Vintage HiFi Audio Forum

Audio Discussion => General Discussion => Topic started by: GraphicFX on August 01, 2014, 02:00:48 AM

Title: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 01, 2014, 02:00:48 AM
Ismy Hafler info similar to the SDA info from my polk SDA's

Since My recent Polk SDA discovery, I've wondered if the L-R / R-L surround info is what is being used in Polks SDA design.
Since I've been running these speakers, I've found no reason to switch on my surround amp. until yesterday. The Hafler circuit seemed to produce the same musical info as what was coming from my mains. So Identical, that there wasn't much of a change between using the surround and not.

What gives..

I'm expecting to hear from you F1 nut on this one. 
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 01, 2014, 02:15:58 AM
What do you mean, "surround info"?
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 01, 2014, 08:27:04 AM
What do you mean, "surround info"?

I have surround channels which use a hafler circuit.  My question is the following:
does polk use some sort of version of the Hafler Circuit via the IC and the SDA drivers?
Title: Re: Hafler circuit used in SDA Crossover
Post by: AdamG on August 01, 2014, 08:57:41 AM
It's not exactly a Hafler circuit, but it is a very similar concept. From what I remember, the SDA effect is the inverse of the opposite channel, and only a limited bandwidth of it as well. I'm not positive on that, as it's just from memory on when I was studying up on the pair I had.
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 01, 2014, 11:57:04 AM
I have surround channels which use a hafler circuit.  My question is the following:
does polk use some sort of version of the Hafler Circuit via the IC and the SDA drivers?

No, SDA's passive technology addresses the interaural crosstalk problem inherent with stereo sound reproduction. It is not an effect.
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 01, 2014, 01:17:25 PM

No, SDA's passive technology addresses the interaural crosstalk problem inherent with stereo sound reproduction. It is not an effect.

Quit busting my balls
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 01, 2014, 05:23:21 PM
I wasn't.
Title: Re: Hafler circuit used in SDA Crossover
Post by: Sir Thrift-a-Lot on August 01, 2014, 05:40:58 PM
I have surround channels which use a hafler circuit.  My question is the following:
does polk use some sort of version of the Hafler Circuit via the IC and the SDA drivers?

No, SDA's passive technology addresses the interaural crosstalk problem inherent with stereo sound reproduction. It is not an effect.

What does that mean?
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 01, 2014, 06:14:46 PM
I wasn't.

I know u weren't  I was just busting Your balls
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 01, 2014, 09:26:50 PM
What does that mean?

It means that if anything is an effect it is conventional stereo reproduction as it is inherently flawed.
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 01, 2014, 09:27:43 PM

I know u weren't  I was just busting Your balls

Got me.....LOL
Title: Re: Hafler circuit used in SDA Crossover
Post by: Sir Thrift-a-Lot on August 01, 2014, 09:57:23 PM
What does that mean?

It means that if anything is an effect it is conventional stereo reproduction as it is inherently flawed.

This sounds like double talk to me.   What does that circuit do that isn't an effect?
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 01, 2014, 11:10:01 PM
I already answered that one, "addresses the interaural crosstalk problem inherent with stereo sound reproduction."
Title: Re: Hafler circuit used in SDA Crossover
Post by: Sir Thrift-a-Lot on August 01, 2014, 11:50:56 PM
How does it address it?
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 02, 2014, 01:50:55 AM
Here's some reading for you.

http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf (http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf)

http://www.vr3mods.com/LCSDAUpgrade.php (http://www.vr3mods.com/LCSDAUpgrade.php)
Title: Re: Hafler circuit used in SDA Crossover
Post by: SunnyDaze on August 02, 2014, 02:09:11 AM
Here's some reading for you.

http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf (http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf)


The link is dead. I found this link on the bottom of the vr3 website and it didn't work from there either.

This thread is making me want to get over to Carl's and check out his Polkage. 
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 02, 2014, 02:41:45 AM
Ah thanks, I didn't realize it was dead.

Try this one, all the white paper info is in there.

http://www.vr3mods.com/uploads/SDA_Handbook_2011_Rev3.pdf (http://www.vr3mods.com/uploads/SDA_Handbook_2011_Rev3.pdf)

Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 02, 2014, 06:53:19 AM
http://www.hifiwigwam.com/showthread.php?18855-quot-Hafler-Surround-Sound-quot-does-it-work-If-so-why-! (http://www.hifiwigwam.com/showthread.php?18855-quot-Hafler-Surround-Sound-quot-does-it-work-If-so-why-!)
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 02, 2014, 07:52:26 AM
http://www.hifiwigwam.com/showthread.php?18855-quot-Hafler-Surround-Sound-quot-does-it-work-If-so-why-! (http://www.hifiwigwam.com/showthread.php?18855-quot-Hafler-Surround-Sound-quot-does-it-work-If-so-why-!)

Just to clarify things a bit, My Hafler setup is powered by it's own dedicated amp, (Crown PS-400) It works well due to good sound and front mounted pots allowing me to dial in just the right amount of surround volume or none at all. which now is usually the case.

But I'll say it again; Cranking up the surround yeilds very little difference, which is why I started this thread in the first place.

That being said, and this being my thread, how about coming over here and checking out My Polkage
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 02, 2014, 08:00:05 AM

That being said, and this being my thread, how about coming over here and checking out My Polkage

My Polkage includes Weedage and Beerage
Title: Re: Hafler circuit used in SDA Crossover
Post by: SunnyDaze on August 02, 2014, 09:34:27 AM

That being said, and this being my thread, how about coming over here and checking out My Polkage

My Polkage includes Weedage and Beerage

And minimal discressionage.  :police:
Title: Re: Hafler circuit used in SDA Crossover
Post by: vstarkwell on August 02, 2014, 11:06:11 AM
Here's some reading for you.

http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf (http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf)


The link is dead. I found this link on the bottom of the vr3 website and it didn't work from there either.

This thread is making me want to get over to Carl's and check out his Polkage.

Carl's Polks SUCK!!!! as does all his other equipment.  :laugh:
Title: Re: Hafler circuit used in SDA Crossover
Post by: AdamG on August 02, 2014, 11:13:29 AM
The polks have a very low impedance, so it may be sending less signal to the rears than a standard load.
Title: Re: Hafler circuit used in SDA Crossover
Post by: schwarcw on August 02, 2014, 11:41:50 AM

Carl's Polks SUCK!!!! as does all his other equipment.  :laugh:

I know, I am tone deaf to knowing what is good and bad sound!
Title: Re: Hafler circuit used in SDA Crossover
Post by: SunnyDaze on August 02, 2014, 11:48:32 AM

Carl's Polks SUCK!!!! as does all his other equipment.  :laugh:

I know, I am tone deaf to knowing what is good and bad sound!

I think you're confusing yourself with me, Carl.
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 02, 2014, 12:49:41 PM
The polks have a very low impedance, so it may be sending less signal to the rears than a standard load.

Nothing is sent to the rears except for the original source material. They are on their own dedicated amp.
Title: Re: Hafler circuit used in SDA Crossover
Post by: GraphicFX on August 03, 2014, 09:16:53 AM
I have still not gotten a definitive answer. so I will ask the question again.

My surrounds (on it's own dedicated amp) running through a Hafler Circuit, even at high volumes barely change the overall sound of music especially during passages where there is a large stereo effect ie; Old stereo beatles recordings, leads me to believe that the hafler surround Information is very similar to the SDA information coming from the mains.

Is Polk using some variation of the Hafler Principle?
Title: Re: Hafler circuit used in SDA Crossover
Post by: F1nut on August 03, 2014, 01:34:41 PM
Quote
  I have still not gotten a definitive answer   

Yes, you did.
Title: Re: Hafler circuit used in SDA Crossover
Post by: schwarcw on August 03, 2014, 02:26:19 PM
I have still not gotten a definitive answer. so I will ask the question again.

Is Polk using some variation of the Hafler Principle?

GFX,

Jesse's reference to the SDA white paper should explain it in detail.  In short, NO.  Matthew Polk patented his SDA technology which is intranural crosstalk cancellation.  Forget anything Hafler when it comes to the Polk SDA.  No common denominator at all.

Enjoy your SDAs.  They are a wonderful speaker that have a signature sound all their own.

Regards,
Title: Re: Hafler circuit used in SDA Crossover
Post by: polkman on October 27, 2018, 08:55:01 PM
What do you mean, "surround info"?

I have surround channels which use a hafler circuit.  My question is the following:
does polk use some sort of version of the Hafler Circuit via the IC and the SDA drivers?

Yes it is pretty much the same as the hafler circuit in that is uses the "Difference signal" culled from the positive terminals of both channels, (through the IC wire) but differs in that it places the surround speakers (SDA effect speakers in Polks case) a designated spacing from the main drivers, and employs a low pass filter of approximately 150 Hz, to allow the SDA effect speakers to reproduce bass in addition to the Primary drivers.

Therefore it is very similar but merely different in implementation.
Instead of rear "Surround" speakers, the polks place them next to the main drivers to create a wider pseudo soundstage, as where the Hafler circuit creates a pseudo surround sound and a larger overall room image to the rear mostly.
Title: Re: Hafler circuit used in SDA Crossover
Post by: polkman on October 27, 2018, 09:02:32 PM
I have still not gotten a definitive answer. so I will ask the question again.

Is Polk using some variation of the Hafler Principle?

GFX,

Jesse's reference to the SDA white paper should explain it in detail.  In short, NO.  Matthew Polk patented his SDA technology which is intranural crosstalk cancellation. Forget anything Hafler when it comes to the Polk SDA.  No common denominator at all.

Enjoy your SDAs.  They are a wonderful speaker that have a signature sound all their own.

Regards,

Actually if you look at the schematics of any of the SDA line speakers, it is almost an identical and very simple circuit. The signal from the positive of both channels drives both sets of the outer SDA array speakers.
They derive a "Difference signal" in the exact same way the Hafler circuit (among other surround effects) achieve the same signal.
That is not to say it is exactly the same, but quite similar.
There is only so many signals you can derive from 2 stereo channels

The sum (what is common to both channels)
The difference (what is unique to each channel)
Left
Right

A great idea and some really nice speakers!
I miss mine at times, but I guess things have changed since I got mine in the 80s!