| Hi and a Few Questions [message #75659] |
Thu, 28 February 2013 15:39  |
Michaelzh
Messages: 23
Registered: February 2013
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Chancellor |
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Hi Wayne!
It has been about 10 years since I last posted message on your board. Time does fly behind us. I feel excited to be here again.
I am kind of reentering into audio lately. I am thinking of putting together something in the fashion of your 7 PI speakers.
I have a pair of corner horns with JBL 2245 woofers (http://audioroundtable.com/PiSpeakers/messages/8818.html) and a pair of JBL 2123J 10" midrange drivers. I would like to use the 2123J in the PI midrange horn and JBL 2245 corner horn as in place of the 7 PI corner horn since I already have them. I would purchase H290Cs and B&C DE250s. I would build the midrange horn because I want to incorporate it in such a way that it "harmonizes" with the corner horn.
Here are my questions:
1) Are 2245 and 2123J usable in the current version of 7 PI speakers?
2) If the answer is yes to 1), will the crossover need to be modified? And
3) Would the relative placement positions between the tweeter horn and the mid horn stay the same as in 7 PI speaker?
Thanks!
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| Re: Hi and a Few Questions [message #75660 is a reply to message #75659] |
Thu, 28 February 2013 16:18  |
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Wayne Parham
Messages: 18787
Registered: January 2001
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Illuminati (33rd Degree) |
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I remember you Michael. Seems like you were considering various compression ratios for constant directivity cornerhorn bass bins at one time. Did you ever build any with higher compression back then? Is that what was in the photos on you link?
Answers by numbers:
1. The 2245 is an absolutely wonderful woofer. You can definitely put it in a constant directivity cornerhorn and use it just like you would the 2226. Scale it up though, to ~ 8ft3 tuned to 30Hz. It'll go lower, of course. 
I can see if I still have plans for the seven π-18 bass bin, if you want. That one used the JBL 2245. Way back when that driver was still available, I used to make a version like that.
2. The 2123 is also an excellent driver, although I didn't test it with the π midhorn. I did use the JBL 2012 though. My suggestion would be to use my crossover as a starting point, and to modify components as needed. You'll notice the seven π schematics show different components for each of the available midrange drivers, so try each of those first. You'll also have to reduce the padding, since you have a 16Ω driver. You might be able to remove padding altogether with a 16Ω driver, but I don't think it will need that much reduction.
3. The midhorn and tweeter should be positioned with their mouths flush, which puts their acoustic centers in the right position relative to each other. Put the tweeter in a little decorative box with about 2" baffle on each side and above the mouth of the tweeter.
Also, check out the Pi Speakers FAQ. It has some good finishing information that you might find helpful in the "Miscellaneous" section.
Welcome back!
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