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S/PDIF vs USB vs TRS vs XLR-Best Sounding?


The S/PDIF out seems harsh. I realize it does not go through any converters I assume on the Fractal and I know it does not when going into the Universal Apollo 8.

Which if the above methods produces the best tone representation of the Axe? What does Fractal recommend? S/PDIFF is easy, and the XLR to TRS as line inputs into the Apollo sound better to me...


What do the Pro Fractal users use when recording an album?


Power User
To be honest I can't hear any difference between SPDIF and audio cable, once I have both of them balanced in terms of volume. If you have a frequency analyser like Ozone you can record both at once and compare. But first you might check that the volumes are the same, that you are not clipping any outputs/inputs, check sample rate is 48k, etc.


ok, thanks. Good to know. That said, does the S/PDIF by pass the D to A conversion going out of the fractal and the A to D in the Apollo 8? So I am bypassing the DACs?


I've recorded with USB and SPDIF and I cannot tell the difference
to be honest I cannot think of a reason why there would be a difference
SPDIF and USB are both digital transport methods..
so with both it's just a stream of binary from Axe to DAW
iirc, the audio is just a payload of the transport mechanism that carries it so it's not altered in any way
in my case it's either:
Axe <----USB---> Mac / Logic
Axe <---SPDIF---> Audio Interface <--- Firewire---> Mac / Logic

and analogue interface [XLR or 1/4" jack] though will mean extra conversions digital to analogue and back..
I've done this too [1/4" jack]
Axe <---1/4" jack cables---> Audio Interface <---Firewire---> Mac / Logic
and this sounded excellent too - which is to be expected

Why SPDIF [or analogue] instead of USB?
my reason for me using 1/4" jack [and later switching to SPDIF] was because the USB connection between the Mac and the Axe was unreliable..
When you're having to do repeated takes simply because the USB failed the frustration starts getting the better of you..
and then you end up having to do even more re-takes cos now your head is in the wrong place and you're playing like shite..
I can't remember when, but at some point the USB issue just stopped.. no idea why..
maybe a Mac update.. or an Axe update.. or both… no idea really..
anyways.. I no longer have this issue and so I use the USB because the work flow is better...


Power User
I don't think there is a better way. I use analog out only because I prefer monitoring software.

Clockwork Creep

Power User
I prefer a digital (USB/Spdif) signal because I don't have to deal with the output level knob.
The audio is recorded at the same amplitude everytime, that is set in the preset. Consistent.
Also, I don't occupy any analog inputs on my audio interface and I can connect something else there...

Theorically, the digital signal should be the highest quality, because it goes directly to daw, unlike the analog signal that also depends on analog to digital conversion quality. But practically, the difference, if your audio interface is any good, shouldn't be that noticeable.
I use SPDIF for many of the reasons expressed by FreeMind - freeing analog slots, no output level issues, no DA/DA conversion. I tried USB but had latency issues and challenges when recording multiple sources outside the PC at the same time. I now feed the SPDIF signal into my UAD Apollo and it's rock solid.


Power User
I've often wondered about this but haven't compared recordings via the different connections. I'm running through a saffire pro 40. I know its not high end but does anyone have any comments on the quality of AD/DA? maybe I should start using USB...bypass the interface's, likely less quality, converters?...


Power User
I use a Saffire Pro 40 and it is crystal clear. Also have a Babyface and use the Axe. I have noticed no difference in Axe direct or analog out of Axe into Saffire. This is only my opinion but so much of the desire to find the ultimate quality AD/DA conversion or signal path is like trying to determine the difference in a billionth of a second and a millionth of a second.

Is there difference? Yes. Will humans be able to identify it? No.


The main concern for me is how many times and in how many signal paths is there an DtoA and AtoD conversion.

For a big mix, the affect can be cumulative and cause noticeable degradation (ironically like trying to avoid playing back a 24trk 2" tape too many times to avoid losing too much from tape shedding.)

In the case of tracking with the Fractal, it's not cumulative. The Fractal's analog and digital path are top-shelf. Either way works fine without compromise.

For my system it's more flexible for me to patch analog. When I am doing demos for the forum, it's all USB though; again just more convenient for my setup and how I work.
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