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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Sun May 18, 2008 7:45 pm Post subject:
FM with triangle-core VCOs |
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The Buchlas produce exponential FM tones unlike sawtooth core oscillators. The overtone content is more limited and sweeter, yet can easily be driven into chaotic results (pitched noise).
Ian is working on a new triangle-core oscillator with very wide-range tracking, and the Thomas Henry VCO-1 is reputed to be a triangle core. I look forward to hearing sine-to-sine FM experiments on each.
For those who are interested in deep index FM, I can see why "stability" could be of concern. As the results would be far more interesting than with sawtooth oscillators, that is. My question is, is stability, even to digital mimicry, important to you regarding such FM depths? A touch of natural noise in oscillator pitch just ruins things completely?
Example of Buchla FM, IIRC including all "noise" tones:
http://virb.com/peake, click play. Is the pitch movement too much for your tastes? Note that this was using a vintage Buchla power supply, not an Eagle or Power One.
This is to increase interest in triangle-core oscillators. The Plan B's FM index isn't as deep, but could probably easily be modified. Topp's upcoming through-zero VCO is triangle-core, right? I'll need a few of those |
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cbm
Joined: Oct 25, 2005 Posts: 381 Location: San Francisco
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Posted: Sun May 18, 2008 8:27 pm Post subject:
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Nice example
-Chris _________________ Chris Muir
http://www.eardrill.com <– My jobby (more than a hobby, less than a job) |
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v-un-v
Janitor
Joined: May 16, 2005 Posts: 8933 Location: Birmingham, England, UK
Audio files: 11
G2 patch files: 1
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Posted: Mon May 19, 2008 1:02 am Post subject:
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Great track Peake! _________________ ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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asafnetzer
Joined: Jun 16, 2007 Posts: 112 Location: Israel
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Posted: Mon May 19, 2008 4:03 am Post subject:
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Very nice Mike, would have never guessed the source. |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Mon May 19, 2008 8:28 am Post subject:
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While I'm happy with my track, I'm not intending to pimp it- I want to generate interest and discussion among those who can create such things! It's a timbral range that some either aren't aware of or don't yet have access to. I'm looking to find all of the sources, and to confirm this sort of behaviour in other triangle-core oscillators. Any thoughts or demos??? |
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GlassX
Joined: Jan 27, 2008 Posts: 50 Location: Brazil
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Posted: Mon May 19, 2008 8:21 pm Post subject:
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What a fantastic topic! And just in time...
I'm not as experienced as Mr Fritz and Mr Henry, I am finishing my triangle core VCO too. It is a completely novel and very simple design. It also switches to a sawtooth core with just one switch. I have it working on a breadboard already, but I'm gonna build a dual version as soon as I can. The FM simulations on SPICE sound great. I tried using thru-zero and it works, with the advantage that it is **VERY** simple to implement on this core. No, I mean EXTREMELY simple - maybe easier than Sync. By building a Dual-VCO module, I can use the Schmitt-Trigger of the first oscillator to reverse the direction of the second.
It works fantastically and I'm just doing some preliminary tests to reduce the offsets and improve thermal stability. I'll try better op-amps and a tempco resistor...
I'm also experimenting a lot with waveshapers, but even as a huge Buchla fan (can you tell? ), I'm not much impressed at all with the Buchla Timbre-Symmetry-Order scheme. The low-order part is just a wavefolder, easily replicable with FM just by having a carrier at the same frequency. The high-order part (absent on the Music Easel) is just a clever mix of regular waves. I'll probably not use timbre modulation at all Maybe a PIC and some wavetables? Who knows!
PS: Your track sounds awesome! I downloaded it to my iPod! Last edited by GlassX on Mon May 19, 2008 8:41 pm; edited 1 time in total |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
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Posted: Mon May 19, 2008 8:39 pm Post subject:
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Very interesting- I look forward to hearing and seeing it, and perhaps building it |
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norman phay
Joined: Jun 29, 2007 Posts: 176 Location: North-East England
Audio files: 1
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Posted: Tue May 20, 2008 3:41 am Post subject:
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The only tri-core VCOs I have are a pair of the Plan B ones, I've experimented with having them modulate each other at the same time, but only with the lin FM input for some reason. I'll have a try with exp fm when I put together this powersupply box I have here. All the other VCOs I have - a pair of ModCan, a pair of MOTM, three Wiards and a single Blacet are saw-core to the best of my knowledge. I'm just finishing up a pair of Oakley VCOs, I've got one going, the other just needs the remining wires soldered in behind the panel. Although they all sound (quite surprisingly) different in their raw state, I don't hear any particular sonic signature that sets the Plan B ones far apart from the others. They are very good oscillators, though, I'm pleased with them.
The Oakleys seem to have the widest-ranging FM depth out of the ones I own, this could be an interesting thing to talk about on another thread, maybe on the modular synthesis sub-board - how different features are implemented across different versions of "the same thing". It's certainly good to have different manufacturer's oscillators because of this.
I've had that impart tangent piece in my computer ever since you posted it on either AH ot T-G-S a while ago, Mike. I think it's very good, when I look in my music mp3s folder, it's often the first thing I'll put on. |
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3vcos
Joined: Oct 26, 2006 Posts: 106 Location: California
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Posted: Tue May 20, 2008 2:27 pm Post subject:
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Wiard VCOs are Triaingle core!
Norman Phay wrote: | All the other VCOs I have - a pair of ModCan, a pair of MOTM, three Wiards and a single Blacet are saw-core to the best of my knowledge. . |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Tue May 20, 2008 4:53 pm Post subject:
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3vcos wrote: | Wiard VCOs are Triaingle core! |
Really? Are you pulling my leg? I've only heard linear FM on those- does anyone have exponential sine-to-sine FM MP3s? |
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3vcos
Joined: Oct 26, 2006 Posts: 106 Location: California
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Posted: Wed May 21, 2008 5:47 am Post subject:
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Yup, I'm certain they are. That said, I'm having a hard time remembering where I got that info. I've spoken with Grant numerous time and been on his yahoo group for quite a few years. I have a feeling I picked it up from him or his wiard yahoo group.
I briefly owned a Wiard VCO and regret selling it very much.
Peake wrote: | 3vcos wrote: | Wiard VCOs are Triaingle core! |
Really? Are you pulling my leg? I've only heard linear FM on those- does anyone have exponential sine-to-sine FM MP3s? |
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ryktnk
Joined: Apr 24, 2008 Posts: 285 Location: london
Audio files: 1
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Posted: Wed May 21, 2008 6:02 am Post subject:
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Hello
Do you mean the FM input of the 258 module, or the control input ?
The FM input is linear, the control input is expo.
I have tried to test this with the TH vco1 and the Electronotes TZO.
Both oscillators needed to have the FM input "untamed" a bit for
stronger depth, also taking off the DC coupling helps for stronger
sound.
Using linear or expo FM on both VCO's creates some pretty crazy
sounds, but not "noise" in the random sense.
Patching a 2nd modulation oscillator into the FM gives much more
noise-like unpredictable sound.
-ryktnk |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Wed May 21, 2008 7:44 am Post subject:
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Hi, the Buchla 258c has linear FM and can be identified by the three audio outputs per oscillator. The B and as far as I know the A and all 1xx models had exponential FM. Also IIRC the 258b has a cap in the FM input path. I may be hooking up a soundcard this week so I'll post solo examples if possible.
The best linear FM I've heard is also on the Wiard... |
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shebb
Joined: May 07, 2008 Posts: 12 Location: usa
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Posted: Wed May 21, 2008 5:33 pm Post subject:
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sounds great
a couple questions, hope it doesn't count as a hijack...
is the difference between linear and exponential just a matter of CV input scaling.
also, why is thru zero any better than this? |
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GlassX
Joined: Jan 27, 2008 Posts: 50 Location: Brazil
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Posted: Wed May 21, 2008 5:46 pm Post subject:
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shebb wrote: | is the difference between linear and exponential just a matter of CV input scaling. |
Yep! Exponential is just 1Volt/Octave modulation. Linear is Volts/Hertz modulation.
Quote: | also, why is thru zero any better than this? |
Thru-zero is just linear frequency modulation with time-reversal. Meaning that the carrier oscillator reverses direction when the modulator changes polarity. For me, it is just a fancy term for Sync. I like it because it locks one oscillator to the other, making tuning muuuuch easier. |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Wed May 21, 2008 5:47 pm Post subject:
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That would be a hijack, but it appears that my questions may go unanswered, so I say let there be hihack |
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GlassX
Joined: Jan 27, 2008 Posts: 50 Location: Brazil
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Posted: Wed May 21, 2008 6:01 pm Post subject:
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Peake wrote: | That would be a hijack, but it appears that my questions may go unanswered, so I say let there be hihack |
I believe I sort of answered to your stability question on my last reply already
Regular linear FM needs HIGH accuracy. I've seen Buchla 200e users complaining that some settings make the carrier oscillator sound out of tune. That's not the 200e fault - just how regular linear FM works.
With the time-reversal sync thingy you can have the two oscillators sort of oscillating together, so, drift will sound like regular vibrato and won't change the timbre, make terrible noises or make your output sound out of tune. |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Wed May 21, 2008 6:10 pm Post subject:
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GlassX wrote: | I believe I sort of answered to your stability question on my last reply already |
Yes, and thank you, and thank you for presenting your project! I'm now after audio examples of the TH VCO-1 and Ian's, when it's available, to see if the Buchla has something that no other does.
GlassX wrote: | Regular linear FM needs HIGH accuracy. I've seen Buchla 200e users complaining that some settings make the carrier oscillator sound out of tune. That's not the 200e fault - just how regular linear FM works.
With the time-reversal sync thingy you can have the two oscillators sort of oscillating together, so, drift will sound like regular vibrato and won't change the timbre, make terrible noises or make your output sound out of tune. |
Linear FM does very little for me, and I wouldn't care if it never appeared on any oscillator in my setup...through-zero, if it approximates Chowning FM, would be very desirable, however... |
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GlassX
Joined: Jan 27, 2008 Posts: 50 Location: Brazil
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Posted: Wed May 21, 2008 6:19 pm Post subject:
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Peake wrote: | Linear FM does very little for me, and I wouldn't care if it never appeared on any oscillator in my setup...through-zero, if it approximates Chowning FM, would be very desirable, however... |
But Chowning FM IS linear...
I didn't notice you were talking about Expo FM on the original post... Now, I feel stupid, because I don't even remember when I used Expo FM... maybe just on an ARP2600 to make noise, I believe... |
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ian-s
Joined: Apr 01, 2004 Posts: 2670 Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626
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Posted: Wed May 21, 2008 6:39 pm Post subject:
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GlassX wrote: | I don't even remember when I used Expo FM |
It would be my preferred input for patching vibrato
I think patching the modulator via a high pass filter would get closer to Chowning style FM, which is actually phase modulation.
There are probably quite a few categories of Chowning FM sounds that don't require high accuracy. Bells for example. A lot of DX sounds detune operators intentionally to add motion etc. |
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GlassX
Joined: Jan 27, 2008 Posts: 50 Location: Brazil
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Posted: Wed May 21, 2008 6:44 pm Post subject:
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g2ian wrote: | It would be my preferred input for patching vibrato |
Oh, mine too! But I was only thinking about audio-rate FM |
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shebb
Joined: May 07, 2008 Posts: 12 Location: usa
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Posted: Wed May 21, 2008 6:57 pm Post subject:
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for me this was a very informative hijack!
I'll probably end up staring a topic anyway, this thru-zero stuff is confusing |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Wed May 21, 2008 7:32 pm Post subject:
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One of the most informative hijacks I've seen, indeed!
GlassX, if you want, check the first post for a track using a lot of exponential audio-rate FM on unstable oscillators and a very unstable vintage power supply. |
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ryktnk
Joined: Apr 24, 2008 Posts: 285 Location: london
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Posted: Thu May 22, 2008 11:45 am Post subject:
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- Last edited by ryktnk on Sun Oct 19, 2008 11:05 am; edited 1 time in total |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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