Just bought possibly the last amp I'll ever need!

[ppia600]

Originally posted by jol50
Did you get further on this? I'm too busy playing with amps to work on the car....and its real cold out.

I've been working too late and its cold here too. I'm off again in a few days so if the weather permits I'll try and figure it out.

[sciberpunkt]

You must have bought the same 5.1 processor/EQ with SRS Circle Surround that I did. I also had an electrical noise problem that was caused by mounting it using the supplied L brackets. I tried soft mounting it with velcro to keep the case from being grounded and the noise went away.

I also noticed that all 5 channels are driven full range so the switch underneath is just a 60/90/120 LPF switch for the sub output. It looks like proper bass management is restored if a complimentary HPF is used on the other five channels.

Coming from quite a bit of home theatre experience, having something like SRS Circle Surround to liven up my dull-sounding XM sat radio was worth $40 to me, But, if the center channel isn't voice matched to the mains, matrixed surround sound just sounds terrible. Now that everything is installed, the real work begins.

I've already spent days tweaking my Alpine SBS-05DC to improve bass response but it still can't match the other four channels in bass output. Even a full octave below the HPF cutoff, bass output is still easily apparent from the other four channels but not at all from the compact DIN-sized Alpine, and that will adversely affect the surround effect.

The SRS Circle Surround II spec I found at http://www.srslabs.com/consumers/technologies.asp explained that the center channel bass is managed independently with frequencies below 200hz sent to the L+R channels and the subwoofer as needed, which would solve this issue but it looks like the NJM2199 IC in the unit is a first-gen Circle Surround processor. Independent center channel bass management is new in CS II. It seems that most of CS II is identical to CS I though.

[ppia600]

I still haven't had the chance to play with it again. It would be a little difficult to isolate the chassis on mine since it iso mounts into the same factory bracket the radio does. Maybe I could cut the trace on the board that grounds it to the case internally. Still.. I'll probably just put it back up for sale because of the lack of hp filters. I could always just run the front output on my deck high passed into the processor, and then use the sub output of the deck to directly drive the sub amp. This way you keep sub control on the deck. But that would eliminate being able to use the parametric bass eq on the processor.... argghhh

[sciberpunkt]

Without an active high-pass filter on the amp, I'd resort to passive filters at the speaker level or preferably RCA in-line filters so I could keep the sub connected to the processor's sub output. That way the bass is properly mixed with the other five discrete channels.

The SRS effect with XM radio is an improvement IMO. It helps hide the compression artifacts and flat dynamic range to some extent.