Hissing tweeter in GK Neo 212-11 or is it the 700rb amp?

[GrandJim]

Got a new GK Neo 21211: love it. Driving it with GK 700RB. The tweeter makes a constant hiss, pretty loud, when the cabinet is in bi-amp mode, receiving 50 watts from the 700rb's small hi-range amp. The gate setting stops it when the signal from the bass degrades below threshold, but it's a nasty hiss and it screws up recording big time. When the cabinet is switched over to full-range the hiss goes away. Treble and presence are WAY down so it's not too much hi signal coming from amp. I figure either the tweeter is bad or the amp section that drives the tweeter is bad. Any ideas?

[billfitzmaurice]

It's the amp. Does the tweeter hiss when the amp isn't on? Speakers only reproduce the signal sent to them.

[GrandJim]

You might be right. When I switch the cabinet to full-range there's no hiss - but there's also no signal coming from the 50 watt portion of the 700 RB. I think when you switch the cabinet from bi-amp to full range the crossover in the cabinet engages and the little 50 watt signal coming from the amp into the cabinet via the Speakon cable just goes...nowhere, I guess. I'm unsure about the internal architecture of this cabinet however. I'd certainly like this hiss to go away. Can anyone suggest how I could troubleshoot this before I pack up the amp and send it to the tech?

[billfitzmaurice]

Originally Posted by GrandJim

Can anyone suggest how I could troubleshoot this before I pack up the amp and send it to the tech?

Troubleshooting is what techs are for. Compare it to another identical amp first. It could be common to all.