How to use a Boss NS-2 Noise Gate

[Article updated October 29, 2017 with some clarifications]

[Article updated January 15, 2018 with some more clarifications]

If you, like me, occasionally use a high gain distortion pedal, you know that these are notoriously noisy when the pedal is on and you are not playing. At one point it just got too much for me and I decided to buy a noise gate.

When it came to choosing a noise gate, at the time it was not very difficult. The only ones my local guitar store carried were the Boss NS-2 and the Rocktron Hush rack noise gate. The Hush was too expensive (and I didn’t have a rack…), so I bought the Boss. As this article describes, it turned out to actually be the best option, as the Boss pedal has a feature that can make it much more efficient. More about that later.

A few words about the noise and where it comes from

Basically, noise can come from all sources in your signal chain, including, but not limited to, your guitar, your effects and your amp. The primary source for noise is almost always gain in some incarnation. This can be your overdrive/distortion pedals, and it can be your amp’s preamp section. The more gain, the more noise.

A compressor is another source for noise due to the way a compressor works. Basically, it turns up the volume of weak signals, and turns down the volume of strong signals. This causes it to amplify any noise already present in a weak signal (typically from noisy pickups).

These kinds of noise are the ones that noise gates are designed to dampen or remove.

How does a noise gate work?

This is a VERY basic description of a noise gate: If the sound coming from your guitar into the input of the noise gate is over a certain (user adjustable) threshold volume, the gate opens and the sound is let through to the output. Otherwise, it cuts the output (closes the gate). So the signal trigger mechanism is at the input and the gate is just before the output.

And please note: The noise gate only removes noise from your effects when you are NOT playing. As soon as there is sound coming from your guitar, the gate opens, letting sounds AND noise from your effects through. Luckily, most times the guitar sounds will mask out the noise, though.

There are noise gates on the market that have additional features, but the above description is the way all noise gates work.

The signal chain and where a noise gate fits in.

Detailed descriptions of how to chain your effects together can be found in abundance on the internet so I will not go in to detail, just show two of the most commonly used signal chains.

The simple serial chain:

<guitar> – <germanium fuzz> – <wah> – <compressor> – <overdrive/distortion> – <tremolo> – <volume> – <choruses/flangers/other time-based effects> – <delay> – <reverb> – <amp>

I am fully aware that there are more types of pedals today than the above chain indicates (bit crushers, organ emulators etc.), but I don’t have any experience with them and while I might have an idea where I would put them in a signal chain, I could easily be terribly wrong and give wrong advice. So I will stay clear of that.

I have included the germanium fuzz pedals right after the guitar, as these are designed to work without a buffer in front, and many of the other types of pedals contain buffers that can affect the sound of the germanium fuzz pedals in a very negative way.

You could argue that the best place to put a noise gate in any signal chain is always dead last, right before the amp. That way, it will remove any noise from all effects. However, there is a problem with the delays and reverbs. A delay effect is the most obvious example, as the delay repeats would be cut off by the noise gate when the guitar stops playing. Reverbs have the same problem. Therefore, we need to put the noise gate before the delay and reverb effects so these effects can ”ring out” when you stop playing.

The effects loop chain:

<guitar> – <germanium fuzz> – <wah> – <compressor> – <overdrive/distortion> – <amp input> <amp loop send> – <tremolo> – <volume> – <choruses/flangers/other time-based effects> – <delay> – <reverb> – <amp loop return> – <power amp>

Again, placing the noise gate just before the delay is probably the best option. This time, it will even attenuate the noise generated by the amp’s preamp section.

So this is it, right? – Problem solved! – Or what?

By no means. There is one problem with placing the noise gate near the end of the signal chain: If you have an effect that generates a lot of noise when it is turned on (like a high gain distortion), this noise becomes part of the signal that controls the noise gate! ”You can just turn up the threshold”, you argue. Yes, that is correct, but you also want the threshold to be low enough to let the signal through if you play very quietly. With just one or two noisy pedals in the chain it can be impossible to find that balance.

So what is the solution?

The solution is simple. The noise gate needs to be split into two. The first half (The sensor that detects the sound coming from your guitar – the input signal) should be placed right after the guitar and detect the signal there, before most of the noise sources, and the second half (the gate) should be placed right before your delay/reverb effects.

”But I cannot just hacksaw my noise gate into two…”

Well, no. You don’t have to. This is where the Boss NS-2 comes in. This is the clever bit.

The Boss NS-2 has an effects loop so you can insert your effects between the input sensing and the output gate. This means that you can create a serial signal chain like this:

<guitar> – <germanium fuzz> – <Boss NS-2 input> – <Boss NS-2 send> – <wah> – <compressor> – <overdrive/distortion> – <tremolo> – <volume> – <choruses/flangers/other time-based effects> – <Boss NS-2 return> – <Boss NS-2 output> – <delay> – <reverb> – <amp>

Please note that I have left the germanium fuzz outside the loop due to the buffer issues described earlier. Boss NS-2 has a buffer so it would mess with the fuzz.

The effects loop chain.

<guitar> – <germanium fuzz> – <Boss NS-2 input> – <Boss NS-2 send> – <wah> – <compressor> – <overdrive/distortion> – <Boss NS-2 return> – <Boss NS-2 output> – <amp input> <amp loop send> – <tremolo> – <volume> – <choruses/flangers/other time-based effects> – <delay> – <reverb> – <amp loop return> – <power amp>

You will notice that the threshold in both signal chains can be set lower, causing more of your guitar signal to get through.

You might argue that it should be possible to do it like this:

<guitar> – <germanium fuzz> – <Boss NS-2 input> – <Boss NS-2 send> – <wah> – <compressor> – <overdrive/distortion> – <amp input> – <amp loop send> – <tremolo> – <volume> – <choruses/flangers/other time-based effects> – <Boss NS-2 return> – <Boss NS-2 output> – <delay> – <reverb> – <amp loop return> – <power amp>

I have heard from multiple people that this works just fine, so by all means, go ahead. However, if you end up with ground loop hum or something, try the first approach instead.

There are several noise reduction pedals on the market now that have similar send/return loop functionality, and it will be possible to substitute them. I wrote about the Boss NS-2 because that was the one I bought back then. Today, there are many competitors. The TC Electronic Sentry pedal and the ISP Decimator G-string pedal are two of the newer alternatives that both have send/return loops. I have not tested any of them so I cannot compare them to the NS-2. However, I have heard that the buffer in both is better.

Disclaimer

Please do not ask me for advice with specific pedals. In your description of the signal chain, it would be much easier for me if you just use generic expressions like “delay”, “overdrive” etc. – I know how this works in general, but there is no way I can possibly know how every pedal in the world works or sounds (or affects the signal chain). Of course, if a pedal is changing the way the signal is routed, it can be a good idea to mention it.

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