Saturday, February 21, 2015

DIY Keeley/BOSS DS-1 Ultra - All Seeing Eye mod!!! (Disambiguation)

I am a bit fanatical about the DS-1 pedal all the sudden.  They kept sending me made in Japan and made in Taiwan models with the rare diodes and op amps, that just sound great.  But finally they sent one with the shitty Mitsubishi op amp so it's time to do the Keeley mod.

This post is a disambiguation.  There are a lot of online "tutorials" bout how to do this Keeley mod yourself, but there's a lot of vague information about the clipping modes.

After an afternoon and evening of sleuthing and experimentation let me say this.  The "SEEING EYE" mod is simply replacing one of the stock dioes with a 3mm LED which is visible on the "TONE" word on the case, you drill it out with a 1/8" bit, and glue it in, and that's the SEEING EYE mod.

The ULTRA mod is the switched part.  With the switch in the "up" position this second diode is the stock diode, a 1N4148.  The "all seeing eye" glows brightly, and the sound is very similar to the standard BOSS DS-1 tone, but with Keeley's wonderful refinements.  When the switch is down, you put a second 3mm LED in series with the stock 4148 diode, for the "ULTRA" mode.  The Ultra mode is the down switch position and there is a diode in series with an LED for the second clipping diode only.  Along with the standard Seeing Eye mod.  The Seeing Eye glows less brightly in this down switch position.  The sound is much, much louder and the clipping is reduced, along with more bass frequencies being heard.

So to wrap it up, the first diode is permanently replaced with the Seeing Eye 3mm LED in the TONE text, and the second diode is replaced with a switching array that allows to you to go between the regular stock 4148 diode.  And a second position (down) which gives the Ultra mode of a 4148 diode in series with a 3mm LED which is not visible, it exists inside the case.

This is a wonderful modification for the shitty newer $20-30 DS-1 you can find used with the annoying sound.  The older Japan and Taiwan models with the Toshiba op amps should not be modified, they sound wonderful.  But with this Keeley setup, the newer DS-1 can sound each bit as good.  I especially like the Seeing Eye mode.  The Ultra mode is a bit off-base from how a DS-1 usually sounds, so I will have to find a use for it.  I am guessing it could prove useful as a bass guitar distortion.  The Seeing Eye mode is more of a general refinement of the stock DS-1 sound.

You can see my photos below for the pedal I modified, and the full list of Keeley mod instructions on a piece of notebook paper.  I also would recommend trying an older Japanese style DS-1.  I would also recommend the Wampler mods that are available online in instructional form.  I did the "JCM" and "18 Watt Marshall" mods and they are both pretty cool.  Now I have to pick a favorite!  Or not... I have 5 orange pedals sitting here now! 

Wednesday, February 11, 2015

Alesis 3630 modification. Is it good? Or the worst ever?

I picked up an Alesis 3630 for $24 on eBay.  I have heard so much about them I had to get to the bottom of it myself.  Also, Billy Corgan used it in his guitar rig on the huge sounding Mellon Collie and the Infinite Sadness, and Daft Punk as a master compressor on their huge sounding albums Homework and Discovery.  So there could be something to it...

The first "mod" is to get a 2 Amp power supply (wall wart) I hear that the original ones are quite wimpy.  This part was about $18.

The second mod is to replace the caps in the power section.  This is where I ran into trouble.  I used 2,200 uF caps in all four position, but then one of them exploded.  I replaced it and it exploded a second time!  This was terrifying and disheartening.  I have heard of this phenomenon but this is my first time encountering it.  I believe that 2,200 uF was far to big a value for C2 and C3, and they were probably drawing too much power.  So I replaced them with 220 uF caps (C2, C3) and C4 and C5 I returned back to their original 1000 uF value.  I was too nervous to try 2,200 uF in there again.

So I cleaned up the mess, replaced a ceramic cap that got shattered (!!) in the first explosion, and let it run for an hour and a half.  This was nerve wracking, I kept expecting more popping caps.  After about two hours I felt OK to put it back together and start passing audio.

Let me mention the first nightmare.  When I pulled the knobs off for the initial disassembly, about 5 or 6 pot shafts got ripped out along with the knobs... nasty.  I don't know if some hapless punter glued them on or what.  So ordering replacement pots, and doing that part of the job, added a lot of extra time and work to this apparently ridiculous project.

The audio quad op amps that came stock were a respectable TL084CN (earlier revisions had much worse).  But I had to see what all the upgrade fuss was about so I installed sockets and a pair of Burr Brown OPA4227PA.  The two of them cost me about $5 on eBay.  So now my total investment in this 3630, including pots, is around $50.  Not bad.

I also replaced C16 and I think C33? (the other side of the board) with Panasonic electrolytic caps, since they are in the audio path.

Removing those caps gave me a little room for the nasty part, which was ripping apart the quad op amps with angled cutters.  Once you get one half of the op amp's legs snipped, you can just wiggle it back and forth a bit and then the other half of the legs will break eventually.  After this, pull the legs out with a soldering iron and some tweezers or grabber of some sort.  Then you can clean up the holes with desoldering braid (and a very hot soldering iron).  Once the holes are nice and open, you can put in a socket.  Then you can put in your new C16/C33.  After all this brute nastiness, now it's time to gently slide in the Burr Brown op amps... ahh....

Another word of caution.  I think the ribbon cable leading to the LED meters could be kind of delicate so be careful.  My left side gain reduction meter doesn't work any more.  I don't know why, but maybe I was rough on the ribbon.

The 1/4" jacks also needed a heavy dose of contact cleaner, and I refreshed the solder points for good measure.  I was getting some audio glitches from here but not after the cleaning.

I don't know which was more disgusting to work on, the Alesis 3630, or the Behringer MDX2100 Composer.  Both pretty revolting.  But in the end, they are both nice compressors to have working in the rack.

How does it sound?  Dirty-six-dirty is about right.  You get this kind of cassette tape, gritty, slightly dark on top, sort of big on the bottom thing.  Think Daft Punk, or Mellon Collie guitars.  Things sound a bit bulbous and sort of cartoon-like, a little low-fi or fuzz around the edges.  Which can be a useful sound, to my ears.  The Composer is a lot crisper and cleaner.  Honestly it wasn't that bad pre-mod either.  By the way--If you own an earlier '90s pre-Rev D. model, you might have to add a couple caps in the detector circuit, you can google this mod.  Mine already had them.  You can also snip some jumpers to take the gate out of the circuit and clean up the sound, but I didn't do this, I guess I wanted it 'kind of stock'.  And if you've got an early one with a comparator IC as one of the quads, that should be replaced with an op amp as well.

This sounds nothing like a DBX.  The compressor's action is not so defined or obvious, or quick I guess.  The attack and release, ratio controls are also not as responsive as I'm used to hearing in other compressors.  You can really smash the gain reduction meters, it seems a lot of people use 3630 like this.

It's too early to tell how much I'll use this, but it has a flattering sound that can work great for fattening up a thin sounding fuzz bass, for example.  I'm sure it would work great in a live-instrument rack, too.

Worst compressor of all time?  I doubt it.  Not bad.  I can't tell you how good it feels to be done with this one though.  I do plan to use it and it's been sounding cool so far!  The power supply lesson learned the hard way was probably worth the project alone.