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Hafler circuit


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5 replies to this topic

#1 of 6 OFFLINE   John Meringolo

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Posted September 20 2002 - 12:54 PM

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

#2 of 6 OFFLINE   ThomasW

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Posted September 20 2002 - 05:13 PM

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.

#3 of 6 OFFLINE   Greg Monfort

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Posted September 20 2002 - 07:57 PM

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
Loud Is Beautiful, If It's Clean

#4 of 6 OFFLINE   Manuel Delaflor

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Posted September 21 2002 - 01:49 AM

John

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.
Here was my gear info... Now is on my profile, in case you want to know

#5 of 6 OFFLINE   ThomasW

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Posted September 21 2002 - 05:42 AM

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 Posted Image

#6 of 6 OFFLINE   John Meringolo

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Posted September 21 2002 - 10:36 PM

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