SPDIF and sample rate

S

s.fitzsimmons

Inspired
When running SPDIF to to an interface, does sample rate come in to play? I know it's at 48kHz via USB, but wasn't sure if it matters via SPDIF.
 
What Drama said. The Axe-Fx II is fixed at a 48kHz sample rate. So if you're doing a digital connection, (USB, SPDIF, or AES/EBU) your session has to be 48kHz as well.
 
If I'm at my other guitar players house, and he is plugged into his interface, (using POD Farm), and I plug into the same interface via SPDIF using the Axe 2, is that even possible with the 44.1 and 48 kHz thing?
 
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Jason W. said:
If I'm at my other guitar players house, and he is plugged into his interface, (using POD Farm), and I plug into the same interface via SPDIF using the Axe 2, is that even possible with the 44.1 and 48 kHz thing?
Click to expand...

Nope. There will be a weird pitch shift thing that will occur. Convert the project to 48k which shouldn't take long in most interfaces.

I ended up doing it will all four of the projects on my computer right before I got the Axe. It was well worth it for the USB Reamping alone. In fact I'm sitting here typing this while a few of my tracks reamp.
 
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I have been recording in LOGIC Pro 9 with projects set to 44.1. When I have high CPU usage, I get crackle when using the USB connection to record directly to my Mac. In those situations, I use the 1/4" outs of the Axe into a POD HD500 effects return, and then use the POD's USB connection to record. It works fine. But I'm not a pro, I'm just a hobbyist.

Do you think the crackle is because I haven't overriden the default sample rate of 44.1 in my LOGIC session and changed it to 48? I just read the help files tonight to learn how to do that, but it's too late to try to get started recording anything to see if I can answer my own question.

Any assistance from a knowledgable person is appreciated.

Thanks
 
Oh yeah, and if I'm just going to use the main outs and run mono, I can just use the left main out, correct?
 
rodzimguitar68 said:
I have been recording in LOGIC Pro 9 with projects set to 44.1. When I have high CPU usage, I get crackle when using the USB connection to record directly to my Mac.
Click to expand...

I have a macbook, and the crackle comes when the CPU usage gets high. It Crackles because it tries to keep the latency low, but does not have the processor power to do so.
Using a lower sample rate should use less CPU power, but as stated, the Axe-FX runs at 48khz. Your project should do so as well.
If processing power is a problem, I would record analog out of the axe fx and record my projects at 44.1 khz.

-Spazi
 
Jason W. said:
Oh yeah, and if I'm just going to use the main outs and run mono, I can just use the left main out, correct?
Click to expand...

Yes, but make sure your patches are truly mono also. If you have stereo delays/panned cabs etc. then you'll lose part of the sound.
 
Will I still need to run 48kHz if I am running mono left main out into the interface, or should it not matter if I choose not to use SPDIF?
 
The sample rate only matters if you're going digital. The moment you use the L/R XLR or jack, it matters nada. BTW, depending on your interface, you may be able to apply a sample rate conversion to the coax from your AFX in real time. It'll probably say SRC and allow you to choose any rate you like, although I personally prefer to just use the analog outs. They're very high quality. There shouldn't be any sonic gains from going digital.
 
The only reason to keeping the signal digital is that you get rid of unnecessary Analog to Digital conversion. (aka: A/D - D/A)

The guitar signal going in to the Axe FX is analog, get's converted into digital and with USB or SPDIF it goes digitally into the computer with no extra conversion needed.

if you record from analog out of the axe fx into the audio interface you are using, you get this chain: Guitar signal Analog converted to digital, then converted from digital to analog, going from the axe fx output to the audio interface input and gets converted from analog to digital again.

depending on your audio interface, a normal sane person will never notice that it got converted multiple times and in a mix you really can't hear it.

Just do whatever works for you mate, and if it sounds good, it's good enough :)
 
Thanks for the info, I gotta keep reminding myself that I'm not asking dumb questions.... or am I...!
 
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