Site hosted by Build your free website today!


My business is official now. It's called "Right Key Repair". Its a nice, friendly name.

Right Key Repair does on-site Pro Audio Service.
Practice Spaces
...Whatever you need, wherever you are - We'll be there.

I ask that requests for work, go to
For all other email, use the Gmail account.

Other news: I have increased the prices for the Univox mini-synth and Paia Fatman mods. This covers the extra time and parts that these jobs were costing me.



Whew... I finally found the schematics for the Korg KPR-77 drum machine!
For all those who have been bugging me for them, here they are: _/=\_


It certainly has been a while since I last updated.

I have a new email address:

The SSM2040 chip has been sold.

I sold my Univox Mini-korg. I modified it to accept external signals. Man that synth kicks ass! The VCF is so full of character. The VCO's are very stable for a synth that is literally, as old as me!

I can modify your Univox/Korg mini-korg synthesizer to accept external inputs for $60(excludes shipping)!

I sold my modified Paia Fatman as well. You can see some pictures of it here: ://:

I can do these mods and more to your Fatman for $100(excluding shipping)!


I bought (2) Arion SAD-3's from Musician's Friend at $19.99 each. Wow, What a great deal!
The SAD-3 actually sounds pretty good.
The problem is is that the SAD-3 is no SAD-1!
I found out that the SAD-3 uses the MN3208 BBD, instead of the MN3205, like in the SAD-1. At 2048, this is half the number of stages as in the MN3205's 4096.
On top of that, there is no compander chip, and lacks the filter stages of the SAD-1.
The SAD-1 is pretty much the same circuit as the famous Tokai TDL-1.

Bottom line is that if you are looking for a cheap Memory Man, forget it!
But, if you are looking for a cheap, simple echo pedal, than get some now!
I already have an MN3208 chip, and there are a few schematics out there that show a much better implementation.
Here's a few links:
Electronic Peasant
General Guitar Gadgets

Here's a link to a description and schematic of the Arion SAD-1: DIY Guitarist.

Still, I am surprised at how good the SAD-3 sounds without the long delays of the MN3205. It is also surprisingly quiet without a compander.
I may try to build a circuit without a compander and see what happens.


I created my first optical theremin!
A single cmos hex inverter chip is all it is.
Maybe my next one will have a smaller switch, so the tin lid can shut. The electrical tape just looks bad.

Here are some pictures of it: 1 , 2 , 3.

Unlike most 555 timer optical theremins I've seen, this one has individual photocells for pitch and volume.
The trimmers are for volume and pitch.
The switch is for the on-board 9V battery.
It only draw 15mA, so it should last a while.
The jack breaks the connection to the piezo speaker (which can get LOUD!) when a plug is inserted.

This is what it sounds like: }0{.
(The echo is courtesy of MS Sound Recorder.)

This went to Rick McCollum of Moonmaan.


I just received my KPR-77 schematics last night.
Stay tuned for mods!
Everyone should get Ray Wilson's Soundlab Minisynth. It's cheap, and the parts are easy to find!


I discovered I have an UNUSED SSM2040 Filter IC. It is in a sealed bag on conductive foam.

It is for sale for $35.

Email me if interested:

Only Paypal payments will be accepted.


I have been building some mods for the Minikorg 700.
Pictures are coming soon.

citizen207 at gmail dot com


I'm selling the Univox Minikorg 700. I want to hold off on going to evil eBay. Everything works beautifully. Pretty good shape, cosmetically.
I am asking $250.


Here's the link to the ADV Snare Mod.

The idea for this mod came from the Electronic Peasant's incredible "Solid State Percussion Synthesizer".
There are some great samples of this thing in action. Listen to ssdrum3.mp3 to hear what the ADV Snare LFO mod sounds like!

Thomas Henry still has the plans and bare boards for $25: Midwest Analog Products.


Uploaded my first AutoCAD drawing. This is going to be my Rackmounted Boss DR-110.
All my rackmounted equipment are in 19" panels.

Here's an alternate layout for a 19" panel of the Midwest Analog ADV Snare.
This layout adds 2 extra jacks to be used for external modulation!


Working on a Saturday!!

Thanks to Jason Amm of Solvent, I recently discovered Joy Electric.
All I can say is 'Wow!'. Its all done with just a Roland System 100, and a CR-78!!
Incedible music, lyrics, and sound!

What the hell I doing?


Uploaded my drawing of the Roland SH-101 VCF.
This circuit uses the Roland IR3109 IC found in many Roland synths including the SH-101, Jupiter 6, and JX-3P.
The VCF could also be easily made with two LM13700 or NJM13600 IC's instead.


This page has a new look. Tell me what you think of it.


I've uploaded the 1983 E&MM article on the Synbal - an analog Hi-Hat module.
These were taken from the Music Machines site, unzipped and converted to .gif files.

I am currently debugging mine, and I've found that the design for the noise source does not work.
The schematic shows the base of TR1 going to the center +6V rail. If you are using a 2N3904 (which I am), then tie the base of TR1 to GND or the 0V rail instead. Here is the schematic with the modification explained: E&MM Synbal Schematic.

This design is the basis for almost all analog drum machine hi-hats in the 80's. A combination of a transistor noise source and a an oscillator 'metal' source, made with a schmidt trigger hex inverter.
The TR-808, TR-606, and DR-110 are all pretty much the same. But, the DR-110 has a (gasp!) digital noise source! Its based on a CD4006 shift register to create a pseudo-random noise generator.
That's the secret to the DR-110's 'trashy' sound!
The simple, yet lovely-sounding DR-55 from 1980, has but a lowly gated transistor noise source, and no metal oscillator. I love that sound!

Ken Stone's CGS Cynare follows what the E&MM Synbal started, and allows complete control over almost everything and trades the Synbal's dual-transconductance VCF for a Steiner Synthacon VCF. I am also building one of these from the PCB I bought from him.


I had read some thread somewhere that someone was looking for TS-204 knobs. I found these online, and they might work. 5mm is a sketchy diameter, but at $.33, its worth a try! :

The Modified TS-204 is sold!
Here's some photos of the unit: (^)
And, as promised, here are the schematics:
Handclap Section pt.1
Handclap Section pt.2
TS-204 Synth Section pt.1
TS-204 Synth Section pt.2
TS-204 Synth Section, Detail of the Modulation circuit
And finally, the Modified Modulation circuit schematic:

Check out Dan Norris's Inline Effects Drumfire DF-500 page

I drew the schematics for this one.
Mods coming for this guy too!
But I've GOT to finish debugging my homemade E&MM Synbal first. Details of that coming soon as well...


The Modified Tama Techstar TS-204 is now up on eBay. Here's the link: _|-

I realized I never put up a link for my pictures of Solvent when he came to town. For those who missed out, here they are: +=+


I rented the remastered DVD of "THX 1138". I saw it maybe 15 years ago. This is another attempt by Lucas to realize his true "vision". Has anyone told him that his "vision" sucks? Look at the new Star Wars trilogy! He is insane. I hate Lucas' new toys- I want the old toys!
I realize now that Front 242's "Geography" is chock full of sounds from that movie.
They probably weren't the first band to use movie clips in their music, but they were the first band I had ever heard to use them.

If you don't have the new Limited Edition remastered version of "Geography"- get it now!
It sure beats the hell out of the remasterd version of THX 1138
- CGI "monkeys", my ass!


I put a new mod on the Tama Techstar TS-204. I included a waveform pan pot for the modulation LFO. It sounds so amazing now.
I will get it up on ebay this week. That is my goal. I put some samples up on the web of it. Check it out /|_

I also put up a sample comparing the Boss DR-110 handclap to that of the TS-204 here.

They are pretty close,but the DR-110 has a bit more complexity to its sound. I am not sure, but it sounds like there is a bit of an upward pitch bend in it.


Happy New Year! I put the DR-110 together in its new housing. It looks and sounds fabulous.
I jammed with a new band last Princess Wishingstar. I hope to play with them more.
I bought a Minikorg 700 on ebay. I am very excited. Soon, Kitaro "Silk Road" lead sounds will be mine!
In other news, I modified my Tama Techstar TS-204 to get FM sounds like a Coron DS7. I will be putting that up on eBay. Details of the mod will be coming soon as well.


I'm so happy I could shoot myself!
I fianlly fixed my Boss DR-110 drum machine!
It's been a while since I put anything up here. I have been busy. I now have a digital camera, so I can document what I have been doing.


I fixed a Korg Delta for my friend Scott Deyo. Once again, it took me a few months of on and off troubleshooting to find the problem.
There was no output from the octave divider chip. I had done some research on the web and found that these suckers run really fast and hot and can burn out. I was sure that that was the problem. I found a source for a replacement circuit as the chip is no longer available. I was also considering trying to make my own.
None of these were very good options. So, I went back in and dug around some more. I don't know why I didn't do this before, but I looked at the schematic I bought and studied the CLOCK circuit more. This is comprised of a hex inverter in linear mode as the master oscillator and some flip-flops.
Previously I had fixed my Boss DR-55. This had a CD4011 chip as a clock that had burned out. I replaced that chip and its been ticking away ever since. This got me to thinking about that Delta clock. Maybe it was the same deal. I did some research on the web, founf the data sheet for the hex inverter. All I had was an 74LS04, but it worked!