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Multi-Way Conventional loudspeakers with crossovers

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Old 8th July 2012, 04:47 PM   #101
tvrgeek is offline tvrgeek  United States
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Whatever works. I won't argue with results.

I had not thought of making them shallower, but had thought about making them shorter. Just worked up passive BSC and 2nd order crossover to add the XT25's. I think the BSC will balance the mid base much better and I won't have to adjust the size. I hope the second order helps on the breakup.
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Old 8th July 2012, 08:24 PM   #102
ODougbo is offline ODougbo  United States
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Talking I Like it

Need to finish the second one...but so far so good.
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Old 8th July 2012, 08:53 PM   #103
tvrgeek is offline tvrgeek  United States
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When you get them done, I 'll come over and measure them.
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Old 8th July 2012, 08:59 PM   #104
ODougbo is offline ODougbo  United States
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What got this started is the box tuning was to high, to lower the tuning the slot/ports would have been the size of straws........:-/

In that respect - mission accomplished; "low" tuning with huge ports. This should be be good; can't wait to finish up.

Another pair right behind....Aye Carumba!!
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Old 11th July 2012, 08:38 PM   #105
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Tvr,

You the nail on the head a couple of times, the full range boxes do chuff a bit, not so much you can hear it over the music.

They are sounding nice, light and quick. I did pull out huge pieces of damping material (since the last time I had them together) and I like them better than before.

The midrange breakup...maybe that's why they need hours of break-in-time.

Let me know when you get you go mobile with mic, etc.




Quote:
Originally Posted by tvrgeek View Post
I just finished doing my own TS measurements on the Fostex. Qes came in at .56 and Qms at 7.35. Fs was 72 with VAS at 7.3L. Not as far off as I have seen. Usually it is VAS they lie like a dog about but this is only a couple of percent. The frequency response on the spec sheet, though very small, is closet to what I measure than the model. Of course, it does not show baffle step but the bad breakup at 6800 is there for all to see. I can't see how anyone could consider this driver a full range. A 200 to 2K is more like it. Even that, the harmonic distortion is about 3.5% This means the 11L boxes are tuned at 60 Hz. I think I would try them at 75 Hz. I am going to play with the electronic LR-4 crossover between 3 and 4K to see if it handles the resonance OK. Not as high as I want, but well into the easier range for a dome tweeter. Too low for a ribbon. I can try LR6, but that does force one to stay electronic.

Last edited by ODougbo; 11th July 2012 at 09:08 PM.
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Old 11th July 2012, 11:37 PM   #106
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Quote:
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When you get them done, I 'll come over and measure them.
Have a nice "6 pack" evening.
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Old 12th July 2012, 08:33 AM   #107
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We may be to busy.....I have a dozen set of speakers that need measuring.

I would like to hear the SR71's that TVR has been working on!!
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Old 12th July 2012, 09:07 AM   #108
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Quote:
Originally Posted by ODougbo View Post
We may be to busy.....I have a dozen sets of speakers that need measuring.

I would like to hear the SR71's that TVR has been working on!!
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Old 15th July 2012, 09:56 AM   #109
ODougbo is offline ODougbo  United States
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Exclamation Chuff - Chuff Eliminated!

Well the chuffing is gone now....built new boxes with 1/16" WIDER slots, also rounded over the inter panels (inside) with round-over bit.

Going to tune by ear A/B, comparing with the other boxes;it's tuned right around Fostex specs (57hz) with the untrimmed filler pieces. I need to be carful not to trim them too much; or will be gluing up more.

Will of course use generator also.

btw, let me know if you need any of these prototypes..........




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This is a recipe for chuff-chuff noises and also requires differenced port length calculations. When feeding old British sports cars, the correctly designed "velocity stacks" meant as much ad 10% more power. This is fluid dynamics. The math is way the heck beyond me. I use a sim to get close and tune to measure. I would be concerned with the above picture that you will get wind noises by the relative small opening on the box end compared to the mass of air in the port.
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Old 15th July 2012, 10:40 AM   #110
tvrgeek is offline tvrgeek  United States
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We can easily measure the actual box tuning with just my WT-2. Then compare what you hear to what we measure. Sometimes surprisingly good things come out of that, and occasionally hints when it does not work well.

While I am in between primer coats, I'll work on getting my portable rig set up.
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