Boss SD-1 SUPER OverDrive - Modded by Keeley

The SD1 has been one of the most utilized pedals in the guitar world. It's been the standard for that asymmetrical clipping type of sound. However, it's known to have a few problems with it. For one, it tends to leak when bypassed. You can still hear it, even when it's off. For two, it tends to be a bit thin sounding at times. Keeley helps try to fix these options, as well as adding some new things to help make this pedal a lot more versatile than before.

UTILIZATION

The peda is housed in your typical Boss enclosure. These things are tough as nails and can withstand all kinds of punishment. The manual no longer is applicable thanks to this being modded, but it's still very easy to figure out. The switch is the biggest feature that this thing has. It allows you to select between two different diodes, but it's really only useful if you're using some gain on the pedal. Everything else is pretty much the same as your typical Boss pedal.

SOUND QUALITY

The pedal sounds great. First off, I'm really glad he did a special buffer in this thing to help prevent some leakage that normally occurs with these pedals. Otherwise, it's almost unusable on the clean channel with the gain up high. I tend to use these as boosters rather than gain adders. That means I tend to turn the gain off and crank the level. This is like a strong clean boost rather than a gritty boost which is how most people use it as. The switch on this selects between two different diodes to give you various flavors of this boost. On top of that, it's a lot thicker sounding than the stock version, which is a definite welcome.

OVERALL OPINION

If you're looking for a solid boost pedal with asymmetrical clipping, I would recommend this pedal. It does a great job, and you can get some aggressive boosting going on without it sounding too thin like certain other pedals do. This version is a bit more versatile and more modern sounding than the Analogman one, but the Monte Allums one has the most features, so feel free to choose which one you personally think is best.

Could be the most commonly used OD pedal that Boss has ever made. The reason is because so many professionals have used this slamming the front of their Marshall JCM800's. Which is pretty much the reason I bought this pedal. I think there are definitely poor things about this pedal but keeley in my opinion has addressed. One being the volume loss and the overall tonal characteristics are enhanced from the Keeley mod. And man does this thing get LOUD!! This mod makes this pedal go from cool but sort of week volume to turn that thing down because its too loud!!

It is a simple layout as all Boss units are, and controls are as followed...

Level, Tone, and Drive

The Keeley mod adds a switch to the right side of the unit that changes the diode clipping style of the distortion.

UTILIZATION

Extremely easy to use and no need of a manual. However, Keeley does include a manual for his 5 start tone stack which what he calls his mod to this pedal. Plus this unit came with an additional chip inside that change the clipping and tone as well. Not sure the name for it...I think it was called the brown chip or something. I never really flipped in and out the chips but once to test...found the one I liked and used that exclusively.

SOUND QUALITY

The sound quality is fantastic if you are trying to slam the front of your overdriven amp. It will do that 80's tone in spades. So my use was normally just as a simple booster to get the amp sizzling even more. Made jamming really much more pleasurable. It was warm and somewhat smooth but I would call is a bit sleazy. This is a pedal you don't take home to mom....it is a pedal that you told tell your parents about but show off to your friends for high fives if that makes sense. It gives you that pissed off Marshall tone that you hear on so many records from the 80's hard rock glam metal genre.

I used it with my Les Paul and Strat style guitar in front of an 80's JCM 800 and Splawn QR. It was more fun to use in front of the 800 than the Splawn since the Splawn already does this sound naturally. If you can get a decent quality JCM 800 fro around $700 and this pedal you have that modded Marshall tone without spending $700 fro some dude to hack up your amp.

Beware though you will need a noise gate because this thing burns the front end of your amp so heavily that it creates a lot of noise. not a bad thing just the normality or operating in this setting. It gets really angry and actually very fun to play some old VH or Ratt riffs with this setup.

OVERALL OPINION

The thing I like most about it was that it gave me that modded Marshall tone for around $100 and you can keep your amp clean from holes or unwanted modding. It isn't perfect but it can achieve desired results for hard rock/ old metal tones. It is not suitable for really low drop tunings unless its pushing an already heavily overdriven amp. This application would probably make your amp tighter and more focused.

Would I get another one of these....probably if I get another unmolested Marshall JMP or JCM 800. I would recommend this mod too as it adds a cool transparency to your stomp box.

Boss SD-1 Super Overdrive modified by Robert Keeley to improve it.

The improvement consists (according to the website of mister Keeley) keep the tone color of the SD-1 "stock" while increasing the gain, making it more precise and definite. It is also to make the SD-1 almost true-bypass and prevent sound leakage especially when the pedal is off and the volume knob is more than three quarters.

Not knowing all the sound of the original Boss SD-1 or other "mods" that can make boxes as MonteAlums or other, I can only congratulate Mr Keeley since the defects mentioned above are not present. No loss of true-bypass, it's perfect.

In case, the SD-1 won a mini-switch in addition to the usual trio (gain / tone / level). This is a switch for selecting a germanium diode rectification (low position) or by LEDs (high position).

Nothing wrong side features, it's reliable, it's well thought out (thank you Boss format), the mini-switch is perfectly placed. Impeccable.

UTILIZATION

The general configuration is very simple, especially as the SD-1 is supplied with a written by Robert Keeley manual to explain the benefits of the change.

The SD-1 offers us an overdrive in the vein of the Ibanez TS-9, but with a sound sharper, more defined, more "heavy" (plus any what) but less "boost of mediums." Basically, you can have all the uses that you have with a Tube Screamer but with a different sound. And that's exactly what I'm looking, I was disappointed by a Maxon OD-808 that I kept 4 or 5 years.

SOUND QUALITY

Admit as much at once, the sound on the clean channel of a tube amp is pretty good without either rock the house. It was quite an overdrive "neutral" without much character rather "right" and a little gum shades game (too compressed?). That said, the knobs do the job and changes brought Keeley SD-1 in the territory of distortions. This type of sound can appeal, but here I still find that my Maxon OD-808 was doing a little better. This Keeley SD-1 is, however, largely the work and can suit many guitarists.

On an already saturated channel, it is a different story and there the sound is sublime. It surpasses anything I've tried in overdrive. It adds that little extra power and sharpness that sometimes missing on this property heavy metal riff or passage well without adding too much fat might make less precise sound. A real butcher!

The two positions of the mini-switches are usable, we pass a compressed sound, sweet and well saturated with germanium diodes in a more open and sharp but also less saturated with LED's.

OVERALL OPINION

I got tired of the sound of my Maxon OD-808 which happily puffed my lower spectrum and boostait me my mediums. The SD-1 is a tube screamer with more aggressiveness, more gain and a better balance bass / mid / high, which makes it less sexy than a Tube Screamer into overdrive on the clean channel of an amp but much better boost in overdrive channel.

I use it for almost 3 months and I think I found my grail in booster overdrive channel. It surpasses anything I've tried in terms of overdrive / distortion for this specific use. For use as OverDrive on a clean channel, I would tend to advise the Keeley BD-2 or TS-9 pedal style if the bump in the midrange and the trough in the low do not mind (that is a shame when you do blues).

However, this price Keeley SD-1 is prohibitive. Objectively, pay over € 150 for a Boss pedal that was changed a few components, it's frankly not given. Subjectively, it is theft. But it is a choice I would do because I have not found anything better yet.