SA4512 jbl box not bass reflex

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   Theres an SA 4512 cabinet that is a front loaded horn style for a 12 or 15. My question is does anyone know what has to be done to "adapt" the 12 hole to a 15 hole?

Edited by tkroeker - 25 January 2021 at 3:18am

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tkroeker Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 06 November 2015 Location: kansas Status: Offline Points: 101	Post Options Post Reply Quote tkroeker Report Post Thanks(0) Quote Reply Topic: SA4512 jbl box not bass reflex Posted: 25 January 2021 at 2:38am
	Theres an SA 4512 cabinet that is a front loaded horn style for a 12 or 15. My question is does anyone know what has to be done to "adapt" the 12 hole to a 15 hole? Edited by tkroeker - 25 January 2021 at 3:18am

Fsurfer Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 22 January 2021 Location: UK Status: Offline Points: 8	Post Options Post Reply Quote Fsurfer Report Post Thanks(0) Quote Reply Posted: 25 January 2021 at 8:55am
	Is this the one? https://www.stageaccompany.com/support/vintage/Sa4512.pdf Edited by Fsurfer - 25 January 2021 at 8:58am

tkroeker Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 06 November 2015 Location: kansas Status: Offline Points: 101	Post Options Post Reply Quote tkroeker Report Post Thanks(0) Quote Reply Posted: 25 January 2021 at 1:02pm
	Yes

smithshorn Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 February 2007 Status: Offline Points: 253	Post Options Post Reply Quote smithshorn Report Post Thanks(0) Quote Reply Posted: 25 January 2021 at 1:43pm
	It's a hole for a 15 inch speaker. You simply make an adapter "plate" to make it smaller for a 12. Built more of these than I care to remember.

smithshorn Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 February 2007 Status: Offline Points: 253	Post Options Post Reply Quote smithshorn Report Post Thanks(0) Quote Reply Posted: 25 January 2021 at 1:52pm
	http://wizardaudio.hu/hasznos/hangfal%20tervek/top/horn/JBL%2 04512%20Mid%201.jpg Edited by smithshorn - 25 January 2021 at 1:56pm

tkroeker Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 06 November 2015 Location: kansas Status: Offline Points: 101	Post Options Post Reply Quote tkroeker Report Post Thanks(0) Quote Reply Posted: 25 January 2021 at 2:10pm
	Cool, thanks

Peter Jan Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 16 December 2008 Location: Belgium Status: Offline Points: 1019	Post Options Post Reply Quote Peter Jan Report Post Thanks(0) Quote Reply Posted: 25 January 2021 at 7:02pm
	They are not exactly horns, rather 6th order BP with one (kinda) flared port. You can block one or two ports of the four ports to tune the bottom end differently. Depending the use of 12" or 15" speakers and/or the need to have a bit more low extention (at the cost of SPL) or rather more sensitivity higher up (at the cost of low extention). I think it was mentioned in the original JBL documentation of the seventies. I have it somewhere in print, don't have it in .pdf.