Sub speaker level input questions

[Skyline]

Hi everyone! I recently upgraded my old velodyne 8" CHT to the 12" DSP model. Now I have the 8" sub hooked up with the center channel by speaker level inputs since I wanted more deeper sound for dialogs etc. It's awsem, just what I wanted. But the problem is when I put in a sound test CD with really low frequencies, and turned up the volume, the 8" seems to make a small rattling sound. At first I thought it was somthing in the room shaking, but upon closer inspection it was obvious it was somthing inside the sub rattling. I never heard it before when it was hooked up by the subwoofer-out directly from the reciever. Also, the bass is very clear so I doubt it's distrotion. This only happens when I have the volume higher than -28db or so level (Denon 3805) with very low frequencies. So my question, or questions, are, does anyone have an idea what is causing this rattling? Is there a problem with the sub? And, does the power from the reciever affect the sub at all or does the amp in the sub affect the center speaker at all in this setup (I think the reciever powers the center speaker only, and the sub does its own thing with its amp)? I'm really into all this hometheater stuff, but don't know too much about the technical aspect (too confusing ). Any feedback would be greatly apreciated, thanks.

 

[Rob Babcock]

An 8" driver hits the limits pretty fast with very low frequencies played pretty loudly. Sounds like it's just plain being overdriven. I had a similar problem years ago with a very nice 8 incher by Cambridge soundworks- the sound was good and it went fairly deep, but it didn't play cleanly at high volumes. You probably will just have to crank the sub down a ways.

How do you have it set up? Are you running the speaker cables to the sub and then out to the center?

 

[Skyline]

Oh ok thanks, makes sense, but I'm sure there was no rattling before, unless I just never noticed. Ya I have my speaker cables from the reciever to the sub, then cables from the sub to the center channel. I have an Infinity Beta C360 center. It's a very clear speaker, but not too good on the bass, I'm guessing like all centers. I use to hate prologic II becuase the sound was so flat (all the dvd menus and tv shows etc), but coupled with the sub I can't get enough. Is this setup normally done, or can it damage anything? Thanks again!