Input Trim

FractalAudio said:
That sounds more like your guitar needs a bright cap. Many guitars have a small treble bleed cap on the volume pot to combat high frequency loss due to cable loading.
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Thanks. Yeah, this especially guitar needs really this mod. Just thought, the Axe could do that instead ;) ....
 
Cliff, I use an expression pedal mapped to CC10 INPUT VOLUME. My normal preset chain is usually, wah, compressor, drive1, drive2, Amp, cab, FX Loop, Delays, reverbs.

So, is that different than the trim on the amp, because it is more like turning the guitar volume down? It sends less signal through the wah/compressor/drives before it involves the amp block?
 
I use an expression pedal to lower "drive" for less gain in some of my patches. However I notice more treble when the drive is lowered. So what direction should I go with the input trim while lowering the gain. Higher or lower to achieve the same freq response through the sweep of my pedal
 
guitarsrule said:
I use an expression pedal to lower "drive" for less gain in some of my patches. However I notice more treble when the drive is lowered. So what direction should I go with the input trim while lowering the gain. Higher or lower to achieve the same freq response through the sweep of my pedal
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Connect the expression pedal to the input trim (if you can - I'm not in front of my axe). If you can't do that, then maybe connect the pedal to a volume block right before the amp.

Edit - Or do it like Rod a couple of posts up.
 
FractalAudio said:
Or use a cable with less capacitance or simply a shorter cable.
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Are short, low capacitance cables known to minimize the loss of treble frequencies when a passive pickup's volume control is turned down?

I realize that cables like this can minimize the capacitance effect (loss of highs) over long cable runs.
But I've never thought about using them as a substitute for a treble bleed circuit.
You'll probably have more overall highs when you have your vol pot cranked and when you roll your vol pot back with cables like these, but will the relative difference between the highs with the vol pot cranked vs the highs with the vol pot rolled back be any better?

Maybe I should look into that.

My experiences with low capacitance cables have been mixed though.
I usually prefer the overall tone I get from standard shielded cables.
The low capacitance cables I've tried (George L, Planet Waves, etc.) often seem to yield too much top end and too much mids for my tastes.
Usually I've gone with low capacitance cables when I had to have longer cable runs though.
I never really messed around with shorter low cap cables.

I have yet to find a treble bleed circuit that doesn't bother me in one way or another.
There's either too much (or not enough) treble gain when the vol pot is rolled back or the pot's taper gets screwed up too much.
I've tried various value caps alone as well as caps with various value resistors in parallel or in series and it's never totally satisfactory.
I always use treble bleed circuits along with an on/off switch so that I can put them in the signal path only when I really seem to need it.
I used to always try to have my vol pots wide open and controlled the vol with a vol pedal for the most tonal consistency across all vol levels.
But I'm starting to like the duller sound better, with the vol pot level not quite on full, more of the time nowadays.

I'm tempted to just always use EMGs (since they are more or less immune to this problem) but they really don't have the tone I'm after most of the time.
I've even tried buffers that plug right into the guitar's out put jack.
There was one made by a company called PAX I think.
And also the Demeter Fat control which buffers the signal at the guitar as well.
But these buffers, while they solve the problem, make it too bright and sterile sounding at every setting of the vol pot.

This has always been one of those niggles that's bothered me about electric guitar tech.
That and guitar cab directivity.
T'would be really nice to completely banish both of these from my rigs.
[And yes, I know about Jay's directivity modifier.
I've been experimenting with these for years now but have not been able to find a suitable source of 1/2" foam (my front-loading cabs can't take the 3/4" foam) up here in Canada.
McMaster-Carr won't ship here for some stupid reason.
And I also know about the directivity characteristics of the CLRs and happen to own 2 of the wedges but have not yet been able to make them work 100% for me for various reasons.]

If this post is not suitable for this thread please feel free to move it somewhere else.
 
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Cliff, I've been playing guitar for well over 40 years, and in this short time I've had my Axe-Fx I've learned more about the mechanics of tone from you and your products than any other source. Thank you so very much for the fantastic level of support you and your folks provide, not only for the people that buy your stuff, but also for the "civilians" that peruse these forums.
 
hillbilly said:
Cliff, I've been playing guitar for well over 40 years, and in this short time I've had my Axe-Fx I've learned more about the mechanics of tone from you and your products than any other source. Thank you so very much for the fantastic level of support you and your folks provide, not only for the people that buy your stuff, but also for the "civilians" that peruse these forums.
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I second that !!
for the first time I wan't to learn about this stuff :)
 
FractalAudio said:
....So what use is a straight gain control at the front? Doesn't the Input Drive do the same thing?

The short answer is "no". The long answer is "probably not".
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From what I understand, the Overdrive control recently added to some of the amp sims (USA Leads e.g) does do the same thing as the Input Trim - Just add straight gain without tonal coloration. Correct, or if not, what are the differences ?
 
shredi knight said:
From what I understand, the Overdrive control recently added to some of the amp sims (USA Leads e.g) does do the same thing as the Input Trim - Just add straight gain without tonal coloration. Correct, or if not, what are the differences ?
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The Overdrive control does not the same thing as the Input Trim. Overdrive Control is used in amps which cascade their full controllable clean preamp circuit with a following overdrive stage - the clean preamp with tonestack fully remains in the signal path when the overdrive channel is used.

Here is the difference shown in examples (simple paradigms)

on MesaBoogie MK Amps (above MkII)

Mesa.jpg


or on the mighty D*mble ODS

Rumble.jpg


Both paradigms just show Input Trim just as a trimmer pot or an input attenuator - well it's more of linear input sensitivity control with abilities to attenuate to -20dB or boost the signal up to +20dB - this is what real amps can't do..... ;)

Cheers
Paco
 
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Great Advice Paco !!

What a community !!

25 years playing and Now I start to see the Light !!

I don't want to sell my analog gear, I really love it but... What a wonderful landscapes out there with this magic box ... Thanks Fas



Sent from my iPhone
 
I use input trim almost on 80% of my patches, as it basicly replaces a booster in front of an amp without any additional cpu load.

I just wished the input trim control wouldn't be burried within the advanced menues so much. When selecting an AMP in the amp list, control knobs A,B and C control level, master and drive. I think D should be mapped to input trim, as it's basicly as important as those other controls.

And yes, I know there's Axe-Edit, but I'm a good-for-nothing front-panel guy. :/
 
Why don't the Diezel models have Overdrive control, like Mesa and the others? I been using input trim in place of the channel volume, which sounds great, but curious why all amps that have a channel volume don't use Overdrive instead of input trim.
 
shredi knight said:
From what I understand, the Overdrive control recently added to some of the amp sims (USA Leads e.g) does do the same thing as the Input Trim - Just add straight gain without tonal coloration. Correct, or if not, what are the differences ?
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Basically yes except that the gain is applied at a different point. For example in a Boogie the Overdrive is applied after the first two triode stages. It's a subtle difference but it does affect the sound somewhat as the gain staging becomes different.
 
Heavyplayer said:
Okay. I just thought Overdrive was added to those amps that have a channel volume.
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You don't need these things at your axefx, because the axefx loading only one channel of the chosen amp ....switching to another amp channel will require X/Y-switching or another preset (or a 2nd amp block and scenes)
 
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