Eric Barbour wrote:This circuit requires a fairly "hot" signal, as it is not really an amplifier in the usual sense. I recommend at least 10v p-p
That is I think at least part of the problem. There is constant balance issues. The carrier oscillator in the TM-1 is transistor based if I remember correctly from poking around.
There are two versions of the TM-1: the early version has a switch to "activate ring mod" and the second has a volume pot for the ring mod. Both had three tubes inside.
The carrier oscillator is about in the DBA Space Ring range (I'd say 2000hz max maybe to like 100 hz maybe...just a guess based on ear and memory). If I remember correctly, there was the Beam Grid tube mentioned in the article above that was the wave shaping (beam grid stuff). There was a 12ax7 too I think (probably a amp stage). In the manual, there was a line that states if using with a guitar or other lower output source that it would need to be amplified the heck out of to get the most out of the TM-1 and suggested a digital preamp for best results.
Functionally, they are just very hard to use from a guitar standpoint (or even as just a normal processor). Kinda seemed like the whole setup needed to be prepared specifically for the TM-1 to run it to its full potential. I also think that a guitar signal might not be diverse enough to get the most out of the waveshaper (in most circumstances).
Eric Barbour wrote:By varying the screen voltage between the plate supply voltage and the actual plate idle voltage, drift effects take over, and the peaks of the waveform start to fold over on themselves. Moreover, this folding is not sharp, as in the famed Serge "waveshaper" circuit of the 1970s. It also happens on top of the modulation, causing some very strange and distinctive effects.By varying the screen voltage between the plate supply voltage and the actual plate idle voltage, drift effects take over, and the peaks of the waveform start to fold over on themselves. Moreover, this folding is not sharp, as in the famed Serge "waveshaper" circuit of the 1970s. It also happens on top of the modulation, causing some very strange and distinctive effects.
I think that is a good way to describe the TM-1. This circuit is probably just the front end of the TM-1. There is a "functional" range to the waveshaper controls that are most effective when in the around 10% range marked near the pots. Outside of those ranges, it is kind of just a distortion.
The combination of the two circuits probably work well with really hot, diverse signals where the changes are less subtle to the ear. It also felt like the waveshaper was important to just get the signal prepared for the modulation stage. Like, can't have one without the other.
Eric Barbour wrote:giving a very good ring modulator effect, with reasonable carrier suppression (provided the input and modulation signals were fairly high in peak voltage). So far, this sounds similar to the differential-amp balanced modulator seen in IC form.
The push pull between the two deflection plates is acting like two gates switching (in this guy's ignorant terms, I guess) between two signals. Then they go to an amplification stage I guess (which is the 12ax7) which is probably why I hear the sound "raptio into superfuzz". So the modulation is actually controlled by a kind of sort of outside clock (ac push pull) instead of opening based on amplitude of the incoming waveforms. It is kinda like switching back and forth really fast with a relay or transistor switch (right?). I dunno. It just feels and sounds different overall to me.
It is probably better in a oscillator/synth/modulator setup than guitar.
But, ramble, ramble, ramble...yea, those circuits are in the TM-1 plus a gain stage/amp at the end (or somewheres) as far as I can tell.
Or, I'm an idiot haha. Just looking at things the way they make sense to me. I guess ic based balanced ain't that much difference in theory to an ac push pull switching setup probably.
Hopefully they fixed the carrier bleed from the first one.
