Mxr - Noise Gate / Line Driver

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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audioguy
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Post by audioguy »

Hey all... I'm looking for a noise gate- I've tried BOTH of the MXRs over at tonepad with NO LUCK. After doing some research it seems that these are buggy builds with only a lucky few successful builds.
Has anyone here taken a stab at a good, verified noise gate or suppressor?

All the best!

Audioguy

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Post by bajaman »

........not yet - I try not to make noisy effects though!!
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bouli
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Post by bouli »

maybe somebody got the schematics of the mxr smart gate or the isp decimator

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Post by marshmellow »

Look here for the Boss NF-1 in the first post.

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Post by audioguy »

Cool, thanks! I'll give it a shot.

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Post by tuemmueh »

Pay some attention, the switching in that NF-1 project seems to be not correct! If you want to build it truebypass there should be no problem ...

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Post by audioguy »

I'll do true bypass... but its gonna have to wait as those trannies are not in my normal stock.

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Post by Redhouse »

marshmellow wrote:Look here for the Boss NF-1 in the first post.
What's the login for that link? can you post the PDF somewhere that is more accessible?

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audioguy
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Post by audioguy »

You have to register for that board like any other. I would highly recommend creating an account as that board is often cross-referenced.

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Post by Redhouse »

audioguy wrote:You have to register for that board like any other. I would highly recommend creating an account as that board is often cross-referenced.
Can't post the PDF somewhere more accessible then?

I can't read German (or whatever language that is) so it's a bit out of reach to register.

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Post by bajaman »

put it on photobucket - it is free and we can all get it :wink:
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Post by analogguru »

In the meantime you can find the service anual for the NF-1 here:

http://www.godiksennet.com/images/sch/BOSSNF-1pg1.gif
http://www.godiksennet.com/images/sch/BossNF-1pg2.gif

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Post by oscarv77 »

Here's the PDF from Musikding.de

Can the jfet switching section be ommitted if the pedal is "true bypassed"?

http://val-tone.com/NF-1.pdf

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Post by Brian M »

I'm looking at the tonepad project
http://tonepad.com/getFile.asp?id=77

in the lower right corner I see some potential problems...

All those trimmers shows would be very "reactive" to each other.
the 2n5485 can vary from .5 to 4 volts. the gate is normally at about 5 volts (with no input) When there is input the gate can't drop below about 2.5 volts.. Probably not even that low in reality. This basically means your Vgs-off has to be in a pretty specific range to get this circuit to work... that's probably the source of the problems people are having.

Calculaions are probably a hair off, becuse that 5.1v zener is probably not zenering that high with a 22k resistor.

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Post by analogguru »

All schematics on the web concerning the MXR Noisegate are wrong including the one from tonepad. Referring to version 2 from 2003 (which I have on my HD):

- Input cap is in reality 10n input resistor 10k.
- The 10µ electrolytic between the 22k and the FET is drawn in the wrong direction - plus should be on the Fet-side.
- Output cap is 10µ instead of 1µ.
- the capacitor before Q2 in parallel to the 100k is a 10n instead of a 1µ.

The source of the FET is connected to U/2 and the drain to the 10µ electrolytic

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Post by Kinki fuzz »

I'm having no sucess with this one, it really pissed me off, I was about to throw it away... so I'll try these things analogguru explains, and I will report, hopefully I will have my noise gate working... at last!

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analogguru
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Post by analogguru »

Does somebody here have an original MXR noise gate / line driver ?

I would be interested how the XLR-jack is wired exactly, that I can finish an accurate schematic of this unit.

thanks,
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Post by Fuzzer »

I know a guy that has one, I'm going to contact him and take photos. You'll just have to wait a while but I'm almost sure he can lend that one to me.

Is it white color?
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Post by analogguru »

Yes, it is white coloured.

I have everything except the wiring of the XLR (if the signal is connected to 2 or 3, and if the other pin is grounded or left open - assuming that there is no balancing transformer inside).

thanks in advance,
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Post by Fuzzer »

All right man, now I am sure its the one I saw, so, talked to the guy and he will be meeting with me this week, so let's hope he brings the box with him.
The Freestompboxes Forum search function is soo great, use the search function..., the S E A R C H function.

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