USB Direct vs Audio Interface

clarky said:
make an aggregate interface… then you get the best of both…
better in fact…
you can play, hear your dirty tone [via the jack cables into the AI] plus the mix through your monitors..
and simultaneously record the dry via the Axe's USB
Click to expand...

I still haven't seen/heard any proof that aggregate devices (on the mac) work properly. They may for a few minutes or even 10 if you are lucky and then break down into sharded nothingness. However if it works, please post your working configuration.

I use use the preamp on my interface and connect the io with spdif. This was a logical decision. Ideally I'd go into the front of the AxeFX but routing wise, it's not the most flexible option. With an aggregate device, I would just use that instead of spdif... but it doesn't work for me.
 
works fine for me
Mackie mixer with firewire and the Axe-2 via USB
8-core Mac Pro, 16G RAM with Mountain Lion
in tha Agg interface, Drift Correction is checked for both AI's

works fine
 
Personally it comes down to this. If your project is at a different sample rate use direct to your interface. If you can make you project 48k then use the axe usb. Everytime you put a signal through A/D (and subsequently D/A) it adds about 3dB of noise. Minor for sure but its something to consider. Remember the Axe FX does A/D on the input and D/A on the out put. Then you put it in your interface and add another A/D conversion. I assume we are talking an additional 6 db to the noise floor plugging into an interface vs axe fx usb. Do not mistake this for noise picked up by your guitar and amplified in whatever you plug it into. Cheers!
 
clarky said:
works fine for me
Mackie mixer with firewire and the Axe-2 via USB
8-core Mac Pro, 16G RAM with Mountain Lion
in tha Agg interface, Drift Correction is checked for both AI's

works fine
Click to expand...

Which Mackie? Are you using the built in firewire on the mac? FW400 or 800? This is good to hear.
 
A definitive (idiots) guide to reamping in the mix would be massively helpful. At the mo my set up is axe fx via usb -> Mac book pro retina (Logic x) -> apogee ensemble -> Monitors and I have no solid idea of how to elegantly reamp in the mix.
 
clarky said:
when I first got the Axe I was recording / reamping via jack cables between the Axe and the audio interface..
I tried using the USB but had some issues..
after upgrading my Mac to Mountain Lion I tried the USB again [out of curiosity] as part of an aggregate interface and it works really well..
so now I use the USB
Click to expand...

And do experience a sound difference between plugging in directly on your external audio interface (so guitar-Axe fx-Soundcard-DAW) and using the Axe fx as a soundcard (so guitar-Axe fx-USB-DAW)? really would like to know this since I have never tried this and always use the first method for recording.

You can also ask yourself: is the Axe fx a better audio interface as your external audio interface? I have no idea.
 
grape said:
Which Mackie? Are you using the built in firewire on the mac? FW400 or 800? This is good to hear.
Click to expand...

it's an Onyx 1620i.. there are no drivers or anything.. you just jack it in and it works..
a lot of you will need an audio interface more than you'll need a mixing desk, so this ain't for everyone..
so the firewire [from Logic's perspective] is 16 in, 2 out - which is no good for reamping
but I need a mixer that's not huge and it does the job well..
when I reamped with jack cables I used my other AI - my ancient TC Electronic Konnekt 24 [which is 4 in, 4 out]
it's ok, but quite limited.. but did the job ok..

that said, I've no prob with an agg interface with the Axe and Onyx.. they seem to play nice together..

audio quality of cable vs USB: I can't say I noticed a difference.. both are good..
the only thing with cable is that you need to watch the input meter on the Axe so you can replicate the level of your guitar jacking into the Axe with the recorded dry signal. not difficult really..
the USB though is convenient and works great..
AI wise, my next GAS will be to replace the TC Elec with an 8 in, 8 out [or more] AI. one that is just an AI and nothing else.. no mixer in it or flash routing or FX etc..
something that is just a nice AI and nothing else..
 
clarky said:
audio quality of cable vs USB: I can't say I noticed a difference.. both are good..
the only thing with cable is that you need to watch the input meter on the Axe so you can replicate the level of your guitar jacking into the Axe with the recorded dry signal. not difficult really..
the USB though is convenient and works great..
.
Click to expand...

Not sure if I understand you. With the 'cable method' (non USB, so output from Axe fx in your soundcard) you record your Axe signal (with effect etc.) signal in your DAW. So there is no recorded dry signal?
 
with the TC I have cable 4 in's and 4 out's and 4 firewire in's and out's

guitar -> TC in1 -> TC firewire out -> DAW: this is the dry
TC has a mixer inside it which 'sends' in1 to jack out3: cabled [via a Redeye] to the Axe INSTR in
Axe output1 cabled to the TC in's 3 and 4: so I can hear the Axe as per normal operation with amp / cab / fx
TC out 1 and 2 to monitors
DAW master outs to TC firewire 1 and 2 so I can hear the mix
all that records the dry guitar..

I have another config in the TC that takes the dry guitar from the DAW firewire 3, routes it to TC out3 which is cabled to the Axe INSTR in
the Axe plays back via cables into the TC ins 3 and 4 just as before, which are then routed via TC firewire to the DAW to record the wet
so that is the reamping config..

it works fine.. I just don't do this anymore.. in fact, I don't use the TC at all now..
 
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clarky said:
to be honest.. you don't need a hotter signal to the DAW.. maybe you would in the days of tape to get out of the noise floor..
but in this digital age.. it's not really needed..
if anything.. the RME is actually adding noise that you may not have if you were using the USB..
Click to expand...

No empirical evidence of noise (and I'm pretty picky). Also, more signal also means more dynamic range, and more 'bits'. Conversely this means less signal = less bits. For me I'd rather have the range.
 
Boerboel666 said:
A definitive (idiots) guide to reamping in the mix would be massively helpful. At the mo my set up is axe fx via usb -> Mac book pro retina (Logic x) -> apogee ensemble -> Monitors and I have no solid idea of how to elegantly reamp in the mix.
Click to expand...

I did a video on this myself :)
You need an additional sound card, i.e. the one that comes with the mac book or whatever.

 
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plyall said:
No empirical evidence of noise (and I'm pretty picky). Also, more signal also means more dynamic range, and more 'bits'. Conversely this means less signal = less bits. For me I'd rather have the range.
Click to expand...

the noise thing yes.. you'll get more noise using the jacks..

but more dynamic range?? more bits?? I don't think this is true at all..
if I recall correctly, whilst on the surface this appears to be a reasonable thought, in real terms I don't think this is actually true..
I think that [for clever reasons that I don't fully understand], the signal with the lower level should contain just as much dynamic detail as a larger one when it's in the digital domain..

try thinking about it this way.. [maybe this is not a great justification, but it works for me]..
we all agree that on the digital audio engineering smart-ass scale, Cliff is a hard 10..
so.. we'd also all agree that the decisions he makes regarding the Axe and the signal path are going to be right up there on the top floor of extreme cleverness..

now take a look in the Axe-II manual at the Input / Output block diagram [a few pages from the last]
you'll see that the USB output marked USB 2/3 is just after the Main Input Source switch
you'll also see that the USB input feeds the same switch..
also, the INSTR input also feeds the same switch..

this tells me the following:
- the signal from the guitar [after whatever smart stuff happens at the INSTR INPUT] has all the digital information that is needed for the Axe to do it's thing..
- the dry signal recorded from the Axe USB 2/3 has to be exactly the same as the original dry guitar signal because it's sent to the DAW from the same switch and therefore at the same point in the signal path..
- the recorded dry signal sent from the DAW to the Axe arrives at the same switch and enters the signal processing path in the same manner as if you jacked your guitar straight into the front panel INSTR IN socket
and if this USB input signal was different, playing the guitar straight into the Axe and playing back the recorded dry from the DAW would yield different results..
so surely if this was true it'd render the whole USB IN for recording the dry pointless…
could you really see someone like Cliff / FAS settling for that?? the whole FAS attention to detail thing is kinda nuts [luckily for us]

this all tells me that the USB recorded dry signal contains all of the frequency and dynamic information as if you jacked the guitar into the front panel…
if jacking your guitar into something else, boosting the signal [for greater dynamic range] and then pumping that into the Axe via USB was the way to go, I think we'd all be doing it.. imagine.. "make your Axe sound better and have better dynamic range.. jack into this gizmo first.. then USB to the Axe rather than use the INSTR IN.."
and clearly this makes no sense..

so.. should you boost your recorded dry in the DAW, the only thing you actually add is level..
and the dynamic relationships between the samples should therefore remain the same.. but louder..
so it seems to me like you're telling the Axe to read the same book [in this case, a sequence of digital samples]… but with a bigger font..
because you've not captured anything different.. you've just made it louder..
 
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clarky nailed it.

Your guitar is noisier than the Axe-Fx. The noise level of your dry signal is determined by your guitar, not by the Axe. If you raise the level of your dry signal, you raise the noise by the same amount; there's no improvement in dynamic range. You just wind up with a level that's harder to work with.
 
Clarky -


First - I'm not thinking purely from a re-amping perspective. This is also how I record (Guitar -> DI Box [Radial JDV] -> Axe -> RME -> Computer).

When I DO re-amp, I also use an analog path (Computer -> RME -> Reamp Box [Radial X-AMP] -> AXE). The DI signal is sent to a separate input on the RME, and on into the computer.

I suppose that the A/D and subsequent D/A conversion could add jitter/noise, but from what I can tell it's certainly not audible.


I see your point, both from the 'Cliff' argument perspective and the block diagram perspective (although I haven't gone back to the manual yet - taking it on faith).

Let me spin the return question to you in the following format: ... if Cliff designed the unit to use 48Khz/24 bit signaling, why doesn't the USB port deliver full scale (i.e. 2^24 bits) worth of signal?

Using all 24 bits to describe/pass the signal would definitely give the most dynamic range. This is one of the many reasons that 24bit recording was invented - to get more dynamic range and a lower noise floor than 16 bit.

Put another way, why not use all of those 16M+ different levels to render the Axe's beautiful output?

If all else fails, I'll just refer you to my license plate: GOZTO11 :D

Edit: I should also add that I record at 44.1K because I don't want to have to do a downstream sample rate conversion when delivering a recording.
 
I totally see your points there..

you do have to consider that the guitar is just one instrument that has a limited dynamic range and frequency range..
and the Axe is designed specifically for guitar
in theory, we could wind it all up to a 96k sample rate and a huge 64-bit word depth..
but then.. would it make a difference??
sure you could possibly measure it if you had sensitive enough kit..
but given the nature of the guitar would it make much difference?? I doubt it..
I could imagine it could possibly make a difference with other instruments / fx though.. especially those with extremely high harmonic content..

one thing I noticed though with cables..
you need a reamping box like a Redeye [I'm guessing your Redial is something similar yes?] to match the impedance of your AI's [or mixer's] output to the Axe IN..
this will suck out some level and extreme high end.. so you have to put that back.. now your input signal is not quite the same as the original..

also.. every box you sling your signal through will add or take away something.. often a little of both..
generally.. adding noise.. taking away the extreme ends of your frequency range..

to be honest… I don't think what you're doing makes much [if any] difference with respect to improving things going into the Axe..
and with all those boxes to get through, you may well be degrading the signal a little [don't know if you'll be able to hear it though - maybe not actually if it's good kit]..

that said.. there is a difference between 44.1k and 48k..
all my work is almost exclusively at 48k..
when it comes to signal processing, this does make a difference

44.1k is a place to drop to after mixing / mastering so you can pop it onto a CD
 
No argument with anything you posted (and the stuff I use is considered good kit ;)). And for the record, I'm not trying to improve anything going into the Axe - I'm just looking to get a good DI @ 44.1K.

A separate question though - perhaps worthy of a separate thread: when you downsample your 48K project to 44.1K, aren't you generating artifacts/harmonics/phase differences? This is one of the reasons I have always stayed at 44.1K.
 
I reckon your setup is certainly about as good as it needs to be if you work at 44.1k
so I'll not argue that one is better than the other…
personally, I started off using the all cable method [at 44.1k]
but now I've switched to the USB at 48k

I think that if you drop all tracks individually from 48k to 44.1k you'll be asking for trouble..
but if the entire mix is handled at 48k and bounced to a single stereo tack at 44.1k, that's ok..
and that's exactly what mastering houses do and have always done in the digital age..

the beauty of 48k and above is that it stands up better to the processing that happens during mixing / producing
cos when you change eq, add fx, compress etc in the digital realm, the higher the sample rate the better..
it lessens / better hides the artefacts created by the act of manipulating the digital audio..

so the rule of thumb is to start at a high sample rate and remain there until the final act of creating the master that's bounced to CD
 
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