Input Clipping Thread

[Shahar]

I think we need a separate thread for this. As I mentioned in the firmware thread (22 beta), I am getting input clipping at 4% with a Les Paul Custom with 498T Bridge Pickup.

The range of this control seems unbalanced. Going down to 3.9% with a passive pickup doesn't seem right.

Just curious, what pickups are you using and how low did you have to go to dodge the clipping?

 

[Andrew Male]

I use EMG active pickups (Het set) and don't get the clipping message at 37%.

 

[Shahar]

I use active EMG active pickups and don't get the clipping message at 37%.

Hammer the low E really hard (pretend you're Keith Moon playing a guitar).

 

[jamesmarshall]

There are way too many variables to make any conclusions from a post like this.

You are going to get so many different answers.
Also, remember this is not input gain, it is adjusting how you are hitting the A/D converter and it is the input sensitivity for the A/D.

https://wiki.fractalaudio.com/wiki/index.php?title=Connections_and_levels#Main_input_level

Axe-Fx III and FM9: the Instrument input on the Axe-Fx III is more sensitive than the Axe-Fx II's, but it has more headroom / dynamic range. Do not set it below 5%, because at this point gain may be affected. The front panel LED meter bridge provides instant visual status for the inputs.

When using a mono instrument, do not set the Input Mode to Stereo or Sum L+R. Select Left Only (default). Otherwise the level will be attenuated.

Input levels can be also controlled via MIDI CCs.

"For a Strat, near 100% on the input level is not unusual. I run my Strat around there. It has vintage-type pickups." [44]

"To get the best noise performance it is important that the Instr In trim is set correctly in the I/O->Input menu. Set this as high as possible without clipping the input." [45]

"You don't HAVE to tickle the reds. Adjust for your hottest guitar and leave it." [46]

"The AFXII has digitally controlled potentiometers before and after the A/D and D/A converters. Therefore it knows what the input and output gains are. It compensates for these gains in the digital path." [47]

"Full-scale is a term that indicates the maximum signal level into or out of an A/D or D/A converter, respectively. With digital converters the best performance is achieved by operating the converter such that the nominal signal level is close to full-scale. The exact voltage is unknown and irrelevant. Most digital gear will have indicators that measure the levels relative to the converter's full-scale value. For example, the input meters on the Axe-Fx indicate the input signal relative to the A/D converter's full-scale value. The "tickle the red" advice aims to operate the A/D converter near its full-scale value as the red LEDs light at 6 dB below full-scale, or -6 dBFS."

(Axe-Fx II) "The Input Trim control in the I/O menu is before the A/D. You can use that to reduce the level into the A/D. If you want 4 dB of gain reduction: A = 10^(-4/20) = 0.63. So you need to reduce your input pad by 37%. The new value is 0.243 * 0.63 = 0.153 => 15.3%" [48]

(Axe-Fx III) "There is no single optimum setting. If you have hot pickups with thick strings and a heavy hand you may need to set it at 10% or less. If you have vintage single-coils with thin strings and a light touch, 100%. Adjust it to tickle the red when playing hard." [49]

(Axe-Fx III) "Set the Input Trim so the meters ON THE FRONT PANEL tickle the red when strumming fairly hard." [50]

"Input 1 is normalized to 1V. The other inputs are normalized to 8V. 20 * log10(8) = 18 dB."

(Cooper Carter) "The Instrument Level is to make it so the A/D converter hears the best signal it possibly can. So say you have a super low output Strat. You crank up the input level so that that Strat is hitting the converter at a level that is making sure it's well above the (very low) noise floor of the Axe-Fx. The A/D does its work and then brings down the signal it outputs to the processor by the same amount you gained up, so that what is coming in is going out, regardless. Conversely, if you have a super hot guitar, like an EBMM JP15, it's already hitting the A/D way above the noise floor, and you don't want to add unnecessary noise by having the input higher than it needs to be to convert the signal at an optimal level. So you turn the input level down a good bit. The converter then compensates for how much you turned down by bringing up the signal by an equal amount before it outputs to the processor. The signal hitting your grid (i.e. pedals, amps, whatever) is in theory unchanged in level from what is coming out of your guitar. You've just optimized the level at which it's being A/D converted. You "can't" really "clip" the input given that it takes drive pedals and what-have-you just as well as an amp does." [51]

"Below 5% the gain decreases so, yes, it will be quieter." [52]

"Input dynamic range has everything to do with the ability to handle low level signals. The normalized gain of even a medium gain tube amp can be over 60 dB. If your input dynamic range is only 96 dB and you leave 6 dB of headroom your noise floor is now a paltry -30 dB. There's a reason modeling products use various techniques to improve input dynamic range including dual-range A/D techniques, channel doubling, companding, pre/de-emphasis, etc. Algorithms are extremely important. However usually the quality of the algorithm is proportional to its complexity. The higher the complexity the more powerful the processor required. One of the main reasons today's modelers sound so much better than they did just a decade ago is the increase in computing power allowing more advanced algorithms." [53]

(Axe-Fx III) "Below 5% that the gain compensation stops increasing." [54]

"The inputs can handle up to +18dBu. Use the Input Sensitivity controls to adjust accordingly." [55]

Firmware 22 for the Axe-Fx III and later add an on-screen warning about input clipping, because signal peaks can clip the signal, even when the Input LED meter doesn't flashes red.

"Many things contribute: number of windings, magnet strength, distance from strings, string type and gauge, pick thickness, how hard you pick, etc. Nothing has changed in the input processing. The clip indicator trips when the input is within 0.5 dB of full-scale. If if trips you should turn down the sensitivity." [56]

 

[Shahar]

There are way too many variables to make any conclusions from a post like this.
You are going to get so many different answers.
Also, remember this is not input gain, it is adjusting how you are hitting the A/D converter and it is the input sensitivity for the A/D.

So, how low did you have to go? And what pickups are you using?

 

[GlennO]

With my LP Classic with BurstBuckers, I don't get the clip light until about 90%.

 

[Shahar]

With my LP Classic with BurstBuckers, I don't get the clip light until about 90%.

SERIOUSLY??? Even when hitting the low E hard? And using Firmware 22?

 

[jamesmarshall]

So, how low did you have to go? And what pickups are you using?

I have 3 sets of higher-output pickups and several medium-output pickups. I had to set my Majesty with DiMarzio higher outputs to 5%, This also works fine for my BKP Holy Divers in my LP, and my EMGs in my signature Ibanez guitars, as well as the JB+ Jazz in my PRS. I have had to take it to 0.5 if I use the boost in the Majesty, but I rarely use it, so that doesn't count and I have had to do that twice in the 2 years I have had it. These settings did not change for me with 22, vs what I had on 21.

 

[giantslayer]

I suspect pickup heights account for a lot of the differences.

 

[Shahar]

I have 3 sets of higher-output pickups and several medium-output pickups. I had to set my Majesty with DiMarzio higher outputs to 5%, This also works fine for my BKP Holy Divers in my LP, and my EMGs in my signature Ibanez guitars, as well as the JB+ Jazz in my PRS. I have had to take it to 0.5 if I use the boost in the Majesty, but I rarely use it, so that doesn't count and I have had to do that twice in the 2 years I have had it. These settings did not change for me with 22, vs what I had on 21.

Thanks James, based on your previous quotes it said lowering it below 5% can affect the gain. As I mentioned I had to lower mine all the way to 3.9%, hence my concern. But that's only when I am really hammering the low E (the way I adjust the gain on my Clarett interface), standard playing doesn't trigger the warning.

 

[TheTrueZoltan!]

I use EMG active pickups (Het set) and don't get the clipping message at 37%.

Wut? I had a Het Set two years ago. These pickups were ridiculously hot when I had them! Have you forgotten to put a battery in the cavity?

 

[jamesmarshall]

Thanks James, based on your previous quotes it said lowering it below 5% can affect the gain. As I mentioned I had to lower mine all the way to 3.9%, hence my concern. But that's only when I am really hammering the low E (the way I adjust the gain on my Clarett interface), standard playing doesn't trigger the warning.

That is the thing you should play it like you normally would. No need to be Keith Moon with the arm all the way up and the hard strum, unless you normally do that. The point is to get the highest output guitar(s) and set them so the clip doesn't light under normal playing or maybe just slightly harder than normal but much. This will allow you to use any other guitar and not clip.

Also, realize I said that when I use my Majesty's 20DB boost I have to set the A/D sensitivity to 0.5 and Have no issues with gain or anything (again 20DB boost/preamp in the guitar). So it is one of those things that if it does not sound off and it works is it an issue? The clipping however I would say it can be an issue since it is digital clipping.

 

[Andrew Male]

Wut? I had a Het Set two years ago. These pickups were ridiculously hot when I had them! Have you forgotten to put a battery in the cavity?

Maybe it's the way you had them set up, they are hot pickups for sure, mine are factory fit from LTD and yes they have a Bat-ter-y. 37% works ok and I'm quite an aggressive downstroker running Power Slinkys, I'm not out here Mike Tyson'ing the strings though.

 

[mr_fender]

Active EMG's can be compressed in their own right if you're running at 9V. The onboard preamp is squashing the dynamics down a bit. Passive pickups might be lower output on average but can be more dynamic (higher peaks) when hitting hard.

 

[Shahar]

Maybe it's the way you had them set up, they are hot pickups for sure, mine are factory fit from LTD and yes they have a Bat-ter-y. 37% works ok and I'm quite an aggressive downstroker, I'm not out here Mike Tyson'ing the strings though.

With that setting, you should be able to easily trigger an "INPUT CLIP!!!" message on the new firmware by playing a palm muted E power chord, not even that hard. I lowered mine to 20% and can still trigger if I hit it hard enough. But to eliminate it altogether, I have to set it to 3.9%.

 

[mr_fender]

That is the thing you should play it like you normally would. No need to be Keith Moon with the arm all the way up and the hard strum, unless you normally do that. The point is to get the highest output guitar(s) and set them so the clip doesn't light under normal playing or maybe just slightly harder than normal but much. This will allow you to use any other guitar and not clip.

This ↑. Hit has hard has you normally hit when you play hard. No need to beat the crap out of the strings if you normally play with a very light touch.

 

[Shahar]

This ↑. Hit has hard has you normally hit when you play hard. No need to beat the crap out of the strings if you normally play with a very light touch.

Point very well taken! At first I was too obsessed with getting rid of that message altogether.

 

[discondition]

Record your guitars DI playing it Keith Moon style, then zoom into the DI and look for clipping there I guess.

 

[TremoloFan]

Because there are so many variables regarding guitar setups (string gauge, string formulation, string height, pickup height, pickup strength, pickup type, etc.) and so many variables regarding playing style (finger picking, using a pick, pick material, how hard you pick and/or strum, what strings you hit while testing, etc.), I believe it could be nearly impossible to do an apples to apples test between two different user's systems. So this is very hard to evaluate in a thread like this.

However, like the OP I am very curious to see how this debate unfolds and if there is a consensus on why we see such huge variances in settings with seemingly similar setups. I've got my popcorn ready...

BTW, with a Gibson R9 LP with Custombucker Alnico 3 pickups set very close to the strings, I can set it at 50% and not clip...any higher and I get an occasional warning when hitting low e or a strings really hard.

 

[Todd McMullen]

I just tested the 22.00 beta 6 and had the same issue. I have Suhr Doug Aldrich bridge pickup in a 2008 USA Charvel SoCal and Seymour Duncan JB in and ESP Eclipse. I have the I/O input at 50%. Have never received the clipping warning until testing the new dyna cab firmware. The pickup height for both is 5mm from low E string.