Kef iQ9 almost blow my to mcintosh amps when bi amp!!!!

[Sakharov]

Hey guys,

Today I almost went crazy when I'be bi amp my kef iq9 speakers (which is indicated in the manual) and it caused my two mcintosh amps to go on safe mode!!!!

Very strangely by disassembling the speaker I find a resister making a shunt between the two negative connectors of each speaker!!!!!! This is not ok, what is Kef doing?

 

[Face]

You removed the gold plated bars between the hf and lf binding posts, correct?

 

[Sakharov]

Yes I did! You need to open the binding post cover to find the resistor.

 

[billshurv]

how were you bi-amping? one amp per speaker or on amp for both woofers?

 

[Sakharov]

Each speakers has 4 binding posts. 2 for HF and 2 for LF
I'm using one amp for each on like the user manual mentiones

 

[billshurv]

if each amp is dedicated to a speaker and they are not balanced output (you haven't mentioned your mcintosh model) then that shouldn't be an issue. You are probably in the 0.1% of amplifiers that don't like it.

 

[Sakharov]

Let me clarify I've the left channel of MC2125 connected to the left speaker HF and the left channel of Mc2200 connect to LF of the left speaker. For the other spearker the same thing but with the right channels

 

[chris661]

If you're still driving the passive crossover, I wouldn't bother with bi-amping. There's nothing to be gained, since you're still driving capacitors and inductors, and still feeding your amplifiers with full-range signal.

Do it properly, bypass the Kef crossover, add a DCX2496, miniDSP, whatever, and set off by recreating what the original crossover did.

Chris

 

[Face]

Or just use a single amp, biamping will do nothing positive in this application.

 

[norman bates]

Make sure that the different amplifier grounds arn't connected together.
Sometimes it happens when crossover grounds are tied together.

My buddy blew up a channel of my Sanusi g5000 receiver trying to bi-amp.

 

[Sakharov]

Guys

The 2ohm resistor is out and everything works like it should. I still don't understand the presence of this between the two (+) binding posts.

 

[Face]

Do you have any way of testing the speaker's impedance? Woofer tester, LIMP jig, etc...

 

[Sakharov]

Nop.

 

[eriksquires]

Well, even with full-range, biamping can yield at least small benefits. For instance, the high pass section won't have the bass current, so the amplifier's power supply will act "stiffer" than otherwise.

The type of problem Sander's Mag tech amps solve. 🙂

No substitute for active crossovers though. 🙂

Best,

Erik

 

[Sakharov]

I've ruffly measured the inpedance with a multimeter and opun removing the 2ohm resistor ir as drooled to 6ohm. Maybe they have added the resistor to make life easy to smaller/weaker amps.