Hafler circuit (1 Viewer)

[John Meringolo]

anyone out there long enough to know what the "hafler circuit" is or where one can be located?

 

[ThomasW]

If you're referring to the ambient recovery circuit it's pretty easy
Left front + to Left rear +
Right front + to Right rear+
jumper between the left and right rear - terminals.
HERE'S more info
The main problem with it is that it's difficult to balance the output levels. The old DynaQuad box used a 50 watt stereo L-pad that burned out after while.
I had friends that made line level devices (same circuit) and then ran the output to power amps. That works ok if the amps have input level controls.

 

[Greg Monfort]

The main problem with it is that it's difficult to balance the output levels. The old DynaQuad box used a 50 watt stereo L-pad that burned out after while.
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I had good luck with this the one time I tried it:

Tie the center channel (-) to a variable pot (0-nominal speaker impedance) to the LF and RF (-) jumper, and the CC's (+) to the LR (-) and RR (-) jumper. Once the pot is dialed in, replace it with a sufficiently high wattage resistor.

Note that the speakers must all be the same nominal impedance and that the amp must use a common ground for left and right channel speakers.

GM

 

[Manuel Delaflor]

John
You can always point your browser to Link Removed This box is an evolution of the original Dynaco Quadaptor (Hafler design which I still own by the way and it works flawlesly) and it appears to have a somehow improved circuity.

 

[ThomasW]

I used the several of the DynaQuad boxes in the late 70's/early 80's. Always ended up burning out the L-pad.
Maybe I was was just too heavy handed in my younger days

 

[John Meringolo]

Wiring the circuit on the speaker level side DOES put very high loads on the amp! Iam looking for a circuit that does this on the pre-amp side.btw check this I found:
US Patent No. 5,386,473
Passive Surround Sound Circuit
Issued: January 31, 1995
Inventor: Robert W. Harrison, Cortland, NY