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Sealed or Ported?

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Sealed or Ported?

Postby bcollins » Thu Apr 15, 2010 1:02 am

This is a very old photo, but...
Image

I have purchased (and received) four new Goldwood GW-1558 15" woofers to replace the old 15" 'Conn Organ Speakers' made by CTS in 1964.

Here are the numbers for the new woofers: Power handling: 200 watts RMS/380 watts max * Voice coil diameter: 2.5" * Le: .8 mH * Impedance: 8 ohms * Re: 5.27 ohms * Frequency response: 31-2,500 Hz * Magnet weight: 50 oz. * Fs: 31 Hz * SPL: 95.6 dB 2.83W/1m * Vas: 14.19 cu. ft. * Xmax: 3.9mm * Qms: 3.68 * Qes: .76 * Qts: .63 *

Parts-Express recommends a 3 ft3 sealed enclosure. As you can see in the photo, I presently have ported enclosures (these are old Peavey PA cabinets). Do you think I should try them out as-is, or seal the enclosures by gluing some MDF covers over the old ports?
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Re: Sealed or Ported?

Postby organtechnology » Thu Apr 15, 2010 12:43 pm

Hi Bob,

I would try them out as is but if you do not like the result, there are some speaker enclosure design sites that have the software for ported, enclosed and infinite baffle enclosures. Also Harrison labs has some slide rule type calculators for speaker enclosures. I saved the URLs someplace but I can not locate them just now. If I find the sites urls I will post.

Pax,

Thomas
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Re: Sealed or Ported?

Postby NickNelson » Fri Apr 16, 2010 6:10 am

You could try WinISD, here:

http://www.linearteam.dk

I'm no expert on this, but I suspect that the maximum cone excursion (Xmax) may be the
limiting factor on a sealed enclosure design.

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Re: Sealed or Ported?

Postby RoyKnight » Fri Apr 16, 2010 8:58 am

Parts-Express has some reasonably priced sub woofer enclosure kits. Would one of those work perhaps?

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Re: Sealed or Ported?

Postby TheOrganDoc » Fri Apr 16, 2010 1:20 pm

Hi,

I was a Peavey repair center tech for some time,
and believe me those boxes were "never intended for Sub Woofer use",
I would however recommend that you use them for the purpose intended, Low Mid's and Highs,
and purchase or Build a powerful Sub-Woofer system that will reproduce at high power at least 32 HZ,
and if possible 16 HZ, that pitch being most difficult to produce well.

Sincerely,..........Mel
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Re: Sealed or Ported?

Postby organtechnology » Fri Apr 16, 2010 1:54 pm

Hey, that's the URL I was looking for! Thank you.

Here is an online version where you put the speaker specs in and it gives box specs out.
http://www.linearteam.dk/default.aspx?pageid=newdriver

Pax,

Thomas
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Re: Sealed or Ported?

Postby organtechnology » Fri Apr 16, 2010 2:06 pm

Hmmm..... how does a 4ft. cube strike you? with a port.

Pax,

Thomas
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Re: Sealed or Ported?

Postby bcollins » Sat Apr 17, 2010 1:51 pm

TheOrganDoc wrote:Hi,

I was a Peavey repair center tech for some time,
and believe me those boxes were "never intended for Sub Woofer use",


I've been using those cabinets for about half a year now, and I have no problem getting 16ft (32Hz) out of them using some old 15" CTS (Conn organ speakers). The problem is they are very muddy sounding in the 100-2000Hz range. That's why I'm replacing them with the new Goldwood woofers. I'm hoping to run them more 'full-range' up to 2KHz. I have them installed as-was, and though I haven't had chance to thoroughly test them, so far they seem to be doing just fine. I [now] have the active crossovers set at 2KHz but I haven't had a chance to really give them a good listen. Mostly I need the really low end for the Skinner Swell Waldhorn 16' (and Bourdon 16') and the Great Double Diapason 16'

I would however recommend ...
and purchase or Build a powerful Sub-Woofer system that will reproduce at high power at least 32 HZ,
and if possible 16 HZ, that pitch being most difficult to produce well.


I have another [2-channel audio output group] setup for 32' - (2) 18" woofers in an infinite baffle, - connected via active crossover with (2) Behringer B2031A active monitors for everything above 128 Hz. The line inputs are also patched over to an 18" Velodyne with active servo amplifier - just for a little more presence, since the 18" woofers in the IB do a better job of shaking the fellowship hall than they do getting sound out into the nave :)

Additionally I have another 4-channel audio output group with two Behringer B2029 subwoofers connected to four bridged mono amps driving(8) Behringer B2031P.

In total, I have 10 channels that are 16' capable. See: http://zionorgan.com/Organs/Opus1/ZionV ... Organ1.htm
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Re: Sealed or Ported?

Postby RandyRock » Tue Apr 20, 2010 12:47 am

I have found Goldwood specs to be....optomistic, to say the least. I would suggest you proceed carefully, particularly in the area of "power handling".
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