Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 4th August 2012, 04:05 AM   #1
diyAudio Member
 
Join Date: Sep 2011
Location: Hartford, WI
Default phase linear filters - any good?

After reading "the audiophile's project sourcebook" by G. Randy Sloan, I am intrigued by phase linear filters. I have even found a DIY kit on ebay for them.

Has anyone ever built one or used one? Are they any good or better for a bi-amp setup than an electronic crossover? and if so, why don't you see more of them used. Just wanting some real world feedback before spending time and money to build one.

thanks, Brian
  Reply With Quote
Old 4th August 2012, 05:11 AM   #2
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: 84
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
I designed and built one years ago as a sub-woofer crossover. I didn't call it 'phase linear' though - rather a subtractive XO. The general principle is using all-pass filters to delay compensate for low pass functions so that high pass can be obtained by simple subtraction.

Definitely worth playing with. The downside is the use of more opamp stages, so it all depends how transparent you find opamps....

Oh and there's something else - the attenuation at the LF end of the HP function rather depends on gain matching, because its the subtraction of two near-identical signals. Works brilliantly in simulation but with real hardware you do have to pay attention to gain stability vs time and temp.
__________________
The great audio capacitor myth : 'There's such a thing as too many PSU caps'.
  Reply With Quote
Old 7th August 2012, 01:55 AM   #3
Davey is offline Davey  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Bremerton, WA.
Brian,

I know what it says, but that's not a phase-linear crossover in the Slone book. As noted by abraxalito, it's a subtracting crossover that uses an all-pass network in conjunction with the low-pass network and to create the high-pass output.

Only crossovers that exhibit a flat (linear) phase response with the outputs summed can be considered linear-phase. (That one doesn't qualify.)

Cheers,

Dave.
  Reply With Quote
Old 7th August 2012, 10:30 AM   #4
diyAudio Member
 
Join Date: Sep 2011
Location: Hartford, WI
Default unsure

I am by no means an electronic guru. I guess what it comes down to is this:

1. Whatever Sloan calls his unit that he has plans for in the book, does it (or would it) sound better than a standard electronic crossover?

2. Do you you think that the premade PCB's sold on ebay as phase linear filters have any chance of sounding as good or better?

Or should I stick to a standard electronic crossover design?

Thanks to all who have responded and keep any input coming.

Peace, Brian
  Reply With Quote
Old 7th August 2012, 12:04 PM   #5
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: 84
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
I my experience of building active crossovers with opamps (over many years) the layout is the primary determinant of how it sounds. Beyond that, simpler is generally better. So the answer to question 1 is 'It depends how you implement it'. I have no experience at all of ebay pcbs so can't even hazard a guess to answer 2).

As to the last question - go for whatever topology seems more interesting. The more involved you get with a circuit, the more you 'own' it so to speak, the more satisfaction you get from it. And that satisfaction alone will make it sound better to you.
__________________
The great audio capacitor myth : 'There's such a thing as too many PSU caps'.
  Reply With Quote
Old 9th August 2012, 06:11 PM   #6
Davey is offline Davey  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Bremerton, WA.
Brian,

All other things being equal, a subtractive crossover (as exampled by Slone) should not "sound" any different than any other topology. The phase response of that crossover can be duplicated by other types, so there isn't any inherent advantage in that aspect.

Some folks might prefer that design (subjectively) because it doesn't require/utilize series-connected capacitors. Maybe that's something to be worried about, but maybe not. When subjective evaluations are the primary determinite then the opinions can be all over the place.

Anyways, maybe your original question is more regarding the audibility of non-flat phase response. There are varying opinions on whether it is even audible and how best to evaluate it. Generally, speaker designers claiming audible superiority of linear-phase response are not making an apples/oranges comparison since other variables are involved.

Cheers,

Dave.
  Reply With Quote
Old 9th August 2012, 10:37 PM   #7
diyAudio Member
 
Join Date: Sep 2011
Location: Hartford, WI
Default thanks

Thanks for all of the good input. For now I think I will focus my money on upgrading other components in the system and stick with a standard electronic crossover. After everything else is optimized, then maybe I will go back and build the design from his book and see if I can hear any difference.

Thanks all, Brian
  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
Oversampling filters - linear vs. minimum phase (and other things) mr_push_pull Digital Source 1 11th April 2011 10:23 PM
Phase shifts with 'all pass' filters - understanding sought! HankMcSpank Solid State 25 11th February 2010 10:13 AM
Phase Linear lumanauw Pass Labs 3 17th December 2005 02:38 AM
How sre phase changes percieved ?[re filters] setmenu Everything Else 2 23rd July 2004 03:53 PM
Phase EQ using FIR filters Grasso Multi-Way 2 2nd July 2003 10:37 PM


New To Site? Need Help?

All times are GMT. The time now is 04:41 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