SD-1 / OD-1 "Tone" Question - 11G Welcomed!

[artdecade]

My understanding is that the SD-1 is an OD-1 with a tone knob. Just out of curiosity, where would I set the tone on the SD-1 to get what would be the typical OD-1 sound? I am just trying to get a reference point for what the OD-1 actually sounds like.

 

[Rich_S]

There's a question for the ages. I'm actually thinking about buying a trashed OD-1 just to find out.

 

[cousinpaul]

There's a website called Eric's Corner that tells how to convert an SD-1 to an OD-1. I'd find it for you but I've got to get to work. I haven't tried the OD-1 mod but his SD-1 to TS808 conversion is pretty good.

 

[artdecade]

Maybe 11G will come in here and drop some education on our heads!

 

[waparker4]

http://www.erikhansen.net/pedalmods.php

 

[artdecade]

Thanks for the link, but I'm not looking to do a mod. I want to know where the tone on a SD-1 would be set to match the tone stack on a stock OD-1.

 

[JoeNeri]

Might be wrong (I often am!), but I do not believe the circuits of the two pedals are the same, even allowing for the tone control. I believe that Boss marketing the SD-1 as "an OD-1 with a tone control" was more along the lines of "here's another overdrive pedal but this one has a tone control."

 

[artdecade]

Might be wrong (I often am!), but I do not believe the circuits of the two pedals are the same, even allowing for the tone control. I believe that Boss marketing the SD-1 as "an OD-1 with a tone control" was more along the lines of "here's another overdrive pedal but this one has a tone control."

Oh... Ha! I guess that could be the case.

 

[Dr. Pants]

I'm sure Keith will chime in eventually.
Until then, I can confirm that the two pedals
have a somewhat different circuitry. The OD-1
is more MXR D+\OCD\DOD 250 in sound. Whereas
the SD-1 is more TS-esque. Or more truthfully, the TS
is more SD-1-esque, as the TS was a lift of the SD.

 

[taxer]

It's even more confusing.

The OD-1 can sound like the SD-1...and the OS-2 can sound like both!

I have both the SD-1 and the OS-2. The OS-2 gives you SD-1 distortion AND OD-1 overdrive. If you are looking to match SD-1 and OD-1 sounds, just buy yourself the OS-2. It really is the two pedals in one.

I don't really use my SD-1. No need for it because that pedals sound is in my OS-2 pedal. Plus the OS-2 has the great advantage of being able to mix both the distortion and overdrive tones together. The OS-2 is the one BOSS dirt pedal to get.

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[artdecade]

I'm sure Keith will chime in eventually.
Until then, I can confirm that the two pedals
have a somewhat different circuitry. The OD-1
is more MXR D+\OCD\DOD 250 in sound. Whereas
the SD-1 is more TS-esque. Or more truthfully, the TS
is more SD-1-esque, as the TS was a lift of the SD.

I didn't know that the OD-1 was closer to the MXR/DOD family. I just figured it was more like the SD/TS. You learn something new everyday.

 

[artdecade]

It's even more confusing.

The OD-1 can sound like the SD-1...and the OS-2 can sound like both!

I have both the SD-1 and the OS-2. The OS-2 gives you SD-1 distortion AND OD-1 overdrive. If you are looking to match SD-1 and OD-1 sounds, just buy yourself the OS-2. It really is the two pedals in one.

I don't really use my SD-1. No need for it because that pedals sound is in my OS-2 pedal. Plus the OS-2 has the great advantage of being able to mix both the distortion and overdrive tones together. The OS-2 is the one BOSS dirt pedal to get.

image removed

Ha - I already have two dirt boxes and that is more than enough for me: Rat & SD. I figure if I can't make a Marshall, Vox, or Carvin sound good with those than I count make them sound good to begin with!

 

[waparker4]

It's even more confusing.

The OD-1 can sound like the SD-1...and the OS-2 can sound like both!

I have both the SD-1 and the OS-2. The OS-2 gives you SD-1 distortion AND OD-1 overdrive. If you are looking to match SD-1 and OD-1 sounds, just buy yourself the OS-2. It really is the two pedals in one.

I don't really use my SD-1. No need for it because that pedals sound is in my OS-2 pedal. Plus the OS-2 has the great advantage of being able to mix both the distortion and overdrive tones together. The OS-2 is the one BOSS dirt pedal to get.

image removed

I believe you mean DS-1... if that pedal blended an OD-1 and an SD-1, you'd get 2 shades of similar

 

[11 Gauge]

Might be wrong (I often am!), but I do not believe the circuits of the two pedals are the same, even allowing for the tone control. I believe that Boss marketing the SD-1 as "an OD-1 with a tone control" was more along the lines of "here's another overdrive pedal but this one has a tone control."

This IMO is correct.

It's easy to forget (or just not even be aware) that tone controls were still kind of a new thing with many drive pedals back when the OD-1 came out.

In the case of the OD-1 however, there are two op amp stages - kinda different from the other op amp-based stuff that came before it. So Boss figured they would put it to use, just not in a tone shaping capacity.

...But op amps are actually pretty good for employing tone circuits around.

The way the 2nd op amp stage is configured in the OD-1 requires that some things be changed to make for (what Boss believed to be) a better tone circuit. An op amp has two inputs - an inverting and a non-inverting. I won't go into details, but suffice it to say that the 2nd stage in the OD-1 has the signal presented at the inverting input, but a tone control (with reasonable simplicity) would do better having the signal fed into the non-inverting input, so that you can adjust it (like the gain/drive of the first and primary stage) at the inverting input.

...So that requires that things be swapped at pins 2 and 3 at a minimum, which is what the "Erik's Corner" page highlights.

Aside from the tone circuit components directly tied to that second op amp stage in the SD-1, there is also a fixed lowpass filter just prior to it.

So the tone circuit in the SD-1 is a "properly engineered" addition as opposed to a "let's just graft this thing in here" kind of approach. Lots of stuff that preceded the SD-1 took that route. It was rare to see something like the Colorsound Overdriver back in '71 or so, which featured active bass and treble via a "Baxandall" tone circuit, and done with old (by today's standards) bipolar transistors.

And much of the stuff just seemed to have a lowpass filter tacked on at the tail end of the circuit that was either too mild or didn't have a good sweep. Some even affected the output if they had no recovery gain stage like the Big Muff had. The Rat had a unity gain buffer after its tone circuit, but it was more to recover signal after the clipping diodes shunted to ground. Pedals like the D+ and DOD 250 had no recovery stages (and no tone circuits, obviously).

But the OD-1 must have clearly been an instance of a design that (in the eyes of Boss) would benefit from a tone control. Using dual op amps really seemed to change things, and lots of the most popular drive boxes still seem to revolve around a dual op amp design today. Timmy, OCD, Zendrive, etc...

 

[artdecade]

Is it the Low Pass Filter in the OD-1 that makes it so distinctive? I know it was used by a lot of Marshall player in the 80s because it made solos really sing (like Jake E. Lee).

 

[taxer]

I believe you mean DS-1...

You may be right.

In all honesty, between the DS-1, SD-1, OD-1, OS-2, blah, blah, blah....are there really such differences as to make these pedals distinct from each other?

My OS-2 can sound exactly like my SD-1. Essentially I got burned by buying the two. BOSS should be a company that cares for the consumer and put a warning on these pedals:

WARNING: Even though we make 175 different Overdrive and Distortion pedals, they are really the same thing just sold with a different name and painted a different color.

 

[waparker4]

In all honesty, between the DS-1, SD-1, OD-1, OS-2, blah, blah, blah....are there really such differences as to make these pedals distinct from each other?

Yes

 

[artdecade]

You may be right.

In all honesty, between the DS-1, SD-1, OD-1, OS-2, blah, blah, blah....are there really such differences as to make these pedals distinct from each other?

My OS-2 can sound exactly like my SD-1. Essentially I got burned by buying the two. BOSS should be a company that cares for the consumer and put a warning on these pedals:

WARNING: Even though we make 175 different Overdrive and Distortion pedals, they are really the same thing just sold with a different name and painted a different color.

image removed

 

[Rich_S]

Okay, let's get this straight... the Boss overdrive and distortion pedals are NOT all the same. The two old-timers in the current line-up, the SD-1 and the DS-1 are fundamentally different designs.

The SD-1 is an overdrive pedal; it uses clipping diodes in an opamp's feedback loop. It is the decendant of the OD-1 which was similar, but not simply the same thing with no tone control (as 11G has detailed above). It is the same basic topology as the Tube Screamer and all of its decendants (booteek and others) that exploded into the market post-SRV.

The DS-1 is a distortion pedal. It uses diode clipping, but the clippers shunt the audio signal to ground, they are not in the feedback loop. It is a fundamentally different design from the SD-1

The clipping-to-ground design is used many other places. The MXR Distortion+ is one example, but is a much more rudimentary circuit than the DS-1. The Rat is another.

I have a DS-1 with the Monte Allums Recto Mod in it, and to my ears it sounds quite a bit like an MXR, but has more available output volume, and of course a tone control. It can dial in a good D+ imitation, but can do other sounds as well.

 

[11 Gauge]

The DS-1 is a distortion pedal. It uses diode clipping, but the clippers shunt the audio signal to ground, they are not in the feedback loop. It is a fundamentally different design from the SD-1.

The DS-1 is also different from stuff like the Rat.

It has TWO gain stages, with the first being like the first gain stage in a Big Muff - bipolar transistor that actually clips even with the distortion turned way down. It jams that into a single op amp stage that gets most of its coloration from the pair of clipping diodes that are shunted to ground.

There's a high pass filter at the op amp stage (which comes second) that lets most of the bass go thru (frequencies down to ~70Hz) - quite different relative to the OD-1/SD-1/TS family of pedals.

The tone circuit on the DS-1 is basically the cousin of the one used in the Big Muff - it blends a treble high pass filter with a bass low pass filter. The stock frequencies are ~1KHz and above on the treble side, and ~230Hz and below on the bass side. This leaves a huge "hole" at all frequencies in between - pretty much the opposite of how most OD's are (or at least were) voiced.

...If you consider that filters remove frequencies at 6dB per octave slope, the "center of the hole" with the DS-1's tone circuit is roughly 500Hz. The OD-1/SD-1/TS, roll off bass below ~720Hz, and then treble above ~720Hz.

In essence, these two pedals could not be more differently designed, and therefore sound absolutely different.