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What I'd like to see out of Adire... (1 Viewer)

David Giesbrecht

Second Unit
Joined
May 28, 2001
Messages
306
Hey I just got an idea for that super tweeter with the 2mm Xmax. First it needs to be a lttle smaller than your typical 25mm dome, more like 20mm or less for better off axis performance. and then we need to design it into a coaxil driver like the HE's to eliminate comb filtering effects and time alignment issues. The woofer its put into needs to have a good Xmax and ts parameters similar to the Hi-Vi M8a so it will extend deep enough to have an F3 of 60 hz in a sealed box. And for the last step, combine it with an Xo point of 1khz so the tweeter will handle most of the mids. There are tweeters out there that you could crossover @ 1khz like the Vifa XT or the Focal TC120 TD5 but they lack the Xmax required for good performance without distortion.
 

Dennis XYZ

Stunt Coordinator
Joined
Jun 1, 2002
Messages
115
Guys, big Xmax (actual excursion, not rated) in a midrange driver is a Bad Thing (Martha :) ). Having a driver capable of big Xmax is a Good Thing. Using that Xmax is a Bad Thing.

IM (Doppler) distortion % = .91 * (Xmax in mm) * (highest frequency in kilohertz)
Source: JohnK on the Madisound board.

Using that math, let's say you want to keep your IM distortion under 1%:
Tweeter plays to 20K, Xmax = .05 mm
Mid plays to 2K, Xmax = .5 mm
 

RichardHOS

Second Unit
Joined
Mar 11, 2003
Messages
454
And what's the lowest useable frequecy a tweeter can play at 90dB with an Xmax of .05mm? And what's going to pick up the slack... a second tweeter? And then an upper mid, and a mid mid, and a lower mid...? Hey, I'm all for complicated designs, but I'd like the option to use 6dB/oct slopes with tweeters as well. ;)
 

David Giesbrecht

Second Unit
Joined
May 28, 2001
Messages
306
First off what is dopple distortion and why will it increase if the tweeter uses a little more Xmax? Higher Xmax in subs and midwoofers has never been a problem why would it be a problem in tweeters? There dynamic loud speakers to, what makes them different?
 

Dennis XYZ

Stunt Coordinator
Joined
Jun 1, 2002
Messages
115
Hey, I'm all for complicated designs, but I'd like the option to use 6dB/oct slopes with tweeters as well.
Your choice. First order designs almost always have higher levels of distortion and/or lower SPL capability than those using steeper slopes. About the only way around it with first orders is to use lots of drivers and lots of crossovers, like a Dunlavy -- not exactly a "simple" system.
 

Bill Fagal

Stunt Coordinator
Joined
Jul 8, 2002
Messages
166
Wow, I sure don't like to rain on parades, but I gotta back up Dennis here--he's absolutely right. There's no way around significant doppler distortion if you ask a flat-mounted small-dome tweet to also sing alto.

First off what is dopple distortion and why will it increase if the tweeter uses a little more Xmax? Higher Xmax in subs and midwoofers has never been a problem why would it be a problem in tweeters?
Doppler distortion is what you hear when an emergency vehicle, sirens blaring, whizzes past you--the pitch of the siren seems to drop down a few notes as it passes. Likewise, if a tweeter dome is cycling through large midrange excursions while simultaneously whistling a high note, that note will sound warbly--higher as the dome swings forward, and lower as the dome swings back--modulated by the lower frequency. Above a certain modulation frequency, your ear may not be able to pick out the warble, but it will still tell you somethings wrong--distortion.

But there is hope if you think outside the box. A properly designed horn-loaded diaphragm has to swing much less excursion for a given freq./SPL, thereby sidestepping doppler distortion. So I would suggest thinking in that direction. Hey, I bet you could still stir XBL^2 into the mix! :)

Bill
 

RichardHOS

Second Unit
Joined
Mar 11, 2003
Messages
454
Your choice. First order designs almost always have higher levels of distortion and/or lower SPL capability than those using steeper slopes. About the only way around it with first orders is to use lots of drivers and lots of crossovers, like a Dunlavy -- not exactly a "simple" system.
I probably wasn't clear with my wording. I didn't intend to imply that 6dB/oct systems were in any way "simple." And of course the doppler distortion is greater in general with (a) a simpler system (2-way vs. 3/4+ way) and (b) lower order XO designs. You pointed out that 6dB/oct systems are typically SPL limited... and you're right. That's why I said it would be nice to have the option of higher Xmax drivers, thus making possible 6dB/oct systems capable of higher SPL without a 12-way design. :) It's always a trade-off... doppler for 6dB/oct in this case. Still nice to have more options. ;)
 

Chris Tsutsui

Screenwriter
Joined
Feb 1, 2002
Messages
1,865
What about ribbon tweeters such as the excellent sounding Raven line. The Raven R3 extends to 500hz, and can be crossed over directly with a good woofer.

There has got to be ways around dopper distortion by increasing surface area or using a multiple diaphragm tweeter of some sort. This reminds me of line arrays, doh..

Jeeze, Design sure is about tradeoffs come to think of it.
 

David Giesbrecht

Second Unit
Joined
May 28, 2001
Messages
306
I guess you just have to decide what you think is better and go with it, with today's technology there is no perfect speaker design there is alway's going to be tradeoffs. Personally I really like the idea of a 2 way coaxil design and if possible use active Xovers.
 

David Giesbrecht

Second Unit
Joined
May 28, 2001
Messages
306
I just thought of this.

How does a full range driver designed to produce frequency ranges from 100hz-15khz get away from doppler distortion? They must have extremly high distortion ratings all things considered.
 

RichardHOS

Second Unit
Joined
Mar 11, 2003
Messages
454
I don't think there is any way around it. Doppler distortion (and other forms of IM) are a fact of life for full range systems and these 2-way mini-monitors that seem to be so popular now. Some definite benifits... some definite trade-offs.
 

Bill Fagal

Stunt Coordinator
Joined
Jul 8, 2002
Messages
166
How does a full range driver designed to produce frequency ranges from 100hz-15khz get away from doppler distortion? They must have extremly high distortion ratings all things considered.
Yup. I like full-rangers a lot for certain things, but they do suffer from doppler distortion. That's probably why they do simple music really well (human voice, for example), but usually slip and fall on complex orchestral music, at least in my experience.

And hey guys, why the sadness at the limitations of dome tweets? Even though you may have heard some cheap ones that sounded really rotten, there's nothing at all wrong with a good treble horn. You can have dynamics, controlled directivity, extension, and low distortion served up with high-sensitivity gravy.
 

David Giesbrecht

Second Unit
Joined
May 28, 2001
Messages
306
What I don't like about the horn tweets is the fact they generally have to be large and that makes using them in a coaxial application impossible unless your woofer has a huge pole peice that can hold a large horn tweeter.
 

Shawn Solar

Supporting Actor
Joined
May 12, 2001
Messages
763
Can't adires XBL^2 technology be applied to exsisting mids and tweets to improve distortion among other things. All things considered what would be the difference between two tweeters with the same specs but one having XBL^2 applied? would it play louder with less distortion.
 

Bob Reimer

Agent
Joined
Sep 17, 2000
Messages
33
According to Dan XBL^2 technology can be applied to all types of drivers EXCEPT planars. Right now I am aware of a large number of projects underway but you know the drill: If I told you I'd have to......

Stay tuned!

Bob
 

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