I finished my twin t drums and everything works except on the snare/noise output I have quite loud humming which is also on the mix output. I already changed the inductor L1 without any improvement. Anyone with a similar problem?
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I don’t think there are many who have built it yet, have you checked the orientation of the transistors ?
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Hmm, looks fine. I think I’m going to replace Q1 and Q3, maybe I picked a bad one.
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Okay, a bit embarrassing, I figured it out. It was my PSU introducing the humming onto the snare/noise. After switching to a different PSU it works fine.
Another thing. I needed to bridge resistors R17, R32 and R47 to bring the trim pot into a range where it is not oscillating.
Now everything works fine. Let’s make some beats!
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damn, I’ve ordered the wrong version of the 4011. Did anyone had success building the 2700 with a CD4011BE?
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unfortunately it won’t oscillate all that much meaning you dont get the resonant ding ding dingawotsit 
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Ok, I have to order again, this time the right version. I tested a lot with different resistor values, and either it oscillates the hole time or never…
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the correct CD4011AE does the magic. It sounds like a drum machine 
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heyy, since I am running out of rack-space and don’t really need more drum-voices, i wonder if someone wants to buy my twin t panel/pcb set? it’s unused, will ship it anywhere in the EU.
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i also add it to the BTS thread 
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on your video the drums mixed sound with the safety valve is really so nice !!! 
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thanks but it’s Sam on this video not me 
but you’re right cool sound with distortion !!!
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Testing this again.
My HiBongo just gives feedback after a few moments with no beat.
My Snare output seems to be mixed with Low Bongo?
snare output is noise and low bongo merged
as for the feedback is it the only thing thats feeding back? i guess the trimpot is at the lowest it can be? if so let me check which resistor would need increasing in size however it may be a funky solder somewhere as if it was just a variation with the chip you are using id think all of the voices would act the same hmm
The low bongo seems to be a bit overpowering, will try and get a vid tomorrow. may have a incorrect component ??
The high bongo was the only one that constantly just gave feedback, I guess I should just check everything…
Do you have a high res of the PCB so I can see the component locations. 
Rob
Thought it was totally goodsed this morning. Just getting faint clicks on all drums 
Plugged in the power to the buss strip and fixed that 
Think the snare is now fixed… Putting Q2 in the circuit seems to have helped 
High is still just feedback. Proving difficult to note where all the components are. High Res Front/Back of all panels would make it easier for trouble shooting.
Rob
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P.S. Liking the snare now
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I love it when there’s build videos with macro close ups of where the components go through the holes. When the 1222 build videos got added to the channel it drove my hype for wanting to get into building as it was very comprehensively documented.
-Fumu / Esopus
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good!!! hope this image helps regarding the feedback.
you may be pleased to know srpring reverb was going to be even more tightly packed than this board however I gotitthe other day and its even to tightly packed to make so need to makeitin a 10cm more spacious pcbs design. so this will be one of the only pcbs that are so tightly packed
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Having the reference number outside the box where it can be seen after assembly definitely helps in troubleshooting…
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