B&C 8PE21 amp?

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Rekkah

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Topic: B&C 8PE21 amp?
Posted: 18 October 2014 at 12:26pm

Hi guys,

Bit of a daft question I know but the B&C 8PE21 is rated at 200w nominal, would I be ok powering it off a Lab Gruppen ip900 (200w @8ohm) will be running 300hz-2.4khz

Thanks.

Edited by Rekkah - 18 October 2014 at 12:28pm

ceharden

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Posted: 18 October 2014 at 6:37pm

I suspect you're going to need more power than that. Midrange has a much higher peak to average ratio, I'd probably be looking at something like 4x power rating for the driver.

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Posted: 19 October 2014 at 9:25am

The IP900 will be capable of driving the B&C IMO. It's RMS output is 200w at 8r, but will supply peaks of current far greater than the rated output. It is desirable to have some headroom, but if you come close to using all of the headroom in an amp that has 4 x the rated power, then I can pretty much guarantee you'll get a nasty whiff of burning voicecoil!

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Posted: 19 October 2014 at 12:56pm

On music with a lot of dynamics I reckon it'd be pretty easy to use all the headroom of an amp with 4x RMS but still keep the average power below the driver rating.

However, I do almost entirely live gigs, so I work on a much higher crest factor. For playback maybe 2xRMS might be more appropriate.

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Posted: 19 October 2014 at 5:17pm

In my experience matching rms power with lab amps is sufficient so far, as posted above these amps have a lot of power headroom, clarity & dampingfactor.
My lab13000 have 6500w@2 ohm, which equals 1625W per 1500W rms 18" drivers, I never hit the peak, but I managed to get power & speakercables hot and blowing all lighters out.

I used a lab1000 for the same midjob, it's almost the double 350w@8ohms, never managed to hit peak/clip, but managed to disturb neighbors 1km away.

My point is: try it! I think it's sufficient for all inside jobs, my guess is that you're running hornloaded, so 200w would be insanely loud, 400w is just 3db more, but a lot of extra heat & distorion, you would be much better of with 2 8pe21 at 400w@4ohm, than one 400@8ohm.
As long as you're not clipping your driver will probably last longer with the 200w amp.

Oh, one more thing, try crossing higher, test it with a tone generator, my turbomids plys till 4khz!

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Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
Rekkah Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 16 September 2014 Status: Offline Points: 32	Post Options Post Reply Quote Rekkah Report Post Thanks(0) Quote Reply Topic: B&C 8PE21 amp? Posted: 18 October 2014 at 12:26pm
	Hi guys, Bit of a daft question I know but the B&C 8PE21 is rated at 200w nominal, would I be ok powering it off a Lab Gruppen ip900 (200w @8ohm) will be running 300hz-2.4khz Thanks. Edited by Rekkah - 18 October 2014 at 12:28pm

ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(0) Quote Reply Posted: 18 October 2014 at 6:37pm
	I suspect you're going to need more power than that. Midrange has a much higher peak to average ratio, I'd probably be looking at something like 4x power rating for the driver.

Gramps Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 17 February 2006 Status: Offline Points: 1046	Post Options Post Reply Quote Gramps Report Post Thanks(0) Quote Reply Posted: 19 October 2014 at 9:25am
	The IP900 will be capable of driving the B&C IMO. It's RMS output is 200w at 8r, but will supply peaks of current far greater than the rated output. It is desirable to have some headroom, but if you come close to using all of the headroom in an amp that has 4 x the rated power, then I can pretty much guarantee you'll get a nasty whiff of burning voicecoil!
	To do a dull thing with style - now that's an art.

ceharden Members Profile Send Private Message Find Members Posts Add to Buddy List The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776	Post Options Post Reply Quote ceharden Report Post Thanks(0) Quote Reply Posted: 19 October 2014 at 12:56pm
	On music with a lot of dynamics I reckon it'd be pretty easy to use all the headroom of an amp with 4x RMS but still keep the average power below the driver rating. However, I do almost entirely live gigs, so I work on a much higher crest factor. For playback maybe 2xRMS might be more appropriate.

tv00 Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886	Post Options Post Reply Quote tv00 Report Post Thanks(0) Quote Reply Posted: 19 October 2014 at 5:17pm
	In my experience matching rms power with lab amps is sufficient so far, as posted above these amps have a lot of power headroom, clarity & dampingfactor. My lab13000 have 6500w@2 ohm, which equals 1625W per 1500W rms 18" drivers, I never hit the peak, but I managed to get power & speakercables hot and blowing all lighters out. I used a lab1000 for the same midjob, it's almost the double 350w@8ohms, never managed to hit peak/clip, but managed to disturb neighbors 1km away. My point is: try it! I think it's sufficient for all inside jobs, my guess is that you're running hornloaded, so 200w would be insanely loud, 400w is just 3db more, but a lot of extra heat & distorion, you would be much better of with 2 8pe21 at 400w@4ohm, than one 400@8ohm. As long as you're not clipping your driver will probably last longer with the 200w amp. Oh, one more thing, try crossing higher, test it with a tone generator, my turbomids plys till 4khz!
	www.facebook.com/babysoundsystem