Sending low HZ to SS improvements

[jfine]

Hard to explain, but here I go.

Running tube monoblocks VTA M125's (125W KT-88's) to JBL L300's (93db ported 3 ways, 15", horn, slot tweeter). Nice amps.

I recently put a JBL B460 subwoofer back in to the system, 18" monster. Comes with an outboard little active crossover, a BX63. You place it in between the preamp and the amp. It sends 70hz and above back to the main amps, and has an output for 70hz and below for the sub amp, which is a bridged mono Crown.

The little active crossover has a nice bypass lever so you can easily put the main speakers back the way they were, or flip the sub back in. Very transparent.

Before this change, if I start listening with peaks in the 80-85db SPL, you can hear the monoblocks begin to compress, a little more and harshness sets in. This is not a fault of the M125's, rather the way I am using them. They aren't going anywhere.

But now the M125's don't have to deal with anything below 70hz. Which IMO SS is better at anyway. The system has been transformed, sounds really nice now when you turn it up, makes you want more, the entire range has become clearer, soundstage opened again. That's a good thing.

Question, it's obvious to me that low hz eat power. When you start losing power the entire spectrum is affected, not just the bass. So I wonder if 70hz and below is where most of the power is used, or, maybe I should think about powering the 15" woofers in the L300's with SS altogether (biamping), it would be something like 800hz to 70hz. Is that frequency range still power hungry, or did I pretty much take the major power hunger away to the sub already?

[grumpy]

One opinion: If you're happy with your current nominal loudness level, I'd stop where you are; if you wanted to push louder (perhaps not the best idea for your ears), there might be some additional benefit in electronically crossing over higher. But if your current system is quiet/buzz-free I'd be hesitant to recommend adding more electronics and amplifiers.

[timca]

I added a JBL 4645C to my setup... crossovered at 50Hz with a BSS FDS360. It also boosts 6DB at 25Hz just like the BX63.
The main speakers (used to be XPL200A, now WB A.C.T.) sound clearer and more open by removing the very low frequency from the spectrum.

[rusty jefferson]

I agree with grumpy on this one. Avoid complexity.

Also, consider rebuilding that BX63 crossover. The power supply caps are likely shot. I've had to rebuild several all with the same issue. It doesn't stop working, but doesn't work properly.