Biamping 8 ohm 3-way with Denon AVR (min 6 ohm)

[daveing]

Hi Diyers,

I have a MiniDSP 8-channel processor, a Denon AVR-3083 (with pre-in for each channel) and a pair of KEF Q7s. I'm getting set up for bi-amping and bass management trough the MiniDSP. The Q7 is bi-ampable - splitting the woofer from the coaxial mid-hi arrangement. The Q7 nominal impedance is 8 ohm. I've just measured each driver separately (Q7 disassembled for refinishing) and they each measure 3 ohms woofer, mid & hi.
The AVR-3803's recommended minimum impedance per channel is 6 ohm.

Am I going to destroy my cheap old AVR if I biamp with it?

I'm surprised the binding post bridges seem to be series linking the drivers to get 8ohm. I would have thought positive to positive and negative to negative binding post bridges are a parallel connection. (drivers at 16ohm each...) Maybe KEF internally flipped the connections so we are getting 4 +6 ohm = about 8 ohm.

Thoughts?
Thanks

 

[dkfan9]

So you are planning to run without the passive crossover? Have you measured impedance after the crossover when only connected to lower binding posts?

 

[newvirus2008]

You wouldn't destroy anything by running biamp / triamp etc. but remember that the impedance written on the plate is just a 'typical value' that could reduce to lower values at certain other frequencies.

The value shown by a meter is the DCR of the voice coil alone.

 

[daveing]

The resistance measured across the lower binding posts only is 4.1 & 4.4 ohm.
Across the upper binding posts is about 4MOhm?

"4 Ohm" is printed on the coaxial driver chassis.

 

[newvirus2008]

With 4 ohms one could drive the amplifier to slightly lower voltage levels while still be very well within the current limit. With 8 ohms, this would involve a higher voltage and lower current.

The system would work nevertheless.

 

[adason]

The resistance measured...
Across the upper binding posts is about 4MOhm?

You can not measure resistance with crossover in place, there is capacitor involved. For multimeter reading it reads as open circuit.
For lower binging posts, woofers, there is likely only inductors involved.
Best way the measure resistance is to do sweep with dats.
https://www.parts-express.com/Dayto...ter-Based-Audio-Component-Test-System-390-807