boss SD-1

[F1sh]

I've been doing various mods to my boss SD-1. I'm almost done with it, but I was wondering if anyone would know how to get a bit more low end out of it?

[Bassybert]

What mods have you done F1sh?

I've got an SD1 and would like to know what sort of things I can change and how they affect the sound. I'm well aware of the fact that Robert Keeley's mods are popular, but i've just bought a house (enough said there) and I can't afford the £60 it's going to cost me to get one of his mods done.

Thanks

Jim

[Oliver]

I've been doing various mods to my boss SD-1. I'm almost done with it, but I was wondering if anyone would know how to get a bit more low end out of it?

Hi,

i think it's the same way as with the Tubescreamer...

If you look at the schematics (TS and SD-1) the Resistor and Cap
that goes from the Gainstage to Ground (Stock is 4k7 and 0,047uF)
at both Pedals. At this Place you can change the SD-1 the same
way for more Bassresponse as the TS.
(see TS-Mods on the Net) I dont know the right values to solder in.

For myself, I like the Basscut and Midboost of the Tubescreamer.
The Sound cuts through better in bandplay for Solos or crunchy
Rhythmplay.

bye
Oliver

[F1sh]

I like the mid bump for cut as well, but I want to experiment with the low cut because I use 2 SD-1s. My main SD-1 for my rythym sounds has the 3 clipping diodes removed, and a burr brown IC installed. DIrectly before that pedal I have a bone stock SD-1 I kick on for leads.

I'd like to mod the modded one with increased bass to give me a little fuller sound since it's almost always on, and it's hard to make up for what is lost at the amp. Eventually I'm going to replace all the cheap caps in both units and maybe try a mixture of LEDs in the stock SD-1 I use for leads to give it more of a mid boost.

Thanks oliver for your help tho, I did just a day or two ago read about the TS-9 mods you were talking about, and I just wanted to confirm it would be the same with the boss.

[modmod]

F1sh,any link to order burr brown ic ? is that a 4558 ? i've just read some info from keely's site,thanks

[phillip]

You can get the Burr Brown ICs from Digikey (www.digikey.com).  The two that I've used in the SD-1 are the OPA2604AP and the OPA2134PA.  I ended up sticking with the OPA2134PA because it seems to be a lower noise device.  They're fairly expensive though...I think the 2604 was about $3.00-$3.50 each and the 2134 was about $2.75 each.

You can also go to the Texas Instruments website (TI owns Burr Brown) and create an account there and order free samples of almost all of their ICs including those two Burr Brown chips  

Phillip

[Marcos - Munky]

Code Select Expand

***** SD-1 5-Star Ge Mod ****

Keeley Custom Shop designed this mod to enhance the tone and functionality of the SD-1.

Freely copy and distribute. We have the right to change our modifications at any time without notification. It is fun to watch what big name people use the mods.

Board Number New part Old part Reason Where to get the part

C10 --> Metal Stack Film 1uF, remove electrolytic, increased fidelity, digikey

C7--> Metal Stack Film 1uF, remove electrolytic, increased fidelity, digikey

R6 --> 2.4k ohm metal film, 4.7k, increased distortion, digikey

C3--> 0.1uf metal stack film, 0.047uf, fidelity and bass response, digikey

C2--> 0.1uf metal stack film, 0.018 fidelity and bass response, digikey

R2--> 620k ohm metal film, 470k ohm, increased input impedance, better bypass, digikey

Add 47pF cap across diodes in clipping section to smooth out distortion, just like TS9, radio shack

On some older units, short out D3 and the 470 ohm resistor in the power supply section to increase the voltage to the circuit. This increase the headroom and gain. Newer units have it shorted already.

Here is the tricky part of our mod, take a germanium (Ge) transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6. If you use a PNP transistor, the Base will be the negative or cathode side, the Emitter will be the anode. Here is a diode drawing Cathode---|<----Anode. This increases the amount of distortion produced by the pedal, it also sound really nice. Try this! Don't leave it out! It's fun. Get your Ge transistors from Steve Daniels www.smallbearelec.com

If you want to drill out the LED and install a 5mm big job, change R30 to a 1.2k-3.3k ohm depending on brightness and battery drain you want, replacing the stock 3.9k ohm.

Keleey mods, if anybody try, please let me know the results.

[WGTP]

From my experience, the diode change will effect the sound more than anything else.  Try a MPF 102 Jfet from Radio Shack or wherever in place of either the 2 SI's or the single.  Put a socket in there and experiment.  Try an LED.  I prefer any of those combos to the 2 SI's like a Tube Screamer.   :wink:

[gringo699c]

change c3 and c2 to the 0.1uf metal film like in the Keeley five star mod and you will get much more bass.
 I also changed the Op amp to the opa2134 burr brown chip...very nice chip.
 Have gotten 9 chips for free from
www.ti.com
 they will send you all you  want and will also ship them next day air at their expense....SWEET!!!!!!!!
Chris

[will]

Hi,

[code]***** SD-1 5-Star Ge Mod ****

Keeley Custom Shop designed this mod to enhance the tone and functionality of the SD-1.

...

Keleey mods, if anybody try, please let me know the results.

I did all of the Keleey SD-1 5-Star Ge Mod mods to my SD-1.  It definitely improved the sound. My unit already had the decent JRC opamp and didn’t have the power supply resistors. I did the mods in 2 stages. I replaced the caps and resistors. That added clarity to the circuit and increased the bass. The clean boost was greatly improved and the range of distortion was increased. I can dial in more distortion than before. A great improvement in sound. I suspect the biggest improvement was changing the electrolytic coupling cap and replacing it with a film cap. Like cleaning mud off your windshield.

The 2nd part I used a 1N60 germanium diode instead of a Ge transistor. I figure it should be very similar. The effect became more tube like in sound. I did loose a bit of gain and the nature of the distortion changed to be a bit growlier than before.  The difference was subtle at times and quite noticeable for other types of music.

It was the success of modifying this effect that I started to get back into electronics and start building other effects. However after building a modified clone of the MXR Dist +, which to me has vastly superior sound, I have only used my modified SD-1 as a boost. I like using it in front of fuzz circuits to make the highs so much creamier.

Regards,
Will

[Marcos - Munky]

Cool, I will try to put my hands in a SD-1 to try them.

[phillip]

The great thing about the SD-1 and the DS-1 is that they're so cheap that you almost can't afford not to get ahold of at least one of each to experiment with.  I have 2 of each of these...great pedals...even better with modifications!

Phillip

[modmod]

hello, what kind of ge transistor should i use ? found this 1n31a http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2223027283&category=132,is that ok for the sd-1 mod ? or should i order the nos work-alike 1n34a from smallbear ? thanks a lot

[Oliver]

I like the mid bump for cut as well, but I want to experiment with the low cut because I use 2 SD-1s. My main SD-1 for my rythym sounds has the 3 clipping diodes removed, and a burr brown IC installed. DIrectly before that pedal I have a bone stock SD-1 I kick on for leads.

I'd like to mod the modded one with increased bass to give me a little fuller sound since it's almost always on, and it's hard to make up for what is lost at the amp. Eventually I'm going to replace all the cheap caps in both units and maybe try a mixture of LEDs in the stock SD-1 I use for leads to give it more of a mid boost.

Thanks oliver for your help tho, I did just a day or two ago read about the TS-9 mods you were talking about, and I just wanted to confirm it would be the same with the boss.

Hi,

how did you make the settings of your SD1s (the first and second)?

I'd like do put a driving Unit in front of my DIY Fulldrive, because
i build the Fulldrive not with the Stock GainBoost, that dont push up the
Level. I build it with a Levelboost.
But sometimes i like to work with more Gain. Thought to build a LPB2
in front of it... Perhaps it can be two Tubescreamers in Series...

would be nice if you could tell the settings of your setup..

thanx !
Oliver

[modmod]

You can get the Burr Brown ICs from Digikey (www.digikey.com).  The two that I've used in the SD-1 are the OPA2604AP and the OPA2134PA.  I ended up sticking with the OPA2134PA because it seems to be a lower noise device.  They're fairly expensive though...I think the 2604 was about $3.00-$3.50 each and the 2134 was about $2.75 each.

You can also go to the Texas Instruments website (TI owns Burr Brown) and create an account there and order free samples of almost all of their ICs including those two Burr Brown chips  

Phillip

thx phillip for your tips ! but OPA2134PA has no more stock from ti.com,is OPA2134UA the same ? thanks a lot

[phillip]

I think that the UA might be the surface mount version, not the DIP-8 that you'd be looking for.

Phillip

[modmod]

what kind of ge transistor should i use ? found this 1n31a http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2223027283&category=132,is that ok for the sd-1 mod ? or should i order the nos work-alike 1n34a from smallbear ? thanks a lot

[phillip]

I'd just order a Germanium diode from Small Bear.  I used 1N34As in my two SD-1s that I modified to the 5-star Ge specs and they work great.

Phillip

[RDV]

thx phillip for your tips ! but OPA2134PA has no more stock from ti.com,is OPA2134UA the same ? thanks a lot

I ordered some OPA2134PA even though they said they were out of stock, I got them a few days later than the others on backorder. The OPA2134UA is a tiny surface mount version. I just went to Ti.com and it looked to me like they're(OPA2134PA) available.

Regards

RDV

[modmod]

thx rdv, just got few samples from TI as philip said,u guys are really helpful,i am only few weeks here though, going to start my first mod once i got all the components, thx guys !