why don't we use predistortion more in the audio world? - Page 12 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 31st August 2012, 05:44 AM   #111
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by DJNUBZ View Post
I don't want this to digress into a discussion on EQ and DRC but could you tell me what benefit you would get doing this in the analog domain instead of the digital domain? It seems to me that the con's far outweight the pros when it comes to EQ.
It would be great to equalize speakers for high-end sound reinforcement, where I don't want latency. At home I am satisfied by digital Audissey.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 31st August 2012, 05:55 AM   #112
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 101
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Can't follow you here Wave - you're saying that digital EQ has inherent latency compared to analog EQ?
__________________
No matter if we meanwhile surrender every value for which we stand, we must strive to cajole the majority into imagining itself on our side - Everett Dean Martin
  Reply With Quote
Old 31st August 2012, 05:58 AM   #113
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by abraxalito View Post
Can't follow you here Wave - you're saying that digital EQ has inherent latency compared to analog EQ?
Yes.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 31st August 2012, 06:01 AM   #114
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 101
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Ah then you need to roll your own implementations. Digital can be effectively minimum phase, just that most of the popular chips (ADC, DACs) implement linear phase and have high latencies. Its not inherent in digital as a technology though as far as I'm aware.

What latencies do you need to achieve?
__________________
No matter if we meanwhile surrender every value for which we stand, we must strive to cajole the majority into imagining itself on our side - Everett Dean Martin
  Reply With Quote
Old 31st August 2012, 09:08 AM   #115
diyAudio Member
 
Join Date: Mar 2007
Location: Oxfordshire
Quote:
Originally Posted by DJNUBZ View Post
I don't want this to digress into a discussion on EQ and DRC but could you tell me what benefit you would get doing this in the analog domain instead of the digital domain? It seems to me that the con's far outweight the pros when it comes to EQ.
One thing that is possible in digital is to EQ with different phase outcomes . I would imagine sometimes analogue is better and other times digital . A mix might be very good .

I would not say this but for the fact we already have information in digital format . Seems to me that is where to play with it if so .

I was trying to dream up a digital format based approximately on Nicam . The idea would be to have a digitally compressed dynamic range with absolutely defined parameters . The signal at any point can be reconstituted back into the original dynamic range if required or points between . It would use the best of all ideas ( part could be analogue under digital control perhaps ) . DVD as storage medium . This format would be ready to use for radio stations or the car without decompression . The compression arithmetic based on perception and taste ( motor car biased perhaps ) . The chips that process it might have user digital processing included . For example buy two DACs and configure them as active crossovers . The ultimate quality would be rather like buying a posh turntable in the past . It would be incredible . For ordinary people very acceptable in the cheapest format ( meaning me in my motorcar ) .

That's what is wrong today . No big leap from ordinary to hi fi today . Even top end . Same miserable sources of sound . Ones which mostly we bettered in 1957 ( Louis Armstrong , Belefonte etc Decca Peter Grimes 1959 )
  Reply With Quote
Old 31st August 2012, 07:34 PM   #116
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by abraxalito View Post
What latencies do you need to achieve?
Length of cables divided by speed of light (that is constant!) maximum.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 31st August 2012, 07:45 PM   #117
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
There is a large, built in latency in the air between loudspeaker and ear. Certainly this is much larger than the latency in DSP? At least for PA applications.
  Reply With Quote
Old 31st August 2012, 08:40 PM   #118
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by Pano View Post
There is a large, built in latency in the air between loudspeaker and ear. Certainly this is much larger than the latency in DSP? At least for PA applications.
It depends on what kind of PA applications. But even for stadium for example floor monitors have to be nicely equalized. My PA systems are famous for "Sensitive microphones". However you understand that that means extremely flat frequency response. Put floor monitors with bumpy frequency response there and everything is screwed.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 1st September 2012, 10:05 AM   #119
diyAudio Member
 
Join Date: Mar 2007
Location: Oxfordshire
I think pre-distiortion is only practical in valves from my own tests . It is almost alchemy as it corrects that which hasn't happened yet . Please tell me I am wrong . I know the simplistic geometric reason . What I find hard to accept is how good the fit can be . I am very new to valves so I hardly know anything . All I know is that building near to zero feedback with valves is possible ( loop feedback ) . I can not think how to do it with transistors as easily . 2 common type valves , 0.5 V in 8 V out 8R . THD , 0.03% at 0.6 W 0.1% 1.6 W 0.43% 5 W , 8 W clipping . No loop feedabck ( no Schade either ) . Schade is interesting . It is simple shunt where driver is no great hindrance . It is a slightly better triode ( 30% more gain for identical distortion ) . It measure much like a triode . However the overall gain is poor . I haven't tried all the RH series , RH88 seems less than ideal . If wanting to know about RH 88 measure the cathode of the ECC 81 with various waveforms , very interesting and perhaps V to I converter is correct ? I also found ECC 82 and 12BH7A usable , they were better than expected . A cascoded ECC 82 looked very like a single ECC81 in all respects ( 90 V g1 ECC82 No 2 ) . These are valves I inherited . The interest also . I am notoriously mean so always use what I don' t have to buy . Most of my valves came from the old Chipping Norton Studio .
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
NAGYS AUDIO Best Audio Cables in the World!!! Guaranteed!!! NagysAudio Vendor's Bazaar 0 25th August 2010 03:17 AM
World Audio Design cs Tubes / Valves 1 30th August 2006 02:33 PM
Looking to enter the Audio world. Need help ibanezcollector Introductions 4 27th December 2005 04:49 AM
Digital predistortion for speaker correction rtarbell Digital Source 14 21st October 2005 09:34 AM


New To Site? Need Help?

All times are GMT. The time now is 04:59 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2