"Crushed Glass" - Low voltage tube obsession gone too far?

[Ben N]

Rick -- a mad scientist in the very best sense.

Thanks

[frequencycentral]

Rick -- a mad scientist in the very best sense.

Thanks

..........I'm a monkey with a machine gun!

[frequencycentral]

Self-effacing bump! Vote for me !! I really need that $100.000 prize money.....!!

http://www.diystompboxes.com/smfforum/index.php?topic=71382.0

[marmora]

Finished my Crushed Glass today!

Sounds great...well, it sounds great if you like noise!  It's loud, it's nasty -  I love it!  Fans of the Atari Punk Console or similar designs will not be disappointed.
I changed the value of C4 to .1uf.  I just wasn't hearing enough change with the original value.  With each frequency control all the way down, the sound cuts out.  Good for a quick on/off control, or so that you can hear one oscillator at a time.
I'm running it at 12v, but I tried 9v to see how it would sound and it works - the tubes just aren't coming to life the same way and the volume is lower.
This would be a great building block for a tube synth or for noise makers.

Here's the layout I used:


I used an IC to show where the tube goes.  Pin 1 of the IC is pin 1 of the tube etc.

Thanks Rick (frequencycentral)!

[frequencycentral]

 

It lives! Wow someone built it! I want soundclips, I need soundclips!

[flood]

of course it lives! i protoed it with 12AU7s, subminis are impossible to find here and shipping to india is meh. besides i have way to many oddballs lying around here.

anyway: i tested it with 12au7s running off 12V. i'm going to build a final version of it, but i'm thinking about wiring the heaters in series and using ECC88s instead - i'm pretty sure we can get some funky peoeeoowowoeoeowoos out of them too, also, they work remarkably well at low voltages. will use a 24V adapter for 12AU7s, and 12V for the 6DJ8s.

rick, i need a bit of help - is the first half of the tube an LFO? call me crazy, but this is a plan i have - use a 6U8 or a 7199 at about 90-150V, set up the pentode as a high gain guitar preamp, and the triode as an LFO to modulate the screen grid.

i actually wondered if i could amplify and rectify the guitar signal with another tube to use it to modulate the oscillator frequency. i know, we'Re well into metasonix territory here, and i should be asking eric barbour instead (i just did)... barbur has a circuit based around VHF triodes using them as PWMs to create pulses.

my objective is to create messed up waveshapers and noise processors, using pentodes, heptodes etc. i can get those tubes pretty cheap locally, or already have a few.

also, any ideas on using the crushed glass as a VCO? get the guitar to modulate the oscillations? i saw somebody do this with an atari punk console on youtube... here's a link - http://www.youtube.com/watch?v=NndG0aCoBa8

i know, a 555 is not *quite* the same thing as a triode... just wanted to know if you thought it possible. thanks!

[rsfc]

Would it be difficult to implement voltage control on these? For modular synth use...

[frequencycentral]

Would it be difficult to implement voltage control on these? For modular synth use...

Probably! You're welcome to try, but I don't see 1v/oct tracking being easy to achieve. Instead, just hook it up to a joystick, stick it through a delay and enjoy the noise. 

[rsfc]

I don't really care about v/oct but it would be nice to bounce around the signal with some voltage.

[frequencycentral]

Maybe the easiest way would be to use LDRs in the feedback path.

[flood]

So I'm resurrecting this very dead thread - Just breadboarded the crushed glass using a 12AU7 last night. Here's my plan - crushed glass, output buffer/mixer, inductorless wah and a 555/4017 sequencer in ONE enclosure as a gift for somebody.

while the other stuff is fairly easy, the crushed glass is a bit hard to control externally - I can verify that using an LED/LDR combo in the feedback path, at 12 V, did very little for me. the only thing i heard was a change in the pulsing. no frequency control as such... on the 100k pot, most of the pitch action seems to be happening within 25k of the travel. so i'll swap the pot out and see if that helps...

More importantly, I'm going to rebuild it with a higher B+ (60-80V) and see what happens. I'm hoping for a change in response, but it's hard to know till you try, right? 60V is not too scary in ters of getting zapped either, Rick's work with miniature boost converters in 1590BB enclosures is astounding. i just found a source for 100uH 1A inductors here, they're on their way - can't wait to try some of those circuits with my own ideas

boy, i sure feel like the thread necromancer here. 

[mac]

So I'm resurrecting this very dead thread

Thanks!

When I heard these cool sounds I thought "Echoes"  
I wonder if fets can do it.

mac

[Thecomedian]

Sorry if this is common knowledge, but what are some substitutes for 6111's?  Is there anything special about them, because I still have a few space charge triodes hanging around.

I hooked on to the 6111 from Dano12's Valvecaster thread, where he used a 6111 in place of a 12AU7 to make his Subcaster. I've breadboarded ideas using the 6111 and then built them using 12AU7. I used two 6111 in my Pepper Shredder build, though the designer recommended 12U7 or 12AU7. So I would say the two are pretty much interchangeable - you just have to change the pinout and power the heaters differently.

How about feeding them both into a ring modulator (couple of rectifier tubes?), and control the whole thing with a joystick.

Yes, yes, yes!! Yes sir, sounds like fun!

As far as necro, I'm glad I have seen this. About the resistor, would it get less hot if you used a 4.3 watt+ resistance? That's the suggested by http://www.mh-audio.nl/DroppingResistor.asp page.

[garcho]

You could use 2 parallel 39 ohm resistors (or 3 56 ohm, or 5 100 ohm), to dissipate the wattage.

[duck_arse]

flood, are you wanting the ldrs/leds to vary the pitch of each section, as a replacement/enhancement for the 100k pots?

[mth5044]

Does anyone have any other low voltage tube synth schematics? Seems like a cool thing to patch together.




....wait I posted in this thread before 

[flood]

quick update - about 70V as B+ did make a difference - the oscillation frequency went way, way up. as did the volume. i haven't scoped it or anything, just threw it together, had a listen and put it off again. am going to muck around with this a bit more.

flood, are you wanting the ldrs/leds to vary the pitch of each section, as a replacement/enhancement for the 100k pots?

well, sort of - i'd like the 100k (or rather 25k, given the usable range) pots to set the base pitch, so to speak, and use an LED/LDR arrangement to vary the pitch. no success so far, i think it may be worthwhile putting the LDR in another place perhaps. needs experimentation.

i'm not looking for perfect Hz/V control or anything (although that would be incredibly cool ) but would like some sort of change using an LFO or simple 4017 sequencer or something.

Does anyone have any other low voltage tube synth schematics? Seems like a cool thing to patch together.

while not really "low" voltage, the metasonix stuff at http://www.cgs.synth.net/tube.html is worth taking a look at.

i'm personally intrigued by the metasonix R-54 supermodule, so i'm going to try and muck around with a 6U8 at 70V and understand how wien bridges work with a solid state clipping section apparently someone got good Hz/V control from the R-54 too.

[duck_arse]

I've "been going to" try this w/ ldrs for the last 3 days now. tomorrow. then, I'll be needing some 7 pin sockets for the 6j6's I've got ......

[duck_arse]

flood, I tried this today, 1 section, just looking at the oscillator output. it works, needs some fiddle.

replace the "top" of the pot with 1M5 (depends on other things) and the "bottom" of the pot with 10k. the ldr in parallel with the 1M5 will lower the f with lower light level.

you can swap the ldr and the 10k resistor, and remove the 1M5. it may behave better/worse, it depends. I was testing with "an ldr", dunno what sort. it was SUPER SENSITIVE, when I juiced the superbright led (in a vactrol), the osc stopped. if I shined a torch through the gaps in the housing, I could get a range like 9Hz~22Hz, with a 47nF cap.

I will try an over and under ldr arrangement tomorrow, maybe.

another fiddle. if you increase the grid resistor on the first section, maybe 3M3, lose the pot and connect the cap straight to the grid. then put a 100k trim and yr ldr in series to ground, across the grid resistor. trim the pot till the osc stops, then back up a bit. my note says "brighter = faster". only 2:1 frequency change was all I got at 12V, 60 might be a different proposition.

and I need a super-dull led, because my ldr didn't want any light shining on it, it seems. I was testing the range with a pot/led combo. this oscillator is the same as the "pulsar", except w/ glass.

[flood]

whoa, awesome, gonna try this immediately - i was about to hit the breadboard and decided to check back here before. the other thing i'll be trying is replacing the 1M resistor at the grid of the second triode with the LED/LDR arrangement. let's see how this goes...