| Re: (Now they're REALLY) Finished Pi 4 with photos [message #60390 is a reply to message #60378] |
Mon, 13 July 2009 01:22  |
Psychoacoustic
Messages: 75
Registered: May 2009
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Viscount |
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| Russellc wrote on Fri, 10 July 2009 12:20 | ...I remember you I believe from the Econowave thread. I have a very similar project...
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Russell, it was partly your E/W 4507 project that motivated me for this Pi derivative. Thanks.
| Russellc wrote on Fri, 10 July 2009 12:20 | ... didnt alter the length of the tubes inside the 4507 cab. I would restore that if so.
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You understood correctly sir, and I did return the length to original.
| Russellc wrote on Fri, 10 July 2009 12:20 | one closed is 34 hz or so... 2 ports closed you are right on about 30 hz, and the response is fairly flat.
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Great- I was looking for those frequencies. I've been enjoying the tuning with four ports open as per Wayne's recommendation. I most certainly will experiment with closing ports once I'm accustomed to these new speakers.
| Russellc wrote on Fri, 10 July 2009 12:20 | The difference in length between the H290 and driver ( JBL in the pic) compared to the JBL wave guide...
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Yes, I feel that the JBL on the Selenium may have been better than the result obtained by mounting on the B&C driver.
| Russellc wrote on Fri, 10 July 2009 12:20 | Reme(m)ber, the E'wave project is just a high freqency unit, waveguide+ compression driver and crossover with compensation. The Low frequency is just a standard 2nd order crossover at 1600 hz or so.
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You know, I got these 4507s and was busting to test them to ensure I didn't get ripped off. I ran a lead from the woofer to the Kegger-designed KPM-100 crossover (intended for HPM-100 E/W) and the JBL/Selenium combo. Didn't expect much... damned if it didn't sound GOOD!
Learned a lot from conducting the B&C/JBL horn experiment; actually witnessing the results rather than trying to digest acoustic theory made a huge difference to this beginner. Appreciate your thoughts on it, too.
| Russellc wrote on Fri, 10 July 2009 12:20 | ...very close to the woofer which can be a good thing, but it seems like I remember a brace about there going from front to back
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Yes Russell, you have a top memory. There is (was) a brace there which I removed to fit the horn as close as possible. Two braces were cut, both totalling more than the original in size. They were mounted in the centre of the triangle formed by port, woofer and horn. In the last photo above a depression in the baffle can be seen where a screw is located.
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