HD24XR frequency response and the future of recorded audio
« on: February 05, 2005, 01:44:10 AM »
Hello,

I was reading the FAQ about the Alesis HD24XR recorder, when the statement in #56 caught me by surprise.



http://www.alesis.com/products/hd24/ADAT%20HD24%20FAQ.pdf

They claim to get 22Hz - 44kHz frequency response when recording at 44.1kHz or 48kHz sampling rates. I did not think this was possible.

Is It?

They also mention in the EC-2 upgrade manual(right at the end-go to www.alesis.com and link over to it) that the quality of recorded audio won't significantly improve from what the HD24XR, or HD24 with the EC-2 upgrade, can produce.

How true is that?

Dean


Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
HD24XR frequency response and the future of recorded audio
« Reply #1 on: February 05, 2005, 02:43:58 AM »
Quote
I did not think this was possible. Is It?


No.

Samuel

pucho812

HD24XR frequency response and the future of recorded audio
« Reply #2 on: February 05, 2005, 05:30:49 AM »
Nyquest  theory states that the highest frequency one could record digitally is half of your sample rate. So either that is a misprint or they are refering to recording at samples rates of 88.2 and up.
thats just as good as digidesign who stated you have 52 i/o on a single 192.  I was told this by one of their product specialist when HD first came out. And boy he didn't like it when I was like wrong.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

HD24XR frequency response and the future of recorded audio
« Reply #3 on: February 05, 2005, 01:04:44 PM »
Thanks,

It sounded too good to be true.

I've heard that this recorder sounds really good anyway, but this must not be the reason. :roll:

They also specify 1.6 milliseconds of latency from analog input to analog output. Is that much delay audible, and/or could that latency lead to monitoring problems when overdubbing through an analog console?

Dean

NewYorkDave

HD24XR frequency response and the future of recorded audio
« Reply #4 on: February 05, 2005, 01:08:27 PM »
That freq. response spec was obviously a typo.

As for quality: as long as the recording is distinguishable from the live performance, then there's still room for improvement!  :grin:

alk509

HD24XR frequency response and the future of recorded audio
« Reply #5 on: February 05, 2005, 01:18:34 PM »
I'm 100% positive that's a typo. It says:

Quote
so if you?re recording at 44.1kHz or 48kHz, the recordings will have a:
[...]
Frequency Response: 22-44 kHz ±0.50 dB


It should have been 24, not 44 - [email protected] SR, and [email protected] SR. It's just carefully mis-worded to deceive you (ever notice how when there's typos in documentation, they never work in detriment of the gear? How come the typo wasn't a "14", for example?)

Whether or not the system can really get to those frequencies at -0.05dB, that's another story. I don't think it can be done without some ill-sounding trick like a REALLY CRAZY anti-alias filter or some analog post-emphasis.

Peace,
Al.

Lest laziness get the best of you!

SonsOfThunder

HD24XR frequency response and the future of recorded audio
« Reply #6 on: February 06, 2005, 01:13:24 AM »
Quote from: "alk509"
(ever notice how when there's typos in documentation, they never work in detriment of the gear? How come the typo wasn't a "14", for example?)
I'd guess that originally the info came from an engineer and then got passed thru to the "tech writer" after passing thru a couple of liasons.  I've seen this happen at my job a couple of times.  They need to let the engineer talk directly with the writer and then let the engineer proof the copy.

Most tech writers should probably drop the word "tech" from their job title.  I'm sure there are some good ones out there though.

 :green:
"The sow would rather have her ear than a purse." - PRR

PRR

HD24XR frequency response and the future of recorded audio
« Reply #7 on: February 06, 2005, 02:26:13 AM »
> 1.6 milliseconds of latency from analog input to analog output. Is that much delay audible

It is like 18 inches or 0.5 meter of path through the air. Do you worry about delay difference between headphones and a monitor speaker at arm's length? Do you, in live-jam, insist on staying within a couple feet of everybody else in the band?

Whether the spec is true or typo, I dunno. If I remember the machine, there isn't much space for the signal to get lost in, not like running it through a PC.


 

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