Frankenstein 3-way crossover points.....help. - diyAudio
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Old 19th February 2013, 07:11 PM   #1
Rob41 is offline Rob41  United States
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Default Frankenstein 3-way crossover points.....help.

I've got a pair of Cerwin Vega PD-3 speakers I bought in the 80's that are mismatched at best at this point.

The original woofers were replaced with Dayton PA-380's and the tweeters were replaced with Dayton PT2C Planar drivers (I still have the original tweeters).

They are using the original crossovers and I now realize how screwed up this is with sensitivity issues between drivers and the fact that I'm still using the stock XO's.

I think I'm learning now but I'm still a noob. I have just ordered a miniDSP 4x10 HD and the UMIK-1 mic, installed the latest version of REW and installed the plug-in software for the 4x10. This will be my first active crossover and first time using any kind of audio software. I will be tri-amping this set-up.

What I'm looking to do to start off is come up with a rough-in for the crossover points that will at least get me in the ballpark.

Here are the drivers:

Woofer: Dayton PA-380...8 ohms...98.5db@1w1m (15")
I'm thinking to cross @ between 1500Hz and 2k?
http://www.parts-express.com/pdf/295-034s.pdf

Mid-horn: Selenium D250X 1" ...8 ohms..107db@1w1m (I don't have yet but figure it must be better than the cheap stock horn that I have no specs for)
I'm thinking to cross @5k?
http://www.parts-express.com/pdf/264-202.pdf

Tweeter: Dayton PT2C...8 ohms...94db@1w1m
http://www.parts-express.com/pdf/275-085s.pdf

I'm using the D250X because it's what I can afford after what I spent on the miniDSP gear. I know the drivers are very mismatched but it's what I have for now and would just like them to sound as good together as they can. Please let me know if my proposed crossover points are all wrong. This is my first time doing any of this so any suggestions are appreciated.
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Old 19th February 2013, 08:15 PM   #2
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The 15" has a terrible 10 dB peak at 2K that will need PEQ to reduce, especially if you cross high, a 15" is beaming (less than 90 degree response) above about 800 Hz.

Without knowing what the response of your mid horn/driver is (which you can measure) you are shooting in the dark.
You need to at least say what mid horn you are using to start guessing at crossover points.

Last edited by weltersys; 19th February 2013 at 08:20 PM.
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Old 19th February 2013, 09:04 PM   #3
Rob41 is offline Rob41  United States
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Here is the horn I'm planning on using:
http://www.parts-express.com/pdf/264-315.pdf

Until I looked at the manufacturers specs on the horn I didn't realize the effect it had on the curves. I see what you mean about the peak at 2K.
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Last edited by Rob41; 19th February 2013 at 09:07 PM.
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Old 19th February 2013, 09:44 PM   #4
Rob41 is offline Rob41  United States
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Now taking into consideration the 15" driver beaming above about 800Hz and the horn frequencies I'm thinking 800Hz and 4500Hz might be a better place to start.
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Old 19th February 2013, 10:12 PM   #5
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Quote:
Originally Posted by Rob41 View Post
Here is the horn I'm planning on using:
http://www.parts-express.com/pdf/264-315.pdf

Until I looked at the manufacturers specs on the horn I didn't realize the effect it had on the curves. I see what you mean about the peak at 2K.
That horn has very narrow dispersion up high and won't match the dispersion of the tweeter you chose.

It's dispersion widens to 90 degree at 1K because of diffraction.

Last edited by weltersys; 19th February 2013 at 10:15 PM.
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Old 19th February 2013, 10:24 PM   #6
Rob41 is offline Rob41  United States
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Quote:
Originally Posted by weltersys View Post
That horn has very narrow dispersion up high and won't match the dispersion of the tweeter you chose.

It's dispersion widens to 90 degree at 1K because of diffraction.
Can you recommend a different style horn that would work better? I'd prefer to go through Parts Express and don't have a lot to spend on the horns.
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Old 19th February 2013, 11:30 PM   #7
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Originally Posted by Rob41 View Post
Can you recommend a different style horn that would work better? I'd prefer to go through Parts Express and don't have a lot to spend on the horns.
I don't see anything at PE that looks very promising, and without seeing polars of the tweeter hard to say what would match up in dispersion at around 4-5K.

The tweeter is only 94 dB sensitivity, why not go with a mid cone?
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Old 19th February 2013, 11:41 PM   #8
Rob41 is offline Rob41  United States
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Quote:
Originally Posted by weltersys View Post
I don't see anything at PE that looks very promising, and without seeing polars of the tweeter hard to say what would match up in dispersion at around 4-5K.

The tweeter is only 94 dB sensitivity, why not go with a mid cone?
That may be the best idea. I was originally thinking I could get a warmer, more natural sound that way. I was only leaning towards a horn because that's what was originally installed.
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