Unity Gain

trancegodz

trancegodz

Fractal Fanatic
The manual says that out 3 and 4 are at unity gain when turned all the way up.

I turned my real Marshall Plexi volume on 2 for a clean sound and plugged my guitar straight into to see how loud it was.

Next I created a preset like on page 30 of the manual. For the test I just had input block 1 connected to output block 3L. Then on the back out 3L went into the front of my Marshall. I turned the Axe FX III front output 3 knob all the way up.

It worked fine but was way way louder than just plugging the guitar straight into the amp. It drove the front end of the amp so hard it sounded like I had the amp on 10 instead of 2. Like a hot rodded Marshall on 10. Sounded good but not at all what I was expecting. I was expecting it to sound just like my guitar plugged straight into the amp.

Is this the way it is supposed to be, and if not what is causing the huge increase in volume?

Edit: Problem is gone. Thanks for everyones help and suggestions!
 
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Should be the same with just Input1 > Output3L - check that your "Input 1 Gain" knob in the "Setup" > "Input Levels" menu is set to 1.0. Also, make sure output levels on the Input1 and Output3 blocks are set neutral.
 
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For clarity, are you running into the front of your Marshall (Input) or an effects return on the Marshall? If you are running into the Input of the Marshall you would essentially be running the Axe as a drive pedal in front of the amp. If you are running into an effects return, it should be closer
 
Werpinater said:
For clarity, are you running into the front of your Marshall (Input) or an effects return on the Marshall?
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He states in OP that it's to amp input ("the back out 3L went into the front of my Marshall.")

Werpinater said:
If you are running into the Input of the Marshall you would essentially be running the Axe as a drive pedal in front of the amp
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His test config is correct to test the first 2 cable connections of a 4CM set up.
 
sprint said:
He states in OP that it's to amp input ("the back out 3L went into the front of my Marshall.")


His test config is correct to test the first 2 cable connections of a 4CM set up.
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There is no amp model in the preset, I missed that, just input to output. Teched an event late last night an didn’t read it right.

@trancegodz are the levels in the Input and Output blocks boosted in any way?
 
sprint said:
Should be the same with just Input1 > Output3L - check that your "Input 1 Gain" knob in the "Setup" > "Input Levels" menu is set to 1.0. Also, make sure output levels on the Input1 and Output3 blocks are set neutral.
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Thanks.

The output level on the actual input block in the preset is 0.
The level on the output block in the preset is also 0.

Here are my settings in the Axe FXIII I/O setup.

Under the I/O menus my input levels A/D sensitivity are all set to 50%.

Under I/O in the audio section my settings are:
A thru D input source are all set to analog.
Input mode 2 set to stereo.
Input mode 3 set to Sum L+R
Input mode 4 set to sum L+R

Under I/O Output 1 configuration my settings are:
A Mode is stereo
B Output level is +4db (the other choice was -10db)
C Phase is normal.

Under I/O Output 2 configuration my settings are:
A Mode is stereo
B Output level is +4db
C Phase is normal.

Under I/O Output 3 configuration my settings are:
Mode is sum L+R
Boost / Pad is 0 db
Phase is normal.
copy input 1 is off

Under I/O Output 4 configuration my settings are:
Mode is sum L+R
Boost / Pad is 0 db
phase is normal.
copy input 1 is off
 
It is at unity gain, line level unity gain. The front of your Marshall wants to see an instrument level not line level, hence the boost.
 
RDeraz said:
It is at unity gain, line level unity gain. The front of your Marshall wants to see an instrument level not line level, hence the boost.
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Thank you. I thought I had a wrong setting somewhere. So it was only my misunderstanding of what unity gain actual is.

I am able to turn down output 3 level on the front a little more than half way to make it match what it is like plugging my guitar straight into the amp. If I want to drive the front end of the amp harder I could do it.
 
trancegodz said:
Thank you. I thought I had a wrong setting somewhere. So it was only my misunderstanding of what unity gain actual is.

I am able to turn down output 3 level on the front a little more than half way to make it match what it is like plugging my guitar straight into the amp. If I want to drive the front end of the amp harder I could do it.
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That's not right. For unity gain you set the knob fully CW.

I suspect your Input 1 Gain is not set to 1.0 in the I/O menu.
 
trancegodz said:
Thank you. I thought I had a wrong setting somewhere. So it was only my misunderstanding of what unity gain actual is.

I am able to turn down output 3 level on the front a little more than half way to make it match what it is like plugging my guitar straight into the amp. If I want to drive the front end of the amp harder I could do it.
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Still serms wrong - the level into your Marshall should only match straight in when output knob 3 is at full.

In your list of settings above, you did not mention the parm I referred to initially: "Input 1 Gain" in the setup/input levels menu - if that's not set to 1.0 - you won't match straight in vs from output3 in your preset.

Also - I assume you are doing this amp input level match test with the cabling from / to the amp's fx send / return disconnected right?
 
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FractalAudio said:
That's not right. For unity gain you set the knob fully CW.

I suspect your Input 1 Gain is not set to 1.0 in the I/O menu.
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I just checked and input 1 gain in the I/O is set to 1.000.

I do have my output 1 configuration output level set to +4db in the I/O audio page.

Using the 4CM method I have output levels 3 and 4 on the front both set full up and it matches what my guitar sounds like plugged straight into the Marshall.

But using the 2 cable method like on page 30 of the manual I have to turn down output 3 level on the front a little more than half way to make it match what it is like plugging my guitar straight into the amp.

I was only using the 2 cable method because of the ground loop I was getting with the 4CM.
I will probably not be using the 2 cable method now that I solved the 4CM ground loop problem I was having.
 
sprint said:
Still serms wrong - the level into your Marshall should only match straight in when output knob 3 is at full.

In your list of settings above, you did not mention the parm I referred to initially: "Input 1 Gain" in the setup/input levels menu - if that's not set to 1.0 - you won't match straight in vs from output3 in your preset.

Also - I assume you are doing this amp input level match test with the cabling from / to the amp's fx send / return disconnected right?
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I couldn't find that before but I just found it and input 1 gain in the I/O is set to 1.000.
There was nothing in the fx send and return at all.
The 2 cable method on page 30 is what didn't seem right with the output levels.

I just got it to work perfectly using the 4CM method. So that's what I will use.
 
trancegodz said:
But using the 2 cable method like on page 30 of the manual I have to turn down output 3 level on the front a little more than half way to make it match what it is like plugging my guitar straight into the amp.
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sorry to hang on, and maybe it doesn't matter at this point, but even with the config noted on page 30 ("fx processor (Pre)" which is: guitar > AxfxInput1 > AxfxOutput3L > External Amp Input), the amp input would only match straight in if the output3 knob is @ full (unless there's another level change going on somewhere).
 
sprint said:
sorry to hang on, and maybe it doesn't matter at this point, but even with the config noted on page 30 ("fx processor (Pre)" which is: guitar > AxfxInput1 > AxfxOutput3L > External Amp Input), the amp input would only match straight in if the output3 knob is @ full (unless there's another level change going on somewhere).
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I appreciate your help. Even though I will now be using the 4CM which works as I expected and am happy, it would be nice to know what was causing the front end amp boost using the 2 cable method on page 30. If I was doing something wrong that caused that behavior it would be nice to know what I did wrong.

Even if it's apparently not supposed to work like that, it drove the hell out of the front end of the Marshall. Like using a Butler Tube Driver.

I am happy using the 4CM method.
 
trancegodz said:
Using the 4CM method I have output levels 3 and 4 on the front both set full up and it matches what my guitar sounds like plugged straight into the Marshall.

But using the 2 cable method like on page 30 of the manual I have to turn down output 3 level on the front a little more than half way to make it match what it is like plugging my guitar straight into the amp.
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Something doesn't make sense about this. If you start with the 4CM test preset and bypass the amp's loop (I'd probably also unplug the cables from the amp fx send/return) you'll end up with the same signal path as a 2CM test preset. Does that actually change the level hitting the preamp? It shouldn't. Nothing would change in the In1 - Out3 part of the signal chain.

I'm wondering if you swapped cables and somehow ran into the thing where the humbuster circuit boosts the level, either due to not plugging the Out 3 cable in all the way, or some other cable jack/wiring issue.
 
Bakerman said:
Something doesn't make sense about this. If you start with the 4CM test preset and bypass the amp's loop (I'd probably also unplug the cables from the amp fx send/return) you'll end up with the same signal path as a 2CM test preset. Does that actually change the level hitting the preamp? It shouldn't. Nothing would change in the In1 - Out3 part of the signal chain.

I'm wondering if you swapped cables and somehow ran into the thing where the humbuster circuit boosts the level, either due to not plugging the Out 3 cable in all the way, or some other cable jack/wiring issue.
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I'll try what you suggest and do some more testing later tonight.

You know on my original test using the 2CM I was using a humbuster cable. It is possible I didn't have it plugged in all the way. If not having a humbuster plugged in all the way somehow boosts the level, that sounds like a definite possibility.

I am using all regular cables now with the 4CM method and everything is working fine.
 
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