Absolute phase - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

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 15th December 2005, 09:45 AM   #1
cs is offline cs  United Kingdom
diyAudio Member
 
Join Date: Jun 2005
Location: .
Default Absolute phase

What are people's views on preserving the absolute phase of a system ? Is it audible ?

My current amplifier project uses an inverting, shunt feedback configuration, as this gives best performance. But should I correct for the inversion, either using an inverting input buffer, or by reversing the speaker connections ?
  Reply With Quote
Old 15th December 2005, 09:56 AM   #2
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
This crops up from time to time. Here's the last thread:
Audibility of absolute phase
There are many more references you can search for.
  Reply With Quote
Old 15th December 2005, 10:19 AM   #3
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
Another question:

Is there any difference using these two setups in stereo

1. Two Inverting amplifiers with exchanged LSP connections
2. Two Non-inverting amplifiers with normal plus/minus connections


And what will happen if
Using alt 1) for left channel and alt 2) for right channel
  Reply With Quote
Old 15th December 2005, 02:16 PM   #4
Jay is offline Jay  Indonesia
diyAudio Member
 
Join Date: Feb 2003
Location: Jakarta
I think there's a thread where Nelson Pass suggested to "correct" the absolute phase. I haven't bothered myself trying to find out first hand whether it is audible or not but I had an experience in digital area...

There was a confusion in DSP/DAC chips about signal inversion, and I couldn't find reliable information so I setup 2 circuits, 1 with inverted signal. The difference was clearly audible (may be the unequal circuit played big role there). But what I didn't expect before was, I had no idea which one is the "correct" one. I had a guess (that the one with less dynamic is incorrect), but how can I be sure?
  Reply With Quote
Old 15th December 2005, 02:47 PM   #5
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"And what will happen if
Using alt 1) for left channel and alt 2) for right channel"

Can sound very bad at high drive levels. This is due to dynamic off-set of amplifier when handling asymetrical signals (music).

Carver (and others) tried this and then dropped.
  Reply With Quote
Old 17th December 2005, 02:52 PM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Djk,
I don't understand your logic for arriving at your answer.

The two options require two different amplifiers.
An inverting amplifier on left channel with the loudspeaker connections reversed.
A non inverting amplifier on the right channel with conventional connections to the loudspeaker.

Both these arrangements will give correct absolute phase at the audio output (if the input signal is correctly phased).

Dynamic offset and asymetric signal handling can't interact between two different amplifiers,

Please explain further.
__________________
regards Andrew T.
  Reply With Quote
Old 17th December 2005, 04:28 PM   #7
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
It's audible, but subtle. Most people don't notice. Listen to the impact of bass drums, for instance--it's slightly more pronounced when the absolute phase is correct.
If your amp is phase-inverting, reverse the speaker hookups.
This is the one thing that saved Douglas Self from being a complete fool in my eyes. He went on and on and on about how people were delusional when they claimed that they could hear things, then was man enough to admit that he was wrong when it was proved that absolute phase was, in fact, audible. Never had I seen a hard core measurements-are-everything guy admit to being wrong. They inevitably ignore instances when they are proven wrong (audibility of passive components being another case--see Jung & Marsh) and keep right on ranting. I respect him for his admission of error.
In any event, it's a low-level phenomenon. It's not the kind of thing that you should loose sleep over. But, being as easy to correct as it is, why not fix it?

Grey
  Reply With Quote
Old 17th December 2005, 11:47 PM   #8
Banned
 
Join Date: Mar 2005
Location: Australia
Mr Rollins thanks, i dont understand yours or Mr self's explanation
of ab-phase being audible perhaps, if you could elaborate more
with some hard scientific evidence to back it, i would be more
convinced, i understand it like this it sounds good/better or
different, that makes it a subjective evaluation which is entirely
based on perception in other words if subjective evaluations had
a scientific basis there wouldnt be subjective and objective camps
i respect both you and self, but i think youre both alittle bit confused right now

regards
  Reply With Quote
Old 18th December 2005, 02:42 AM   #9
diyAudio Member
 
Join Date: Feb 2004
Location: Racine, Wisconsin
Get this guy an emergency shipment of periods! Mastertech, do you know about those little dots that end sentences?

Here, take some of mine................................
  Reply With Quote
Old 18th December 2005, 05:18 AM   #10
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
Personally, I'm rather amused that anyone would ever lump me into the same category as Doug Self.
It sounds as though mastertech has gotten himself lost in a philosophical conundrum.
Answer this, Grasshopper, and you will find the answer: How do we know anything at all?

Grey
  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
Audibility of Absolute Phase RHosch Everything Else 59 26th March 2014 12:52 AM
FS - Absolute Sound Cloth Ears Swap Meet 0 28th April 2007 11:58 PM
An absolute noob sagar Introductions 3 24th December 2006 08:01 PM
Is absolute phase nonsense? EC8010 Everything Else 49 24th November 2003 02:37 PM
absolute phase ... mrFB vrs SE :) Steve Eddy Everything Else 133 30th May 2003 04:53 PM


New To Site? Need Help?

All times are GMT. The time now is 11:55 AM.


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