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Multi-Way Conventional loudspeakers with crossovers

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Old 15th February 2013, 04:26 PM   #21
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Join Date: Mar 2007
Location: California
Quote:
Originally Posted by 454Casull View Post
Need a crossover for a center channel I want to build this summer.

See attached for a pic of the front baffle. Volume is likely to be 1-1.25 ft^3, sealed. Front baffle dimension is 8"x20" WxL.

Drivers are:

Vifa DQ25SC16-04
Fountek FR88EX
2x Silver Flute W17RC38-08

The unit will be below ear level but can be tilted up to have its forward axis meet the ears.

Not looking to spend too much, as you can see from the driver selection. I am OK with steel-core inductors but would prefer poly caps. I expect the crossover points should be somewhere around 2 kHz and 400 Hz. Slopes are up to you.
Isn't the center channel mostly for voice? The bandwidth on that is something roughly like 100Hz - 3000Hz. You could keep it simple and use a single 4" or 5" extended range driver with no crossover. Tang Band makes some reasonably priced full range drivers that would work well. IMO I don't see a need to make a complicated 3-way for the center channel...

-Charlie
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Old 15th February 2013, 05:28 PM   #22
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Location: Toronto, ON, Canada
Quote:
Originally Posted by CharlieLaub View Post
Isn't the center channel mostly for voice? The bandwidth on that is something roughly like 100Hz - 3000Hz. You could keep it simple and use a single 4" or 5" extended range driver with no crossover. Tang Band makes some reasonably priced full range drivers that would work well. IMO I don't see a need to make a complicated 3-way for the center channel...

-Charlie
SPL and off-axis response.
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Old 15th February 2013, 10:50 PM   #23
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Quote:
Originally Posted by Jay1111 View Post
Mid and tweet are from zaph, woofer from manufacturer.
The W17RC38-04 is on Zaph's page. Would it make any sense to use this instead of the -08 version?

Are you able to generate polars (horizontal and vert) with your software?

Thanks
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Old 15th February 2013, 11:37 PM   #24
Jay1111 is offline Jay1111  United States
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If you wanted to use the 04 version I could modify the design for it, it would be more accurate. The sim will be very close as is though.

No I cant generate polars.
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Old 16th February 2013, 04:12 PM   #25
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Originally Posted by Jay1111 View Post
If you wanted to use the 04 version I could modify the design for it, it would be more accurate. The sim will be very close as is though.

No I cant generate polars.
Will it affect the crossover components or the system sensitivity?

Is the tweeter HP at 3700 Hz because the crossover becomes simpler? Or is it because the response is easier to keep smooth?

Sorry for all the questions.
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Old 16th February 2013, 04:41 PM   #26
Jay1111 is offline Jay1111  United States
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Quote:
Originally Posted by 454Casull View Post
Will it affect the crossover components or the system sensitivity?

Is the tweeter HP at 3700 Hz because the crossover becomes simpler? Or is it because the response is easier to keep smooth?

Sorry for all the questions.
Sensitivity might be a challenge, might lead to crossing the woofers over a lot higher.

The mid/tweet crossover was where phase, smooth response, and acceptable impedance all lined up the best. Trying to force a lower xover with a smooth response caused the impedance to drop very low. This is the benefit to having a very small/clean mid with tight CTC spacing, there isnt a negative to crossing this high.
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Old 16th February 2013, 06:26 PM   #27
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I'm sold.

Will be ordering parts in a week or so. Let me know if you come up with any improvements or catch any errors in the parts list.

Which components require tight values? I'd like to replace the 68 uF with a 69 uF.

Last edited by 454Casull; 16th February 2013 at 06:53 PM.
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Old 16th February 2013, 07:00 PM   #28
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How much does DCR matter on the inductors?

Also, L9 0.1 mH is shown as 20 ga on the schematic but 16 ga on the parts list. Which one to use?

Last edited by 454Casull; 16th February 2013 at 07:20 PM.
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Old 16th February 2013, 07:22 PM   #29
Jay1111 is offline Jay1111  United States
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The 69 uf cap wont make a difference. DCR is fairly important, depending on the location. Everything is spec'd for the DCR of 20ga air cores except for the woofer. You could use a lower DCR part for the 3.9mh inductor on the mid without much change. I wouldnt mess with any of the other inductors. Here is the response exactly as spec'd (with the 69uf cap).

An 18ga iron core on the woofer will raise its level another db.
Attached Images
File Type: png center response.png (57.6 KB, 152 views)
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Old 16th February 2013, 09:04 PM   #30
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Can you look over this when you have a chance?
Attached Files
File Type: pdf parts list 2013-02-16 r1.pdf (102.6 KB, 18 views)
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