BPLM adjustment

mashthepedal · « **on:** 8 Feb 2005, 02:15 pm »

I did something unintended with my system and wonder whether I could ask for some help. I had my system upgraded from a 2 channel to a 5.1 yesterday and today I was retrieving the settings from the SP 1.7 so that I could write them down. When I got to the BPLM portion of the menu I selected it and was prompted with " Do BPLM routine " and I accidentally selected yes. I heard some unpleasant noises coming from the sub and my large speakers as well, it wasn't really loud and it quickly shut down. Now there is a hissing noise coming from the sub that goes away if I power the sub off and on but then it seems like I have no output from it. If I play a DVD in a spot where I know there is a lot of bottom end the sub comes on and the continuous hiss returns. The sub is very heavy duty, 1000 watt internal amp and 2 big drivers so I can't imagine I did anything lasting to it. Is this just an issue of having to reset it? James, I would be particularly grateful if you would help me out. Thanks, Kevin

Mike Pickett · « **Reply #1 on:** 8 Feb 2005, 06:33 pm »

Hi Kevin;

When you select "yes" to "do BPLM routine" the SP1.7 resets back to the lowest BPLM setting of -24 db. This is intended to prevent users from blowing up their subs if the BPLM has previously been set to a high value. This is probably why you aren't getting any signal from your sub. I'm also not exactly sure what happens if you turn the processor off while running the routine.
Hopefully all you need to do is rerun the BPLM routine, hitting select at the chosen limit.

Mike

mashthepedal · « **Reply #2 on:** 8 Feb 2005, 07:27 pm »

Hi Mike, thanks for your reply. I went back into the menu, said no and reset the level manually. I now have lots of sub input but it still sounds noisy, like a whooshing sound internally on the sub. It is a Thiel, given that it's new to me suspect these problems are unrelated. The circuit board for the amp rattles at high output levels, can't imagine selecting yes for the BPMS pink noise adjustment could have done anything nasty to it. Do you agree? Thanks, Kevin

Mike Pickett · « **Reply #3 on:** 8 Feb 2005, 08:25 pm »

Hi Kevin;

I agree. It's unlikely that the BPLM signal at -24 could damage any sub, especially a heavy duty one. Do you have another piece of gear you can plug it into, just to rule out the 1.7 as the source of the noise?

Mike

mashthepedal · « **Reply #4 on:** 8 Feb 2005, 08:33 pm »

Hi Mike, once again, thanks. The noise is present even with my 9B SST and my SP shut down. When you do select the BPLM it is a weird noise, it seems to turn off fairly quickly. Can you explain to me what it is please? Kevin

Mike Pickett · « **Reply #5 on:** 8 Feb 2005, 09:24 pm »

Hi Kevin;

Just to clarify: Is the sub shutting down when you run the BPLM, or is the test signal shutting off?

If the noise is present with the SP1.7 turned off, there has to be something up with the sub, and it should definitely not shut off while running the BPLM routine. The BPLM test signal is low frequency pink noise, similar to the regular test signal generated by the speaker level tests. Have you run the speaker level test signal through the sub, and if so, do you get the same result?

Mike

Bob15 · « **Reply #6 on:** 9 Feb 2005, 01:12 am »

Can I sneak a question in here?
Do most people who have killer subwoofers set the BPLM to zero or do they still tend to limit it? For instance, the top of the line from Revel Performa, Velodyne or SVS which cliam they can't be overdriven?

mashthepedal · « **Reply #7 on:** 9 Feb 2005, 02:08 am »

Hi again Mike. Can't give a definitive answer to your questions, will have to check with the home theatre guy who did the set up. It sounded to me tho like the signal shut off during the test, in the meantime they tell me that Thiel subs have had an issue with the noise floor and they may have to upgrade the amp. Kind of shocking for a $5000 plus sub. thanks again, Kevin By the way, I'm also curious about Bob's question, where would you recommend setting up the sub assuming your main, center and surround speakers are capable of handling a fair bit of bass.

Mike Pickett · « **Reply #8 on:** 9 Feb 2005, 02:46 pm »

Hi Kevin;

The BPLM signal will keep playing until you hit select, so it sounds like your sub is shutting down in response to the signal. I would definitely have it looked at.

Bob;

The class D amps that power these subs seem to be impossible to clip, so the claims may actually be true. The neighbours may not appreciate it... but I recommend running the routine anyway, just to be sure. If you get all the way to 0.0 with no cllipping or bottoming, then set it there and enjoy. If you break a window in the process, you've found another use for the BPLM.

Mike

Mike Pickett · « **Reply #9 on:** 9 Feb 2005, 02:51 pm »

Hi Kevin;

The BPLM signal will keep playing until you hit select, so it sounds like your sub is shutting down in response to the signal. I would definitely have it looked at.

Bob;

The class D amps that power these subs seem to be impossible to clip, so the claims may actually be true. The neighbours may not appreciate it... but I recommend running the routine anyway, just to be sure. If you get all the way to 0.0 with no cllipping or bottoming, then set it there and enjoy. If you break a window in the process, you've found another use for the BPLM.

Mike