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Alignments [message #47358 is a reply to message #47356] Fri, 22 July 2005 11:09 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18791
Registered: January 2001
Illuminati (33rd Degree)

For every driver, there's a continuum of alignments that are possible. There is a reasonbly wide range where response is flat and in this range, a larger box just provides deeper bass extension. For an example a JBL 2226 in a 2.0ft3 box tuned to 50Hz has f3 of 65Hz, 3.0ft3/50Hz has 55Hz f3 and 4.0ft3/50Hz has 50Hz f3. Any larger or smaller and response becomes underdamped.

Moving the Helmholtz frequency down a little bit shifts the alignment towards an overdamped condition. This has a benefit of being forgiving of certain conditions. Adding series resistance from long wire runs or heated voice coils won't make the box sound boomy. On the other hand, it isn't an alignment that works well in wide open spaces without a sub. A flat or even slightly underdamped alignment sounds better if used in open areas, particularly if no subs are used.

When the box is tuned to 40Hz, all box sizes from 2.0ft3 to 5.0ft3 work well, having flat response and cutoff somewhere between about 40Hz and 60Hz. They are slightly overdamped, so they are forgiving of high power levels and long wire runs. Larger boxes, up to 5.0ft3, yield an EBS alignment that rolls off about 40Hz.

There are lots of prosound 15" drivers that have been made to work well in 2.0ft3 to 5.0ft3 boxes tuned to 40Hz. That's a standard target, so many manufacturers have made speakers that have suitable electro-mechanical specs for this application.

So the difference is largely a matter of bass extension. You have about a half octave span to play with, and about 2x box volume to work with too.



Re: Alignments [message #47359 is a reply to message #47358] Fri, 22 July 2005 11:52 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Thanks Wayne. My Altec 416's sound better tuned to the same F3 but in a bigger box. They breath much better; you can hear it. Is it possible this is what Charley is experiencing with the JBL's?

Re: What TillE said [message #47360 is a reply to message #47357] Fri, 22 July 2005 11:54 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Looks good. You like the P audio ehh? They certainly seem to give a lot for the money over there.

Re: Alignments [message #47364 is a reply to message #47359] Fri, 22 July 2005 12:24 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18791
Registered: January 2001
Illuminati (33rd Degree)

Sometimes, boxes that are too small will give underdamped alignments. Other times, it's just a matter of extension. Really depends on the electro-mechanical specs of the part.


Three reasons for the P.Audio horn [message #47373 is a reply to message #47360] Sat, 23 July 2005 06:06 Go to previous messageGo to next message
wunhuanglo is currently offline  wunhuanglo
Messages: 912
Registered: May 2009
Illuminati (2nd Degree)
The first is that the price is right; you can get JBL clones for 1/3 the price of JBL

Second is that there ain't a lot of 1.5" throat horns around, very few actually and P.Audio has most of them

Third reason is that the baby cheek thing seems to work well up close, as opposed to the PA CD types, although the 1.5" P.Audio at 12" X 12" looks more like Jessica Alba's ass than a baby's.


Re: Three reasons for the P.Audio horn [message #47374 is a reply to message #47373] Sat, 23 July 2005 09:11 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
I am afraid I am not familiar with her. I gotta get out more. This looks good it's good to see the wheels turning. The idea of a back loaded horn 12" coaxial sounds nice to me right now also. Have you heard any of the P-audio's?

Maybe we should take this out of Wayne's space [message #47376 is a reply to message #47374] Sat, 23 July 2005 11:27 Go to previous message
wunhuanglo is currently offline  wunhuanglo
Messages: 912
Registered: May 2009
Illuminati (2nd Degree)
Meet me over there.

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