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Add a distortion inside, how to reduce noise ground?
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Add a distortion inside, how to reduce noise ground?

by diplowave on Fri Jan 20, 2017 4:02 am

I have already included several distortion FX inside several x0xb0x. I powered them with the 12VDC directly on the 7805 regulator. It is very effective but we collect more background noise than if we use an external regulated power supply. The advantage of having an integrated distortion is if possible to have no external power supply ...
Is there a way to reduce this noise?
What a shame is that if i use it combined with the VCF IN, the distortion is unusable.
External source-> VCF in-> VCA-> mixer-> dist.
After all i know that it is preferable to use a distortion at the input of VCF and not at output of the mixer. But in my case, it is out of mixer.

On the other hand, it can be used by distorting the internal signal of the x0xb0x VCO-> VCF-> VCA-> mixer-> dist.
It's 0K for Acid Core!
But there is still more background noise, than a distortion connected to a regulated external power supply ... It's boring.

Image

diplowave
 
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Re: Add a distortion inside, how to reduce noise ground?

by antto on Sat Jan 21, 2017 6:45 am

diplowave wrote:I have already included several distortion FX inside several x0xb0x. I powered them with the 12VDC directly on the 7805 regulator.

ugh, why from there?
why not use the.. 12V supply rail like the rest of the x0xb0x?

Is there a way to reduce this noise?

add smoothing capacitors

What a shame is that if i use it combined with the VCF IN, the distortion is unusable.
External source-> VCF in-> VCA-> mixer-> dist.
After all i know that it is preferable to use a distortion at the input of VCF and not at output of the mixer. But in my case, it is out of mixer.

On the other hand, it can be used by distorting the internal signal of the x0xb0x VCO-> VCF-> VCA-> mixer-> dist.
It's 0K for Acid Core!
But there is still more background noise, than a distortion connected to a regulated external power supply ... It's boring.

i'm not sure i fully understand what you mean, but distorting the VCF input signal (which is, the oscillator) will be kinda dumb
you want to distort the output.. i'd put a distortion at the end, after the mixer or after the VCA

antto
 
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Re: Add a distortion inside, how to reduce noise ground?

by diplowave on Sun Jan 22, 2017 2:04 pm

[/quote]
ugh, why from there?
why not use the.. 12V supply rail like the rest of the x0xb0x?
[/quote]

I tested this option, but it's the same result.

Is there a way to reduce this noise?

add smoothing capacitors

I tested with a x0xb0x who has audio grade electrolytic capacitor's, it's the same result than a x0xb0x with cheap capacitors.

diplowave
 
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Re: Add a distortion inside, how to reduce noise ground?

by antto on Sun Jan 22, 2017 3:02 pm

diplowave wrote:I tested this option, but it's the same result.

if your distortion's power supply is not noisy, and you still get noise, i'd guess it's any one of the following:
- you're pushing the gain too much
- your distortion is noisy itself
- something else

I tested with a x0xb0x who has audio grade electrolytic capacitor's, it's the same result than a x0xb0x with cheap capacitors.

heh, i think you misunderstood me
"audio grade capacitors" sounds a bit like audiophile stuff
what i meant was, if the power supply from which you power your distortion circuit, is noisy or unstable - you add capacitors and/or other elements to smooth it out
example: many of the capacitors on the IO board are not there to filter audio, they are used as reservoires and as smoothing, then also pretty much each section of the synth circuit also uses capacitors to filter or "decouple" itself from its power rails

check your distortion, check the actual noise
try feeding another audio signal into it, feed silence, short its input to ground (if that's safe) and see what happens with the noise in those tests

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