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Discussion in 'Archived Threads 2001-2004' started by John Meringolo, Sep 20, 2002.
anyone out there long enough to know what the "hafler circuit" is or where one can be located?
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.
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 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
You can always point your browser to Dynaco 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.
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
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