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Re: [ARSCLIST] A/D conversion, USB Audio and etc.
Hi, Andy,
This is an interesting discussion.
First, considering that the last time I looked at the PCAVTECH Web Site, very
high marks were given to the Lynx Two and the Lynx One and the DAL were one
step down--along with others--I don't think that we should rule out sound cards
for good quality work.
Certainly the PCAVTECH's noise graphs don't show any noise spikes in the
spectrum which would be how I'd expect the PC to degrade the audio. Since we're
looking at a maximum audio frequency of < 48kHz (Nyquist says we must have no
response at 48kHz with 96ks/s sampling) and the lowest frequency outside the
power supply in the computer is probably 133MHz today, the possibility of
crosstalk is much lower than it was when PCs were running 4.7MHz as the clock,
and other things were running slower.
My RME Multiface uses a firewire cable, but has a dedicated, proprietary
interface card in the PCI slot. So, yes, I use an outboard card, but I was
considering the Lynx and the DAL. I felt I got more bang for the buck with
adequate sound from the RME. It solves interfacing with ADAT at the same time
it gives me 8 in and out.
I use a Zefiro ZA-2 card in my first audio computer for precisely the reason
you state--keeping analog out of the box. I think DAL and Lynx have addressed
this problem. I variously used my Panasonic SV-3800 DATs and Sony CDR-W33s as
the A-to-D converters for the ZA-2. I generally use the internal converters in
the RME as they go to 24/88.2 and 24/96.
Digitizing cassettes at 24/96 and not using a Dragon is, in my opinion, not
well coordinated.
I think your assessment of getting a better playback deck as you reflected upon
it is correct. Remember, the auto-azimuth of the Dragon makes it stand head and
shoulders above any other unit I can think of.
While new digital toys are nice, plug a Dragon directly into the DAL and see
what happens. You'll be amazed.
As to USB, I looked at M-Audio and saw that even an inexpensive unit was listed
at 101 dB dynamic range.
I think there may be an issue of measuring the preamp unterminated or with a
lot of gain cranked in.
If the equivalent input noise (Ein) is -125dBu and the gain is 60dB, then,
indeed, the output noise is -65dBu. But, don't forget, that 0dBFS may also be
at +24 or +18dBu on the same scale, so you have to add that to the -65 for a
total dynamic range of 89dB (assuming +24).
This is, of course, one of the arguments about using higher output condensor
mics for recording--you swamp the input preamp's noise. An Ein of -125dBu as
referenced above is not particularly good. However, with a 150 ohm output
microphone or terminating resistor, the Ein cannot be better than -131dBu based
on thermal noise. If your microphone puts out -60dBu at 94dB SPL, then your
noise floor will be at 23 dB SPL. The Neumann TLM103 has a self-noise level of
under 10dB SPL. Then that raises room background noise issues.
USB audio is not the problem. Just like CDs weren't the problem when they
didn't sound as good as LPs. In both cases, it's the implementation, not the
technology.
The challenges are complex.
Cheers,
Richard
--
Richard L. Hess
http://www.richardhess.com/tape/
Quoting andy kolovos <akolovos@xxxxxxxxxxxxxxxxxxxxxxxxx>:
>
> Richard and Others,
>
> Thanks for the feedback--
>
> Just so you all know, we have been using the DAL CardDeluxe with the
> AES/EBU adaptor
> for around two or so years now, and have been really happy with it. My
> only concern is more one of lagging doubts and peer pressure. Whenever I
> mention to people what I'm using for A/D transfer I usually get the, "oh,
> really...hmmm...that's nice" response. The criticism that follows ranges
> from blanket concern about using an internal card to do the A/D conversion
> to (on one occasion) issues with the DAL CD itself. The DAL people insist
> that their card isn't hampered by the same "noise" problems other cards
> face when doing A/D conversion in the guts of the machine. As far as my
> ear goes--all seems aok. I do, however, have a pretty bad ear, probably in
> part the result of a youth spent coming to terms with lots of loud punk
> rock. I am also simply and archivist and a folklorist who knows a little
> bit about audio, not a trained audio engineer. With this in mind, I tend
> to listen to trained audio engineers when I need advice. The DAL CD was
> recommended to me by an engineer we've worked with when doing radio stuff.
> Although I trust his judgment, I do catch some heat for using the card (or
> perhaps more correctly "a card") as my A/D converter.
>
> Since I have a captive audience of experts here, and since I don't recall a
> specific discussion on the matter in the last two years, (and also since I
> think the utility of such a discussion would go beyond just me) would folks
> feel like picking up this issue for a list discussion?
>
> 1) Is it always (or even) an issue to do A/D conversion with internal
> cards? Many people treat this as gospel. Are there exceptions to this?
> My needs range from 24/96 conversion of C-60 and C-90 cassettes to 16/44.1
> transfers of analog audio excerpts. Is internal conversion more
> problematic for longer runs?
>
> 2) From another angle, what are the merits and drawbacks to USB and
> FireWire audio input, especially when compared to putting a digital signal
> through an internal card? (Aside: I have an admittedly low-end M-Audio
> USB-Audio/Mic pre-amp, the USBPre. I bought it as a cheap way to record
> interviews for my dissertation. Frankly, the thing blows. The noise it
> generates just being plugged in (no mic attached) is higher than a lot of
> cassette tape hiss I've heard. I think I was getting a steady noise signal
> in the -50db range. I actually called M-Audio and hung on the phone with
> them for about 45 minutes to figure out what the deal was. The unit they
> had there produced a noise signal in the -40db range! Their only response
> was to the effect that I was doing better than they were.) In my small
> experience, USB audio tends to be pretty darn noisy.
>
> I posted my initial query in an effort to stay on top of what is out there
> and to see what to look for if money turned up in the near future. My real
> issue may have more to do with landing better analog play-back gear, so
> perhaps trying to goad the powers that be into springing for a Nakamichi
> Dragon or a TASCAM 122MKIII might be what I should be doing rather than
> lusting after new digital toys.
>
> Thanks in advance,
>
> andy
>
> At 09:19 AM 01/21/2004 -0800, Richard L. Hess wrote:
> >Hi, Andy,
> >
> >I think there is a missing piece here:
> >
> >Why are you bypassing the converters in the DAL CardDeluxe? They are rather
>
> >competent as I understand it (it was on my short list--I ended up with an
> RME
> >Multiface). Even Bruel and Kjaer have used it in the acoustics PC-based
> >instrumentation, as I understand it. Http://www.pcavtech.com who actually
> tests
> >cards in depth gives it an excellent rating.
> >
> >While you're asking for AES/EBU output and the DAL CardDeluxe is SPDIF in
> >natively, DAL sells an AES/EBU and TOSLINK input adapter for $92.
> >http://www.digitalaudio.com/DIGITALAUDIO/myarticles.asp?P=5216&S=75&PubID=4
> 401
> >
> >I'd be curious if the other responders to this feel that the CardDeluxe
> >converters are inferior, and in what way.
> >
> >I can see applications where you'd rather route/run AES/EBU data than analog
>
> >audio, but I'd like to understand the application. Many transfer suites are
>
> >compact enough that the runs aren't long.
> >
> >Cheers,
> >
> >Richard
> >--
> >
> >Richard L. Hess
> >http://www.richardhess.com/
> >
> >
> >Quoting andy kolovos <akolovos@xxxxxxxxxxxxxxxxxxxxxxxxx>:
> >
> >> Folks,
> >>
> >> Since we're on a product-suggestion line right now, I'm looking for
> >> recommendations for an external 24/96 A/D converter with AES/EBU output.
> >> Not interested in USB.
> >>
> >> Price range is $200-$2,000 or so, but leaning toward the middle of that
> >> range. Would be going into a PC via a DAL CardDeluxe.
> >>
> >> Any thoughts?
> >>
> >> Thanks,
> >>
> >> andy
> >> *********************************
> >> Andy Kolovos
> >> Archivist/Folklorist
> >> Vermont Folklife Center
> >> P.O. Box 442
> >> Middlebury, VT 05753
> >> (802) 388-4964
> >> akolovos@xxxxxxxxxxxxxxxxxxxxxxxxx
> >> http://www.vermontfolklifecenter.org
> >>
> >
> >
> *********************************
> Andy Kolovos
> Archivist/Folklorist
> Vermont Folklife Center
> P.O. Box 442
> Middlebury, VT 05753
> (802) 388-4964
> akolovos@xxxxxxxxxxxxxxxxxxxxxxxxx
> http://www.vermontfolklifecenter.org
>
>