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Problem with bi amping speakers

I tried to biamp my PSB Stratus Golds tonight using a Dussun V6i 150 watt SS integrated amp for the woofers and a Nobis Contigore 40 watt tube amp for the mids/highs. The contigore is similar to a Dynaco ST70. I used the preamp out on the Dussun and ran one cable to the preamp in on the Dussun and the other cable to the Nobis. Took the jumpers off the speakers and connected both amps to the respective terminals using the 8 ohm output on the Nobis.

When I turned on the amps, they both worked well for about a minute. Then I heard what sounded like feedback from a guitar amp, then ok, then feedback again, then the Dussun amp tripped. the Nobis kept playing. The feedback sound lasted for about 2 seconds each time.

Took it back apart, and both the Dussun and Nobis work fine alone. So what about my connections would cause this problem. I use a 2 male phono to a single female phono. One male end goes in the preamp out on the Dussun, the other male goes in the preamp in on the dussun, and an interconnect goes into the female end of the connector. There is one of these for each channel.

So, what am I doing wrong?
manitunc
manitunc OP
795 posts
 
yes, one set from Dussun to low, one set from Nobis to mid/hi. I was playing a vinyl record on an Oracle Delphi V which has never had an issue with feedback, so I dont think that was the problem.
apachef1
164 posts
 
Do your speakers instruction manual talk about bi-amp configurations? Not all speakers with dual binding posts and jumpers can be bi-amped only bi-wired. Don't try to bi-amp until you get more info from PSB.
apachef1
164 posts
 
The more I read your post It seems like you may be getting a feedback from having your tube amp connected to your integrated amp. How close is the tube amp to the integrated on your audio rack?
marakanetz's avatar
marakanetz
5,473 posts
 
Your set-up as I understand is missing description about Y-connectors that should connect Dussun's poweramp section to Dussun's preamp and than to Nobis.
If you did not follow it than certainly your Dussun will have loud guitar-amp feedback.
Another my guess(assuming that Y-connector is present) is that load impedance of disconnected woofer is too low that causes the amp to oscillate.
manitunc OP
795 posts
 
The PSB Golds are set up for biamping and there are instructions for hookup in the manual which I followed.

The tube amp was sitting on the floor for this test, and the integrated was about 5 feet off the floor, directly above.

I used a y connector, two males to one female. The male ends pluged into the preamp out and power amp in on each channel and the female connector was attached to an interconnect running to the tube amp's input.

The PSB woofer does go down to 2 ohms at about 100hz, but I use the same Dussun integrated normally with these speakers without a problem. I was just trying to add the tube amp for the mid/hi to see how it worked, and maybe sweeten the sound.
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