Crown Xs1200... am I supposed to be impressed? A little rant on power.

Did you have the XS1200 bridged?

Did you have the gain knob for channel 1 set to max?

Was the LFE output level then recalibrated?

It has the juice, no question about it. It just may not have been set up properly. The XS1200, on a proper circuit (ideally a 30A) it should have close to the same power output at 20Hz as a pair of EP2500s.

I am referring to the power output from the amp, so...yeah.


He might have removed the EP2500 and put the XS1200 in place without adjusting the sub pre-out on his receiver (LFE out).

That and if the amp was on a 15A circuit with other items (such as the 300W light you speak of), the XS1200 would indeed be starved for power, so to speak.


So you have it set up bridge, gain max, and on what kind of circuit? What else is on the circuit?


Que? Are you running anything between your receiver and the amp right now? Which receiver do you have?


You're being paranoid. And actually, I don't believe anyone has taken hi-rez pics of the inside of an XS1200. You could be the first, if you'd like.

LFE = Low Frequency Effects channel. It's the ".1" part of 5.1 (or 7.1). Most receivers will send lower frequencies from the other channels to your sub via the LFE/subwoofer output.


I'd say it is "enough" but more is always better (within reason). Sealed subs are considered to require more power at the lowest frequencies because they don't have the benefit of output from a port. But isn't the XS1200 rated at 1200 watts into 4 ohms stereo? 650 watts sounds like the EP2500 spec. With most amps you'll get less power at 20 Hz than 1 kHz. That's to be expected and nothing to get concerned about.


Clipping isn't really good for either the amp or the subwoofer, but if you're only tickling the clipping lights a little bit I wouldn't worry about it.

Perhaps you are expecting too much from your 12" driver. Changing from one fairly powerful amp to another isn't going to make a huge or dramatic difference. Double the power will, after all, only yield 3 dB more sound output. While sub placement and the room size & acoustics can play a major role in how a subwoofer sounds, you can only get so much output from a sealed 12" sub.

If you're still not impressed with your friend's 15" sonotube sub then it could a combination of the room size/acoustics, sub and/or listener placement; the actual material (movie or music) being played; the crossover, EQ or gain settings; and your expectations. The least likely "problem" is the XS1200, in my opinion.

I almost hate to say it, but do you know anyone with a 18" sonosub/LLT subwoofer (or maybe an IB installation) that you can check out? Another useful question might be what subwoofers have you heard recently that you were impressed with?

The amp doesn't have RCA input? If not there certainly can be level issues comming from an RCA line out.

Perhaps, and I'd maybe have fully agreed if he hadn't mentioned the part about getting the clipping indicators lit up.

If he can drive the amp to clipping, I wouldn't think more input signal is necessary. Higher input level often gives the impression of more power, I've seen/heard that before.


To stealthdude, how much is enough depends on your expectations. I know that sounds cliche and it's really helpful. It would, however, be helpful to define your expectations in order to receive sound advice about the subs and or the amp(s). Pardon me if I missed that along the way...

yeah I agree. I missed the part about clipping the amp. Hard to imagine why it's not pumping it out hard.

I run a pretty modest sub setup. And it's downright scary. Two 15" powered subs, using the cheapie PE Dayton 15" cabs. Lower end drivers, A 500watt Bash amp in each.

I run em way hot most all of the time. I run way loud compared to most too in general.

The XS1200 was bridged and wired correctly.

How did you connect the speaker wire to the amplifier?

Simply put, the XS1200 in bridged mode on either a TC-3000 or TC-2000 LLT, set up properly, should have substantial output capability.

I'd do 8ohm bridge.


Provided you supply the amp with a good circuit, yes.

The key point is..
How much AC voltage is available when the amplifier is being pushed to its max...
It is very easy for a 15A circuit to sag as much as 10%..
Which then makes the input AC voltage only 108V with the resulting decrease in output power..
Also as the power supply rails decrease it is easier to drive the amplifier into protection and/or clipping which can take out a loudspeaker very quickly at those levels..

Use an accurate AC voltmeter and post back the actual measured voltage while the amplifier is running @ high power output, then we can help you troubleshoot the system further..

Exactly.

I'd be surprised if that's the issue. He's not running sine waves at full power, right?

Six of one, half-dozen of the other in terms of power isn't it?

Typically, the 8 ohm bridged rating is the sum of both channels when run at 4 ohms stereo.

I'd run each sub off it's own channel, but parallel the amp inputs so each channel gets the same signal.

One doesn't have to do that to expose limitations of their current power setup/circuit/whathaveyou. Hell, with my XS900, I can make a lamp sharing its circuit dim in rhythm with music when I turn it up to a certain point.

Even so, even if the A/C circuit has limitations and there is some line sag, I would be really surprised if that is THE issue here. Amplifier power is important but it isn't everything. We all know that doubling the amp power can only produce another 3 dB SPL. I think this statement by the OP says a lot:

"So I said lets connect the XS1200 thinking this is what’s going to make or break the system. To my surprise I didn’t really notice too much of a difference."

The EP2500 isn't exactly a wimpy or worthless amp. Simply replacing it with a XS1200 or even a CE4000 isn't going to make a dramatic night and day difference, especially given all the many other factors that could influence how the sub sounds in a particular situation/environment.

But, hey... I could be wrong! By all means, go ahead and hook up the Fluke and watch the line voltage. It would be interesting to know how much it fluctuates, assuming the Fluke (or any DMM) is fast enough to accurately expose/measure those fluctuations.

most likely the voltage on the subout is too low. PA amps

clipping's not gonna hurt the sub, but is bad on the amplifier.

Good luck trying to see voltage spikes/drops on a dmm for transient peaks.

If you want to measure something, measure the line out for the sub channel on your preamp. Then you'll find an answer.

Most PA amps require an input of greater then 1 volt. Many home preamps aren't near that level except at higher volumes.

You guys do realize the XS series amps start to roll off at 22 hz...
It also has a moderately low damping factor. It is a nice amp but definitely NOT my first choice for a serious sub setup where most guys are looking for flat response down into the 15 hz or lower regions.

Before you buy a pro amp, you need to check the FR in the A&E sheets. A lot of them put a 6-12 db roll off below 20 to max the rated power out since there is rarely a call for subsonic reproduction in a live audio setup. Even the vaunted EP-2500, which I do sell, starts to limit the response as it approaches the top end of the power range (it runs out of power supply). Comparing a bridged EP-2500 at 1.5 KW bridged vs a single channel of our reference LFE amp (Face Audio F-2000TX) 1200/ch, it isn't even in the same league for power, extension and control. The Face amp is -3db at 5hz and is optimized for low frequency power.

Last but not least, when you build a serious LFE setup, budget for putting in the correct amount of line voltage to feed the amp(s). I wouldn't run an XS-1200 or an EP-2500 on anything less than a 20 amp line for LFE. Especially when you realize that the low frequency response will be given up as the power supply sags (which is why the EP-2560 is rated -3db at 5 hz but only at 10 db below rated output).

You do realize you're wrong...

http://www.avsforum.com/avs-vb/showp...&postcount=411

It does not being to rolloff until 12.5Hz, where it is a mere -.1 dB down, and finally just -2.3dB down at 5Hz. So if anything, its low frequency response is superior to the Face amp.

And damping factor is extremely overrated.

Sure.


I've read too many accounts that suggest otherwise. The key here is both amps being properly set up and fully functional, and of course the limitations of the drivers being used (which you've mentioned). It could be that the OP is just expecting too much out of a 12" driver.

Well shoot. My room is near perfection on the audio side of things. Bring it on over, I'd gladly hook it up to one or both my subs for you.

This was mentioned a few posts ago, but the OP says he can make the clipping lights come on. When the clipping lights are coming on, you're at (or at least near) the limits of the amp.

If that is the case, what is stronger input signal going to do for more output?