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Amp sim noise

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Amp sim noise

Postby jthzp9 » Tue Oct 27, 2020 10:48 pm

Hi all,
So I consider myself a newbie at recording and was looking for some feedback regarding guitar amps and amp sims.

My set up:
Guitar > warm audio active DI > focusrite Scarlett 18i8 (2nd gen) > Mac mini 2018

My question:
When I’m playing my guitar into my guitar amp and and have a fair amount of gain dialed in I like to roll back the volume on my guitar so I can have a clean tone. The amp cleans up, volume gets a little quieter and the noise floor also decreases. If I were to turn the volume all the way down, put the guitar in a hum cancelling pup position or unplug the guitar, the noise floor is barely noticeable (even with the amp gain/vol settings loud enough that would be almost uncomfortably loud!)

However... when I use the same guitar, plugged into the recording set up described above, There is always noise when I use amp sims! With the guitar unplugged or volume all the way down and plugged in there is always an unusable noise floor present. This is even present at conservative levels of gain and volume dialed in on the amp sim.

I continue to read about proponents of amp sims being superior in that they impart less noise than a real amp. However, in my experience thus far, this is just simply not true. Whether it is due to the interface, computer or usb protocol I am not sure. What I do know is, it is unacceptably noisy in my opinion.

I know that the focusrite Scarlett is not exactly the top of the line audio interface, but would upgrading to something like an RME really make that big of a difference? Obviously another take is just to use a real amp, but I do enjoy the convenience of amp sims for quiet recording and would like to be able to use amp sims when necessary.

Any suggestions would be much appreciated!!
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Re: Amp sim noise

Postby CS70 » Tue Oct 27, 2020 11:42 pm

Well, they are two completely different signal paths, so it's not really about amplifiers and sims in general, but about your specific setup.

Have you tried to plug the guitar directly in the interface? In most interfaces at least one preamp doubles as an instrument in.

I guess you're plugging the DI into a mic preamp? If you do, you're taking your perfectly fine instrument input, bring it down to mic level and then re-amplifying it with the interface preamp to get it to a reasonable line level. What's the reasoning?
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Re: Amp sim noise

Postby forumuser931182 » Wed Oct 28, 2020 12:05 am

It does seem that the warm audio di is unnecessary and could actually add a small amount of noise.
The noise you mention however is probably from the amp sim you are using. If you record the guitar directly into your computer ( try without the warm audio ) without feeding through an amp sim is the noise level ok? If so try playing with the amp sim controls when it is a track effect and see if you can get the sound you're after without too much noise. Maybe try other amp sim effects as well and maybe noise gates.
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Re: Amp sim noise

Postby jthzp9 » Wed Oct 28, 2020 12:10 am

Plugging directly in to the hi-z input of the Scarlett does not yield any better results. This ultimately makes me think that it is the noise floor of the AI that I’m hearing because it is apparent even when the guitar is unplugged or plugged in and volume down.

I originally put the DI in place because it gave me the ability to know that I had a reliable 1M ohm impedance for my DI signals. I’ve also always read that passive pickup instruments sound better with active DIs. I owned an active guitar and agreed that it sounded better than my passive pickups when DI’ed so assumed this must be true.

Lastly, I’ve also read that if you are at mic level that the signal is transferred over longer lengths with less signal degradation due to the impedance matching on the front end of the DI and then the signal being dropped with a lower impedance needed at the preamp. This was slightly experimental on my behalf to see if it helped with lowering the noise floor of my AI due to needing to turn up the preamp less. I’ve noticed little to no difference in the noise floor but do think it sounds better than direct to the interface itself.

I will post some clips of the noise I’m referring to tonight.
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Re: Amp sim noise

Postby CS70 » Wed Oct 28, 2020 12:41 am

jthzp9 wrote:Plugging directly in to the hi-z input of the Scarlett does not yield any better results. This ultimately makes me think that it is the noise floor of the AI that I’m hearing because it is apparent even when the guitar is unplugged or plugged in and volume down.

Could be for sure - something in your cabling or in the interface itself picking up noise, the computer itself, grounding issues etc. The electronic experts in the forum will hopefully come in but in the meantime you could try to borrow another interface and check. Or - aren't these Scarletts capable to work in standalone mode? Bit late now but it could be possible to devise some experiment that eliminates the computer and would allow you to detect a noisy singal out of the interface...

Could it also be the specific amp sims? Do you get the noise even with a "clean" low gain amp emulation?
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Re: Amp sim noise

Postby Sam Spoons » Wed Oct 28, 2020 12:41 am

It sounds like it may be a gain structure issue to me, the Scarlett is capable of very good noise figures so I'd be surprised if that was the problem on it's own. Some audio files would definitely help identifying where the noise is originating, it's not always possible to tell but many noises have an identifiable character.

You seem to have eliminated the possibility as you say "This ultimately makes me think that it is the noise floor of the AI that I’m hearing because it is apparent even when the guitar is unplugged or plugged in and volume down." but electric guitars, especially single coil equipped electric guitars, are notoriously noisy beasts and any gain you apply, wherever it comes from will increase that noise
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Re: Amp sim noise

Postby blinddrew » Wed Oct 28, 2020 12:46 am

Any difference in the noise when you touch or release the strings? I'm just conscious you've not got a proper ground anywhere in your recording chain but you probably do when using your amp.
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Re: Amp sim noise

Postby jthzp9 » Wed Oct 28, 2020 1:27 am

Ok here is a couple clips of the signal and noise I'm getting.

https://soundcloud.com/user-500797446/d ... m-audio-di

There is a two bar click in between the clips, please keep in mind the last two are much louder than the first four!

Clip 1: Scarlett (no amp sim)
Clip 2: Warm audio (no amp sim)
Clip 3: Scarlett (amp sim no playing)
Clip 4: Warm audio (amp sim no playing)

*** PLEASE BE MINDFUL OF YOUR LEVELS FOR THE NEXT CLIPS, AMP SIM AT RECORDING LEVEL!!!***

Clip 5: Scarlett (amp sim, playing)
Clip 6: Warm audio (amp sim, playing)



The levels were set for both so that the highest peaks are coming in at -6dbfs on the way in, before the amp sim.

Amp sim is Scuffham 2 S-Gear.


The guitar is a HSS strat. My frustration is not the noise that you can hear as I flick through the different pickup configurations, but the white noise that is prevalent throughout. That does not change is ultimately the reason I'm not happy with the amp sims. If I had normal amp noise, it wouldn't bother me as much. The never ending "digital ocean" sound is maddening to say the least.

I can record clips of the same guitar through my amp and that noise is not there when I turn down the guitar, it is completely quiet save a little warm hum of the amp in the room that is barely even perceivable.
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Re: Amp sim noise

Postby jthzp9 » Wed Oct 28, 2020 1:30 am

To give a little more info on my system.
I use a panamax M5300-PM as a power conditioner. All of my gear is hooked to it and it is running to the wall outlet that I have checked with an outlet tester and says that it is a grounded outlet.

Computer, monitor, audio interface are all going to the power conditioner.
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Re: Amp sim noise

Postby forumuser931182 » Wed Oct 28, 2020 3:23 am

Regarding warm audio 1 megohm input, the focusrite should also exhibit this when the input is set to "instrument" in the software control panel. Also a balanced cable/input will be less prone to hum/noise however as you are using a short lead from guitar to audio interface you shouldn't have to many issues with an unbalanced lead.

I tried the Schuffman amp sim as a send effect in my daw and didn't get any noise when I brought the input signal down. I tried this with various presets. Do you get the noise with presets or just patches that you have set up yourself.
If you record the guitar straight and then apply the Schuffman sim as a post effect do you get the same result?
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Re: Amp sim noise

Postby forumuser931182 » Wed Oct 28, 2020 7:59 am

Actually tried it live and I noticed the noise. Is it just because the amps are all set with quite high gain. First preset American Clean has noise but Clean Duke which is a different amp has less noise.
The built-in noise gate seems to be post-amp? Maybe try a separate noise gate plugin that is situated before the Schuffman plugin.
I won't post anymore, I'm not even a guitarist haha.
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Re: Amp sim noise

Postby CS70 » Wed Oct 28, 2020 9:41 am

jthzp9 wrote:Ok here is a couple clips of the signal and noise I'm getting.

To my ears, that could be combo of a really pushed gain stage mixed with some interference from the computer equipment. There's a dodgy connection somewhere (you can hear the crackling), possibly the cabling.

These are the classic things that are easy to debug if you are in the room and hard to do remotely, as there's a lot of guess-try-and-see involved. I'd ditch the DI for the moment to eliminate one factor, and start debugging with just guitar and interface.

Some possibilities:

1) Sam's idea on the gain structure is definitely an option. Are you positive the jack sockets you're using are in "instrument" mode? If they were set to line, you would have to push the gain a lot in software to hear anything and that would lead to exactly that kind of "noise even if you aren't playing anything" - because you would amplify a lot whatever tiny amount of noise there is.

2) Have u tried using a different cable? I've experienced that the mechanical tolerances can be so that a cable's jack plug works perfectly in a socket and is noisy in another. If the amp's socket is just a little bit smaller than the interface's that could lead to a solid contact in the first and not the second.

3) Also something that's different between playing the amp and playing the sim is that in the latter case you are probably nearer to the computer - especially the computer screen. However, it does not sound like typical RFI to me (well, a little bit mixed in but the bulk of the noise sound like very high gain).. but it could be worth moving around.
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Re: Amp sim noise

Postby jthzp9 » Wed Oct 28, 2020 3:36 pm

This noise occurs without the guitar even being plugged in or with the guitar volume all the way down. While you can obviously hear some RFI in some of the clips I posted, that is even lower noise than the “digital woosh” noise That is ever present.

Even at fairly conservative levels when I setup the amp sims (s gear is not the only one that does this) you can hear the noise.

Absolutely positive that the input is set to hi-z instrument.

I use a mogami neutrik connection TS 18” guitar cable. I’ve used others and this is by far the best cable I own. No noise on other guitar amps, and really no noise with the audio interface DI. Again, just my two cents but it does seem to be a noise floor issue.

If this is true, what are my options?
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Re: Amp sim noise

Postby merlyn » Wed Oct 28, 2020 5:44 pm

jthzp9 wrote:While you can obviously hear some RFI in some of the clips I posted, that is even lower noise than the “digital woosh” noise That is ever present.

You seem to have a bit of a misunderstanding here. Fundamentally digital audio is noiseless -- if you put in a stream of zeroes (silence) you get a stream of zeroes out.

The "whoosh" is thermal noise, and that comes from analogue electronics. Every resistor adds a bit of noise -- that is completely unavoidable. The higher the resistance the more noise so I think you will find using high Z inputs adds more noise.

I've got an amp sim -- Guitarix and it does have noise. The more gain is used the more noise. But this is not coming from inside the plugin -- it's the analogue noise on the input that's being amplified. If I disconnect Guitarix from the hardware inputs there is no noise. Although amp sims are digital models of analogue gear it would be a pretty nutty developer who included noise in the emulation to get that real analogue feel. :D
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Re: Amp sim noise

Postby jthzp9 » Wed Oct 28, 2020 10:29 pm

Ok, so this is not my DI track but was made for folks trying to make kemper profiles. It sounds like it is an active guitar with humbuckers into some bit of outboard gear. I don't know this to be true as there is no info to go along with the track but just my assumption.

https://soundcloud.com/user-500797446/di-guitar-example

Clip 1: clean DI
Clip 2: SGear 2 (everything at noon except the input gain which was clippping the plugin turned down slightly, signal is not clipping the output meter) > NAD IR impulse response

Even as great as the DI track sounds, the same noise is still there. So not sure what to think.
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