Question Quadraphonic (4 Channel) Speaker Setup?

[sean]

I have long wanted to experiment with 4 (active) speakers in a modest listening room to try and create the impression of a far bigger hall or auditorium. This false quadraphonic arrangement would probably need to feature delay and echo from some sort of intermediate box of tricks (XLR in and XLR out). I will be staying with 2 channel stereo source and figure speakers 3 and 4 will copy speakers 1 and 2.

I understand that car audio has been in this area for some time now to make “big music within the confines of a car” and surely similar processes can be introduced to a modest listening room such as mine?

Anybody here tried such a thing and what kit is required? I guess this is in analogue domain and happens after pre-amp as present outputs from DAC and Linn are all analogue?

Be well, SeanS

(I was going to acquire a lesser set of XLR active ATC, or similar for speakers No3 and No4).


Currently in “treated” room 4.8m x 3.1m x 2.4m high:
dCS Bartok2 DAC or Linn Sondek into Benchmark LA4 pre, out via XLR to 2.1 setup of ATC SCM50s and JLA Fathom f113V2

 

[MF 1000]

Hi Sean
you would need to use some type of DSP unit to both split the signal and incorporate the necessary time delays. Initially a simple 3 way RCA splitter woukd allow you to test out the idea for little cost, allowing you to use two amps and four speakers ….offering a degree of front to back balancing etc, and to see if time delay is an issue too.

I use Behringer DSP units in my multi speaker (though only two front facing channels) setup which has the facility to add in time delays as well as frequency correction, but this is all carried out after my DAC and preamp.

Im unsure if Mini DSP (another DSP brand) can do this in the dignitable domain - Andrew (Bencat) or Tony (TonyJ) are the best persons to ask on this piece of kit.

Hope this helps

 

[Nopiano]

I’m ancient enough to have owned a quadrophonic receiver, which was probably around 1975-6. By far the most consistent sound for concert hall effects can be recreated more easily than the decoded SQ, QS and CD-4 formats. And that’s the ‘hafler effect’.

Rather than give you my attempt at explaining it further, you could read more here.
https://en.wikipedia.org/wiki/Hafler_circuit

It will be much more realistic than doubling up the stereo signal behind you.

(The title might be better if it said 4-channel, as I thought at first it was going to be about Quad ELS.)

 

[MF 1000]

The OP, Nick, did state that he was trying to replicate a false quadrophonic setup …as in most of our cars these days, hence the use of a ’doubled up’ stereo signal etc.

The Hafler circuit was an interesting read tho

 

[Camverton]

I used to use Trifield processing which was implemented using a Meridian G68 processor. I thought it was very effective at turning the “aural picture at the end of the room“ from box speakers into a sense of being in a real acoustic, which helped with the suspension of disbelief.

I have since largely given up with box speakers in favour of panels and omnis and don’t find it so necessary to use trifield, which was always a bit of a fag accommodating three extra speakers. Whilst trifield can be used with electrostatic panels I found it trickier to set up well and in any case less necessary.

When I was using trifield I often preferred using it with the two channel layer of a SACD then the SACD‘s multi channel layer.

Other than trifield. AV processors also had a plethora of processing modes to “enhance“ two channel recordings on a surround system. The snag was finding a good enough processor. Tag McLaren used to make very good processors, which can now be bought for a song, as well as the aforementioned Meridian. It can be a bit of a rabbit hole and if one is not careful one can spend more time finding, and setting up than enjoying music - always a potential trap when playing with hifi!

 

[Nopiano]

The OP, Nick, did state that he was trying to replicate a false quadrophonic setup …as in most of our cars these days, hence the use of a ’doubled up’ stereo signal etc.

The Hafler circuit was an interesting read tho

Fair point, and I did read that, Keith, but I was trying to make a case for something that would actually sound like a hall ime, rather than something dependent on electronics with processing, delay lines etc., or merely making the same sound behind - which a concert hall doesn’t do, even if a car does.

I was always amazed how this simplest imaginable circuit could reveal so much ‘ambience’.

Hafler boxes used to be a thing one could buy, for those like me who can’t be trusted with a soldering iron.

 

[audio_PHIL_e]

Many years ago I had a JVC JA-S11G with A,B and A+B speaker outlets. I hung my (front) KEF Concord-IV speakers on the A o/p and my (rear) KEF Celeste-III speakers on the B. It sounded massive. Not quite what you had in mind but I was happy with it.

 

[Nopiano]

For an interesting bit of audio history, Mr Google found me this. The relevant article is the page number 208 onwards. It’s an entire magazine so takes a moment to load.
https://worldradiohistory.com/UK/Everyday-Electronics/70s/Everyday-Electronics-1975-04.pdf

 

[sean]

Lovely! I do so like meaningful responses.
MF1000, I will look up the catalogues of Behringer and MiniDSP.
Nopiano, I will update myself on the Hafler Effect and I have changed the title of the thread as you rightly suggested.
Camverton, I had never heard of Trifield, I think the AV processor element has value.
Audio_PHIL_e, you hit the nail on the head with your JVC comment.
Nopiano, Google item needs reading, but love the Sony SQA100 decoder/amplifeir on P209.

Yes it would be best if I could trial this whole notion without squillions being deployed yet again....I suspect there are sacrificial hardware candidates sitting out there on well known flea-bay websites etc.

Further Questions:
Is there a proper technical term for what I am aiming to achieve?
How would a professional audio/rigger/roadie go about this?

Be well.......SeanS

 

[Nopiano]

Nopiano, Google item needs reading, but love the Sony SQA100 decoder/amplifeir on P209.

Yes it would be best if I could trial this whole notion without squillions being deployed yet again....I suspect there are sacrificial hardware candidates sitting out there on well known flea-bay websites etc.

Further Questions:
Is there a proper technical term for what I am aiming to achieve?
How would a professional audio/rigger/roadie go about this?

Yes, those little Sonys were super looking things. (A shop across the road from where I worked sold them back in the day!). A basic Hafler circuit with a pot would be very cheap if you’re handy with making these things, but with an active speaker system it needs to be done at preamp/line level as far as I can tell. Given the quality of your kit I’d be wary of much experimenting, tbh! Do you have any passive speakers to play with, and maybe an old AV receiver?

There were various boxes made in the 1970s that seem to have been intended to do what you want with passive speakers and traditional amps but they’re all ancient now. There’s thisLafayette Dynaquad on US eBay, for example, but I’m sure it would need careful testing first.
https://www.ebay.co.uk/itm/23470457...Wh2ruRIThq&var=&widget_ver=artemis&media=COPY

Funnily enough, that same Everyday Electronics magazine carried the phrase of that era, namely ’pseudo quadraphonic’, though I think that has perhaps passed its sell-by date as a suitable descriptor.

Surround sound or Ambisonics might suffice. What do others think?

As to what a roadie would do, I can only hazard a guess that they’d have desks with delay lines to feed a rear signal. There are some here with studio know how, so maybe someone will pipe up.

 

[sean]

Thanks all for your replies and in particular Nopiano.
This has turned out to be much more difficult than anticipated.
I think in honesty it is not possible to create a surround sound from my existing components (even with a second pair of active speakers I have tucked away).
The use of higher grade balanced components and active speakers works against what is commonly available.
It could be done with a TV/Cinema 5/7 channel receiver and passive speakers, but at a generally lower level of fidelity....which is not what I have been aiming for.
The nearest is probably the Hafler effect circuit, which is not readily available to be used with active speakers.

I would just add that I have now learnt about Trifield and a number of other facets, previously unknown to me....thank you.

I am always open to any last suggestions.........be well, SeanS


PS...why am I a "New Wammer" when I joined way back in 2012.....?

 

[Andy Stephenson]

Thanks all for your replies and in particular Nopiano.
This has turned out to be much more difficult than anticipated.
I think in honesty it is not possible to create a surround sound from my existing components (even with a second pair of active speakers I have tucked away).
The use of higher grade balanced components and active speakers works against what is commonly available.
It could be done with a TV/Cinema 5/7 channel receiver and passive speakers, but at a generally lower level of fidelity....which is not what I have been aiming for.
The nearest is probably the Hafler effect circuit, which is not readily available to be used with active speakers.

I would just add that I have now learnt about Trifield and a number of other facets, previously unknown to me....thank you.

I am always open to any last suggestions.........be well, SeanS


PS...why am I a "New Wammer" when I joined way back in 2012.....?

A pseudo 4 channel effects box used to be sold by Tandy and is still occasionally sold on eBay.

Look for a "Realistic Quatravox QV3 four channel synthesizer"

I believe the rear channel's sound is derived from the difference between the left and right sound of the front channels.

Not sure how it would be with active speakers. But they are generally so cheap that it may be worth a try.
Be aware though that the speaker connections are RCA plugs.

Andy

 

[glenhb]

Thought this might be of interest.
This album was released in 1979 on The Beach Boys own "Brother" label. The only release not by the Beach Boys on the label.
Two members of Flame (Blondie Chaplin & Ricky Fataar became members of the BB's during the Carl & The Passions / Holland / In Concert album period.
This album was recorded using the Dynaco system to include ambient sounds when played back through a four speaker Hafler circuit. (Dynaco was founded by David Hafler and Herb Keroes in 1950)
The album included a circuit diagram showing how to wire up your speakers to achieve the intended effect. Apparently the album is acknowledged by some as the first Quadraphonic recording?
I've not attempted to play the album through a Hafler circuit but a long time ago I did experiment with such an arrangement and found that live albums always tended to sound a little bit more "live". One particular favourite was Mike Oldfield's live "Exposed" album.