Stompboxology Ring Modu-Matic

[soggybag]

I have always wanted to build this Ring Modulator from Stompboxology. I found the Schematic very difficult to read. I just redrew it with Eagle PCB. Maybe someone else will find this useful.

This project has some very interesting ideas. It runs on a single 9v supply. But, it also uses a 5v and half 9v and half 5v voltages also. The carrier oscillator uses the 9v supply. While the rest of the circuit uses the 5v supply.

The carrier is run through an adjustable low pass filter. I'm guessing this softens the triangle wave form into more of a sine to cut down on harmonics.

There is a interesting approach to stopping the carrier oscillator that uses a PNP transistor.

I've been trying to make PCB for this using Eagle. I'm on my third attempt... Eagle is new to me, there is a lot to learn.
http://www.super-freq.com/?p=127

[Taylor]

I'll be very interested if you work up a PCB layout. I've been very interested in the Stompboxology ring mods. I've heard many people say this Boscorelli guy (if he exists) makes his designs overly complex, but they are very interesting, and clearly a lot of thought has gone into them.

I find lowpassing both the carrier and the instrument gives nicer (to me) sounds. Lowpassing the output can also give you just the lower sideband, somewhat like a frequency shifter.

[soggybag]

Filtering the output sounds like a good idea. I hadn't thought of that.

[soggybag]

I'll post the PCB when it's finished. I'm new to Eagle, so the process is involving a lot of trial and error. I made about our aborted attempts at the board so far. I just deleted each and started from scratch each time. This current version I'm working on looks like it will work out.

[Taylor]

Have you seen the other Stompboxology ring mods?

http://moosapotamus.net/IDEAS/stompboxology/RingMods.htm

I haven't looked through them in depth, so I don't remember offhand what all the differences are. Some have LFOs to control the oscillator, stuff like that. It's a really nice article that explains many different paths to ring modulation, and what advantages and disadvantages there are to each.

[soggybag]

I bought several of the issues that Charlie posted, from Mr. Boscorelli through his Stompboxology.com web site. I traded with another forum member (I forget who) to collect as many Stompboxology issues as I could and Charlie offered to post them.

I've had the Ring Mod issue for almost ten years! And, I still haven't built anything from it yet! I did order parts to build many of the projects a long time ago. I'm finally getting around to these projects.

On a related topic, I just built up Tremolo-Matic X from the Stompboxology Tremolo issue. I used a PCB another forum member post several years ago. You can look it up. Maybe I'll post this as a topic. It's a great sounding tremolo. It was a pretty easy build. There are several possible mods.

[sean k]

Hey Soggybag, I'm just working up a PCB for the modu-matic on page 4. Is this the one you're interested in. My version is just a freehand one which I'll use sharpie on copper. Do you want to see it?

[soggybag]

Hey Sean, I would like to see your layout. Here's what I have so far. It took me several tries to get this far. The first few tries were complete failures. This one might work. As is there are a few connections missing so what's here will not work yet.



You can see that dual pot in the lower right corner. I'd like to change this to separate pads or to three small pads like the pot in the upper right. I'm pretty new to Eagle so I'm still learning how to get it to do what I want.

I'm having a problem deleting a via I created. You'll notice there's a square pad in the upper/middle right side. I can't seem to delete this? I had created vias to add jumpers. Later I started using the top layer. I'm still not clear on exactly how to add a connection from the bottom layer to the top layer?

[sean k]

This is what I've come up with. I tend to make them with the IC's parallel but it ends up taking alot of space. Have you noticed that the 100k bias resistor that sits on IC4 pin5 and IC3 pin3 is actually repeated by the connection with C ?

[soggybag]

Looks good Sean. I should try another one with your arrangement. I don't think setting the chips parallel necessarily makes the layout larger.

I started over again myself. I'll post another picture when it's worth looking at.

[soggybag]

Here's a new version. This is still not complete. It has all of the traces in place. But the dual gang pot in the lower right is a problem. I added vias for all of the connections to this pot. I'd like to replace this part to get it's pads out of the way. There are a few jumpers in red. C5 needs a trace running to the via.

[Taylor]

How are you going to get your boards made? Since you have a silk screen layer and vias, I'm assuming you're getting pro boards made by a fabrication house. If so, I'll buy one or 2 from you - should make the price a little cheaper. I've built a Ring Stinger, which is awesome, but I also want to have a clean ring modulator.

[sean k]

Heres mine with the first layer of sharpie which I'll go over one more time to beef it up slightly. As you can see it's kinda rough compared to what you guys are doing but I guess if it does the job...

Good work Soggy

[soggybag]

Great work Sean. You are the king with a Sharpie. It's got that old school EH vibe.

[El Heisenberg]

Er, theres a diy stompbox magazine?

[soggybag]

There was around 2000. But it's gone now, it was never popular at the time it existed and the guy that published it has mysteriously vanished and has never been heard of again. There was some talk on the forum a few years ago of hiring a private detective to search for him. All regular searches have turned up nada.

All that's left are a few issues of his new letter and a book. From the numbering of the numbering of the new letter it appears that there are a fair number of these that are some where to be discovered. The new letters are posted here: http://www.moosapotamus.net/IDEAS/stompboxology/stompboxology.html

From the list you can see there must be at least 13 issues which look to come in 4 volumes. Figure it came out quarterly. That would be 52 issues! We have 6 available to us. If the guy had stuck it out another few years I bet his new letter would have caught on.

I found the going discrete issue very informative.

Mo' Trem'lo
Stompboxology  Vol. 4, No. 4

Vibrato-Rama!
Stompboxology  Vol. 5, No. 1

Ring Modulators
Stompboxology  Vol. 8, No. 1

Going Discrete
Stompboxology  Vol. 13, No. 2

Frequency Division & Subharmonic Synthesis
Stompboxology  Vol. 13, No. 3

Envelope Effects
Stompboxology  Vol. 13, No. 4

[Gila_Crisis]

do someone finished to build this? how does it sound?
i really love ring modulators but since now i never built one, 'cause i never founded a reliable project to build!
but this one looks interesting!

[soggybag]

One step closer. I just finished my PCB. I'm going to try and make a board this weekend.

The board was created by an amateur and is completely untested. Use at your own risk!

[Gila_Crisis]

cool! let us just know if it works

[Morocotopo]

On a related topic, I just built up Tremolo-Matic X from the Stompboxology Tremolo issue. I used a PCB another forum member post several years ago. You can look it up. Maybe I'll post this as a topic. It's a great sounding tremolo. It was a pretty easy build. There are several possible mods.

Soggybag, did you built the tremolo-matic X with my PCB? I´d be interested in knowing your impressions of it. I love this tremolo, It´s the best one I´ve ever tried, BUT, I find it a little too noisy, it makes a bit too much white noise... does yours do the same? I´ve refrained from boxing it because of that. I had plans to mod it to try to make it less noisy, or even make a similar FX but with different technology, but never got around to it...