2857

I’m not familiar with this; how would you patch this up in a DUSG?

1 Like
2858

I don’t think you can, as the DUSG doesn’t have a Hold input (along with the Window output one of the '73 EG’s more interesting features) – anyway the idea is to have the EG cycling at high speed and to have a gate from another EG (or anywhere else) holding it at regular intervals: in addition you have to have something modulating the EG cycle rate and/or window size, otherwise you’ll get periodic sequences (which can also be useful of course).

1 Like
2859

If this is a joke, it’s a good one!
Your recording also sounds like proper fm radio.

Anyway, you gave me an idea for a patch, so thnx for that.

1 Like
2860

I can assure you it’s not a joke! I was totally surprised. I’m very genuinely curious for someone to explain how this is happening.

I just flipped the system on again and it is still doing this. Mind you, the level is quite low so I have to boost the output a bit, but it is definitely audible and recordable. Here’s a recording I just pulled now using the exact same patch. This time, I start the recording with my fingers not touching the end of the patch cable so you can hear the background noise/feedback. Then the instant I contact the banana cable end, the radio signal comes in. About halfway through I un-touch and touch the cable again.

To start, I’m trying to figure out if it’s something specific about my environment or setup that is causing this, or whether it’s something that anyone with a (Serge) ring mod can patch.

2 Likes
2861

I don’t get any sound with this patch. Just tried it. Absolute nada.

2862

Hmm! The mystery grows. Can I ask what your setup is (e.g. 4U, 3U, R*S, Paperface, etc)? Just to try and narrow down the root cause?

Also, I highly somewhat suspect that it could be dependent on how conductive your finger is. Like if your skin is really really dry, it might not work. Unlikely though.

2863

I don’t quite know how it happens, but I’ve actually had this experience as well, back when I had Eurorack. If I turned up a distortion module I had enough, and turned the gain up on my output, I could get radio signals.

3 Likes
2864

I’m on a 3U R*S system. You mean the output of the Ring right? How is that suppose to make a sound? The ring doesn’t produce any sound even if in a feedback patch (sending output back to the inputs).

1 Like
2865

Yeah. I’m listening to the Ring Mod out. I wonder if it matters that I’m on a banana 4U system, since the cables don’t carry ground like the Eurorack cables do (totally grasping at straws here).

So, I’m not saying that it’s producing any proper output. It’s kind of like what @diodemover mentioned above – it sounds kind of like just low noise initially, but if you turn up the output then it becomes clearly audible.

In fact I bumped into this while setting up a real feedback patch on the Ring Mod, as I was about to patch the open cable into something. But as soon as I touched it, I heard this static-y noise which turned out to be radio. I don’t have an explanation for why this is happening – hence why I’m asking!

1 Like
2866

I really love the hold input on the 73 EG, I’ve been looking at ways to add the same functionality to the DUSG (I have another 2 panels serge system from 1978 to build). Serge himself proposed to jut stick a -10V offset to the CV input but even if it slows it quite a lot, it’s still rising/falling. Someone already achieved it by interrupting the integrator with a vc switch, but in involves quite a lot of added circuitry, so I’m not sure to go this way.
Still a DUSG with HOLD and CYCLE inputs is tempting so it may worth the effort :slight_smile:

1 Like
2867

Ya, if I understand correctly a ring mod is essentially an AM radio modulator/demodulator… and your patch cable is essentially an antenna… Looking at a possibly similar schematic it looks like there is an option for a LPF on the output (the optional capacitor across the output opamp). If that wasn’t there, that opamp could easily be running at above audio rates to acquire an am signal… maybe?

Screenshot_20240115_082152
Screenshot_20240115_0821521079×1303 101 KB

So from a very broad inspection to have the signal from the antenna being multiplied (x * y) by a potentially very fast oscillation (opamp potentially running higher than audio rates because of no capacitor limiting it on the high end).

If you can get an eye on the pcb here is the location of C1 (at least on this version… In the white circle.

Screenshot_20240115_091154
Screenshot_20240115_0911541080×248 80.7 KB

5 Likes
2868

I’ve never gotten radio interference through the ring mod of my Sing to Me-ish panel but I do sometimes hear radio through the lower section of the Wave Mult. I moved my system around my room until I found the least amount of radio signal. I get radio through my guitar sometimes and the fix is usually just shifting my playing position.

2869

undoubtedly :slight_smile: this reminds me of a (possibly dumb) question though, whose answer has eluded me for a while (never having used a DUSG): what extra functionality is there actually in the DUSG that isn’t there in the positive/negative slews and/or the '73 EG? I mean I do know it’s basically a positive and negative slew chained together which obviously saves trouble and patchcords, but what can it do that those earlier models can’t? (meaning, I guess: if I was designing a panel and space wasn’t an issue, why would I want DUSGs instead of individual pos/neg slews and '73 EGs?)

2870

I think the main advantage often cited is better tracking and a higher frequency range. The DUSG in my opinion trades off cv utility for better performance as an oscillator.

3 Likes
2871

I guess it’s less of a (pseudo) S&H per se, and more a “stepped random” output? That is, it replicates one common use of a S&H, but the lack of an input means you are not really sampling some existing voltage source?

2872

yes, exactly – maybe imitates rather than replicates, and in fact “pseudo-random stepped CV” would probably be a more accurate title for what it’s doing (as even with the added modulation to make it less periodic, of course nothing truly random is happening)… but fwiw it’s a serviceable workaround to get pretty close to that classic S&H bleep-bloop effect without having the actual function blocks for it.

I do have the 1975 Noise Source on another pair of panels here that’s waiting to be put together, I don’t expect to be using this workaround too much after I finally get those working…

1 Like
2873

As @q_ben replied the main advantage to me is the way higher frequency range, I found myself frustrated more than one time by the low-to-mid range of the earlier designs, even more when working with subharmonics.
Apart from that I really love the openness of the POS/NEG slews/EG, I found them more patch-programmable than the later DUSG in this regard. I think I’ll be really happy to have both when I’ll get to build my second set of panels :slight_smile:

I wonder if Serge/Random*Source worked on this (max frequency range) for their recently released Paperface panels, or if the circuits are identical to the originals.

2 Likes
2874

This may or may be the best place to ask but is there a Serge themed podcast out there in the world? I’m thinking of a Serge/LW equivalent of Source of Uncertainty, which has Buchla-related interview, module explorations and performances. Audio, not video.

4 Likes
2875

I abandoned the 73 oscillator for my take on the NTO/PCO for similar reasons. The PCO core will go well into the ultrasonic and is great for stuff like subharmonics.

1 Like
2876

Yeah on my Homebuilt the 73 VCO tops out at something like 5khz, I spent hours on the issue but somehow never managed to fix/debug it (I think its supposed to go up to ~12khz), I should get back to it someday.

I didn’t knew you also designed your own NTO/PCOs! Did you implemented a pulse out or something else on the PCO? (We chatted on the serge discord about my Haible pcbs :wink: )