"Off-axis response" in comps.. what does this mean?
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Bronze Member Username: Tj80Vancouver, BC Canada Post Number: 34 Registered: Aug-05 | I'm planning new components... CDT EFs, CDT HDs or Image Dynamics chameleons... those seem to be the front runners right now. I can't really go with custom locations for the install. They're going to go with the woofer in the door, and the tweeter up in the door, beside the A-pillar. Does this fact influence what types of components I should be looking at? One thing I've heard a few places is references to "off-axis response" when talking about components.. But I can't really find a good explanation of what this means. The name "off-axis" makes me think it might be something to do with imperfect mounting locations. Anyways, just don't want to end up with a system that isn't well suited to the constraints of my vehicle.. |
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Gold Member Username: Jonathan_fGA USA Post Number: 4733 Registered: May-04 | Off axis performance relates to how well a component system will perform in a typical door location (or anywhere off axis, basically when the speaker isn't pointed directly at you). You can generalize off axis performance, fact is that 6.5" mids can't go far past 2-2.5khz and do well off axis. Most you can hope for is between 3-4khz. This is called beaming, or directionality, when the wavelength produced is smaller than the speaker diameter, the dispersion narrows to a "beam". There are also node and lobe distortions that occur within the cone at this point, basically they are chaotic resonances and can sound screechy and harsh. Problem is that low crossover frequencies require a good tweeter to meet with the mid, which cheapie companies aren't going to do. It also puts a crossover point in a critical vocal region, 2khz can be really harsh with a bad crossover. Again, better left to high end manufacturers. To put this in perspective, a good off axis component system will have high order crossovers (3rd or 4th order are the best, or even higher for the very few manufacturers that use them), a low crossover frequency, and well matched drivers. If I were in your situation, constrained to factory spots, I'd get CDT HD Braxials and put those in the doors, and if you want another tweeter up top, get the Upstage kit or Image enhancement kit. |
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Silver Member Username: Mikechec9Http://www.cardomain.c... Post Number: 934 Registered: May-05 | i was just reading up on that kit. wondering how well it really works. |
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Bronze Member Username: Tj80Vancouver, BC Canada Post Number: 35 Registered: Aug-05 | Wonder if the tweeter bracket on the braxials would get in the way of the door panel. It's not a seperate speaker grill, it's part of the door in my car, and since it's a lease.. I just can't be cutting. I'll have to take it apart and do some measuring maybe. Looks interesting though. |
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Gold Member Username: Jonathan_fGA USA Post Number: 4735 Registered: May-04 | "i was just reading up on that kit. wondering how well it really works." Works very well. Competitors have been doing the same thing for years. |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 10188 Registered: Dec-03 | what Jon said. simply put, when a speaker is pointed directly at you, it's on axis. when it isn't aimed right at you, such as when you sit next to a door speaker, or when the speaker is aimed toward the ceiling etc, it's off-axis, and as a result, often it's also out of phase somewhat. |
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Bronze Member Username: Tj80Vancouver, BC Canada Post Number: 36 Registered: Aug-05 | Doesn't look like braxials will fit  That sucks, they look like the best solution. Which puts me back at having the tweeters up high on the door, by the a-pillar. Would I be better off with coaxials? I hadn't planned on going that route, but by the sounds of it, having the tweeters up high like that is not exactly optimal. I guess now I'm leaning towards the CDT EF61CF's since it doesn't look like I can make the braxials work. Any thoughts? |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 10224 Registered: Dec-03 | try the door and A pillar.. see how it sounds with the speakers sitting in those locations. |
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Bronze Member Username: JustababyboyPhilly, PA Post Number: 41 Registered: Jun-05 | What is the difference between the CDT HD-63's and the HD63Z's? |
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Bronze Member Username: Tj80Vancouver, BC Canada Post Number: 39 Registered: Aug-05 | They have a different crossover, which is supposed to reduce some peaks in the midrange response.. or so I gather from the website. http://www.cdtaudio.com/hd_zseries.htm |
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