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Hafler's passive pseudo-quadraphonic speaker hookup using a stereo amp

scott.french

scott.french

New Member
I am interested in hearing of anyone's results from utilizing David Hafler's blueprint to attain ambient rear channels from 4 speakers and a 2 channel amp -- in concept his theory is a cool idea. If I can get some positive :sigh:feed back on this then I may ask if my way of tinkering with it will get similar results. Scott
 
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I first experimented with this hookup more than 30 years ago. It can sound quite good IF you get the level of the rear speakers right, they are a good match to the front speakers, they are at least as far from your ears as the front speakers (no delay in this setup), AND the recording works well with the setup. Be sure your amp can tolerate a common ground between channels - most can, and those that can't generally provide clear warnings in the manual. But I have managed to blow up an amp with this setup.

Oh, and by the way: Welcome to AK, Scott!
 
same info as rich. look around and see what value pot to use to match the levels. i have an old eico quadaptor from the late 60s that i used for years. its basicly a hafler hookup with a volume control for the rear channels.

chicago at carnegie hall sounds great with this type of hookup!
 
Dynaco Quadaptors use the technology and can usually be had cheaply on eBay. I can't find a recent sale price but I seem to recall them going for $20-$30. That might beat building something on your own.
 
scott.french said:
I am interested in hearing of anyone's results from utilizing David Hafler's blueprint to attain ambient rear channels from 4 speakers and a 2 channel amp -- in concept his theory is a cool idea. If I can get some positive :sigh:feed back on this then I may ask if my way of tinkering with it will get similar results. Scott
Click to expand...
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Gotta link??

Is this anything like the ambient rear channel setup Brian Eno advocated years ago (early 70s?) That system gave a very nice 3d effect to music - I used to wire all my car stereo system that way ... back inna day.

If memory serves, you baiscally run a speaker lead from L+ and R+ only on your amp to a 3rd speaker placed in the rear-center of your listening area. Its ambient sound so it doesn't need to be as good a speaker as the fronts
It plays the sounds that are unique to either left or right - sounds that play on both fronts cancel out and aren't played in the rear.

Can't find the exact article for the ENO hookup (think the diagram was on the back of the Discrete music LP) but this page seems close ...
http://www.audiosignal.co.uk/Resources/A_year_of_surround_sound_A4.pdf
 
This also found its way onto my hard drive at some point. I've been wanting to try it, but don't really have a room large enough in which to do it properly.

attachment.jpg


I know I found this image here, I'm just not sure who posted it originally.
 
I had a Dunaco Quadaptor. I set up Magnepan MG2s in front with these crummy Sony speakers in the rear. Every time I played "Riders on the Storm" (Doors) our dog, who hated thunder, would believe it was the real thing. My impression is that it works well in recordings with a natural acoustic. Pan pot stereo sounds kind of stupid.
 
Fedallah said:
This also found its way onto my hard drive at some point. I've been wanting to try it, but don't really have a room large enough in which to do it properly.

attachment.jpg


I know I found this image here, I'm just not sure who posted it originally.
Click to expand...

That was my drawing. I posted it here on AK.

You don't need four identical speakers. The fronts can be your regular speakers, and rears or sides can be small ones, like RS Minimus 7's or 77's. The additional speakers take very little amp power, probably less than 10%. There will be no low bass from those speakers, as bass is mono and will cancel out.

This gives a very spread effect with the sound extending way past the outside speakers. Or if placed to the rear, a near 360 degree effect.
 
hafler passive pseudo-quadrzphonic speaker hookup

From a newbie-- thanks to everyone for their feedback and diagrams on the Hafler circuit.
Since this circuit does work as claimed then I need to ask if I can use a second [solid state] amp to get the effect-- this amp would drive only the additional speakers and therefore would have the return grounds lifted per the Hafler diagram.
This amp is actually a reciever, a Marantz 2226b, which has a common speaker ground. I am using it as a tuner source for my C20, and in turn, as a headphone amp sourced off of the C20. The reason that I ask if I can use a second amp [the Marantz reciever] is because I did not hear any audible sound from the 2 additional speakers when I hooked them to my mc240. I had the return grounds lifted to those speakers per the hafler diagram.
I was not surprised that the speakers were silent because prior to the hookup I ohmed the internal resistance between the mc240 left and right speaker output ground screws and there was no connection seen on my meter. If I was a technician I would understand why but that does not matter.
Anyone please reply as you may- Scott
 
Scott - My understanding is that this will only work on an amp with a common ground. Also, I would not recommend using only the hafler-connected speakers on an amp; I have damaged an amp this way, presumably due to the odd load the hafler-connected speakers alone make. I once had a transformer-based device that did this at line level, and the "matrix" surround feature in many old surround adapters (pre-Dolby Digital) do essentially this.
 
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stuartk said:
I tried it a number of years ago too. The results were interesting, and it was an inexpensive, easy DIY project.

Lots of links found with: http://www.google.com/search?hl=en&q=hafler+difference+circuit&btnG=Google+Search
Click to expand...
I did that too after reading the Haffler article and seeing the diagram in I believe Audio Magazine (I miss that magazine) I used that setup through the 1970's. I now have a Sanyo SQ/QS decoder and I use that, if only I had the adaptor in the 70's!
Below find a list of records that I found in a book at the library of records that sound good with this method. The list is from the early 1970's so there are many others since then. BTW the CD's of these records work the same if they didn't tamper with the mix.


Beach Boys: "Sunflower" (reprise S 6382)
Beach Boys: "Surf's Up" (Reprise RS 6453)
Beatles:"Let It Be" (Apple 34001)
Beaver/Krause:"Gandhavara" (Warner WS 1909)
Berio: "Sinfonia" (Columbia MS 7268)
Berlioz:"Requiem" (Philips 6700 019)
Blood, Sweat and Tears: "Child is Father to the Man"
Boston Pops Orchestra: "An Evening at the Pop's" (RCA Red Seal LSC 2827)
Boston Pops Orchestra: "Irish Night at the pop's" (RCA Red Seal LSC 2946)
Britten: Noye's Fludde" (London OS 25331)also (Argo ZNF 1)
Crosby, Stills and Nash (Atlantic SD 8229)
Eileen Farrell: " I've Got a Right Sing the Blues"( Columbia
CS 8256)
Fiddler on the Roof:Original Cast (RCA Victor LSO 1093)
"The Flame" (Brother 2500)Recorded in Dynaquad
George Harrison: "All Things Must Pass" (Apple STCH 639)
Quincy Jones: "Walking in Space" (A&M SP 3023)
James Last: "El Condor Pasa" (Polydor 24-4509)
Last Night of the Proms (Philips 6502 001)
Mahler "Symphony #2" (RCA LSC 7066)
Mahler "Symphony #8" (CBS 2013)
Lee Michaels (A&M 4199)
Pink Floyd "Ummagumma" (Harvest STBB 388)
Shakespeare: "Macbeth" (Caedmon SRS S 231)
Simon and Garfunkel: "Bridge Over Troubled Waters" (Columbia KCS 9914)
Jimmy Smith:"The Best of Jimmy Smith" (Verve 68721)
Stockhausen: "Electronic Music" (Deutche Grammmophon SPLM 138811)
Stockhausen: "Kurtzwellen" (Deutscche Grammophon 2707045)
Strauss: "A Hero's Life" (Philip's 6500 048)
Strauss: "Salome" (RCA LSC 7053)
Mary Travers: Mary"(Warner WS 1907)
Vaughan Williams: "A Sea Symphony" (Angel SB 3739)
Wagner:"Sigfried" (London OSA1508)
Webber/Rice: "Jesus Christ Superstar" (Decca DXSA 7206)
The Who: "Live at Leeds" (Decca DL 79175)

Conventional stereo recordings recomended by Dynaco
Cannonball Adderley: "Country Preacher" Live at Operation Breadbasket (Capitol SKAO
404)
Bach: "Cantata 130,67,101" (London 26098)
Beethoven: "Symphony #5" (RCA LSC 2466).
Bizet: "L'Arlesienne Suites" (Columbia MS 6546)
Brahms: "Piano Concerto #2" (RCA LSC 2466)
Brahms: "Symphony #4 (RCA LSC 3010).
Jack Bruce: "Harmony Row" (Atco S 33-365)
"Johnny Cash at San Quinten" (Columbia CS 9827)
"Los Chiriguanos of Paraguay" (Nonesuch H 72021).
"Cinemoog" (Mercury SR 61279)
Ray Conniff and the Singers: "Bridge over troubled Waters"(Columbia CS 1022).
John Denver: "Poems, Prayers and Promises" (RCA LSP 4499).
The Doors: "Absolutely Live" (Eletra 9002)
The Doors: "Morrison Hotel" (Eletra 75007)
Les Elgart: "Sound Ideas" (Columbia CS 8002)
Emerson, Lake & Palmer (Cotillion 9040)
Esquivel: "Infinity in Sound" #1 and #2 (RCA LSP 2225 and LSP 2296 respectively)
Esquivel: "Latin-esque" (RCA LSA 2418).
"Everything You Ever Wanted to Hear on the Moog" (Columbia M 30383).
George Greeley: "Popular Piano Concerts of Famous Film Themes" (Warner WS 1427)
Hayden: "Creation" (Deuche Grammophon 2707044)
"Horowitz on Television" (Columbia MS 71006)
Dick Hyman: "Moog-Electric-Eclectics" (Command S 938)
"The Wonderful World of Antonio Carlos Jobim"(Warner WS 1611)
"Kenton at the Las Vegas Tropicana" (Capitol ST 1460)
Morgana King: "It's a Quiet Thing" (Reprise RS 6192)
Kingston Trio: "Best" (Capitol ST 1705)
Led Zepplin II (Atlantic SD 8236)
"Charles LLoyd in the Soviet Union" (Atlantic SD 1571).
Harvey Mandel: "Games Guitars Play" (philips PHS 600325)
"Mantovani in Concert from the Royal Festival Hall" (London PS 578)
Rod McKuen: "The Earth"(Warner WS 1705)
John Murtaugh: "Blues Current" (Polydor 244016).
"The Naked Carmen" (Mercury SRM I604)
New York String Ensemble: "Tapestry" (Columbia CS 9442).
"One Stormy Night" (philips PHS 600205).
"O Sacrum Convivium"(Argo ZRG 662)
"Johnny Otis Live at Monterey" (Epic EG 30473)
"Project: Comstock" (Warner WS 1463)
Rachmaninoff: "Piano Concerto #2" (RCA LSC 2068)
Rascals: "Peaceful World"(Columbia G 30462)
Rolling Stones:"Satanic Majesties Requests" (London NPS-2)
Edmundo Ros:"The New Rhythms of the South"(London SP 44054)
Santana: "Abraxas" (Columbia KC 30130)
Santana: "New Album" ( KC 30595)
Santana: "Santana" (CS 9781)
Satie: "Gnossiennes [Through a looking Glass]
Schubert: "Symphony #5" (RCA LSC 2344).
Shostakovitch "Symphony #5" (Philips PHC 9081).
Simon and Garfinkle: "Scarborough Fair"(Columbia CS 9363)
"Something in the Wind" (A&M SP 4207).
"Soviet Army Chorus and Band" (Angel 35411)
Tchaikovsky: "1812 Overture" (RCA LSC 3204)
Tchaikovsky: "Sleeping Beuty" and Swan Lake" excerpts (London Spc 21008).
Vivaldi:"Gloria" (Argo ZRG 505).
 
Any amp used must be a common ground type. Also, if fed a mono signal there will be no output on the rear/surround speakers if the balance is centered.

You can use a separate amp but the added surround speakers add almost no load.
 
I used to have a Realistic receiver ages ago that had 3 screw terminals for speakers. Left, Right, and a common negative. I discovered this effect by accident when the two negs that were twisted together came loose from the terminal.

Basically it cancels any mono information from the signal I guess because a lot of the vocals disappeared.

Never set it up as part of a 4 speaker system but I would imagine it would make a neat effect.
 
I used the Hafler system for three years in the late 90s using my Pioneer SX-6 receiver (which still works perfectly [& never been repaired either]). I also tried one speaker back there with good results.

BTW: this system doesn't actually generate a true quad output because the signal going to both rear speakers is the same, just like with the Dolby Surround and Dolby Pro-Logic systems.

Anyway.......

Surround effect varied a lot, depending on the source. Many more recent TV shows sounded very good, including The Simpsons, some having good directional and/or static effects & some just ambience. Using my Hi-Fi stereo* VCR, I heard even better/clearer effects, with surround-intensive movies like The Abyss sounding excellent.

Certain music could sound quite nice too, though sometimes there would be random instruments and vocals (sometimes the lead vocal!) popping up back there, though depending on the music that could actually be a fun experience! I could swear that some recordings purposely added out-of-phase elements to the recording to "activate" this system & actually, those same recordings usually work well with Dolby Pro-Logic too.

A cool extreme-low-budget system that actually works. :yes:

FYI: I had read in the article where I first saw this system to use speakers with at least an 8 ohm impedance, especially when using just one. I followed this advice and never had any problems. Btw, to control the volume of the rear speakers, once I tried using an L-pad rated at 75 watts. But at anything more than a whisper level, for some reason the Pioneer immediately went into its protect mode.

* for the system to work the source signal MUST be in stereo, but even then the signal won't always contain the out-of-phase elements needed to activate the rear channel(s).
 
Reporting back on the hafler hookup

I am making here an initial report on my Hafler experiment
This is what I did:

1. I plumbed the Mac C20 to drive the Mac240 to drive the main speakers.

2.In addition I plumbed the C20 to direct its second stereo output signal into the Marantz integrated reciever's tape 1 monitor input. This provided a volume controlled identical signal that the 240 was recieving.

3.I loaded the left and right speaker outputs of the Marantz unit with an 8 ohm 25 watt resistor just to be safe.

4.Next I did the Hafler hookup across the left and right channel speaker output positives of the Marantz unit.

The net result is that I can now on the fly adjust the volume level of the surround speakers [relative to the overall sound] if need be. [Of course I realize that the constant adjusting of various audio system parameters can get in the way of enjoying the music-- the primary purpose of our shared hobby.]
Anyway, the results with some music sources was amazing.
I do have a bit more to report about the sonic results but for now I have my Hafler hookup, even if I had to do it in a different way. The 240 could not used for the surround speakers because it does not have a common speaker ground.
Thanks to fdrennen for the list of recordings that are cool with the hafler hookup. And thanks to everyone else too. -Scott
 
Fedallah said:
This also found its way onto my hard drive at some point. I've been wanting to try it, but don't really have a room large enough in which to do it properly.

attachment.jpg


I know I found this image here, I'm just not sure who posted it originally.
Click to expand...

Take the above circuit and connect a fifth "Center" speaker between the green wire and the blue wire. Instant home theater. I used to do this in car audio in the 1970s as well. Center dash speaker, two front door speakers as mains and two 6 x 9s in the rear deck for surround. It can take some tweaking with series/parallel resistors to fine-tune the level if the speaker sensitivities are quite different.
 
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