Avid Pro Audio Community

Avid Pro Audio Community

How to Join & Post  •  Community Terms of Use  •  Help Us Help You

Knowledge Base Search  •  Community Search  •  Learn & Support


Avid Home Page

Go Back   Avid Pro Audio Community > Legacy Products > 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Mac)

Reply
 
Thread Tools Search this Thread Display Modes
  #151  
Old 06-22-2003, 12:48 PM
Chaasm71 Chaasm71 is offline
Member
 
Join Date: Feb 2003
Location: Vancouver Canada
Posts: 68
Default Re: Digi 001 discontinued?!

The 'scientific facts' presented regarding the effect of ultrasonic frequencies as they pertain to audio were presented by people who work for a speaker manufacturer. I'm not saying they are definitively wrong, but I'd question the motivations of the person presenting it to you. Tanoy sells speakers...they want you to buy them and pay LOTS of money to do so. So...they better present their speakers as doing something really special. If there are already speakers that can cover 20-20k with flat response, what's left? I don't know about you, but if Dr. X at Microsoft presented 'scientific' research that 'proved' that test subjects found the whiring noises of PCs to be more pleasing than Macs, would you run out and buy a PC? I'd certainly take it with a grain of salt.

One interesting point is the idea of the ultrasonics beating between tracks that were recorded separately. That could make a difference, but I think that the DAs filter the sounds down below 20kHz before such interference could occur. Does anyone know what the input bandpass is for these higher sample rate converters? If they DO have a 20-20k bandpass, then those ultrasonics would never get printed to disk, and so never get a chance to beat during reconstruction. Interesting idea though. It could imply a design change in AD DA converter filters to capture such an effect.

Charlie.
Reply With Quote
  #152  
Old 06-22-2003, 02:07 PM
clorox clorox is offline
Member
 
Join Date: Oct 2001
Location: New York, NY
Posts: 393
Default Re: Digi 001 discontinued?!

Quote:
Originally posted by Chaasm71:
The 'scientific facts' presented regarding the effect of ultrasonic frequencies as they pertain to audio were presented by people who work for a speaker manufacturer. I'm not saying they are definitively wrong, but I'd question the motivations of the person presenting it to you. Tanoy sells speakers...they want you to buy them and pay LOTS of money to do so. So...they better present their speakers as doing something really special. If there are already speakers that can cover 20-20k with flat response, what's left? I don't know about you, but if Dr. X at Microsoft presented 'scientific' research that 'proved' that test subjects found the whiring noises of PCs to be more pleasing than Macs, would you run out and buy a PC? I'd certainly take it with a grain of salt.

One interesting point is the idea of the ultrasonics beating between tracks that were recorded separately. That could make a difference, but I think that the DAs filter the sounds down below 20kHz before such interference could occur. Does anyone know what the input bandpass is for these higher sample rate converters? If they DO have a 20-20k bandpass, then those ultrasonics would never get printed to disk, and so never get a chance to beat during reconstruction. Interesting idea though. It could imply a design change in AD DA converter filters to capture such an effect.
<font size="2" face="Verdana, Arial">I understand your point, but I look at everything with a skeptical eye. I was an Electrical Engineering major in college, and what he's saying sounds like some of my coursework.

However, I disagree with his main point. I'm interested in the 96kHz+ sampling for the CAPTURE and the PROCESSING phases. The interactions of the ultrasonics, and the mathematical retention of data, would happen during the computer's processing.

I'm not trying to imply that we need to reproduce inaudible frequencies from our speakers. Once the interactions of the ultrasonics have produced their beats, those are all we need to output. BUT , you have to capture and process them FIRST.

In other words, I'm not going to go out and buy super tweeters. [img]images/icons/grin.gif[/img]

My friends in surround sound would disagree. There exists a group out there who wants to capture high sample rates because they need it for precision placement of sharp transients in 3-d space because we can hear 5-15 microsecond delays between our ears. But that's another topic.
__________________
http://www.the-outside.com
various Macs and PC's
002r and Mbox
Reply With Quote
  #153  
Old 06-22-2003, 02:27 PM
clorox clorox is offline
Member
 
Join Date: Oct 2001
Location: New York, NY
Posts: 393
Default Re: Digi 001 discontinued?!

Quote:
Originally posted by Park Seward:
Charlie,

The only spec I found on the Digi site:

Per measurements on an Audio Precision Cascade-2 the frequency band-edge measurements:
192 I/O @ 192 kHz
Frequency Response: - 0.2 dB @ 50 kHz, - 2.0 dB @ 88 kHz
192 I/O @ 96 kHz
Frequency Response: - 0.2 dB @ 38 kHz, - 2.0 dB @ 44 kHz.

DUC reference:
http://www.digidesign.com/
ID:25827 Created:10/14/2002
<font size="2" face="Verdana, Arial">Thanks Park! You've just given two great examples of A/D converters capable of capturing these ultrasonic frequencies.

Quote:

I have the sinking feeling that while some units will sample at higher rates, they do not have a wider frequency response. Therefore, why bother?
<font size="2" face="Verdana, Arial">

Well, you just gave examples of units that will do the job. As always, my suggestion is research before you buy. Don't buy a 96kHz converter with a 20kHz frequency limit.

Again, thanks for the great post!

Slowly narrowing the analog divide, sample by sample. . . .
__________________
http://www.the-outside.com
various Macs and PC's
002r and Mbox
Reply With Quote
  #154  
Old 06-22-2003, 02:30 PM
Chaasm71 Chaasm71 is offline
Member
 
Join Date: Feb 2003
Location: Vancouver Canada
Posts: 68
Default Re: Digi 001 discontinued?!

Clorox, given Park Seward's specs that say that the HDs sampling at 192kHz are capturing info up to around 88kHz, it is seemingly possible for the audible beat signals from ultrasonic data to be captured. So...maybe there is something interesting going on here... I'll talk with a guy I know at work who is our resident DSP expert and see what he can tell me. Cool ideas, people! Keep 'em coming.

Charlie.
Reply With Quote
  #155  
Old 06-22-2003, 02:43 PM
Park Seward's Avatar
Park Seward Park Seward is offline
Member
 
Join Date: Jul 2001
Location: Grants Pass, OR
Posts: 4,284
Default Re: Digi 001 discontinued?!

Quote:
Originally posted by clorox:
The trumpet with a mute shows significant energy up to 100 kHz before dropping into the noise floor.
<font size="2" face="Verdana, Arial">Interesting that the big band recordings of the 40's were made with ribbon microphones with a top end of 15k (-6db). But the muted trumpet still sounded like a muted trumpet.

(Spec from the RCA 44BX factory spec sheet http://members.iinet.net.au/~vk6ft/micman/rca44bx.pdf)

Please list your reference as to the amount of energy the 100kHz harmonic has referenced to the fundemental tone. you state "significant energy". How significant?

Quote:
Sibilance in human speech has been shown to have energy above 40kHz.
<font size="2" face="Verdana, Arial">I was not talking about sibilance, I was talking about the human voice. The voice has no energy at 40k! I believe it is physically imposible for the membranes to vibrate that fast! Sorry I don't have a reference.

Quote:
Playing an A on your guitar will be producing a sound wave at 440Hz, but there are also many higher harmonic tones which may be out of the range of your hearing! Without these harmonics, that note would sound like a 440 Hz sin(e) wave.
<font size="2" face="Verdana, Arial">If the "tones" (harmonics) are out of the range of human hearing, then how do we hear them???
__________________
Park
The Transfer Lab at Video Park
Analog tape to Pro Tools transfers, 1/4"-2"
http://www.videopark.com
MacPro 6 core 3.33 GHz, OS 10.12.1, 8 GB RAM, PT12.6.1, Focusrite Saffire Pro 40, PreSonus DigiMax, MC Control V3.5, dual displays,
Neumann U-47, Tab V76 mic pre, RCA 44BX and 77DX, MacBook Pro 9,1, 2.3 Mhz, i7, CBS Labs Audimax and Volumax.
Ampex 440B half-track and four-track, 351 tube full-track mono, MM-1100 16-track.
Reply With Quote
  #156  
Old 06-22-2003, 03:04 PM
Park Seward's Avatar
Park Seward Park Seward is offline
Member
 
Join Date: Jul 2001
Location: Grants Pass, OR
Posts: 4,284
Default Re: Digi 001 discontinued?!

Quote:
Originally posted by clorox:

As for mics, usually all you see on the frequency diagrams is 20-20K, but you must understand that the mic response doesn't hit a brick wall just because the diagram stops. It continues on a natural curve out of human hearing range. Of course, mileage varies per mic model. My AKG C1000's have basically flat response to 20k, but the workhorse SM 57 is already down around -10dB at that point. [/QB]
<font size="2" face="Verdana, Arial">I asked Herr Martin Schneider, Neumann Mic Development, about the frequency response of Neumann microphones. He told me that the average Neumann mic will exhibit a 6 db drop for each octave above 20k. Since a 6 db drop is almost half, don't expect much at 100k.
__________________
Park
The Transfer Lab at Video Park
Analog tape to Pro Tools transfers, 1/4"-2"
http://www.videopark.com
MacPro 6 core 3.33 GHz, OS 10.12.1, 8 GB RAM, PT12.6.1, Focusrite Saffire Pro 40, PreSonus DigiMax, MC Control V3.5, dual displays,
Neumann U-47, Tab V76 mic pre, RCA 44BX and 77DX, MacBook Pro 9,1, 2.3 Mhz, i7, CBS Labs Audimax and Volumax.
Ampex 440B half-track and four-track, 351 tube full-track mono, MM-1100 16-track.
Reply With Quote
  #157  
Old 06-22-2003, 03:30 PM
clorox clorox is offline
Member
 
Join Date: Oct 2001
Location: New York, NY
Posts: 393
Default Re: Digi 001 discontinued?!

Quote:
Originally posted by Park Seward:
Interesting that the big band recordings of the 40's were made with ribbon microphones with a top end of 15k (-6db). But the muted trumpet still sounded like a muted trumpet.
<font size="2" face="Verdana, Arial">Of course it did. No one's saying that you can't make a good recording unless you sample at 96kHz. My dinky studio doesn't have the capability yet, but I'm still recording. [img]images/icons/grin.gif[/img]

That's not what this is about. This is about capturing sound, to the best of our ability, as close to the original as possible. What we're talking about are subtle differences.

No one has said that you can't make a trumpet sound like a trumpet at lower sampling rates. I bet you could make a trumpet recording at 12kHZ, and it would still sound like a trumpet. Just not a very good one.

As for all those great old recordings, from the 20 's to motown, I love 'em. But those engineers would've KILLED for today's technology.

Quote:

Please list your reference as to the amount of energy the 100kHz harmonic has referenced to the fundemental tone. you state "significant energy". How significant?
<font size="2" face="Verdana, Arial">
Alright. I've taken some heat for quoting speaker manufacturers. Here's a link to a University of Berkeley study. If that's not good enough, I don't know what is. Only one condition: if I post it, you've gotta promise to read it.

http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm

As you can see, a trumpet has 2% of its energy in the inaudible range. Crash cymbals have 40%. Jangling keys have 68%. I don't know what qualifies as "significant", but you need to realize that as you move higher up in frequency, the less energy it takes to produce sound, so 2% is a lot bigger than it seems.

In other words, 2% at 20kHz is a lot more than 2% at 20Hz. I don't have the energy to explain the physics; PLEASE trust me or research it yourself. Just think about how many more Watts a bass amp needs to produce the same level of sound as a guitar amp, and you get the idea.
[img]images/icons/smile.gif[/img]

Quote:

I was not talking about sibilance, I was talking about the human voice. The voice has no energy at 40k! I believe it is physically imposible for the membranes to vibrate that fast!
<font size="2" face="Verdana, Arial">
Unless your talking about someone sitting there and singing "AAAAAHHHHH", most of us consider the human voice to consist of many components, including the processes of breathing and sibilance which involve the lungs, vocal chords, teeth and tongue.
Quote:
If the "tones" (harmonics) are out of the range of human hearing, then how do we hear them???
<font size="2" face="Verdana, Arial">If you've come this far in this thread and still don't understand how you can hear the interactions of ultrasonic frequencies, then please re-read.

The berkeley study goes one step farther than I do and suggests our brain picks up these frequencies even if we can't hear them. I don't know about all that; my argument relies on the more down-to-earth, easily-provable, scientifically-proven "beat" theory.
__________________
http://www.the-outside.com
various Macs and PC's
002r and Mbox
Reply With Quote
  #158  
Old 06-22-2003, 03:32 PM
Chaasm71 Chaasm71 is offline
Member
 
Join Date: Feb 2003
Location: Vancouver Canada
Posts: 68
Default Re: Digi 001 discontinued?!

Park and Clorox, I think you guys are kind of debating two different things. Clorox is pointing out why two different instruments (lets say guitar and oboe) sound different when they play the 'same' note: because the 'overtones' of the guitar are different than those of the oboe. I think Park is just questioning how high do those frequencies extend such that there is enough energy in them that we can hear them. I.e., if there is only 0.0001% of the total energy of the wave in a harmonic at 18kHz, you won't hear it. Also, the harmonic series is a theoretical model based on some simplifying assumptions. At very high frequencies, non-linear effects (= real world stuff that makes simple models fail) come into play. So, although based on the harmonic series, you might guess that we should have energy at arbitrarily high frequencies, the reality is that non-linear disipative effects prevent things (like ear drums and microphone diaphrams) from vibrating that fast. At the very least, those higher frequencies no longer follow the harmonic series, and you get so called inharmonicities (the harmonics don't follow nice ratio relationships, and sound unplesant to our ears).

To elaborate on Clorox's post, if you don't know, I'll blab a bit about what overtones are... If you do know, skip to the next post! [img]images/icons/wink.gif[/img] If you use a Fourier series (see my first post on this thread) to expand the a wave form, different instruments have different amounts (amplitudes) of the various sine waves (frequencies) which build up the total waveform. So, some sounds have lots of the fundamental frequency, and very little harmonic content. These sounds tend to sound very dull, like a pure sine wave. Other sounds have lots of the higher frequency sine wave content (overtones). These sounds are much brighter and 'colourful'. It is the presence of these overtones that tell your brain it is hearing middle C played on a piano and not on an alto sax even though both instruments have the same fundamental frequency when they play this note.

This actually reminds me, a great way to see this is using a tool called a spectrum analyzer (a tool that does Fourier transforming in realtime using an algorithm called a Fast Fourier Transform or FFT and lets you see frequency content in a signal). Back in my MSc, I was a teaching assistant for a physics of music course which was being taught to arts students. The prof was Dr. Unruh, who in addition to being a cosmologist (he does theoretical research on black holes and quantum gravity), is also quite knowledgable about the physics of music. Anyhow, he gave the class a web link to an on-line osciloscope/spectrum analyzer program that runs on PCs (there is probably a Mac equivalent out there). I loaded this thing onto my computer, and plugged in a cheap little computer mic to my sound card, and in real time, I could look at the frequency content of whatever went into the mic. It was really fun. I played a note on my guitar, and I could see the fundamental note on the analyzer, plus various harmonics above it. Then I played the same note on a different string, the fundamental frequency was the same, but the harmonics all changed in amplitude (thinner strings had higher frequency content, which is why they sound brighter). Then I sang the note. Same fundamental, totally different harmonics. Singing ooooohhh had different harmonics to singing ahhhhh. If there is a similar application for Macs (I'll have a look), then get it, install it, and fiddle around.

Charlie.
Reply With Quote
  #159  
Old 06-22-2003, 03:35 PM
clorox clorox is offline
Member
 
Join Date: Oct 2001
Location: New York, NY
Posts: 393
Default Re: Digi 001 discontinued?!

Quote:
I asked Herr Martin Schneider, Neumann Mic Development, about the frequency response of Neumann microphones. He told me that the average Neumann mic will exhibit a 6 db drop for each octave above 20k. Since a 6 db drop is almost half, don't expect much at 100k.
<font size="2" face="Verdana, Arial">Average Neumann Mic, huh? What are the specs on their high-end mics designed for drum overheads? I'm willing to bet you'll be surprised.

Check out the SENNHEISER MKH800. Flat to 50kHz.
__________________
http://www.the-outside.com
various Macs and PC's
002r and Mbox
Reply With Quote
  #160  
Old 06-22-2003, 03:47 PM
Chaasm71 Chaasm71 is offline
Member
 
Join Date: Feb 2003
Location: Vancouver Canada
Posts: 68
Default Re: Digi 001 discontinued?!

Thanks for the links to the prof at Caltech, Clorox. Interesting stuff.

Charlie.
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
003 Discontinued? bootc Pro Tools 10 58 12-05-2011 07:15 PM
Is 003 really discontinued? ripekeai Pro Tools 9 15 03-29-2011 07:05 PM
Digi 003 Rack Discontinued? Tritono9 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Win) 12 06-04-2010 07:39 PM
Digi 001 discontinued? Dino Bonanno 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Win) 1 01-13-2004 08:22 PM
001 being discontinued??? fabpab 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Win) 5 11-10-2002 05:18 AM


All times are GMT -7. The time now is 11:37 AM.


Powered by: vBulletin, Copyright ©2000 - 2008, Jelsoft Enterprises Limited. Forum Hosted By: URLJet.com