Hafler effect?

[icehockeyboy]

Reading the Holographic thread here, it reminded me of an experiment a lot of people tried some years ago.

It involved using a third speaker, wired using positive from say the right speaker, and negative from the left.

It was certainly an interesting result giving a strange but enjoyable effect, supposedly bringing back lost information on the record, that you would not get just using two channel stereo.

Anyone else tried this?

[The Grand Wazoo]

I think it was ideally meant to be two extra speakers and with some slight delay in the rear ones. I tried it out of interest a long time ago.
A crude way to introduce a delay is to feed the rears through a tape loop.
It's quite fun for a while.

[Ali Tait]

I think stereo was originally intended to have a centre speaker if memory serves.

[walpurgis]

There were various interpretations of the Hafler circuit which was supposedly intended to use the out of phase information from the stereo signal. I may even still have a Dynaco (Hafler) 'quadrophonic' connection box somewhere.

The general idea was to take a wire from the positive speaker terminals of left and right amplifier outputs and feed them through a second pair of speakers, commoning the negative sides of the speaker terminals.

A variation was to take a feed from the commoned negatives on the speakers and place an 'L' pad (8 ohm?) in series back to one of the amplifier negative terminals, using the 'L' pad to adjust levels.

The above could also be done with one speaker by commoning the postives and connecting to the positive speaker terminal then to the amplifier negative via an 'L' pad.

I'm fairly sure you need a pretty tolerant amp to get away with all this.

I tried various interpretations of the above and found the most effective was to just use a pair of tweeters with a series capacitor and connected between the two positive terminals and situated towards the rear of the room, but pointing up at the ceiling at an angle which would bounce the sound back down towards the listening position.

[Mr Kipling]

Paul Klipsch pioneered the 3 speaker system for use with his corner folded-horn speakers. The third speaker handled only the common in-phase signal. The R + L earths connect to it and the other connection goes to earth on the amp. The full Hafler set-up used this system plus the two rears

[jon1]

I have a custom made 5.1 preamp with hafler built in sounds ok



jon