MXR Noise Gate

[Sweetalk]

This same stompbox was my first build over two years ago.

It still works great.

I did all the mods over on Tonepad.

You can get decent volume swells out it too.

I smoothed the choppy stuff down by doing some adjusting to the controls....and then I matched the FETs up by measuring the hfe on about 50 and then trying different pairs until I found the pair that worked the best.  Keeping track of the hfe help me sort through the which was which.

I have this in my old chain which is all mounted in one big stompbox now and it sure works great.

Lately I have fell in love with my RP7 Valve.....I hardly ever use the chain.....I have been planning to link both together......but can't think of a reason why except to experiment.....I would then have true quadraphonic sound and I now have enough amps to support that.    Someday when I'm not so obsessed with learning new songs I will hook it all up.

Glad to see you have such a good stompox debugged and in service.

It should last you a long time.

There's only one FET in the MXR Noise Gate, you mean that you matched the hFE of the NPN Transistors right?... I have to try that, with any transistor I have the same results. The volume swells are pretty nice!. It should last a long time, I have a MicroAMP build with Tonepad's layout that have about...4 years or so.

[KMS]

That's right......not the FET.  I did not match them with the same hfe.....I did try that.  I made a list of all the hfe data and numbered each tranny in acending hfe order 1,2,3.....then plugged one in (lowest hfe seems like it was 70 and kept it in while increasing hfe at the other three pin socket until I went through my entire pile (highest hfe was over 300 but I remember getting bad results with it no matter what)...I made notes of the changes I noticed during each test (this took a week).

I then used next hfe larger and kept it in while testing the rest of the pile at the other three pin socket.

I went through about 50 transistors to do this and have about 20 that I used due to so many near duplicate hfe results....I wanted a good spread of hfe.

It seemed to be that when I found a pair that made a real smooth gate across the entire frequency range that that same pair would also attack faster and thus cut the note off sooner than I liked.

So I settled for some minor choppy on the low note but smooth on the high note type gating to get the kind of attack I wanted.  Of course I kept the controls the same during the entire test with release on fast , attack on fast, and threshold on longest note possible.  I thought about continuing the test with the controls at new settings but then I would be testing it for something that I don't use that much.

Like I said it was my first build and I enjoyed the testing.  Most of the changes are subtle....(but some are not)..different hfe will affect all the parameters to some degree.

One last thing.....I did this with adjustable regulated power supply set to 8.4Vdc because a battery wears down during the testing.

Later

[Sweetalk]

What hFE have the transistors that you finnaly put in the circuit?

[KMS]

I don't remember that and pitched the data......it was two years ago.  It won't matter that much because you will be locked into whatever hfe the tranys you have offer.