DEBUG: Tonepad MXR Noise Gate

[Fp-www.Tonepad.com]

It seems that this circuit is touchy with regards of the FET used. I have built it a couple of times with great results, although in some rigs some noise remains, it is mostly very efficient and quiet noise gate, the mods add to it too.

I'm glad to see thedefog talk about his experience with the build. Use a socket the FET and also make sure that you know the FET pinout, some FETs are 180 degrees off, even when they have the same part number, it depends on the manufacturer.

[thedefog]

It seems that this circuit is touchy with regards of the FET used. I have built it a couple of times with great results, although in some rigs some noise remains, it is mostly very efficient and quiet noise gate, the mods add to it too.

I'm glad to see thedefog talk about his experience with the build. Use a socket the FET and also make sure that you know the FET pinout, some FETs are 180 degrees off, even when they have the same part number, it depends on the manufacturer.

Very good point about FET orientation Francisco. I've got a drawer filled with them, and they definitely vary in pin out between manufacturer. I love when they actually silk screen D-S-G on them. I usually go for those ones first until I run out.

It's amazing how I still get burnt occasionally by pin out. You think I'd learn after screwing up like 20+ times in the past. Haste makes waste I guess.

[askwho69]

I have figure out the problem if not working! i tried turning 180 degrees using 2n5484 (i dont have 2n5485) then it works ! the schematic i think is wrong? any ideas about transistor i useD?

[carlosjofernandez]

I have built the version of tonepad´s callate 2 , NEVER worked, I did it twice, the last time with all right components , 2N5485, various zeners, all the modification whatsoever, IT NEVER WORKED , I found extremely dificult to believe the "happy" builders that swear they had it working , They never show an image or a diagram or a video. Seeing is believing. The ones who are thinking of building this clone will encounter only a cicuit which mutes the signal all the time and they do not fix it.

[lonewolf]

have you checked the section on build reports on the tonepad site? I had most of the same problems you mention(biggest was the volume drop and the stuttering effect) there are ways to solve both of those problems..the volume drop can be solved by changing the 1M resistor from the gate to the 1uf cap... they also talk about changing the 1uf cap/680 ohm resistor..check the build reports at tonepad..I used sockets for the resistor swaps and for Ra..I used 3904 and NTE 451 for the FET(sockets ) ...works as well as the MXR one I had in 1978

[hannibal827]

I found extremely dificult to believe the "happy" builders that swear they had it working , They never show an image or a diagram or a video. Seeing is believing.

Here is a video: http://www.youtube.com/watch?v=KEJZlCwfm6I
Here is another one: http://www.youtube.com/watch?v=HmoMJkGsjhw

While I am not the person who posted these videos, I too have built this device, from Francisco's layout, and it does work.  I second lonewolf's post--you really do need to read the build reports at the Tonepad site and try all of the suggestions.  I would recommend doing this in general, not just for this project.  There's a lot of information and ideas that aren't covered in the layout .pdf.

[askwho69]

I found extremely dificult to believe the "happy" builders that swear they had it working , They never show an image or a diagram or a video. Seeing is believing.

Here is a video: http://www.youtube.com/watch?v=KEJZlCwfm6I
Here is another one: http://www.youtube.com/watch?v=HmoMJkGsjhw

While I am not the person who posted these videos, I too have built this device, from Francisco's layout, and it does work.  I second lonewolf's post--you really do need to read the build reports at the Tonepad site and try all of the suggestions.  I would recommend doing this in general, not just for this project.  There's a lot of information and ideas that aren't covered in the layout .pdf.

can you give us how you made it work?

[hannibal827]

the volume drop can be solved by changing the 1M resistor from the gate to the 1uf cap... they also talk about changing the 1uf cap/680 ohm resistor..check the build reports at tonepad..

This is basically where I started, but specifically:

I changed the 1M resistor between the gate and the 1uF cap to 1.8k.
I added a 68pF cap across pins 1 and 2 of the op-amp. [EDIT: this would be *instead of,* not *in addition to,* the 47pF cap in version 2]
I changed the 150k resistor to 1.5M.
I changed the 680ohm resistor / 1uF cap to 4.7k and 2.2uF, respectively.
I tested my NPN transistors [2N3904] for hFE and made sure to use a matched pair.
I used a 2N5952 for the FET.
I built the basic [older] version of the circuit, without the momentary switch or the attack / decay controls, because none of these things sounded good in the breadboarding stage.

All of this stuff is covered in the build reports at Tonepad, but if you would read them carefully, you would notice that there is no "one size fits all" solution to this circuit.  Everyone's circuit seems to behave differently, which is why you need to test everything out and determine which values are best for you.

[EDIT] It should go without saying that I didn't use the "Callate 2" PCB, since that isn't the circuit I built, but I'll say it anyway.  I built on perfboard, basically copying the layout from the first .pdf, the one from 2003. 

[Morocotopo]

Hey guys, I built this schem from Tonepad´s project. I made some of the mods proposed, can´t recall wich ones, but the thing is, I got it working well but it closed a bit too soon for my taste. Not unusably so, but... I remade it using an old 741 opamp (had to design a new PCB) and that way I got it to close at the very last moment, better than with a modern opamp. Not sure why... I ended up using a J113 FET.i added an attenuation and an attack control. 

Hope it´s of some use.

[tupinamba]

Hi there,

I built the Tonepad Callate Gate 2 and it  works great... Or should I say : I built two of those and one of them works great ! :-)
You can have a look here :

The two builds have exactly the same components... But now is where it gets strange :
After I made the video, I switched one of the 2N3904 : I put the one from Circuit A to Circuit B and vice-versa. Circuit A was still working but not Circuit B. Then I switched back and... Circuit A is not working anymore, with its original 2N3904 or the other one, whereas Circuit B is now working with both transistors!
I know it sounds crazy... I have tested it several times to be 100% sure, and this is really happening. What a mystery. This circuit has magic in it! :-)

[EDIT] : I tweaked a bit (but did not change any component) and now they both work! As I said : magic...

[Fp-www.Tonepad.com]

Nice demo.
The few I've built have all worked... they all were put together using transistors and ics of the same batch.
You've at least given people with non-working ones another chance at troubleshooting it.

[tupinamba]

Yes, that was the idea. It really is worth a try. I'm not (yet) using the mods. The only change I made is replacing the 1M resistors with 1,8k ones (actually a 2k ones, I did not have 1,8k at home...), as I read on the forums. Now I have it all working good. The idea is to use it with my stereo SID synth, hence the two circuits...
What I wonder now is if I can use a stereo input jack and only one 9V battery for both circuits... I already used a stereo 500k pot, but this cannot get me into trouble... Any ideas on the subject?

[EDIT] I put everything in its right place now. I'm using a single 9V battery, a stereo input (my source is a SID stereo synth) and I kept two mono outputs. It works like a charm!
I'm thinking of adding a pot to get smoother release, but this is yet really great! Thanks to the Tonepad crew and the DIYstomboxes community!

[rankot]

It's quite an old thread, but I read really lots of MXR/Tonepad Noise gate threades trying to figure out how to make it work. After all that trouble, this is what I done, so I share this experience in case someone else have a similar problem:
- replaced 680 ohm resistor and 1u capacitor going from pin 2 to ground to 4k7 and 2u2;
- replaced 1u/NP capacitor with 10n;
- replaced 1M resistor going from gate to attack/release pots with 1k8;
- replaced 150k (Ra) with 47k;
- tried NE5532, TL072 for opamp, but it stared working well only when I used LM1458;
- tried different JFETs, including 2N4393, J309, 2N5485 with Vgs(off) of 2V and more, but it started to work when I used 2N5457 with Vgs(off) of 0.46V.
- Attenuation pot is actually really important, it must be used in conjunction with Threshold to get gating.

I didn't check hfe of my BC548B transistors, but they are all in range of approx. 300, and I am too lazy to desolder them to measure hfe.

If anyone needs voltages, I can measure and post them.

[jalien21]

[years later...] Hey, yeah. Is the offer for voltages still good? I haven't been able to find a good reference for a working MXR gate

[rankot]

[years later...] Hey, yeah. Is the offer for voltages still good? I haven't been able to find a good reference for a working MXR gate

No problem, If I just find some spare time in next few days. In case I forget it, please repeat the request next week.

[Rob Strand]

[years later...] Hey, yeah. Is the offer for voltages still good? I haven't been able to find a good reference for a working MXR gate

There was a long thread started by member jfrabat a little over a year ago.    It started off with JFET and zener problems but it soon became clear the MXR Noise Gate has many opportunities to behave badly.    The problems seem a lot worse than the posts on the "build sites" imply.   It was looking like the circuit was unfixable without building one and redesigning parts of the circuit, then, da daaa,  a new poster stepped in and did just that.

[Rob Strand]

So here's the crazy debug thread, the good mods are given by member aspangev at the end of the thread,
https://www.diystompboxes.com/smfforum/index.php?topic=122682.0

Here's some fixes to the schematic, forgot all about doing that,
https://www.diystompboxes.com/smfforum/index.php?topic=122689.0

[jalien21]

Oh, thanks a lot! I missed those debug threads during my first pass.. they look helpful. I did find the zener problem at least, and saw that I could get the JFET gate voltage to move with playing, but not enough to get close to the threshold. I'll pick it back up this weekend

I made a little baby SMT layout for this board on EasyEDA. I'll update the design once I get it working and can share it if anyone is interested in practicing their surface mount soldering chops. It was my first time using their browser layout tool and ordering from jlcpcb. I've got to say.. pretty impressed. It was easy, fast, cheap.