Ive tried the ramp and triangle outputs of your vco, both sound different after going through but not as hairy as i expected even when everything’s at 11
yeah unfortunately simple waveforms going into distortions and overdrives dont tend to come out very interesting. the safety valve for instance accentuates harmonics here and there in the sound, a simple triangle/square/sawtooth doesn’t really have much for the valve to “chew” on to make interesting, likely the triangle and sawtooth just sound a bit more of a bloated version of themselves. it gets interesting when other things happen for instance transient sounds are put in like drums, as this has things for the valve to accentuate, or a waveform going into a filter this will have things to accentuate in its sound, sadly static waves just yeah sound not that interesting going through it, or any sort of overdrive for that matter, without other things being done to them for instance wave folding etc. I hope that makes sense!
do you have any other modules??? a filter? delay? anything to funky thee waveform up a bit??? before it goes into the distortion?
another example is a guitar, the guitar suits saturating overdriving effects well because there are a lot of other parts to the sound on top of the carrying note from the vibration of the strings, overtones and buzzes that can be accentuated, that are not present in simple waveforms from a simple oscillator for instance
likely it sounds like both of the modules you are using work perfectly! though 
another example if you have a vca. or anything to adjust the level of the oscillator going into the safety valve, that will adjust the sound even, especially triangle waves
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Ah right all is clear now, stuck jn the funky filter and splashback delay and now it sounds killer
Cheers for the help
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What is the 10k resistor from the opamp pin 5 to ground for?
I built a stripboard/point to point version and it was kind of weak sounding.
I removed the 10k resistor from the non inverting input to ground and it doesn’t seem to fart out as much on low volume settings. Also, the volume control range is much nicer, probably because the resistor alters the taper of the volume pot.
I can even plug in my bass guitar now via a buffer, which sounds very cool.
Maybe it’s because i’m using used ecc82’s? I haven’t found any problems yet so for now i’m leaving out the resistor 
With R3 in place the signal is attenuated by a voltage divider which has the upper part of RV3 over the parallel combination of the lower part and R3. (RV3 is B100k). Removing R3 increases the latter resistance, so increases the signal level. It also linearizes the response to the pot which with R3 in place is very nonlinear:
(I think that’s more or less right, it assumes the impedence into RV3 is small.)
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Thanks! It’s what i expected it to be for. Very nice that you made the little graph!
I only have two oscillators to test it out with at this moment, which are both not very hot. As well as my passive bass guitar. Maybe the 10k is better with higher synth levels. I’m going to make a switch for it probably. And maybe a little guitar pedal style boost module to go with it
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yeah that’s cool!!! always good to mod stuff thats what its all about cool!
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Ok guys, I have read through this thread and am wondering what the consensus was on the 27R resistor? Change it to a 10R 1/4w, short it out or does it need a 1/2 watt? I am just about to populate the board so would rather solder once and not have to get the solder sucker out. 
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It’s easier to reduce or eliminate a resistor after soldering it (add a resistor in parallel, or a jumper) than it is to increase it. And higher wattage does no harm if there’s space for it so… if still in doubt, go with 27R 1/2 W.
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Thanks for the fast reply. I just searched high and low for some 1/2w 27R but have none. I am going to put two 56R in parallel instead.
Not having a lot of luck with this one. 
It “works”, the valve gets warm and the LED lights up (not using sockets, but I bent the valve pins a bit so the connection is good), but the ‘on’ volume is a lot lower than than the ‘off’ volume. There is some change to the sound, but it’s a bit more like a saturating compressor than the crazy distortion I was hoping for. It doesn’t self-oscillate. I tried adding a jumper across the 27R but nothing changed, and adding a jumper across R3 just made it stop working entirely, but maybe that was a sloppy solder job. I snipped that jumper and it’s back to how it was before, I’ll worry about the taper after it works properly.
Any ideas? =/
Okay!!! Just kidding!
It’s pretty weird, but it does seem to seem to work now! With the 27R jumper, all knobs turned all the way to the right, then putting in a signal from the VCO to let it warm, then removing the VCO input, it self oscillates! Once it’s oscillating, removing the jumper will cause the pitch to go higher and higher until it’s inaudible, then the light will fade off and there will be nothing. Retouching the jumper will make the pitch drop and the light come back on again.
To anybody building this for the first time, I’d say skip the 27R and replace with a jumper. To install the tube, put it through the board then bend the pins back as much as you can outwards to make a good connection, then pull the valve back through towards you from the front, so the connection is really, really tight.
EDIT: It’s still a bit finnicky and doesn’t boost as much as I want it to. Still, it self oscillates a nice low bass note, and it has some effect on the sound, especially if the sound is already loud and a weird waveform.
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I don’t think you want to jumper r3. I removed it entirely, which seemed to help a bit with low signal levels. You’d want to replace the pot with an audio taper though.
The 27ohm resistor is there to limit the inrush current, but will also limit the heater voltage to 8 volts, while it should be 12. Some good tubes may still work, but in reality this is way too low to have good electron emission. This means gain will be lower (already really low at 12volts anode voltage) and performance will not be stable.
Also, in the long run, this will be bad for the tube because the filament will lose it’s emissive properties.
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I’ve built mine yesterday with this tube (JJ Electronic - ECC83S - 12AX7, 7025) and got no output when “on” with input from 1222. Bypassed it works just fine. The 3mm diode is on. I tried 27r 0.6W, 10r 1/4W and now I have jumper across. It’s powered by standalone PSU. Should I desolder the tube and try another maybe from Electro Harmonix?
Thank you for answers.
just to be sure, Is it a +12/-12V ?
maybe check here 
Thank you for answer,
yup, I’ve got two FC power supplies in modular case and one standalone for testing I’ve got plenty modules from Sam so it’s not my first rodeo. But I’ve got stuck on this one. When bypass is on it’s working fine.
bypass is just a connection between input and output jack, even if the module does not work and even without power the bypass should still work.
maybe check again your components, your solder …
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Thank you for reply, I guess some reflowing job didn’t kill anyone… yet. I’ll try it.
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Its the valve I have , so should work.
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Thank you all for advices, I didn’t know how big “plonker” I am. I’ve used TL082 instead of TL072 and got little short on 1uF legs. I guess no more wine & soldering for me 
So I replaced caps, IC and reflowed near everything but still no output for me. D1 is only on when I touch some joints on volume pot or pins 6, 7 on tube and these are moments of grounding hum joy (at least some kind of sound). Got any tips pals or is it dead?
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