Subwoofer issue...

[augerpro]

Need some advice. I just got around to hooking up three subs using the Peerless SLS 12" driven by a Dayton SA240B, sealed. Listening to Pink Floyd's "Another Brick in the Wall part 2" it made a sharp knuckle on wood sound. I'm assuming the sub is bottoming but what I need to figure out is whether it is a sub limitation or the amp clipping. I'm thinking it is the amp because there is fine line between it sounding fine and popping, and when it pops the woofer really moves, as if the amp was just throwing out DC. Here are two clips, the first from far away is easier to hear the abrupt pops (at 3, 7, 16, and 19 seconds in), and the second is up close where you can see how the woofer is bumping along fine to the beat, then suddenly jumps (3, 8, 17, 19, and 24 seconds in).

[OlderMongrel]

3 subs? How are they wired? 3 of those in parallel is 1.9 DCR, awfully low. If so try again with just 2 (sub level would need to be raised a bit to keep up with the sats).

John

[augerpro]

They are three separate subs, each with its own amp.

[BOBinGA]

Hi Brandon,
Where do you have the gain control on the sub amp set? It sounds like might you have it all the way up and you are overdriving the amp. Turn the sub amp gain down to about half and see if that helps.

But also remember that the SLS subs only have about 9mm of Xmax, so don't expect them to run like even an RSS sub.

-Bob

[augerpro]

The amps are being fed with a DCX2496 which I've had all over the place to figure the gains, but right now they +10dB input gain and 4dB output gain at the DCX, then the input gain on the amp is the 3 o'clock position. I've played with them a bit and may have made some headroom, but there is not much more I can do now and I still have the problem.

[Pallas]

I suspect that it your problem amp clipping. My experience with the SLS12 is that when overdriven it's pretty graceful.

Of course, the best way to find out is to take the sub playing at the highest level - I assume you're doing some sort of multisub system, and given your measurement chops, knowledge, and DSP horsepower you're doing something more sophisticated than "gain matching" - and swap in a more powerful unit. See what happens.

Keep in mind that your plate amps are ~150W into 8Ω, and given that the impedance of your nominally 8Ω subs is likely well over 8Ω for much of the upper bass, you probably need more voltage swing than SA240 can supply.

IMO, the PE 240W amp is fine for a fairly efficient 4th-order sub. It drives an XLS12 Application Note sub pretty well, for instance. But for closed boxes one wants a little more power.

[augerpro]

I suspect that it your problem amp clipping. My experience with the SLS12 is that when overdriven it's pretty graceful.

Of course, the best way to find out is to take the sub playing at the highest level - I assume you're doing some sort of multisub system, and given your measurement chops, knowledge, and DSP horsepower you're doing something more sophisticated than "gain matching" - and swap in a more powerful unit. See what happens.

Keep in mind that your plate amps are ~150W into 8Ω, and given that the impedance of your nominally 8Ω subs is likely well over 8Ω for much of the upper bass, you probably need more voltage swing than SA240 can supply.

IMO, the PE 240W amp is fine for a fairly efficient 4th-order sub. It drives an XLS12 Application Note sub pretty well, for instance. But for closed boxes one wants a little more power.

Thanks for the replies everyone. Yeah these are integrated pretty well into the system after two days of measuring and tweaking gain/slopes. Nearly got rid of a nasty 100-250hz suckout I had, EQ should take care of the rest. I have a pretty solid Boston Acoustic amp (rebadged Sherwood Newcastle) that I'm going to try, just wanted to make sure my diagnosis was right.