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ErinsAudioCorner

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hardisj

hardisj

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Grey text on a black field is unreadable. Please change.

I appreciate the feedback.

You're the second person to comment that so I made the change to white.

I'm still trying to determine if this is the theme I want. I like it for some things but do miss the layout of my old site in other regards.
 

briskly

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KEF's plug is in front of a normal dome driver in a coaxial system
The existence of a plug that blocks a significant portion of the exit makes the KEF HF unit a compression driver by default, though with a low compression ratio (I believe it is roughly 2). This gives a slight increase in high-frequency efficiency.
 

HammerSandwich

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How about a chart that uses thin lines except for thicker ones on the 30/60/90 curves?
 
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hardisj

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How about a chart that uses thin lines except for thicker ones on the 30/60/90 curves?

I think I know what you mean... just differentiate those lines? I could. But if I were going to differentiate them I'd probably do it the other way around and make the 0/30/60/90 curves the thicker ones and the thinner ones would be for the incremental steps between them. I'll chew on it, though.
 

Juhazi

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The existence of a plug that blocks a significant portion of the exit makes the KEF HF unit a compression driver by default, though with a low compression ratio (I believe it is roughly 2). This gives a slight increase in high-frequency efficiency.

I dont' classify that KEF as a compression driver. The devil is in details, to get attenuation/compression to match and control tweeter's radiation to get smooth dispersion throughout the passband

https://www.shop.us.kef.com/pub/media/wysiwyg/documents/ls50/ls50_white_paper.pdf
http://www.kef.com/uploads/files/THE_REFERENCE/REF_White_Paper_preview_path_200514.pdf

REFERENCE-TWEETER.png


Phase shields in alu dome tweeters are for the same purpose, eg.
http://www.seas.no/index.php?option...afcg&catid=25:seas-vintage-drivers&Itemid=366 (phase shield is not mentioned, but I have used the tweeter and there is a piece of plastic tape glued on the backside of the grille) or https://www.madisoundspeakerstore.c...b26adc-c000-4-aluminum-dome-tweeter/?mobile=0

sb26adc-c000-4.jpg
 

briskly

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Phase shields in alu dome tweeters are for the same purpose, eg.
They are related in only a loose sense: their function is to correct for undesirable wave propagation.
The shield is a means to address path length differences from the physically displaced dome tip to the edge. These should serve as a means to correct axial response. As typical of piston-like drivers, the far-field directivity roughly follows the Fraunhofer diffraction of a circular slot.

The key function of phase plugs is to generate the appropriate wavefront at the exit aperture. These are ordinarily approximations to the plane wave, but conical waveguides require a spherical wavefront for one-parameter wave propagation. Stated another way, the spherical wavefront is of the necessary shape to not excite the higher-order modes of the conical horn beside the zeroth mode. The spherical cap is fine as an emitter shape here, but as the white paper mentions, the axial motions of a conventional tweeter are not well suited to emitting a spherical wavefront. Here the function of the phase plug is to reorient the volume velocity generated from the tweeter's motion.
 
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hardisj

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I gotta say, I definitely did not see this thread going all the ways it has so far. :D
 

617

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I appreciate that! Glad you found the information useful. Just out of curiosity, how did you find my old site? Were you a forum member on diya, TT, diyma? I used to post the links there. Just curious if I know you from another forum.

Good question. Probably techtalk? It was a long time ago. I seem to remember you had a great little article showing how no bandpass transducer could reproduce a square wave? I was never on diyma and diyaudio was and is too crazy and big for me.

Back in those days there weren't a lot of people testing drivers besides Zaph of course. Maybe there were people testing subwoofers but that wasn't my interest. You'd get snippets for Linkwitz and a few others but as you know distortion testing is hard to do right.
 
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hardisj

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Made a little more progress. Site has been updated to include the Kef LS50 drive unit testing.

https://erinsaudiocorner.com/

I still have at least 20 more old tests to pull over. I tested over 100 drivers in the span of about 5 years but not all of the data is recoverable. But I'll get all I can on the new site.
 

Wafflesocks

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Hi Erin, I remember mulling over your site, and all the hard work you had done. Welcome back. Are you on the midwest audio club forum? A lot of the techtalk people spend time on there.
 

Hemi-Demon

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hardisj

hardisj

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Hi Erin, I remember mulling over your site, and all the hard work you had done. Welcome back. Are you on the midwest audio club forum? A lot of the techtalk people spend time on there.

I am not. Actually, I don't know if I've ever heard of it. I have heard of the MWAF but didn't know there was a club for it. If you think the group would be interested in what I'm doing and they'd be cool with me joining, feel free to shoot me a link via PM and I'll sign up. :)
 

Biblob

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hardisj

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Could you explain what the main differences are between home hifi and car audio?

As far as goals, hi-fi in the home and hi-fi in the car are the same: to achieve a quality reference playback system.

The problem with the car, however, is it is a terrible environment. Highly reflective, not much room for positioning of speakers in order to eliminate modal issues, assymetrical speaker layout wrt main listening position (MLP). A specific example is inter-aural cross-cancellation. Home audio setups have the luxury of putting the listener in the center of a mostly symmetrical environment and speaker setup. In a car you sit to one side of the speaker setup. Therefore, the apparent source width is skewed between the sides and the HRTF is nowhere near the same (in a car with a driver on the left, the angle from the MLP to the left side speakers is usually no more than 20 degrees and the width on the right is typically > 45 degrees).

It's funny, though, that thanks to car audio I have a pretty high understanding about sound science and DSP configurations because in order to get great sound in a car you have to understand various facets of sound reproduction. Unfortunately, there's not much documented in this realm other than a couple white papers (one from Volvo/Dyn and one from JBL) and some things aren't as easily transferred from the home environment to the car environment.

I could go on and on. I've been messing with hi-fi car audio for a very long time now and I have to say that it is easily the most challenging environment but thanks to that it has taught me to learn about acoustics and made me a better person for it. Heck, Geddes wrote the whitepaper stressing the importance of spatial averaging when he worked for Ford Automotive. :)
 

Biblob

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As far as goals, hi-fi in the home and hi-fi in the car are the same: to achieve a quality reference playback system.

The problem with the car, however, is it is a terrible environment. Highly reflective, not much room for positioning of speakers in order to eliminate modal issues, assymetrical speaker layout wrt main listening position (MLP). A specific example is inter-aural cross-cancellation. Home audio setups have the luxury of putting the listener in the center of a mostly symmetrical environment and speaker setup. In a car you sit to one side of the speaker setup. Therefore, the apparent source width is skewed between the sides and the HRTF is nowhere near the same (in a car with a driver on the left, the angle from the MLP to the left side speakers is usually no more than 20 degrees and the width on the right is typically > 45 degrees).

It's funny, though, that thanks to car audio I have a pretty high understanding about sound science and DSP configurations because in order to get great sound in a car you have to understand various facets of sound reproduction. Unfortunately, there's not much documented in this realm other than a couple white papers (one from Volvo/Dyn and one from JBL) and some things aren't as easily transferred from the home environment to the car environment.

I could go on and on. I've been messing with hi-fi car audio for a very long time now and I have to say that it is easily the most challenging environment but thanks to that it has taught me to learn about acoustics and made me a better person for it. Heck, Geddes wrote the whitepaper stressing the importance of spatial averaging when he worked for Ford Automotive. :)
Yes, the listening environment is completely different ofcourse. And because of that the design goals are harder to achieve and/or design elements become more critical.
I was wondering, are car-audio generally speaking usable for home hifi? I assume it is, but wonder what compromises comes with using them.
 
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hardisj

hardisj

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Gotcha. Yea, there's no reason why you can't use car audio drive units in a home. Home audio drive units like Scanspeak, Tang Band, Vifa, etc are commonly used in car audio. In fact, I'm using scanspeak beryllium tweeters in my car right now.

If you are interested, here's a short video one of my friends made of me at car audio finals this year in Louisville, KY. He did about 10 other videos highlighting people's systems if you want to look at his other vids.

 

Biblob

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Gotcha. Yea, there's no reason why you can't use car audio drive units in a home. Home audio drive units like Scanspeak, Tang Band, Vifa, etc are commonly used in car audio. In fact, I'm using scanspeak beryllium tweeters in my car right now.

If you are interested, here's a short video one of my friends made of me at car audio finals this year in Louisville, KY. He did about 10 other videos highlighting people's systems if you want to look at his other vids.

Awesome, just as I thought. Do you use the Scan-Speak 10F/4424G00 for midrange? I saw some Frog Audio drivers tested on your old site, they seemed very lineair!

Do you know some reccomendations on drivers from the top of your head? :)
 
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