Yet Another Tonepad MXR Gate thread...

[mwynwood]

Hi everyone,
I've been building the Tonepad MXR Noise Gate from this: http://www.tonepad.com/getFile.asp?id=35 (Rev2 Nov 19, 2003)

Little did I know it's quite infamous around here for being a "tricky build"... and it would come as no surprise that I am having trouble with it 

It passes signal fine, but doesn't actually DO anything at all. While I was debugging I took the FET out and it made no difference at all... still passed signal...
SO, something weird is going on...

I used:
Q1: 2N3904 (http://australia.rs-online.com/web/p/products/294-312/)
Q2: 2N3904 (http://australia.rs-online.com/web/p/products/294-312/)
Q3: BF245C  (http://australia.rs-online.com/web/p/products/168-5539/)
IC1: RC4558P (http://australia.rs-online.com/web/p/products/303-444/)

I've done heaps of searching and found a bunch or different bits and pieces, but none that seem to have worked for me, or tips that I don't really understand. 

• http://www.diystompboxes.com/smfforum/index.php?topic=82933.0
• http://www.diystompboxes.com/smfforum/index.php?topic=65599.0
• http://www.diystompboxes.com/smfforum/index.php?topic=47709.0
• etc...

Is there a nice black and white answer to the mysteries of the Tonepad Gate?
Are there components that are known to 100% work?
Any hints and tips greatly appreciated! 

[Maik]

Hi
Check the building reports. 23 people got it working...

[mwynwood]

haha yeah, I've read those a couple of times. It's bazaar!

[nomorebetts]

Does the knob have any affect at all?  If you turn it all the way one way then all the way the other way, can you notice your notes being cut off as they decay?

I also had trouble with this build.  I got it working but it was very choppy when the gate clamped shut.  In the end I got better cables and a better power supply and my noise issues disappeared.  So mines sitting in a cupboard.

Since you can remove components with no change... I agree something weird is going on!   
Check your offboard wiring (again) and take some voltage measurements I guess. 

[mwynwood]

Does the knob have any affect at all?

Nope 

I just tried making these changes:


But still not working... it's doing my head in! haha

[Fender3D]

The FET must be selected, just like in phasers or other circuits where they act as a variable resistor.
Otherwise you may try biasing it with a different voltage, with different value resistors going to FET and Vb.

[.Mike]

I've got an original unit. I don't know if you have found my posts on the MXR Noisegate, so if you haven't...

Differences between Tonepad schem and original unit

Full voltages

Gut shots, sound sample


I hope you get yours working, but... ermm... it's really not that useful of an effect. Downward expansion makes so much more sense for guitar.

Good luck!

Mike

[Vardok]

Hi. I built the original tonepad MXR noise gate like buddy did and I have the exact same problem. I used JRC 4558D for the OP amp, 2n3904`s and 2n5952 for the JFET. I checked all my joints, tried 10 different 5952`s and it does the same thing ... the signal passes through fine, no volume drop, but the noise remains and the pot has no effect. I`ve built quite a few stompboxes with no problems whatsoever, so I`m very confident in my skills.

Should I try different JFET types?

Any additional help would be awesome.

Thanks,
J.

[Blackened]

Mwin I'm having the same awful problem! The pot is not making any change on the output. I've tried taking it out from the circuit and it works exactly the same way!!! should't it stop the signal??
I was about to try the same changes you tryed, but stoped in front of your post (and cried  )
Maybe a unvoluntary connection??
Did you have any progress?