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Output 2 noise is pretty low

naka2112

Inspired
The gain channel on my Bogner has a certain amount of hiss when nothing is connected to the input. This would be normal, as all amps I have do this on a high gain channel.

When I go out of the output 2 on My Axe Fx 2 XL, with unity gain, into the front of my amp on a high gain channel, I've noticed that the hiss increases a little. I've been trying to see if I can eliminate this slight increase. Last night I came to the conclusion that a certain amount of hiss increase is going to be unavoidable because there is two A/D conversions, which introduce noise, and then there is the fact that another electronic device is in the chain.

So I decided to do an experiment.

I have a Voice Live 3 by TC electronic, which has a guitar effects processor built into it. You can set it up so that it is in front of your amp. So I decided to put it in front of my Bogner on a high gain channel, in a unity gain scenario. Guess what? The noise was way way way worse. The hiss increased dramatically. It made me appreciate how little noise is being introduced by the Axe FX 2.

So, I believe some noise is unavoidable, and the little bit of hiss that is introduced by the axe in the 4CM is minor compared to other devices.

Side Note:

To get rid of the hum in the 4CM i did the following.

1. I made a really short humbuster cable and it goes from Output 1 to the return of my amp
2. I use a short George L TS cable from the send of the amp to the FX return on the Axe
3. I do not use a humbuster cable going from Output 2 to the front of my amp. I found it there was even less hum when I used ordinary TS George L cables and a Radial Bigshot A/B/Y between Output 2 and the amp input. I use output B on the bigshot with the iso transformer activated, and the ground lifted. I went with the Radial Bigshot because it has a very good iso transformer that does not impact the tone when activated.

If anyone knows of an even better iso transformer, that uses unbalanced connections, please let me know.

Good luck guys!
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Yes, it is very difficult to minimize the hiss when putting a digital processor in front of a high-gain amp due to the A/D and D/A conversions. The XL is probably one of the quietest processors made but there will still be some residual hiss when using high gain. The Output 2 Boost/Pad feature was specifically intended to minimize hiss in these scenarios by running the D/A converter as "hot" as possible and then reducing the signal level after the converter with an analog pad.
 

notalemming

Fractal Fanatic
Yes, it is very difficult to minimize the hiss when putting a digital processor in front of a high-gain amp due to the A/D and D/A conversions. The XL is probably one of the quietest processors made but there will still be some residual hiss when using high gain. The Output 2 Boost/Pad feature was specifically intended to minimize hiss in these scenarios by running the D/A converter as "hot" as possible and then reducing the signal level after the converter with an analog pad.
I tried the 4cm yesterday with my Triaxis & was trying to adjust the out 1 & out 2 boost/pad but I could only boost out 1 & pad out 2. Is that normal? By the way it's labeled, I should be able to boost or pad both outputs. I am on an older AXE II without the output 2 mod, v15.03.
 

naka2112

Inspired
I tried the 4cm yesterday with my Triaxis & was trying to adjust the out 1 & out 2 boost/pad but I could only boost out 1 & pad out 2. Is that normal? By the way it's labeled, I should be able to boost or pad both outputs. I am on an older AXE II without the output 2 mod, v15.03.
I noticed the same thing. It seems to make sense with output 2. As I increase the boost/pad, the noise decreases without an increase in volume. I think it boosts before the converter, and then Pads the same amount after the converter. The net gain is zero, but the signal to noise ratio is improved.

Output 1 doesn't seem to behave the same way though. When I increase the boost/pad on output 1, the volume increases, as does the noise. It's almost like its only boosting, but not padding after the converter.

Perhaps fractal can comment on this.

Thanks.
 

notalemming

Fractal Fanatic
What I was hearing was output 2 got softer when adjusting it, output 1 got louder when adjusting it. Noise was not much different no matter how I set it.
 

naka2112

Inspired
Wow, I definitely noticed the noise going down on output 2. Are you sure you had the fx block activated? And the levels on the front panel maxed for unity gain?
 

naka2112

Inspired
Just rereading your original post. It might have something to do with you not having the mod on output 2.
 

javajunkie

Moderator
Moderator
To get rid of the residue hiss, use the gate block as an expander. Place the gate block after the fx loop block. Use a very hi ratio, and a quick attack release time. Start with the threshold all the way down and raise it up until this hiss disappears.
 

notalemming

Fractal Fanatic
That could be it. I was getting levels about even on the meters on the front of the Axe ( just below the red). I had the output knobs at about 3 o'clock so not quite maxed. I know I made a couple of errors as this was my first try at 4cm. The clean sounds were great but besides the noise, anything that was supposed to be hi gain had much less distortion than the same preset without the Axe as if the volume on the guitar was rolled way back. I ended up with is just in the Triaxis effect loop like I had the G-Force set up for years. It worked fine that way & was a huge improvement over the G-Force!
 

notalemming

Fractal Fanatic
That could be it. I was getting levels about even on the meters on the front of the Axe ( just below the red). I know I made a couple of errors as this was my first try at 4cm. The clean sounds were great but besides the noise, anything that was supposed to be hi gain had much less distortion than the same preset without the Axe as if the volume on the guitar was rolled way back. I ended up with is just in the Triaxis effect loop like I had the G-Force set up for years. It worked fine that way & was a huge improvement over the G-Force!
I will check that out next time I am at our studio!
 
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