posted
Guys a question for you...I'm not sure WHAT the solution here is. Equipment : P1R head unit, Orion xtr pro 1000 class d, 1000x1 @ 1 ohm, (2) Orion 12" dvc subs 1000 each. I put the amp on a voltmeter and read a peak at 31.15v on a sine sweep...that's like a little under 1000 watts. First of all, the amp should do more. My voltage at the amps 12 v inputs is 13.1 at its lowest durin the peak, car running. During the sweep, at peak voltage, the subs are bottoming out...my first inclination here is that they could handle more power. Am I right? Am I underpowering them? If so, waht should I do with my box. I know these can be louder! Its a sealed box, 1 cu ft per sub. Orions ported design is 1.7 per sub, tuned to 31 hz. Any suggestions guys? Thanks!
Is the amp running below its rated impedance? I've heard that an amp below its rated has no control over the woofer/s-but I never got an explanation for this...
Try inverting the woofers and wiring out of phase, get a little displacement and see if it sounds better.
posted
well there are alot of things that can affect this...
about the amp not playing full power. the is probably do to an impedance problem. although you may have wired your subs to the correct nominal load, there is something called box impedance rise that can/will greatly effect the actual impedance seen at the amp. and further more, the frequency being played will change this impedance also. i have seen reports of a 4 ohm sub in a sealed box having an actual impedance of over 30 ohms at certain frequencies!!! if this is the case, your amp will never put out its full power.
now as for the subs bottoming out... this is happening because you are OVERpowering the subs. but there are so many variables. first is the frequency. what frequencies is is bottoming out on? im assuming it only happens at the very lowest of frequencies, as that is the most common. if you playing a sine sweep down to 20 hz at full power, you bet there will be some problems! alot of problems! second is the box size. if the box is too big, the air suspension isnt adequate, and the sub cannot control itself. but my guess is that the frequency is the biggest culprit. another reason could be how the sub/box is mounted or used. in certain cases, the sub will play fine when all the doors of the vehicle are closed and the trunk is closed, but once you open the trunk or a door, there is less air compression in the vehicle and the sub will unload, ie bottom out. anyways.. hope i helped a little bit..
[ 11-16-2001: Message edited by: timmi ]
Posts: 1854 | From: freezing in FAIRBANKS ALASKA | Registered: Aug 2000
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posted
Good help guys, thanks. I'm definitely gonna try the inverted idea. About that, I have a phase switch on my head unit as well as on the amp...I'm guessing I can wire them up regular and do the switching with either control? Also, another thing I did was reset my gains using a multimeter, damn I learned something new. It was wierd how if you crank the gains past the optimum point you actually LOSE output, that's really interesting. Needless to say, doin sine sweeps and test tones for 5-10 minutes to set it all up definitely had the cones warm...I bet the motors were cookin! Oh well...just wanted to say thanks for the help guys!
quote:Originally posted by timmi: although you may have wired your subs to the correct nominal load, there is something called box impedance rise that can/will greatly effect the actual impedance seen at the amp. and further more, the frequency being played will change this impedance also. i have seen reports of a 4 ohm sub in a sealed box having an actual impedance of over 30 ohms at certain frequencies!!! if this is the case, your amp will never put out its full power.
[ 11-16-2001: Message edited by: timmi ]
this is very true. your amp will only see the driver's maximum impedance at the resonant frequency (Fs) of the woofer.
most of the time your amp will be doing much less power than it's rated at because of in-box impedance rises and phase shifts in the speaker.
quote:Originally posted by timmi: well there are alot of things that can affect this...
now as for the subs bottoming out... this is happening because you are OVERpowering the subs.
Yes! The 1000W on a sub is usually it's THERMAL rating, meaning the power it can take before frying the VCs. That rating means nothing about it's suspension and how much power it takes to move the driver past xmax in any given enclosure.
quote:but there are so many variables. first is the frequency. what frequencies is is bottoming out on? im assuming it only happens at the very lowest of frequencies, as that is the most common. if you playing a sine sweep down to 20 hz at full power, you bet there will be some problems! alot of problems! second is the box size. if the box is too big, the air suspension isnt adequate, and the sub cannot control itself.
Good advice here. This is the reason for proper enclosure design. The enclosure must match not only the driver, but the power being fed to it. More accurately, design the enclosure for your listening purpose, and only feed it enough power to keep your subs safe. ; )
Also, make sure your gains are set properly. You could very well be hearing clipping.
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