Audacity Forum

Dear Folks,

OK, the saga continues. Bought a Presonus Inspire 1394 A-D -> Firewire unit for digitizing my vinyl. Got it hooked up to my stereo and my MacBook Pro fine. Directed Audio MIDI setup to make this the default input and output device. Set the sample rate to 48kHz, 24 bit. Unit plays just fine, VU meters in the Inspire control panel look good, output through my speakers sounds good.

Launch Audacity 1.3.5. Tell it to use "Core Audio: Inspire 1394" for both recording and playback. Set quality to 48kHz, 24-bit sample rate. Back to project, confirm quality is set to 48kHz, 24-bit. Hit input monitor and there's zero signal. Confirm that by recording a patch. Silence. Inspire control panel says there's sound, and I can hear the sound in my speakers. Audacity says I got dead air.

What have I got set wrong?


pax / Ctein

OK, I figured out what has to be set wrong, by messing with Garageband and CuBase (the audio app included with the Inspire)-- the system defaults to audio input channels 1 and 2 (which are the mike inputs) instead of 3 and 4 (which are the phono/line inputs). Problem is that I can't figure out how to configure that in Audacity-- how do I tell it *which* audio inputs I want to use from a particular device?

Garageband and CuBase have control settings for that, so I was able to make them work. Far as I could find, Audacity doesn't, and this doesn't seem to be settable in the MacOS Audio MIDI Setup or System Preference Sound control panels.

Suggestions?

pax / Ctein

I'm not an Apple person - but I seem to remember from reading other postings that the problem may be with the 24-bit setting - IIRC Apple Macs seem to have a problem with this in Audacity (not sure whether this is a bug or a "feature").

From looking at the specs and the manual fgor your box on the Presonus site I can't see if you can reset the bitrate - it looks as though it only operates at 24-bit, so this may give you a problem.

Hopefully one of the Mac users will be able to comment on this in more detail - but meanwhile try Searching the MAC sections of the forum for "24 bit", "24-bit" or "Presonus"

WC

Dear Waxy,

No it's not got to do with the bit depth. If I plug an input into one of the mike jacks (audio inputs 1 and 2) on the Presonus, then Audacity sees the signal just fine. When I run audio into the Presonus via inputs 3 and 4 (the line/phono inputs I need to use to trascribe the vinyl), Audacity sees nothing.The two stereo channels in Audacity are looking at Presonus inputs 1 and 2, and I can't figure out how to switch Audacity to look at 3 and 4.

Anybody know how to change Audacity's settings for this?

pax / Ctein


PS-- yes, I know the Presonus is working correctly; I can use it with other apps.

If there isn't any way of switching the inputs using the Presonus Inspire 1394 control panel, then try setting Audacity to record 4 channels - it may not work, or Audacity may record the line inputs on channels 3 and 4 (it depends on the drivers).

Dear Steve,

OK, setting Audacity Audio I/O preferences to 4 channel recording worked-- when I click the record button, it automatically creates four tracks and the phono audio comes thru on channels 3 and 4. I know how to delete channels 1 and 2 after I record, and mix 3 and 4 into a stereo track

Now, how do I get VU meters set up to monitor what's happening on 3 and 4? I only see two VU recording meters and they seem fixed on channels 1 and 2. Is there some control for establishing more VU's or associate the existing ones with specific channels?

One of the reasons I want to use Audacity for transcribing my vinyl is that the VU meters' peaking bars make it really easy to get the input gain set right to insure no clipping.

Thanks!

pax / Ctein

Ctein wrote:setting Audacity Audio I/O preferences to 4 channel recording worked-- when I click the record button, it automatically creates four tracks and the phono audio comes thru on channels 3 and 4.

Oh good, I hoped that it would do that.

Ctein wrote:Now, how do I get VU meters set up to monitor what's happening on 3 and 4? I only see two VU recording meters and they seem fixed on channels 1 and 2. Is there some control for establishing more VU's or associate the existing ones with specific channels?

Oh dear. Sorry I can't help you with that one - I've not got a multi-channel sound card to even look at the issue. I'll see if I can find out.

While I'm doing that, you could test if you can record in 32 bit (Edit ? Preferences > Quality). If you can record in 32 bit, that gives you a HUGE amount of headroom, so even if you record way below 0dB (and then Normalize), you will loose nothing in terms of SNR. (the dynamic range of 32 bit float will be considerably greater than the dynamic range of your audio equipment, allowing you leave yourself lots of headroom).

Dear Steve,

Thanks for the help so far. Seems terribly unlikely that Audacity would support multichannel recording with no way to monitor the signal strength.

Yeah, I could (and can) record 32-bit, but that just puts off the gain fiddlin' nonsense to later on. I'd rather get it right from the get-go; it's no more work to do trial recording than to fiddle late- actually, probably less. It'd just be better if I didn't have to even bother. Feels kludgey to me.

pax / Ctein

Ctein wrote:Seems terribly unlikely that Audacity would support multichannel recording with no way to monitor the signal strength.

Hi - Steve asked me, and I don't know because I don't have a multi-channel device, though it would not surprise me if this was actually true given our patchy multi-channel support. I'll see if I can find out any more, and Steve could also PM Andy Latham as he records multi-channel I think.

Ctein, Is there any way to send the phono inputs as some kind of "master" or "mix" output, which might force them into channels 1 and 2? Have a look at the manual?

Another possibility is a standalone software VU meter. There are a number of these for Windows, but I can't find any for Mac on a quick search.


Gale

Dear Gale,

No, unfortunately, the Inspire is not a mixer-- it's designed solely to digitize four channels of audio and send them to software. It happens that Channels 1 and 2 are the Mike/Instrument inputs and 3 and 4 are the Line/Phono inputs. You can't swap them around nor mix the digital signals.

A standalone VU meter would be usable, so long as it showed persistent peak level like Audacity's. If it doesn't, not much value.

pax / Ctein