Input level issue...

thehydeout

thehydeout

Experienced
Something I've been trying to deal with from day 1 with my Axe but didn't want to post without some audio samples. Using the 4CM method to put my Triaxis in a patch just for matching tone purposes I notice the input level gets a little dead. Very much like just rolling off the guitar volume a little, it loses that high end sparkle. I've been through all the input level adjustments many times and nothing brings it up to where it is plugging straight into the Triaxis input. My interest is just wondering if this is normal or maybe my Axe has some flaw in the input stage.

Anyway I finally found some time to make some recorded samples. Mic'd cab with SM57. It is audibly noticable but even moreso obviously when actually playing. I'm in the minority of Axe users going into power amp and cab so here's the setup for the following clip:

Patch is nothing but straight through with FXLoop block. Just some mindless staccato-ish noodling

Section 1:
Guitar>Axe input (Front)>FXLoop Block>FX Send to Triaxis input>Triaxis outputs to FX Return>Axe output 1 to Mesa 20/20>2X12 EVM

Section2:
Guitar>Axe input (Rear)>FXLoop block>FX Send to Triaxis input>Triaxis outputs to FX Return>Axe output 1 to Mesa 20/20>2X12 EVM

Section 3:
Guitar>Triaxis input>Triaxis outputs to FX Return>Axe output 1 to Mesa 20/20>2X12 EVM

There was really no noticable difference taking the Axe completely out at this point and going straight to the power amp from the Triaxis.



Let the opinions begin!
 
What do you have the boost/pad set to in the I/O audio section? If I have the boost/pad turned up higher than 9db I get a noticable change in tone and output level. I using the 4CM with a Bogner XTC . At 9db I don't loose any audio that I can tell and the noise floor gets lower. The higher you turn it up the lower the noise floor but the audio signal sufferes.
 
I've tried adjusting all the different levels that can effect the signal. I have the boost/pad at -12 right now but I've tried it at 0 with no noticable difference. This seams to be isolated to the input section since I can run the outputs of the Triaxis into the Axe FX return and it's fine. Thanks!
 
I've also found a significant drop in volume in the FX loop.

I could compensate by raising the signal on the Out 2 for 7dB.

Alternatively you could try the settings on the FX loop block.

It's definately not related to your unit.
 
Goldtop's suggestion actually prompted me to look at the signal flow diagram in the manual again and I found the same solution that seems to work well. I assume you mean Out 2 Global EQ. First I just boosted the output level about 4-5db and it does a nice job of getting the signal to the Triaxis up where it should be. Seems to work even better leaving the output flat and boosting only the higher freqs a little. I wouldn't think that should be necessary but it does the trick. In the short time it takes to switch cables around there's no discernable difference now really. Another case of not being able to see the forest for the trees I guess!

Thanks for the pointers!
 
Uhm....so what's going on here? Impedance issue? I was ready to go for an Axe-Fx2 for "4 cable"-use and really wish it would sound as straight cable (or rather just a nice transparent buffer) with efx off. Anyone care to explain this signal loss...and tell me there's a way to avoid it?
 
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The "Unity-Gain Thing..."

Guys,

I'm wondering if this might be the result of the Axe-FX II's automatic unity-gain buffering/gain-staging? I believe there have been many posts/threads regarding this, but I'm NOT sure if that's what is causing your difference in gain?

IF it's true about the unity-gain, then I suppose it's possible that your input-gain on the "real" Mesa Triaxis could be a few (6 -7) db's-of-gain louder than unity, and as such, causes it to sound that much hotter than the Axe-FX II modeled version only. In other words, the 6-7db you're compensating at the GEQ could be the amount you "gained" from your: guitar-output's initial-level--->through "real/actual" Mesa Triaxis--->Axe-FX II's FX-Return--->Power-Amp--->Cab(s)...

Here's a pretty good technical-description of what I'm talking about from Axe-FX II user/forum-member viabcroce:

"It might worth mentioning that, in this case, the unity is achieved before and after the A/D converters: if guitar signal is low, it's amplified before the A/D input and then digitally reduced after conversion to bring it back to the original value; if guitar signal is high (or boosted), it's reduced before the A/D input and then digitally amplified after conversion to bring it back to the original value: this way you can control your sound via the guitar volume and/or saturate the virtual pre input as you would with any analogic amp, but the A/D converters always receive the optimal (same) amount of signal."

Also, I don't think we can always assume (...not saying you did, I wouldn't know?) a one-to-one relationship between the actual Mesa Triaxis' control/parameter-settings and the "numbers" associated with the parameters on the modeled Triaxis in the Axe-FX II...

Does that make sense?

Btw, (fwiw) I will probably be using my Axe-FX II similarly (Axe-FX II--->real-amp's FX-return--->Power-amp-section--->Cab - atleast until I can afford to experiment/invest-in some solid-state/FRFR-gear!)

Bill
 
Billmeedog, I think you misunderstand. There's no modelling or efx involved. The issue is losing signal strenght (top end too?) just by going through the Axe (without any efx or modelling) on the way to his Triaxis.
 
Is the noise gate on in the Axe-Fx II? Check "LAYOUT" and then the "INPUT/GTE" - turn "THRESH" fully counter-clockwise to disable it. Also, I know you said you've already checked this but I can also hear a difference depending on what the INSTR IN is set to on the INPUT tab of the I/O menu.
 
Trazan said:
Billmeedog, I think you misunderstand. There's no modelling or efx involved. The issue is losing signal strenght (top end too?) just by going through the Axe (without any efx or modelling) on the way to his Triaxis.
Click to expand...

This is correct. My real concern and reason for the post is just wondering if this same issue is happening before going to an amp block and causing the little bit of signal "deadness" I encounter overall. Or it could be just some impedance difference happening in Guitar>Triaxis vs. Axe>Triaxis.
 
It should be low impedance from to axe-fx to high impendance on the triaxis so I wouldn't think that would be an issue? i haven't tried the 4 cable method for a very long time with 2. I using the loop but w/ an effect unit, not a preamp so I don't have things at unity necessarily (just a good signal to the eclipses A/D converters).


there used to be a 6db cut on the loop in the axe-fx for clip protection. but I don't think that is the case on the II. That would ruing the unity gain. It should be no boost/pad, output volume full and you get unity gain.

If anything in the patches change the gain structure - preset volume, effect level changes, etc., that will effect the output level and it will no longer be unity gain.

I assume that has been taken into account by you though.
 
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RichHowe said:
Is the noise gate on in the Axe-Fx II? Check "LAYOUT" and then the "INPUT/GTE" - turn "THRESH" fully counter-clockwise to disable it. Also, I know you said you've already checked this but I can also hear a difference depending on what the INSTR IN is set to on the INPUT tab of the I/O menu.
Click to expand...

No I have the noise gate off. That's become one of the first things I do on a patch and don't care for it being on by default. I don't use a gate unless I have to which is only on some of (my) high gain tones. On that same page I tried switching to the 1meg setting of the Input Z instead of Auto with no audible difference. Of course the lower settings cause more of the same effect. And yes the first I was working with was Instr IN level. Even at the max setting I get the same issue it just gets more "ratty" sounding. I currently run it at about 68%. Thanks!
 
Keep in mind that even if you only have all shunts in your signal chain the noise gate in the layout menu on the input/gte tab will still be enabled. So, you're really comparing Guitar>Triaxis to Guitar>Noise Gate (Axe-Fx II)>Triaxis which will obviously not produce the exact same sound. This may not be your issue but I just wanted to make sure you understand that even with no modelling or efx the Axe-Fx II could still be impacting your tone with the noise gate.
 
year2525 posted on page 1 of this thread that he also finds a significant volume drop in the fx-loop. Could someone from Fractal please explain? I'm about to order one, but this scares me a bit since I'll be getting it for 4-cable use....
 
Thanks Rich. Yes I understand. It's become one of the first things I do. Going into the input/gate tab and pulling the threshold all the way down to defeat the gate.

Thanks Sean. That was why I set up a patch with nothing but FXL block and checked to see there were no boost or cut anyplace I could think of to check. Except I have the boost/pad up a little to lower the noise floor some. As straight and dry as possible otherwise. You mentioned you run an eclipse. The Axe contains all the effects I think I could ever need and more so I don't have a need for anything else at this point but this issue also made me wonder if I did run an effect unit such as my G-Force in the loop would it experience the same signal issue? Noticable in say the high freq reverb tails from that unit being diminished and such?

Thank you all for your input.
 
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