off-topic: dumb question about 5.1 DD subwoofer output &

[dprice]

Please pardon the off-topic post...I tried hooking up a pro-audio power amp (800 W bridged mono @ 8 ohms) to an old JBL 18" subwoofer. Turning up the subwoofer output to maximum and nearly maxing out the gain on the amplifier resulted in a modest ground hum and surprisingly little bass output (considering the capability of the system). I've tried this twice (Carver 1.5) with basically the same results. I have not tried using one of the powered subwoofer units or a "subwoofer amp".

Here's the question - are the output/input levels mismatched thus requiring a pre-amplifier to deliver a hotter signal to the main power amp?

Extra question - is a "subwoofer amp" really that different from a regular power amp?

Yes I had a 5.1 source, yes it was configured properly, yes it delivered a signal, yes the amp was set for bridged mode, yes the driver is 8 ohm, no I don't want to buy anything until I figure this out....

Thanks,

Don

[bdraw]

I would check your leads, a amp that strong can play despite a short, in either the signal cable or the speaker leads. If it isn't clipping then I would look to the signal cable first. Try another cable that you KNOW works fine.

[dprice]

I'm pretty sure I tried 2-3 different cables because we moved the amp 2-3 times trying to defeat the ground hum by plugging into different wall outlets. I admit that we didn't specifically test the signal cables to see if they were good but we did use more than one and I checked at least one with a multi-meter (home-built RG6-QS with crimp-on gold RCA plugs).

Another odd data point...my younger brother tried basically the same experiment using an Ampeg SVT III bass head and had similar results...pronounced ground hum (or similar) and minimal bass.

Hmmmm...which retailer doesn't really care if you "test" gear and return it...

Thanks,

Don