Input Trim

Rex said:
Nope. Saturation means asking a circuit to produce more signal than it's capable of. That's when distortion starts.

You're thinking about using as much of the range of the A/D converter as possible. That's a good thing, because it lowers the noise floor. But in the case of electric guitar, it's not so important. The noise that your guitar produces is usually much stronger than the noise of the A/D converter.



That's because of the A/D converter's built-in limiter. It prevents the converter from going into saturation (clipping) when it gets hit with a too-strong signal.
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Thanks Rex for your good explanations.
My point is to make all users aware that if the values are too high, there is a risk of losing sound quality.
Although the user adheres exactly to the specifications in the manual. And the red LED only lights up from time to time.
It seems that not only the level but also the set value has an influence on when the limiter kicks in. IMO
At least at values above 90-95% and higher, the impression is there.

For guitars with higher output levels, the level display is probably active earlier than the limiter kicks in.
 
It's starting to sound like maybe there is a case for having the ability to set A/D input level per preset assuming one's presets are dialed in for specific guitars, at least for those like me where there is a big difference between my strongest guitar (can tickle red at 10%) and my weakest guitar (cannot tickle red at 100%). Up to now I thought I was fine to set it to 40% for my strongest guitar with no audible sign of digital clipping (though well past the point where it can tickle the red) and no obvious impact on the signal of my weakest guitar - but maybe there is a wee bit of optimization that could be realized by having a strong guitar preset at 10%, and weak guitar preset at around 85% to maximize dynamics without the compression issue noted above.
 
sprint said:
It's starting to sound like maybe there is a case for having the ability to set A/D input level per preset assuming one's presets are dialed in for specific guitars, at least for those like me where there is a big difference between my strongest guitar (can tickle red at 10%) and my weakest guitar (cannot tickle red at 100%). Up to now I thought I was fine to set it to 40% for my strongest guitar with no audible sign of digital clipping (though well past the point where it can tickle the red) and no obvious impact on the signal of my weakest guitar - but maybe there is a wee bit of optimization that could be realized by having a strong guitar preset at 10%, and weak guitar preset at around 85% to maximize dynamics without the compression issue noted above.
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Seriously, guys, just follow the instructions in the manual, and you’re golden. No audible impact on tone = no audible impact on tone. This is all about sound. That which isn’t audible doesn’t matter :)
 
Rex said:
Seriously, guys, just follow the instructions in the manual, and you’re golden. No audible impact on tone = no audible impact on tone. This is all about sound. That which isn’t audible doesn’t matter :)
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I have, of course, read and followed the instructions in the manual - just responding to the suggestion above that there is a "sweet spot", and to my experience with the whole tickling the red procedure which doesn't really indicate a whole lot given one guitar that can't tickle the red at any input level and another that can't not tickle the red at any level more than about 8-10%. Also, as I mentioned above - one can definitely get digital clipping while following the published instructions given that "tickling the red" is somewhat inexact - to avoid this I think one has to rigorously test for digital clipping and set a signal lower than the point that digital clipping starts to appear which is a lot lower than I realized for a long time.

GlennO said:
FYI, I'm not seeing any compression. On the left is input level at 50%, on the right 100%.
View attachment 92857
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I don't hear any compression either (I was not the one that noted that issue above) - all I hear is digital clipping starting to happen at higher values for stronger guitars.
 
sprint said:
I have, of course, read and followed the instructions in the manual - just responding to the suggestion above that there is a "sweet spot", and to my experience with the whole tickling the red procedure which doesn't really indicate a whole lot given one guitar that can't tickle the red at any input level and another that can't not tickle the red at any level more than about 8-10%. Also, as I mentioned above - one can definitely get digital clipping while following the published instructions given that "tickling the red" is somewhat inexact - to avoid this I think one has to rigorously test for digital clipping and set a signal lower than the point that digital clipping starts to appear which is a lot lower than I realized for a long time.


I don't hear any compression either (I was not the one that noted that issue above) - all I hear is digital clipping starting to happen at higher values for stronger guitars.
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I can’t speak to that. I’ve never played a guitar that can tickle the red on any input level. It must have very hot pickups.
 
With my 90's American Standard Strat with stock single coils, I can go up to about 85% before I start barely tickling the red LED with hard chord hits. With a softer attack, I can easily go to 100% and not hit the red. Your pick attack has just as much to do with it as the pickup's output, especially with really dynamic passive pickups.
 
Rex said:
It must have very hot pickups.
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I didn't think so but I have not owned a lot of guitars so maybe - My strongest guitars (Carvin and SG with C22B and 498T bridge pickups respectively) both measure around 13k Ohm on the bridge, and my strat @ 8k Ohms is the weakest - nothing far out of the normal zone for those guitar types afaik. Mr Fender makes an interesting point above about the pick attack - I've always used hard strums when setting the A/D input value but maybe that's too much and I should be strumming more realistically for this - hard strums make sense to me if listening for digital distortion in order to eliminate a setting that could possibly clip even if only in a more extreme case.
 
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Passive pickups can be very dynamic. The output difference between a really hard hit and more typical picking can be surprisingly large when there's no compression going on. Your test chord hits should reflect your hardest normal pick attack. If you routinely rock the Townshend windmill and pound the hell out of the strings, do that when setting the input level. If you tickle the strings like a butterfly wing and never hit hard, there's no point in doing so when setting the input level.
 
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