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Old 9th October 2009, 04:06 PM   #1
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Default Ribbon tweeters and cabinet placement

I'm building a pair of 2-ways with Fountek NeoCD2.0 tweeters and am not sure if I should place them centered or off center on the baffle board. Baffle board is 10.5 inches wide. Cabinet is 11.5 inches wide.
Concerned about minimizing diffraction issues.

Advice?
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Old 9th October 2009, 10:28 PM   #2
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There are good arguments fore mounting off centre
But seem there are some issues as well
Look at what usually happens
Speaker listening setup is usually with the narrow part of front baffle towards the middle/listener
And why is that
One would ideally expect it the other way round, to have better phase allignment to midwoofer, having tweeter further away
Well, I suppose its probably due to the narrow side of baffle having less reflection issues
Off center placement could seem like a winn and loose game

I would rather think of a way to move the tweeter backwards to get better phase allignment with midwoofer

A shallow waveguide seems like the perfect solution to all of it
Or maybe mount it in its own curved baffle, placed on top of woofer box
Or a combination of both

Last edited by tinitus; 9th October 2009 at 10:32 PM.
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Old 10th October 2009, 12:15 AM   #3
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I tend to mount tweeters off centre (if i mount them on a baffle).

Edge can be used to simulate diffraction.

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Old 10th October 2009, 01:45 AM   #4
tinitus is offline tinitus  Europe
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Another option is cutting away edges
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Old 10th October 2009, 03:05 AM   #5
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I had read that ribbon tweeter's project sound differently than dome tweeters and that they are less prone to causing diffraction problems. Hence the reason for my original post.

True or false?
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Old 10th October 2009, 03:22 AM   #6
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Of axis response is different from the dome tweeters. Neo 2 for example has a good horizontal dispersion but vertical of axis is horrendous. As a wide generalization, they are more directional which can be beneficial or a hazard to the outcome.
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Old 10th October 2009, 02:53 PM   #7
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Quote:
Originally Posted by R-Carpenter View Post
Of axis response is different from the dome tweeters. Neo 2 for example has a good horizontal dispersion but vertical of axis is horrendous. As a wide generalization, they are more directional which can be beneficial or a hazard to the outcome.

Yeah, I was aware of that. However, I thought the wide horiz. dispersion characteristics of ribbons would be considered less directional?

But it still doesn't answer the question regarding diffraction issues from domes vs ribbons and whether or not to offset the ribbons on the BB's.....
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Old 10th October 2009, 03:07 PM   #8
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Quote:
Originally Posted by speakerdoctor View Post

But it still doesn't answer the question regarding diffraction issues from domes vs ribbons and whether or not to offset the ribbons on the BB's.....
Answers are there, and how to do it, but maybe we just dont agree

If you study it you will see that most try to avoid wide baffles around tweeters
Waveguides, curved baffle, cut aways are just a practical way of dealing with a wide flat baffle
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Old 10th October 2009, 03:27 PM   #9
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My guess is that you can treat ribbons with similar of axis response to the domes similarly. Long ribbons like Neo 2.0 do not need side offsetting and before you even get to diffraction there are other issues that are critical for ribbons and their crossover points, distortions and lobbing at the crossover F.

I don't think you going to find your answer here without doing sample baffles and a multitude of measurements.

The other thing you could do is upholster front baffle in decorative fabric. Ultrasuede looks good.

Last edited by R-Carpenter; 10th October 2009 at 03:35 PM.
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Old 11th October 2009, 06:18 PM   #10
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Thanks folks for your responses. The baffles are already built. I've given the dimemsions previously. In fact, the cabinets exist. I'm just modding them to accept the ribbons.

With regard to the xover, I realize I'm faced with a challenge. I'm planning on a 3rd order at 2Khz for the ribbon and 1st order for the woofer (HiVi F8).
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