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Transformers For CGS67 Active Ring Mod - UK/EU
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Transformers For CGS67 Active Ring Mod - UK/EU
Reality Checkpoint
I am contemplating building the CGS67 Active Ring Mod: http://www.elby-designs.com/webtek/cgs/cgs67/cgs67_rrm2.html

The design calls for 2x 3K:3KCT Coupling Transformers, and I am having a devil of a time tracking them down. I think my google-fu is lacking right now, so if anyone has a link for them in the UK or EU, I would be most grateful to receive it. thumbs up
Revok
I think many center tapped audio transformers will work for this.

"It is best to use a transformer with an impedance of 3k or greater, though lower impedance coils will work. Note that the DC resistance of the coils is much lower than the specified impedance. If the transformer you buy has both coils center tapped, just ignore or cut off the center tap wire on one coil."
-CGSRR Real Ring Modulator page

The passive page also lists the Mouser# 42TM018-RC for a 10kCT-10kCT audio transformer. LT44 has also been used for passive ring mods which is 10k-2kCT and might be more easily found in the UK/EU. It looks like this UK company carries them:
https://www.esr.co.uk/electronics/transformer-audio.htm
Jarno
Rapid has these:
https://www.rapidonline.com/vigortronix-vtx-101-007-pcb-audio-transfor mer-88-2124

According to datasheet, 2.4k:2.4k, and centertapped (well,two separate windings). Should be good.
I used hunkin'big Edcor transformers for mine, but because of the low impedance, I needed driver amps for it.
Reality Checkpoint
Thank you for the replies. I hadn't noticed the CGSRR when browsing the Elby site.

Now that I find that I can get these transformers I will go ahead and order up a pcb. (I have gone with the Mouser# 42TM018-RC as I am about to do a big order with them anyway.)
Rex Coil 7
Jarno wrote:
Rapid has these:
https://www.rapidonline.com/vigortronix-vtx-101-007-pcb-audio-transfor mer-88-2124

According to datasheet, 2.4k:2.4k, and centertapped (well,two separate windings). Should be good.
I used hunkin'big Edcor transformers for mine, but because of the low impedance, I needed driver amps for it.


LINK =
https://www.edcorusa.com/xsm_series

$15.00 bucks USD each plus shipping. 20hz to 20khz freq response (per their webpage, linked above).



I've built a number of the "Real Ring Modulators". I use 3mm blue "water clear" LEDs as diodes instead of the same-old/same-old germanium diodes. Works WAAAYY better.



Rockin' Banana!
Reality Checkpoint
Thank you Rex!

I looked at the Edcor site, and apparently they build them to order with a lead time of 8 weeks. sad banana

Interesting to hear about the LEDs instead of germaniums. In what respect do they work 'way' better?
Rex Coil 7
Reality Checkpoint wrote:
Thank you Rex!

I looked at the Edcor site, and apparently they build them to order with a lead time of 8 weeks. sad banana

Interesting to hear about the LEDs instead of germaniums. In what respect do they work 'way' better?
They don't pull the signal level down anywhere near as much as the germaniums do. Germaniums also tend to remove a lot of low end, and emphasize mid range. The LEDs are far more "full range", there's a lot more low end. They also leave far more of the signal level intact so the sound isn't anywhere near as quiet coming out of the ring modulator. I put one between two Dot Com VCO outputs (one VCO as modulator, one VCO as carrier) ... actually, I use FOUR of those CGS Real Ring Mods in my own 5U modular ... they are built into the cabinet and are normalized to the 4 VCO outputs at various junctures. The picture below is the ring mod controller panel for all four of them in my rig. I then boost the output of the ring modulator, but not very much, by using a feedback circuit on the mixer I use to mix the ring mod output with the "dry" VCO outputs. The feedback circuit (just running the mixer output right back into the input ... like the old Minimoog trick) produces plenty enough signal boost for the ring mods so there is no need for an active signal booster of any kind.

So far more of a "full range" frequency response, and less gain drop. OH WAIT! ... and also the LEDs do not distort nearly as easily as the germaniums (it takes a LOT more input gain to make the LEDs clip). When the LEDs are driven to clipping, it's a much different type of clipping sound. Not as midrange heavy, less "fizzy" and more "crunchy", and of course more output gain level is available.

So .... "WAY better" .... at least from my perspective!

I am building a custom fuzz/processor/EQ/thing for a fella that is going to use it with his Serge/Buchla rig, it will have one of these passive/transformer type ring mods with my LEDs-as-diodes recipe going on inside of it. Now that I think of it, you may even know that guy?!??!

seriously, i just don't get it













Reality Checkpoint
Thank you again for the comprehensive reply - makes things much clearer for me.

Rex Coil 7 wrote:
Now that I think of it, you may even know that guy?!??!


I couldn't possibly comment!

MapacheRaper
I love the idea of replacing germaniums with blue leds. Thanks for sharing!

Do you think this could be useful for distortion/fuzz and another circuits?

The cheaper transformers that I found when looking to build this circuit:

https://www.ebay.es/itm/2X-LT44-Transformer-and-4-X-BAT48-Schottky-Dio des-Ring-Modulator-Kit-ff/111235853074
Rex Coil 7
MapacheRaper wrote:
I love the idea of replacing germaniums with blue leds. Thanks for sharing!
Thank you very much.

MapacheRaper wrote:
Do you think this could be useful for distortion/fuzz and another circuits?
Yes, absolutely. I built roughly 300+ guitar pedals using these same methods and ideas over the course of about ten years. Here's a few examples .....













I stopped building these about four years (maybe five?) ago ... I just wanted out of the industry. I primarily sold to recording/touring professionals. But when the mainstream consumers began wanting my designs everything changed in a negative way. I just wanted to serve the professional players, I didn't want to deal with consumers that were accustomed to return policies and free shipping and immediate delivery expectations of mainstream consumers. Everything I built was 100% hand made, one at a time. Professional players understand what that means, mainstream consumers do not. So I got out.

(Jan 07, 2019 - I talk too much! ... I'm no longer monitoring this thread, please feel free to send me a private message if you wish to correspond, I'll be happy to hear from you)

thumbs up
SoundPool
Reality Checkpoint wrote:
Thank you Rex!

I looked at the Edcor site, and apparently they build them to order with a lead time of 8 weeks. sad banana

Interesting to hear about the LEDs instead of germaniums. In what respect do they work 'way' better?


Unfortunately Edcor's cost much more in Europe than in the USA (taxes but mostly shipping weight I imagine). This is the only place I've found that seems to stock the model you would probably want to go with for either the active or passive ring mod, but much more $ than in the US. https://www.don-audio.com/Edcor-WSM10K-10K
Reality Checkpoint
Thank you!!

Wish I had seen this an hour ago before I clicked the complete order button on my Mouser order. Oh well, at least I know where to get them from in the future.
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