Am I Clipping the Compressor?

[sprint]

I have a compressor in the attached clean preset that seems to clip/distort on very hard strums (the type you do to check if it's possible to clip the output). The output signal is not clipping, but on very hard strums I intermittently hear some distortion in the clean signal. I don't think it's the amp (tube pre) as I've experimented with bringing the amp drive way down and the clipping is still there. My instrument input is at 75% (gibson sg 498Tpup) - if I bring it way down to 30% or so, and/or turn off the compressor the clipping does not happen on hard strums. I also looked at the block meters and though the compressor input looks high on hard strums it does not seem to be max'd. It looks to me like the compressor setting I have causes this distortion. Any advice? I struggle getting compression right generally - maybe this is normal.

fyi - I'm testing directly thru headphone to eliminate any external gear issue possibilities.

 

[unix-guy]

I have a compressor in the attached clean preset that seems to clip/distort on very hard strums (the type you do to check if it's possible to clip the output). The output signal is not clipping, but on very hard strums I intermittently hear some distortion in the clean signal. I don't think it's the amp (tube pre) as I've experimented with bringing the amp drive way down and the clipping is still there. My instrument input is at 75% (gibson sg 498Tpup) - if I bring it way down to 30% or so, and/or turn off the compressor the clipping does not happen on hard strums. I also looked at the block meters and though the compressor input looks high on hard strums it does not seem to be max'd. It looks to me like the compressor setting I have causes this distortion. Any advice? I struggle getting compression right generally - maybe this is normal.

What Compressor type? I think the Tube type (maybe others) can distort. There's a post somewhere from Cliff.

 

[sprint]

Analog compressor

 

[sprint]

 

[chris]

My instrument input is at 75% (gibson sg 498Tpup) - if I bring it way down to 30% or so, and/or turn off the compressor the clipping does not happen on hard strums.

is the Input Meter on the front panel turning red at 75%?

 

[sprint]

is the Input Meter on the front panel turning red at 75%?

Yes - I'm tickling the red as per standard practice I think (unless I got that wrong), but it is not red continuously. Note though that this is the only circumstance (this compressor on with these settings) that I have this issue (cleans with no compressor do not exhibit this). Its almost like tickling the red on input in conjunction with compression generates some audible input clipping on clean tones where as tickling the red with without compression does not.

Edit- It's also not consistant - sometimes it takes really hard whack on the strings, but other times (and this is what concerns me as it's within normal playing) a medium strum generate some crackle as the chord tails off

 

[Don Watters]

Yes - I'm tickling the red as per standard practice I think (unless I got that wrong), but it is not red continuously. Note though that this is the only circumstance (this compressor on with these settings) that I have this issue (cleans with no compressor do not exhibit this). Its almost like tickling the red on input in conjunction with compression generates some audible input clipping on clean tones where as tickling the red with without compression does not.

Edit- It's also not consistant - sometimes it takes really hard whack on the strings, but other times (and this is what concerns me as it's within normal playing) a medium strum generate some crackle as the chord tails off

I have the same thing happen with my Music Man Majesty (not boosted), with the input set at 5%. It doesn’t even tickle the red with normal playing. But I get drop outs when I dig in. This is directly on the input of the AFX3, without a compressor involved. It’s just the way it works. There’s not enough headroom on the input to deal with hot pickups.

 

[jlynnb1]

do you have a gate on the input?

 

[chris]

I have the same thing happen with my Music Man Majesty (not boosted), with the input set at 5%. It doesn’t even tickle the red with normal playing. But I get drop outs when I dig in. This is directly on the input of the AFX3, without a compressor involved. It’s just the way it works. There’s not enough headroom on the input to deal with hot pickups.

hmm i have my majesty(s) at 10% or so, never hear this type of thing on cleans and i hit it hard. i'll try again.

 

[sprint]

do you have a gate on the input?

Yes actually - I just shut down for the night - will try turning the gate off tomorrow AM to see if there is a difference - note though that this is a clipping noise / static / crackle - at the end of the chord - not a signal dropoff like from a gate.

 

[Smittefar]

You have a very fast attack. That will sometimes cause transients to sound clipped

Edit: you have lookahead turned on. That should eliminate most of the clipping sound caused by the compressor

 

[mr_fender]

I have the same thing happen with my Music Man Majesty (not boosted), with the input set at 5%. It doesn’t even tickle the red with normal playing. But I get drop outs when I dig in. This is directly on the input of the AFX3, without a compressor involved. It’s just the way it works. There’s not enough headroom on the input to deal with hot pickups.

Max input level on Input 1 is +16 dBu (about 4.89 volts RMS). That's quite high for any passive guitar pickup. If for whatever reason that's not enough, try using Input 2 instead. Its max input level is +20 dBu (about 7.75 volts). For comparison, pro line level is +4 dBu (about 1.23 volts)

 

[sprint]

So back on the trail of this today:

• tried a different cable - same issue.
• tried a different guitar - same issue.
• confirmed gate off.
• reduced compression - clipping less audible but still there.
• turned off compression - clipping much less audible but still there.

After experimenting with the instrument input level, I think I'm hearing input clipping (as Mr Watters is experiencing also above also). I think it is more noticeable in this context given that the patch is designed to be very clean and the amp output eq is somewhat extreme (removes all the mids and boosts high end to yield a somewhat passable acoustic tone from my sg). I always thought that tickling the reds on input would not yield any clipping noises but if you strum really hard on a very clean patch with high end frequencies boosted you can hear clipping. I liked the instrument level at 75% for this guitar but I guess I'll have to dial it back and adjust patches accordingly (50 seems to remove the issue) - kind of surprised though as I thought it was safe to be "tickling the red" but hard strums will clip - just never hear it with any distortion at all in the patch.

Thanks all for the help on this.

 

[chris]

So back on the trail of this today:

• tried a different cable - same issue.
• tried a different guitar - same issue.
• confirmed gate off.
• reduced compression - clipping less audible but still there.
• turned off compression - clipping much less audible but still there.

After experimenting with the instrument input level, I think I'm hearing input clipping (as Mr Watters is experiencing also above also). I think it is more noticeable in this context given that the patch is designed to be very clean and the amp output eq is somewhat extreme (removes all the mids and boosts high end to yield a somewhat passable acoustic tone from my sg). I always thought that tickling the reds on input would not yield any clipping noises but if you strum really hard on a very clean patch with high end frequencies boosted you can hear clipping. I liked the instrument level at 75% for this guitar but I guess I'll have to dial it back and adjust patches accordingly (50 seems to remove the issue) - kind of surprised though as I thought it was safe to be "tickling the red" but hard strums will clip - just never hear it with any distortion at all in the patch.

Thanks all for the help on this.

tickling the red is fine, but hitting it very hard can put it in red "for real" and you could get clipping. you shouldn't get any "tickle" when strumming normally. it should tickle only when hitting your hardest. 75% for humbuckers seems high to me, though there are always exceptions.

if you adjust the Input Level down, you shouldn't need to do anything to any presets, as you don't get additional gain from the Input Level.

 

[sprint]

tickling the red is fine, but hitting it very hard can put it in red "for real" and you could get clipping. you shouldn't get any "tickle" when strumming normally. it should tickle only when hitting your hardest. 75% for humbuckers seems high to me, though there are always exceptions.

if you adjust the Input Level down, you shouldn't need to do anything to any presets, as you don't get additional gain from the Input Level.

Thanks - definitely the tests I've done indicate 75% is too high as you indicate - never noticed this before but I've been on a mission lately to re-level all my patches so that the clean scenes match up well with the distorted scenes within and across patches. It's been interesting because in doing this levelling with big DAW meters you quickly realize how dynamic tones can be within the Axefx - it's a really wide range particularly for cleans so going back and forth between clean and distorted with a very even perceived level and absolutely no clipping possible on any outputs is more challenging than I thought. Worth it though as I am now much happier with clean/distorted and distorted clean transitions.

 

[chris]

Thanks - definitely the tests I've done indicate 75% is too high as you indicate - never noticed this before but I've been on a mission lately to re-level all my patches so that the clean scenes match up well with the distorted scenes within and across patches. It's been interesting because in doing this levelling with big DAW meters you quickly realize how dynamic tones can be within the Axefx - it's a really wide range particularly for cleans so going back and forth between clean and distorted with a very even perceived level and absolutely no clipping possible on any outputs is more challenging than I thought. Worth it though as I am now much happier with clean/distorted and distorted clean transitions.

yup, clean tones are way more dynamic. high gain tones are self-compressing. i often find my high gain tones a bit lower than the level set line, to allow my clean tones more headroom for playing soft vs hard. not saying to do that, but in many situations, that's what happens. really depends on how i play any given preset. but you're on the right track for sure.

 

[Zedhed]

Simple rule I stick to is; No red on input, all tickling to be done is on the output.

 

[sprint]

Simple rule I stick to is; No red on input, all tickling to be done is on the output.

In my experience, tickling the red on output can lead to a more reduced enjoyment than tickling the red on input, however, to each their own, who am I to advise others on how to engage in their tickling,

 

[mr_fender]

Don't just rely on a single blinking LED. The easiest way to check if you are clipping the input is to record a DI track from USB Input 5 or 6, hit hard on some big open chords and then zoom way in on the waveform peaks and look for the telltale plateaus of chopped off peaks. Adjust your input level and repeat until you don't see any more clipping. Keep in mind that the level scaling is not perfect once you get down low on the input trim control, so you may need to compensate with the Input 1 Gain control as well to keep your relative input level roughly the same.

Here's a quick sweep I did in Reaper with my Les Paul clone, Duncan JB bridge pickup and 11-48 strings, pounding hard on a 6th string E power cord:


You can clearly see the significant clipping immediately on the higher input level settings, but notice how the much lower settings also increase in overall level, except for at the 0% setting. This is where you'll need to use the Input Gain control to compensate.

Let's take a closer look at each setting:








Based on these, somewhere between 5 and 10% on the input level would be the magic spot for my Les Paul's JB pickup. I almost never actually pick as hard as I did in the test, so I could probably go up a few percent more and still be fine. I tried to keep the zoom levels consistent and the picking attack consistent for each setting, but I'm no robot. I think it still illustrates the point though.

 

[sprint]

Don't just rely on a single blinking LED. The easiest way to check if you are clipping the input is to record a DI track from USB Input 5 or 6, hit hard on some big open chords and then zoom way in on the waveform peaks and look for the telltale plateaus of chopped off peaks. Adjust your input gain and repeat until you don't see any more clipping. Keep in mind that the level scaling is not perfect once you get down low on the input trim control, so you may need to compensate with the Input 1 Gain control as well to keep your relative input level roughly the same.

Here's a quick sweep I did in Reaper with my Les Paul clone, Duncan JB bridge pickup and 11-48 strings, pounding hard on a 6th string E power cord:
View attachment 74283

You can clearly see the significant clipping immediately on the higher input level settings, but notice how the much lower settings also increase in overall level, except for at the 0% setting. This is where you'll need to use the Input Gain control to compensate.

Let's take a closer look at each setting:
View attachment 74284
View attachment 74285
View attachment 74286
View attachment 74287
View attachment 74288
View attachment 74289
View attachment 74290

Based on these, somewhere between 5 and 10% on the input level would be the magic spot for my Les Paul's JB pickup. I almost never actually pick as hard as I did in the test, so I could probably go up a few percent more and still be fine. I tried to keep the zoom levels consistent and the picking attack consistent for each setting, but I'm no robot. I think it still illustrates the point though.

Interesting - with my SG (498T bridge pup) I'm getting down onto the 40-45% range to have no audible clipping on hard full chord thwacks. The results above make me wonder if there is a lower range of input clipping (peaks chopped off just a little) which, though it may not yeild audible clipping, does generate some subtle tone differences to the raw guitar signal entering Axefx (compared to 0 input clipping).