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Amp sims, Reaper and clipping!

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Amp sims, Reaper and clipping!

Postby garrettendi » Thu Dec 05, 2019 3:34 pm

Hi guys, Last night I was working with an amp sim, and noticed the track in Reaper for the sim was clipping as much as 16db but the main master bus was well into the green, occasionally yellow. According to my hearing there was no clipping or un-musical distortion on my headphones, and my headphones were set at a level such that I could hear myself talking over them (I try to take care of my hearing even though I'm already fully Deaf!).

Going into the amp sim, is a "pickup replacer" VST (think like an IR but for pickups instead of speakers) into a TS808 sim. I am not clipping going to my AI, that seems fine!

Is this something to be concerned about?
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Re: Amp sims, Reaper and clipping!

Postby Wonks » Thu Dec 05, 2019 3:56 pm

As has been said many times here, there is no actual clipping by level alone when working within the floating point world of most DAWs.

Was the channel fader at 0dB? If it was less, than that's one reason the master bus was showing lower. If the mater bus fader was less than 0dB, then that's another one. And on some DAWs, the pan control lowers the output when centred by the pan low value, normally by 3 or 6dB.

So if you can't hear any clipping, I wouldn't worry too much, but do bear in mind that amp sims and TS808 sims are probably going to give you a much hotter output than input.
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Re: Amp sims, Reaper and clipping!

Postby garrettendi » Thu Dec 05, 2019 4:00 pm

Thanks Wonks. Channel and master faders were both at unity, but I had another look at the screenshot I took last night and it seems I also had a channel strip plugin on the guitar amp track, as the last plugin on that track.

My reason for concern is because as you all know, my hearing is not up to snuff. Can I trust them on this?
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Re: Amp sims, Reaper and clipping!

Postby garrettendi » Thu Dec 05, 2019 4:01 pm

Also, would you then say as its within the DAW that I don't need to apply proper gain staging after the amp sim to bring it back down? Maybe with the Reaper Volume plugin?
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Re: Amp sims, Reaper and clipping!

Postby CS70 » Thu Dec 05, 2019 4:04 pm

Most DAW engines work at either 32 or 64 bits. That allows them to deal with truly large (and/or extremely precise) numbers without significant computational errors (so long the numerical algorithms they use are "stable", which for well known DAWs are). For the musician, this translates to an incredibly large dynamic range - so that there's very little chance of overloading a bus from a DAW channel.

You can read a little about number representation on computers and the effect on samples (aka music) at my blog post at https://www.theaudioblog.org/post/compu ... th-numbers

The consequence of this is that, so long you don't overload the physical inputs and your master bus (or any channel that goes to a physical analog out) does not clip, you're gonna be fine.

Still, it's a good habit to keep things in the green, for a couple reasons: one is that the number representations and then numerical recipes which concretely realize the mixing may be tested and keep being precise for "reasonable" ranges. It's not a given, and it may work just fine, but the are certain ways of calculating with computers which stay perfectly fine with a range but are a little more unstable outside its boundaries.

The second reason is that certain plugins may simply be coded to expect "reasonable" levels, and even clipping on purpose for crazy high samples to emulate their real-world counterpart. For obvious reasons, individual plugin code sees much less use than your average DAW mixing engine so there's more probability that samples outside the "physically doable" range make that code fail.
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Re: Amp sims, Reaper and clipping!

Postby garrettendi » Thu Dec 05, 2019 4:07 pm

Thanks CS70.

I guess this is not something I need to worry about, but I'll use the volume plugin to bring it back down for the reasons you state,

I'm still not sure I trust my cochlear implant well enough to really hear if its clipping though.... :?
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Re: Amp sims, Reaper and clipping!

Postby Wonks » Thu Dec 05, 2019 4:13 pm

It won't digitally clip unless the output level is really really high, and then it will be the D/A converter clipping, not the actual audio in the DAW (until you come to render it to a file). But you are using plug-ins that are designed to distort, so you'll hear that, which would make it harder for you to tell.
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Re: Amp sims, Reaper and clipping!

Postby CS70 » Thu Dec 05, 2019 4:14 pm

I'll use the volume plugin to bring it back

A simple workflow I employ is to have a gain plugin (the Blue Cat's Gain 3 is free and works very well for this) as last insert effect for each channel and use it to bring the level so that I can leave the fader in the -6dBFS - +6dbFS range, fine tuning with it so that the output of each channel stays in the sweet spot between -18 and -9 dBFS.

Most DAWs have a gain knob in the channel, but I tend to use BC because that knob in Sonar/Cakewalk sets the gain before the inserts, so changing it after having set up the sonics, affect them (for example, reducing the gain into a compressor makes a great deal of difference to the compression itself, and so on).

I do try hard to keep level sensible throughout - between each plugin - and bring it back to the sweet spot if needed after any processing I may apply.
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Re: Amp sims, Reaper and clipping!

Postby garrettendi » Thu Dec 05, 2019 4:16 pm

Thanks guys,

I'll bring the levels back to normal and get a second opinion on hearing "non-musical" clipping

EDIT: That's what I'm taking from what you guys explained?
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