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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
 
I dont know how to post a diagram, but its pretty simple. From the preamp out on the SS amp I have a y connector with two male and one female ends. One male goes in the preamp out jack, the other male goes in the amp in jack and the female connector takes an interconnect cable which runs to the tube amp for that channel.

Speaker connections run from the SS amp to the woofer connection and from the tube amp to the mid/hi connection. The jumper between the two is removed. This is the way the PSB manual shows it should be hooked up, and the only way that makes sense.

I will try to reconnect it all again this weekend and see if the problem repeats.
hifihvn
943 posts
 
Manitunc, sorry for not being clear. I meant the manufacturers diagrams for the amps and speaker. You made your connection part clear.
manitunc OP
795 posts
 
http://www.dussun.com/english/v6.html

here is the dussun website that shows the rear of the unit and the connections
hifihvn
943 posts
 
Manitunc, hopefully you check the speakers out first, like Almarg suggested. He catches stuff the rest of us overlook. It's cheap insurance to do it first. I'm worried that the protection in the amp may not work 100% of the time, if it is something like the speakers causing it. If it is mechanical feedback, that may not be as risky, like something in the speakers, that may be still tying the two amps outputs together. Whatever caused it the first time, is most likely there yet. Your original wiring looks right.
hifihvn
943 posts
 
I guess the amp's protection kicking in has me worried. The amp running out of that much power just doesn't seem right. So something wrong must be happening.
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