film type cap in a large enough value, or it might be too big. They will probably have electrolytics, tantalums, and possibly even monolithic ceramics in large sizes, but I'd advise against using them. But if you want to experiment, knock yourself out. It's certainly not that expensive to try. This is really only an issue if you reduce R13, IMO.

Tell us how it works out!

[CA_Dan]

I'm in the process of performing the Mondo-MIJ modification to my DS-1 (also picked up for $15!). I'll post before and after sounds, but based on the link 11-gauge posted it should sound great.

[pchilson]

Well I picked up a bunch of parts today. I seem to have picked a 22pf for C7 instead of a 220pf. I can get that next week when I'll be down there again.

As you run down these changes are they more or less to be done as a whole or are each of them mutually exclusive?

Can I pick and choose (not that I'd know why, just going by description) or is there a rhyme and reason to hitting them all?

[11 Gauge]

Originally Posted by pchilson

As you run down these changes are they more or less to be done as a whole or are each of them mutually exclusive?

Can I pick and choose (not that I'd know why, just going by description) or is there a rhyme and reason to hitting them all?

There is no need to hit them all - I actually advise against it. It's a real PITA to have to backtrack and undo a bunch of tweaks if/when you realize that you probably have gone overboard.

I basically start with these changes with almost any DS-1 mod, and work my way from there:

C3 - reduce (to approx. .027uF - .033uF) to tighten things up, regardless of other mods.

C7 - enlarge to 220pF to smooth out the op amp a bit.

D4, D5 - change, to increase clipping threshold slightly - the stock silicons conduct at around 550mV - I like to push them up to 700mV to about 900mV, with around 1100mV being the upper limit. You could actually leave one stock and just push up the other "side."

...and either increase C12 (to approximately .068uF) OR increase R17 (to 12K-18K), especially if you have bright pickups, single coils, etc.

Everything else are just personal touches, or things that you might want to do to push either the EQ or gain in a certain direction, maybe with the exception of rebiasing Q2, to reduce the excessive treble, but this requires pushing the op amp harder via the R13/C8 tweaks in most cases.

So I'd start with those (in the order listed), and test with each one that you change. Don't be afraid to stop part way through. You can always continue with more mods if you change your mind later on.

[pchilson]

Thanks,
I'll grab a 220pf tomorrow and see about it this weekend.

[JohnnyCrash]

Its best to try the pedal with all of your guitars and amps to see what you don't like - and then go from there.

The major issue with DS-1's is the fuzz factor - I hadn't heard one in years, but remembered I didn't like it for reasons I'd forgotten. I found one for cheap and after hearing what you guys said of DS-1's as well as other's reviews I had a sketch of its problems, limitations and good characteristics.

From there I only decided what to do after finally getting the pedal and playing it through a lot of my gear (about a dozen amps and nearly as many guitars).

While it sounded great through my modified plexi 50 (I built it with ridiculously more mids and bottom), it didn't sound as good with some guitars and amps. I tracked it down to fizz. I also wanted more thickness from the midrange.

Reducing fizz and increasing mids was what I wanted in my opinion, with my gear, BUT for others (especially metal heads) the pedal is great as-is. From there I experimented with at least four incarnations of mods before deciding on the final tweaks.

In my opinion and with my 2 or 3 days of modding, it seems the Q2 tranny is the main heart of the DS-1 sound. It needs to be biased close to what it is stock for it to get really crunchy and have all of those harmonics - but it also can get thin and fizzy due to this. Slightly balancing the fizz factor from there was easy with 11 Gauge and 5thumbs easy to understand technical break down.

Figure out what's "broke" before you decide on how to fix it. It'll save you a lot of time... I lost two full days experimenting on something that shoulda took me 30 minutes.

[czech-one-2]

So, did anybody try that bs170 mosfet/SHO mod? I'd like to here some feedback on the mod before I heat up the iron yet again and subject my DS-1to another round of torment.

[11 Gauge]

Originally Posted by JohnnyCrash

Unfortunately, they're a little more (on sale for $39.99).

For some reason, MF is STILL listing them at that price. I just got a catalog for Music123, and lo and behold:

---The DS-1 brand new, for 29.95---

I've been told that MF, M123, SMD, ZZounds, etc. are all basically the same thing with different names, but only M123 is listing that 29.95 sale price.

Just wanted to pass this on again for anyone who prefers to chop up a new unit instead of a road rashy one from eBay or CL...

[JCSIFU]

Originally Posted by czech-one-2

So, did anybody try that bs170 mosfet/SHO mod? I'd like to here some feedback on the mod before I heat up the iron yet again and subject my DS-1to another round of torment.

I did. It is a nice mod, although the bass to me is very loose and farty but that could be because I'm playing through a vibroverb (15" speaker). I dropped the value of C5 to .15 and it helped a little. I am going to put a 2N7000 in next and try it. I can hear every note even at full gain and it has a nice bite to it as well. It's a keeper, but for me I will try to fix the mud I hear when palm muting a low note...like when playing a boogie on the low e and a strings.

[czech-one-2]

I just want to say one thing to .011. Ive been going through your suggestions one at a time over the last few days,and have finally got my DS-1 sounding pretty much exactly where I want it. I've modded dozens and dozens of pedals,always just blindly following some forum suggestion or mod book,but not really having a grasp on what each component is altering and why.Your descriptions are right on and easily understandable,with no air of arrogance or Technical elitism.
I'd love to see you write a book on the topic of modding or building pedals.
Thanks for your time on this forum,its much appreciated by us
guitar players who dont have a Masters Degree in electronics.
BK

[pchilson]

Originally Posted by czech-one-2

I just want to say one thing to .011. Ive been going through your suggestions one at a time,and have finally got my DS-1 sounding just where I want it. I've modded dozens and dozens of pedals,always just blindly following some forum suggestion or mod book,but not really having a grasp on what each component is altering and why.Your descriptions are right on and easily understandable,with no air of arrogance or Technical elitism.
I'd love to see you write a book on the topic of modding or building pedals.
Thanks for your time on this forum,its much appreciated by us
guitar players who dont have a degree in electronics.
BK

+1000

Much appreciated by us laymen. JC as well. Thanks for these threads.

[czech-one-2]

Ditto JC !

[11 Gauge]

Originally Posted by czech-one-2

Your descriptions are right on and easily understandable,with no air of arrogance or Technical elitism.
I'd love to see you write a book on the topic of modding or building pedals.

Aww shucks...thanks!

No arrogance? I sure try to avoid that whenever possible. I hope to never fall off the pedestal you've so kindly put me on! I do try hard to keep out the alchemy and B.S. as much as humanly possible.

I've got stuff in the works, but can't discuss it here, for obvious reasons. I'm hoping that what I do share here will suffice for our communal purposes.

I just try my best to keep it fun and simple, with the emphasis on experimenting and learning.

And YES - huge kudos are in order for Mr. Crash. What he's willing to try (and repeat, again and again) and what he gets done in a super short period of time are an immense contribution!

[czech-one-2]

By the way, Heres what I settled on in my MIT pedal-

Diodes- one 914/one 1N4148 ........why? it sounds great!
C1/C13 .047 metal film
C2 - 1uf metal film
C3 -.01 metal film
C7- 220pf
C8 - metal film 1uf
C10 .047 film
C12 .047 metal film
C14- 10uf electro
R14- 10k carbon comp [mojo factor ]
[actually,I've got a ton of them from 808 mods!]
R35- 1k + a brighter blue led

Thats it,thats all it needed,and some of these were just quality upgrades with the same values.I've done almost all of the wampler mods and both keeley mods,this one just sounds ........right
I tried the R9/R13 mod again and still didnt care for it,to me it takes away some of the attitude and rawness of the DS-1.But I really liked the sound of mine stock,which may be the determining factor with how far to go on these mods.
My DS-1 has the Rohm BA728N chip which some have said to be second only to the MIJ TA7136AP chip,which may be why it didnt need/like the R9/R13 mod.But again,I'm just going off something somebody said in a forum.


.011- Brians book has been indespensible to me,and really taught me how to go about tweaking these things. But what the book lacks is a thorough description of WHY your changing a component,such as your
DS-1 tutorial. I feel like He just didnt have time to go into it,so he felt just giving the specs is enough.I must have gone through my SD-2 three times with his suggestions,never really knowing what the hell I'm actually accomplishing with each component change,just trying to use my ears.Thats no way to go about messing with your favorite pedal!

Thanks again you guys!

[ChipOnly]

Just a heads-up for anyone interested, music123.com is currently offering free shipping, I think it only last another couple days. Anyhow, you can pick up a ds-1 for $29.99 shipped....

[JohnnyCrash]

Originally Posted by czech-one-2

I just want to say one thing to .011. Ive been going through your suggestions one at a time over the last few days,and have finally got my DS-1 sounding pretty much exactly where I want it. I've modded dozens and dozens of pedals,always just blindly following some forum suggestion or mod book,but not really having a grasp on what each component is altering and why.Your descriptions are right on and easily understandable,with no air of arrogance or Technical elitism.
I'd love to see you write a book on the topic of modding or building pedals.
Thanks for your time on this forum,its much appreciated by us
guitar players who dont have a Masters Degree in electronics.
BK

+1

11 Gauge has helped me so many times, and without any snobbery. In my excitement to mod this cheap pedal I completely forgot to thank him.

Thanks 11 Gauge!

[czech-one-2]

Wow, I'm really digging the modded DS-1.Perfect all around heavy overdrive/distortion with a great solo tone and just the right amount of compression without going overboard.[some compression is essential IMHO when using solid state amplification.]
The mods seemed to improve clarity,note seperation and increase midrange a bit.The low end is noticeably tighter too.The tone control is useable in a much greater range,and the ice pick is gone,as is the fizzy high end.
My vintage MXR dist + is off the pedalboard and on to a new owner.

Funny .011,you mentioned NEVER change r39 cause two of my previous attempts had different values here.One was even called the 'ultimate DS-1 mod'.