Hi Tom,

I read this post by Patrick Bateman on DIY audio. It answered questions I had about open back vs closed back mid drivers for Synergy horns.
http://www.diyaudio.com/forums/multi-way/244508-monster-massive-12.html

Per Mr. Bateman,

"It's complex:
In a horn with sealed back drivers, like a Synergy horn, the Fb of the midranges is somewhere around 500hz.
In a horn with open back drivers, like a back loaded horn, the Fb of the midranges is significantly lower. For instance, if you remove the back off of those sealed midranges, the Fs will drop to something like 150hz.

OK, so I've established that the same driver will have a different bandwidth depending on whether the chamber is on the driver.

Here's where things get tricky:

Removing the back chamber ALSO lowers the efficiency. For instance, a 5" midrange with a backchamber will have an Fb of around 500hz and an efficiency of about 95dB. Remove that backchamber and the FS goes down to about 150hz, but the efficiency also drops significantly; perhaps as low as 87dB or so.

Someone really needs to build one of these things, and I unintentionally came close when I built this" End quote.

It's funny how with horns all roads seem to lead to 500hz.

My question is; If you wanted a Synergy horn that could cross over at 350hz with sealed back drivers, so you could get the higher efficiency, how big would the drivers have to be? Just off the top of your head. :)

And second, would drivers of that size be possible to implement? Would the horn still use four drivers?

Yes, I think Patrick is right. Somebody should build such a horn. Wink-wink, nudge-nudge.

Thank you in advance for your reply.

Jamie

Big speakers and little amps blew my mind!

• http://www.diyaudio.com/forums/multi-way/244508-monster-mass

 RE: Sealed back mid drivers for Multiple Reentrant Horns - weltersys 12:32:58 09/28/14 (1)
 RE: Sealed back mid drivers for Multiple Reentrant Horns - Mr_Steady 13:24:29 09/28/14 (0)
 RE: Sealed back mid drivers for Multiple Reentrant Horns - Mr_Steady 10:19:29 09/27/14 (0)

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 RE: Sealed back mid drivers for Multiple Reentrant Horns - weltersys 12:32:58 09/28/14 (1)
 RE: Sealed back mid drivers for Multiple Reentrant Horns - Mr_Steady 13:24:29 09/28/14 (0)
 RE: Sealed back mid drivers for Multiple Reentrant Horns - Mr_Steady 10:19:29 09/27/14 (0)

AA won't let me edit the subject line, or delete and repost.

My bad.

Jamie

Big speakers and little amps blew my mind!

I'm afraid I misspoke. I meant Synergy horns when I wrote reentrant horns. I apologize for the confusion. I jumbled the terms up in my head, and AA won't let me edit the subject line.

Your response let's me know that larger sealed drivers would work for synergy horns.

Thank you for your response. I know you know your business.

Jamie

Big speakers and little amps blew my mind!