Bad clipping when using amp sims in real time

tbarnaby
KVRer
11 posts since 31 Jul, 2017

Post Mon Jul 31, 2017 2:19 pm

Hello,

I'm using Reaper as my DAW and Behringer UMC404HD as the audio interface.

The amp sims / Cab IRs are working great on a dry recorded track. However, last night I wanted to just rehearse a bit using the amp sims. So I set up Reaper to monitor the recorded signal so I could hear the amp sim in real time. However, there was a significant amount of clipping occurring in the monitor mix. At first I thought it was level related, but I turned everything down and it still happened. And it happened during loud and soft parts. The clipping seemed to reduce when I removed some unneeded effects, but did not go away entirely. So I'm wondering if this is processing / buffer /latency related since the software can't "look ahead"?

Are there some settings I can tweak to make this use of the sims (real time practicing) sound better?

Thanks!

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EvilDragon
KVRAF
17062 posts since 7 Jan, 2009 from Croatia

Re: Bad clipping when using amp sims in real time

Post Mon Jul 31, 2017 2:46 pm

What's your CPU usage like (check it in your OS's performance monitor, not Reaper's)?

Sounds like audio dropouts rather than clipping.

tbarnaby
KVRer
11 posts since 31 Jul, 2017

Re: Bad clipping when using amp sims in real time

Post Mon Jul 31, 2017 4:18 pm

EvilDragon wrote:What's your CPU usage like (check it in your OS's performance monitor, not Reaper's)?

Sounds like audio dropouts rather than clipping.
Overall CPU usage is about 30%. Looking at the individual cores, one core is at 50% and the rest are lower.

Could be dropouts maybe, but its very static-y sounding. Happens about every 2-5 seconds when playing.

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Kazrog
KVRian
766 posts since 24 Oct, 2009

Re: Bad clipping when using amp sims in real time

Post Mon Jul 31, 2017 4:50 pm

Sounds like a buffer underrun. Many times, it's the audio interface drivers creating a bottleneck (especially with budget hardware.) If you adjust your buffer and/or sample rate, you can probably arrive at something acceptable.

More info would be useful, though:
  • Operating system / version / bits (32 or 64)
  • DAW (recording software) / version / bits (32 or 64)
  • CPU make/model/speed
  • Audio interface hardware
  • Sample rate and buffer size of your session when experiencing the issue
Shane McFee
CEO/CTO - Kazrog LLC

tbarnaby
KVRer
11 posts since 31 Jul, 2017

Re: Bad clipping when using amp sims in real time

Post Tue Aug 01, 2017 11:00 am

Ok, I tried a bunch of stuff before posting the question. But I didn't try rebooting, which cleared up the problem. Sorry - rookie mistake. Thanks for the help guys!

Just for your information ...

* I tracked the problem to the amp simulation plugins. Recabinet was fine, every Kazrog amp sim I tried had the issue. However, Lepou amp sims worked fine with no sound issues.
* I tried changing the quality level on the amp sims but that had no effect.
* Other details ...
OS: Window 10 64bit
DAW: Reaper v5 x64
CPU: AMD A10-7700K, 3.4GHz
Memory: 16GB
Audio Interface: Behringer UMC404HD
Sample rate: 48K
Buffer size: Two possible relevant settings in Reaper
Request Block size: 512
Media buffer size: 1200ms

tbarnaby
KVRer
11 posts since 31 Jul, 2017

Re: Bad clipping when using amp sims in real time

Post Wed Aug 02, 2017 3:03 pm

Here's a little more information and a workaround/solution for anybody else that might experience this.

* First I was wrong that the reboot completely fixed this. It might have helped, but I think the main thing was that I was experimenting with a different Thermionik amp sim. I've noticed that some Thermionik amp sims are ok, while others are nearly unusable (as a real time solution). Just as an example, the Damage 120 is nearly unusable, while the Plexi is ok (a few pops, but manageable).

* As I mentioned before, the Lepou amp sims all worked ok with maybe a slight pop here and there. BIAS amp sims also worked with just a few pops here and there.

* I tried tuning a bunch of settings, but only one helped. In the UMC404HD control panel, I changed the "USB Streaming Mode" setting from "Low Latency" to "Standard". And that cleared up the problem for all the amp sims that I've tried so far. Also, at this setting I do not notice a delay between what I'm playing and hearing - so this is fine. The next level up is "Relaxed" and I definitely hear a delay there.

Jotunbjorn
KVRer
19 posts since 28 May, 2016

Re: Bad clipping when using amp sims in real time

Post Sun Sep 03, 2017 8:18 am

I think I ran into this bug today. When loading a project in Reaper that has the Damage in one track I noticed that the CPU usage was way higher than normal. Loading a preset in the plugin rectified the problem.

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Kazrog
KVRian
766 posts since 24 Oct, 2009

Re: Bad clipping when using amp sims in real time

Post Sun Sep 03, 2017 9:18 am

One thing to keep in mind is that none of my plugins work as well on AMD CPUs as they do on Intel. Intel lost a class action lawsuit over this - it's related to their math library, IPP, that is used in all of my plugins and is supposed to be AMD compatible. It's great, and makes things like Thermionik and KClip possible, but it's not smooth sailing on AMD hardware always. If you get to know the quirks of your machine, you can make it work, though.
Shane McFee
CEO/CTO - Kazrog LLC

Jotunbjorn
KVRer
19 posts since 28 May, 2016

Re: Bad clipping when using amp sims in real time

Post Sun Sep 03, 2017 10:25 am

I did some digging. It seems that the Savage just has super high CPU usage when both smooth mode and power amp depth are on. I have an Intel 3770K @ 4.5GHz.

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Kazrog
KVRian
766 posts since 24 Oct, 2009

Re: Bad clipping when using amp sims in real time

Post Tue Sep 05, 2017 9:18 am

Jotunbjorn wrote:I did some digging. It seems that the Savage just has super high CPU usage when both smooth mode and power amp depth are on. I have an Intel 3770K @ 4.5GHz.
That is true. I'm working on a lower CPU footprint Depth mode for the lower quality slider settings. The challenge has been making sure it still retains enough detail to not end up with that cartoonish low end you get from most other modelers.
Shane McFee
CEO/CTO - Kazrog LLC

StateOE
KVRer
19 posts since 2 May, 2010 from Han's Island, Disgraced by O'Hara's Treachery

Re: Bad clipping when using amp sims in real time

Post Thu Sep 07, 2017 7:50 am

Kazrog wrote:One thing to keep in mind is that none of my plugins work as well on AMD CPUs as they do on Intel. Intel lost a class action lawsuit over this - it's related to their math library, IPP, that is used in all of my plugins and is supposed to be AMD compatible. It's great, and makes things like Thermionik and KClip possible, but it's not smooth sailing on AMD hardware always. If you get to know the quirks of your machine, you can make it work, though.
This is interesting to know. I still use an old AMD FX-6100 on a build I made many many years ago, although I am still wanting to build a new machine with an i7, and all Thermioniks work well at Quality 6; I just disengage the Depth on all of them and force mono, because of course, Depth will destroy any of them. Until I do build my new machine, it is worth it to me to sacrifice the power amp low end control, then to make up for the low end on the IR. Thanks for explaining the details. I hear an extra roundness between Quality 5 and 6 that is utterly analogous to listening to the ride cymbals of a well mastered album at 44.1 kHz and 96kHz (not to open a Pandora's Box on this forum, so let me just say to those who disagree that you're completely and totally, infallibly right). I realize that I'm still running Thermionik at 44.1 in the end, but the internal oversampling really does make a difference to me, and feels completely and totally real. Anyway, very cool to know some of the mechanics of why your plugins work the way they do. Thermionik really is in its own class, too awesome for mortal computers haha!

In my opinion, it's a waste of your time to try to make Thermionik's Depth control work for less powerful systems. The things you've already achieved using your chosen techniques have been truly astounding, and I'm just curious to see where you go with your ideas. It sucks to have to divide resources between new, exciting research and experimentation and simply trying to make fantastically powerful plugins work all-encompassingly (à la Mitch Hedberg) with less powerful hardware. There is a world of plugins dedicated to working with even the least powerful of systems, but you have a niche here with Kazrog, something elite, if you will, and backwards hardware compatibility, for lack of a better term, is more akin to being all things to all people, and less meaningful. It's none of my business, but those are my two cents! I digress.

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Topeznor
KVRist
132 posts since 18 Jun, 2015

Re: Bad clipping when using amp sims in real time

Post Thu Oct 19, 2017 9:29 pm

A bit late to the party, but it may still be useful to some of you.

If you are tracking/jamming and want the best possible latency, turn off your graphics card driver. Things will look a bit weird but you'll still be able to operate the plugins if needed. As an example, my Audient ID22 works fine at "low latency" settings and 128 buffer. Anything less and the sound craps out. Disabling the video card allows me to go as low as "minimum latency" at 64 buffer with zero artifacts.

The thing is that not only Nvidia driver itself shits on input latency, but also involves the dxkernel.dll driver and causes massive interrupts from calls from the hal.dll driver. Checking lateny monitors may seem that 0.4ms is not a big deal, but disabling the video card shows that there is more than that.

Internet/Ethernet devices can also be disabled if needed. Some fo them are also very problematic.

Of course this is a bit of a pain in the ass, and doesn't work when mixing (because you want to actually see thigs the right way, lol). I'm actually buying aan AMD card just to try if its driver works better with audio. Word of advice would be buying an audio interface with good low latency drivers. That leaves you only with Zoom, unless you want to pay RME prices.

I kinda knew this myself when I bought the ID22, but man does it sound good...

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Kazrog
KVRian
766 posts since 24 Oct, 2009

Re: Bad clipping when using amp sims in real time

Post Fri Oct 20, 2017 9:15 am

I'm still rocking my dual RME Fireface 800 setup here. Not the latest and greatest, but still incredibly low latency and great sound, absolutely rock solid reliability. It's so great I'm actually afraid to upgrade, especially since I'm always doing mission critical work.

Just make sure you get a Firewire 800 card with a TI chipset if you go that route (most stable) - the old Firefaces are pretty affordable on the used market.
Shane McFee
CEO/CTO - Kazrog LLC

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Topeznor
KVRist
132 posts since 18 Jun, 2015

Re: Bad clipping when using amp sims in real time

Post Mon Nov 06, 2017 7:22 am

Bumping this just to tell you that swapping the Nvidia card for an AMD one worked like a charm. Truly night and day difference. If you can't do anything else to lower your latency, just try it! My ampsim experience has never been better!

Losing a few fps in games is a bearable tradeoff for a huge boost in ASIO performance! :D

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Kazrog
KVRian
766 posts since 24 Oct, 2009

Re: Bad clipping when using amp sims in real time

Post Mon Nov 06, 2017 9:38 am

Topeznor wrote:Bumping this just to tell you that swapping the Nvidia card for an AMD one worked like a charm. Truly night and day difference. If you can't do anything else to lower your latency, just try it! My ampsim experience has never been better!

Losing a few fps in games is a bearable tradeoff for a huge boost in ASIO performance! :D
Wild. Using an NVIDIA card on both desktop and laptop, no latency issues whatsoever, but again, RME drivers seem to transcend everything.
Shane McFee
CEO/CTO - Kazrog LLC

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