VMPS larger problem

ctviggen · « **on:** 16 Jan 2006, 04:53 pm »

I seem to have a ton of problems with my system lately! Anyway, I purchased two used Largers. When I hook the left one up to a working channel of my QSC amp (yes, even though I sent the darn amp back to get fixed, still only one channel properly works) and play a song with a lot of bass, the drivers on the left Larger move quite a bit. When I hook the right one up to the working channel (leaving the IC the same) and play the same song, the drivers on the right one move dramatically less. Assuming the speaker cable is ok (one thing I've not switched as of yet), what could cause this difference in output? What actions should I take to debug this?

Thanks.

nathanm · « **Reply #1 on:** 16 Jan 2006, 05:29 pm »

Install the grille cloth.

Brian Cheney · « **Reply #2 on:** 16 Jan 2006, 06:08 pm »

Visible excursion is usually of no consequence unless the VC is bottoming out. You can always replace with modern drivers which will take a few years to loosen up, but I wouldn't do anything in your case.

ctviggen · « **Reply #3 on:** 16 Jan 2006, 06:24 pm »

The difference is not only in movement but in output. The "right" larger's output is dramatically different than is the "left" larger's even with the exact same signal. There just has to be something different between the two Largers. Heck, I can measure the difference using test tones, should you desire a more scientific analysis.

Please withhold the facetious comments.

woodsyi · « **Reply #4 on:** 16 Jan 2006, 06:37 pm »

Bob,

You can test each driver by removing the jumper and run each driver separately to see which driver is not working properly. If each driver works, then its got to be a connection issue somewhere -- jumper, speaker wire or binding post.

monotube · « **Reply #5 on:** 16 Jan 2006, 07:39 pm »

Bob,

Soon after I bought my 2 used Largers I noticed a difference in driver excursion, and a difference in output. Closer examination revealed that the drivers were not identical from one cabinet to the other. The seller did tell me that he did not purchase them at the same time.

A driver difference is possible if one Larger has the optional megawoofers and the other does not. Or, perhaps Big B may have changed drivers at some point due to his constant efforts to improve his products. As with any used item, prior owner tinkering may also be a factor.

You may want to eyeball all the drivers (and the passives) closely to see if there is a difference in yours as I found with mine. Hope this helps.

Bruno

Jack D. · « **Reply #6 on:** 17 Jan 2006, 01:13 pm »

Brian,

You didn't mean the drivers in your subwoofers take a few years
to fully break-in, or did you?

By the way, whatever happened to subsonic filters?

Jack D.

woodsyi · « **Reply #7 on:** 17 Jan 2006, 01:38 pm »

I wouldn't be surprised at all if the largers take years to break in if at all. Yesterday I wanted to check my subs out after what Bob was experiencing. So the grill covers came off (3 year old, dog and a cat) and went on Real Trap test tones. From 10 to 19 Hz, all the drivers and get a serious work out in excursion. From 20 to 29 Hz, some work. From 30 and up, hardly any movement. If breaking in speakers requires surrounds loosening up, it will take music with 10 to 25 Hz signal. How many software with that kind of bass do you play in a year? I am thinking of running this 1st track over and over for a few days (if I can get my wife to bear with me) to loosen up these subs.

Brian Cheney · « **Reply #8 on:** 17 Jan 2006, 05:50 pm »

Compliance of suspension changes quite a bit over the life of a woofer, depending on usage.

Factory breakin includes at least 24 hrs on a 20Hz to 250Hz sweep repeated every 5 seconds at 2W average input. That's more first octave bass than the system will see the rest of its useful life. And it does change the sound.

Campindog · « **Reply #9 on:** 18 Jan 2006, 03:12 am »

Any chance one is 4 ohms and the other is an 8 ohm version? Not even sure if that was an option, but if it was....