Digital clipping

[Sebastian]

There is some limiting in the Delay blocks. Could be clipping there.

The general rule-of-thumb is to set all blocks but the Amp block to around 0 dB. Then adjust the Amp block for the desired level. The levels in the other blocks (except the Drive block) should only require minor adjustments, if any, to compensate for the Mix.

That's what I do.
Exceptions are pitch, delay and reverb blocks when I put them in serial: as a rule of thumb I always set the level to +3 dB, as this seems to keep the dry signal at the same volume as when the block is bypassed.

[cfm.lint]

Here's two clips of the stock 59 bassguy preset on Seymour Duncan SH1n neck pickup in humbucking mode and split. Is this what you guys are referring to?

http://soundcloud.com/cfm-lint/59-bassguy-stock-preset
http://soundcloud.com/cfm-lint/59-bassguy-stock-preset-pu-split

[FractalAudio]

Here's two clips of the stock 59 bassguy preset on Seymour Duncan SH1n neck pickup in humbucking mode and split. Is this what you guys are referring to?

http://soundcloud.com/cfm-lint/59-bassguy-stock-preset
http://soundcloud.com/cfm-lint/59-bassguy-stock-preset-pu-split

You have your cabinet sims turned off.

[cfm.lint]

OMG, feeling guilty now I made you spend 39 keystrokes on that post. For reference, here's with the cab sims on:
http://soundcloud.com/cfm-lint/59-bassguy-stock-preset-cab

[FractalAudio]

Sounds normal to me. Bassmans aren't known as particularly clean amps, that's their charm. Mic up a real one and crank it. Make a recording. You'll be surprised.

[Patzag]

Here are the waveforms in Logic of the same preset with only the level reduced from 0 to -15 dB.
No clipping on either on OUT 1, but obviously the 0dB sounded wrong.

[FractalAudio]

Probably clipping the input to your audio interface. The Axe-Fx II's outputs can get pretty hot.

[Patzag]

Nope. My audio interface is the Axe FX. this is a direct recording into Logic using the Axe as the audio interface (USB). The clipping is very noticeable audibly, as you can imagine, but does not show on the output clip. As a note, the levels on the recoding are below 0.0 dB.

If I may make a wish/suggestion here to create a metering block. Possibly strictly as a debug function to actually check the levels of block outputs which might be suspect.

[FractalAudio]

My guess is you have the Boost/Pad turned on. This should only be used in unity gain mode/4CM.

[Patzag]

No boost turned on. But I did do a little further work on this to see why this could occur.
I followed someone's advice somewhere past to reduce the gain on the OUT 1 / OUT 2 if my presets were mostly too hot and clipping the output.
I had a couple of presets which would clip so I set my overall level at -3 so that anything a little hot should not destroy my sound.
It turns out that this is quick fix but not a good long term idea:
I went a bit "absurd" on this to check out the consequences. I lowered the gain on out 1 to -12dB (as far as it would go, then went back to my amp block and cranked it to +6 dB. Oh that sounded really nasty. No output clipping, but the clipping coming out of that amp block is really ugly.

Now I took the testing one step further on this to find out if this was one amp only or what. I was using wrecker. With the GLOBAL output brought back to 0, the master at 10, clipping occurred (audibly) at -9.9 dB on the LEVEL. Drive was at 7.8, a bit of boost on bass and miss, nothing too drastic. I disabled the PEQ I had upstream with no change in the clipping.

Note that all this without triggering the red Clipping LED once.

I tried the cab and it too allows increase of the LEVEL parameter beyond audible clipping before the LED comes on.

Here's my theory: The limiter you have on the Delay block will effectively reduce the level and prevent OUTPUT clipping even if the signal is already clipped within the signal chain. Why do I think that? Because when I bypassed the delay block, the clipping LED came on and stayed present until I reduced the amp level to -7.7 dB when playing very hard. With the Delay block back on, clipping went "undetected".

I know this is NOT how all this is intended to be used, but because it CAN be used that way, proper warning should be made somewhere (such as the wiki or manual) that internal digital clipping may escape detection if the main outputs on the global EQs are lowered and/or if a delay block is being used in series.