oh cool! however quite intriguing the input of the PO35 doesn’t work! this module can take very low signal and boost it to crazy town! so im not sure what’s going on with the PO35
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also another thing! you can poke the3mm led through the hole for a more direct light!
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My output volume is about half of the bypass, and status LED is not working. I can get it to fire on if I touch the tube leads
Tone/gain/volume do affect the output and otherwise seems to work.
hmm functioning the volume on should be in nearly all instances louder if volume up. im not sure what to suggest except check the soldering especially on the tube as it may take a bit more heating to get a good joint.
status led yeah I guess its e3ither check the polarity of check solder joints around the resistors near it and the LED itself, even with a continuity tester
good luck!
Yes I realized that on the second one 
But fortunately I got ultra bright orange LEDs so it’s pretty great looking on both modules!
Can’t wait to finish the Megadrone and put it through one of these 
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This is the first module in a very long time where when I test the power pins (to avoid smoke!) I am getting both of my -12v connected to all of the ground pins. I’ve checked polarity on the elec. caps and made sure there’s not any solder bridges anywhere but I still am hearing these pins beep. Has anyone else run into this with theirs and/or what else can I check?
probably because the -12v is used for the heater filament through a 27r it could be enough to make it bleep. if you haven’t already soldered the valve in already remove it and then test it it should not bleep. if you have soldered in the valve snip one of the legs off of the 27r and see if it bleeps then when your happy solder the 27r leg back in place from the top.
some digital multimeters could treat the heater circuit as a complete connection. (it goes from -12v and gnd)
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Before you do any surgery, you may want to measure the resistance between −12V and ground. You should see the 27 ohm plus the filament resistance (which varies, it’s ~80 ohm when warm but much lower when cold):
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I need to ask, why is a 12V filament is being put through a 27 ohm resistor on a 12V supply?
to be honest with this module, and this valve the heater filament is actually 6.3VAC which isn’t available in just a modular power connection. so 12v DC seemed quite fitting bearing in mind its a full wave. -12v generally has less current consumption so figured to pop the heater on that side of the power supply. however I found when I built this module the first time without a resistor is generated a bit of hum in other modules, a try 27r resistor eradicated the issue. I was going too improve this to get more glow out of the tube itself in this iteration but after fiddling with the circuit in January I wasn’t happy how it was turning out with the mods I was doing to it, so I made the decision to basically make it exactly the same as the one I had in my modular I was looking to replace.
its not the right way of doing it but it works, and I can show for a module that was used nearly daily for about 2 and a half 3 years and still works fine doing its thing I figured its fine.
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It’s 6.3 V if connected in parallel, right? I.e. if you connect the heater supply across pins 4−9 and 5−9 instead of between 4−5. With 12 V and the series resistor you get 12/(12.6/0.15+27) = ~110 mA which is less than the 150 mA it’s designed for but obviously good enough since it works 
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Re flowed mine, 27r getting suuuper hot. I dunno maybe my tube is messed up cause I could never get the stripboard version to work with it either.
@CTorp Which tube are you using?
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27r getting suuuper hot
110 mA through 27 ohm is 27×0.11×0.11=0.33 W so you want a 1/2 W or so.
EDIT: Turns out we’ve covered this before (with graphs, even 
):
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ECC83S
20 chars blah blah
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That’s the one i have coming as well… :-/
Thanks for the info @lookmumnocomputer and @fredrik . I went ahead and just desoldered one of the legs of the 27r and checked the power header again and I didn’t receive any “beeps” for connectivity. So I think we’re good. I had already put the entire module together when I was testing it so everything had been soldered in. This was just easier to do it this way.
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Simple question… What should this sound like? Mine appears to do stuff. It’s like a high and low pass filter with gain… Not sure it’s quite right.
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ill do a video this week plugging things into it. and what it does best.
the one thing it doesn’t do well is single square waves for instance, it would just make them louder as there are no funky harmonics to amplify and saturate. so there are some instances it literally just sounds like you are plugging it in to make it louder, with a synth anyway as sometimes signals are so simple there is nothing for it to “crunch” on.
I had a video planned for it but I’m still waiting for something to turn up on it. but ill do a loose video on it within next couple of days.
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a couple of neat things to do.
-plug in a couple of oscillators into a filter, then plug it into this module then into a VCA use as usual subtractive synth voice, switch it on, plenty of extra boosted sounds from that but best results with at least 2 oscillators as just the 1 doesn’t create enough of a complex waveform for the module to eccentuate certain harmonics.
-dont plug anything into the input use as drone, gain knob will be frequency
-plug a mic are mic even a contact mic into the input, the safety valve has enough gain to act as a mic pre amp. or any similar sensor… a solar panel?? even as a light microphone?? haha just an idea.
plug in sine or triangles to get that bloated basss sound like Bruel and kjaers overloading
like most things like clippers and things that blow headroom out of the water its good to add to signals mixed together after a mix bus if you want to see how they interact together. Like drums and synth into the module etc.
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