Tonepad MXR Noise Gate to 'smart' gate

[FunkyGibbon]

Hi,

Regarding this thread about Tonepad's MXR Noise Gate (among other things):

http://www.diystompboxes.com/smfforum/index.php?topic=29051.0

I would like to implement this for use with a fuzz (probably a Big Muff).

The idea is that the signal is read at the input (where the bass is clean), but this info is used to gate the OUTPUT of the fuzz (hopefully to achieve nice choppy fuzz sounds a bit like a Chunk Systems Brown Dog).

Just to clarify, is this the implementation as discussed?:




Thanks.

[Br4d13y]

i wanna bump this, kinda interested

[Fp-www.Tonepad.com]

Perhaps you want to check the 10uF cap orientation, if you're using a positive ground effect that cap would be ok and it would replace the input cap of the fuzz, otherwise it needs to be reversed.
Also, you may want to try reversing that cap, adding resistor to ground (100k maybe) and a send jack. The return seems ok too, besides the orientation of that other 10uF cap, which might need to be reversed too depending again on the dc bias of the signal coming in on the return.

In a few words, this could work but observe correct polarized capacitor orientation.

[FunkyGibbon]

Thanks for enlivening this one!

So, if it's a normal negative ground effect used in the effect loop, the positive terminals of the 10uF electros should face away from the send and return jacks, rather than towards them as they do now?

I'll add a pull-down resistor just before the send jack too.

Thanks,

Christopher

[Mark Hammer]

Is the switch shown really supposed to be a momentary?  I'm thinking back to my own grey box back in the 70's and as I recall, it was a full-fledged latching stomp.  Looking at the schematic, as well, it would seem that with the switch closed in latching fashion, that leaves Q3 off and the resulting D-S resistance high ( = no attenuation by Q3).

[El Heisenberg]

Doea this actually work? I have an mxr noise gate breadboarded
and im not happy with it.

[.Mike]

Is the switch shown really supposed to be a momentary?  I'm thinking back to my own grey box back in the 70's and as I recall, it was a full-fledged latching stomp.  Looking at the schematic, as well, it would seem that with the switch closed in latching fashion, that leaves Q3 off and the resulting D-S resistance high ( = no attenuation by Q3).

I just opened mine up to check. It's a block-logo from 1980, although I've been told it is the same circuit as the script-logo.

The switch is an SPST latching. Set meter to 2000K setting... measures 0 ohms... press switch... measures 200K+ ohms and climbs... click it again... back to 0 ohms... repeat.



Mike

[DimebuGG]

- The 1uF/NP in parallel with 100K resistor is actually 10n(0.01uF).
- Output cap is 10uF instead of 1uF.
- The 10uF in junction with Q3 has its postive side facing the FET and goes to it's Drain. Source goes to Vb.
- Input cap is 10n also.

[El Heisenberg]

Are j201s ok in this circuit??

[El Heisenberg]

Well...

I did another search and read every single thread i could find on the subject. Some schematics have the FET drawn wrong.  I realized i never checked tonepads build reports. While some said the circuit worked wonderful, even amazingly, most stated that changes needed to be made to the circuit. I tried them all, but kept the ones tjat worked.

Put a 68pf cap between pins 1 and 2 on the opamp.
Increased the 680 ohm resistor to 4.7 and its associated cap from 1uf to 2.2uf.
Not sure which way to orient the 10uf cap to the FET.
Reduced the 1meg resistor from the FET to 'ra' to 1.8k

these changes totally fixed the circuit. I dunno how people can get the stock schematic version to work. Especially the ones drawn "incorrectly". Must be voodoo or somethig.

Im still interested in improving the performance by using the "loop" mod.   

[El Heisenberg]

By 4.7 i meant 4k7

[.Mike]

Not sure which way to orient the 10uf cap to the FET.

I believe it is positive side towards the FET.

You can see the "+" pointing toward the FET on my gutshots.



Mike

[MikeH]

I have NEVER been able to get this damn thing to work.  Tried all of the fixes from the tonepad build reports, tried numerous fets; I have NO IDEA why I could never make it happen.  Go figure.

[El Heisenberg]

The loop idea didnt work for me. Made the circuit act funny. Muted noise from my rangemaster and ORange squeezer but whwn i turned on the fuzz, there was MORE hiss when i increased the thresh hold.

[MikeH]

Would you mind posting your voltages if you have a chance?  I'd like to compare mine to them.

[.Mike]

If you guys post your voltage, I'll take voltages from my original unit for comparison.

I completely traced my unit on Thursday. It matches the tonepad schematic except:

- Input cap  = 10nF / .01uF
- Cap listed at 1uF NP = 10nF / .01uF
- Output cap = 10uF
- FET Drain connected to positive end of electrolytic
- FET = 2N5953
- Reverse polarity diode included

Also:

- FET Source connected to Bias
- Zener has either an N or a Z on one side, and either 163 or 165 on the other side.
- With a 9.71v battery, Bias = 4.79v



Mike

[Sinster]

Well...

I did another search and read every single thread i could find on the subject. Some schematics have the FET drawn wrong.  I realized i never checked tonepads build reports. While some said the circuit worked wonderful, even amazingly, most stated that changes needed to be made to the circuit. I tried them all, but kept the ones tjat worked.

Put a 68pf cap between pins 1 and 2 on the opamp.
Increased the 680 ohm resistor to 4.7 and its associated cap from 1uf to 2.2uf.
Not sure which way to orient the 10uf cap to the FET.
Reduced the 1meg resistor from the FET to 'ra' to 1.8k

these changes totally fixed the circuit. I dunno how people can get the stock schematic version to work. Especially the ones drawn "incorrectly". Must be voodoo or somethig.

Im still interested in improving the performance by using the "loop" mod.   

I'm going have to try this.. since I can't get mine working.

[Sinster]

Which tonepad drawing?  There's two of them.

If you guys post your voltage, I'll take voltages from my original unit for comparison.

I completely traced my unit on Thursday. It matches the tonepad schematic except:

- Input cap  = 10nF / .01uF
- Cap listed at 1uF NP = 10nF / .01uF
- Output cap = 10uF
- FET Drain connected to positive end of electrolytic
- FET = 2N5953
- Reverse polarity diode included

Also:

- FET Source connected to Bias
- Zener has either an N or a Z on one side, and either 163 or 165 on the other side.
- With a 9.71v battery, Bias = 4.79v



Mike

[.Mike]

Which tonepad drawing?  There's two of them.

I believe they are the same base schematic. One just has suggested mods, and a board designed accordingly. I used the "Callate Gate 2" schematic for my tracing.

Also, I forgot to mention, my original doesn't have the 2.2M pulldown. And the switch is latching, not momentary, but if you're true bypassing, that doesn't matter.



Mike

[El Heisenberg]

I built mine with the momentary AND true bypass.

Ill post voltages tomorrow.