Simple Stereo Noise Limiter/Gate

[Rio]

Hello,

I was looking for a simple stereo solution for a noise gate to reduce noise of a pair of SID 6581. I know, that is a common thread already here:

... but, there are some limitations for me. For example, it is not soooo easy to get all the parts or transistors must matched (!) and so I was more looking for a rather simple smart solution. So I found the following:

http://www.electroschematics.com/250/stereo-noise-blanker-suppressor-limiter/

which looks very simple. But the author mentioned:

Quote

The maximum input level is 210mV and the distorsion is less than 0.01%.

Would that be ok for the SID 6581? Or is there something against the solution or would the output voltage of the SID be too high for that?

Greetings,

rio

Edited January 24, 2018 by Rio

[Antichambre]

Hi,

Seems not enough, SID Audio out is 2Vpp.
http://www.sidmusic.org/sid/sidtech3.html

I found this schematic in an old book, this is mono but you can maybe use 2 circuit in // and a TL084 instead of two TL082.


Best
Bruno

PS: tell me if you need translation from french.

[Rio]

thx, but therefor I haven't the negative VCC– for TL082 or TL084.

I search a solution, where I can reuse the 9V~ or 14Vdc or 5Vdc of C64 optimized PSU schematic.

Greetings,

 

EDIT:

Could that following circuit (Figure. 3) work too? No additional OPAmp is needed:

https://www.edn.com/electronics-blogs/the-practicing-instrumentation-engineer/4422750/Simple-circuits-reduce-regulator-noise-floor

rio

Edited January 24, 2018 by Rio

[Antichambre]

Yes you're right.
This is another one, stereo, single rail, based on LM13600.


Best
Bruno

[Rio]

hey,

What does A1 stand for?

greetings, rio

 

what about that:

Quote

EDIT:

Could that following circuit (Figure. 3) work too? No additional OPAmp is needed:

https://www.edn.com/electronics-blogs/the-practicing-instrumentation-engineer/4422750/Simple-circuits-reduce-regulator-noise-floor

 

Edited January 24, 2018 by Rio

[Antichambre]

A1 is summing both channel before detection, A2 is the detection and control the LM13600.
 

Just now, Rio said:

EDIT:

Could that following circuit (Figure. 3) work too? No additional OPAmp is needed:

https://www.edn.com/electronics-blogs/the-practicing-instrumentation-engineer/4422750/Simple-circuits-reduce-regulator-noise-floor

This is for regulation, to replace a 7805, if I well understand.

Edited January 24, 2018 by Antichambre

[Rio]

Hey,

LM387 is expensive ....! And is A1 also a LM387?

greetings, rio

[Antichambre]

Any low noise single rail op amp is fine... But you can use dual rail op amp, it doesn't matter here. All the circuit has an offset of 6V (12V/2).
For 9V supply the 6V offset becomes 4,5V, for 14V supply it's 7V.

LM387 is an old IC, this book too(1989).

Edited January 24, 2018 by Antichambre

[Noise-Generator]

I found this one and try it out as soon as I have the missing parts:

https://www.hgamps.com/guitar-noise-gate/

 But it's for guitar and it means some Resistors need to be "reduced"? R1 higher or lower value or will the 1 M pot do the job?