Hi all, I just built the LMNC MS20 stripboard filter last night. The output is VERY low, like almost inaudible…I can hear the cutoff and resonance working and the LEDs are lighting.
What is the normal operation of the LEDs? BOTH of mine are lighting up when there seems to be a heavy load. Are these supposed to operate independently?
Someone also mentioned on a different thread to try passing audio through the filter without any power. I tried that and did not get any sound out of the filter.
I should mention that I daisy-chained all of the grounds between the sockets and the pots. The stripboard layout makes it look like there are separate grounds between CV-CV IN-RESONANCE and the OUTPUT jack. Would having them all on the same ground make a difference?
The LEDs are in the feedback loop, so they only light up when the resonance setting is high enough that the feedback is clipping. They’re hooked up to the same signal, just in two different directions, so will light up at the same time.
Strictly speaking the LEDs will never light up at the same time. They light up in an alternating fashion. But if the frequency is high enough mere mortals can not see that. Aliens probably can
So, let’s assume I hooked up the LEDs wrong since mine are both lighting up on high loads. Would that be enough to affect the output volume, or is that a separate problem?
That is hard to say, because you could have made any mistake. Did you add the 10K resistor from pin1 to pin 2? And I’d suggest you meticulously compare the your soldering to the bread board and to the schematic.
They’re fed the same AC signal, so they are both lighting up at the same time, unless you’re some weird robot that can see several hundred or thousand pulses per second as individual pulses (in which case you probably have bigger problems with modern electronics then these LEDs…)
Daisy chaining the grounds is fine.
In fact all the grounds should be connected together, including the input jack sleeve which is not shown on the stripboard diagram.
Did you cut the traces under the ICs and near the transistors?
Did you install the 470nF output coupling capacitor?
Hey Dud, that’s actually my post! I put that there when I noticed that someone else had a similar issue, but didn’t seem to post a solution, so I started a new thread.
It’s possible that it’s a faulty component…I can’t imagine a cold solder or a faulty weld would allow it to work at all…that’s what is throwing me. The fact that’s it’s working like it should, but at a really low volume.
I’m posting pics of my strip board in case anyone has a better eye than me!!!
maybe not a defective weld but a small burr between the lines for example, are you shure that you put the correct value for resistor and pot (maybe check an check again)
a error of resistor (multimeter), or eventualy a defective components
i don’t know …
(in which case you probably have bigger problems with modern electronics then these LEDs…)
