# Bateman's Building HLCDs again



## Patrick Bateman (Sep 11, 2006)

If anyone's curious, I'm building some new HLCDs for my Mazda6. I posted the thread over on diyaudio, as Dr Geddes and Dr Smith don't post here. If you're interested in following along, the data is in the threads "28 Days Later" and "Cloning a $3200 Speaker for $400"


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## edouble101 (Dec 9, 2010)

Post it here


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## Justin Zazzi (May 28, 2012)

I am interested in following along.
Can you please post a link to the thread?

Thanks!


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## Patrick Bateman (Sep 11, 2006)

here: 28 Days Later - diyAudio

And also some bits and pieces here:

Cloning a $3200 Speaker for $400 - Page 5 - diyAudio


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## [email protected] (Nov 7, 2010)

Quick question... you said "it has a copper cap on the pole piece for reducing distortion", isn't the cap to reduce induction? (and a byproduct maybe reduced distortion?) Just curious, I am no speaker engineer, but I do like to know how stuff works..


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## Patrick Bateman (Sep 11, 2006)

[email protected] said:


> Quick question... you said "it has a copper cap on the pole piece for reducing distortion", isn't the cap to reduce induction? (and a byproduct maybe reduced distortion?) Just curious, I am no speaker engineer, but I do like to know how stuff works..


Google "the effect of Faraday ring" and you'll find a 37pg article that describes how they reduce inductance and distortion.


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## [email protected] (Nov 7, 2010)

So, cliffnotes, it reduces both? 

Does it reduce distortion through reduced inductance?


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## req (Aug 4, 2007)

i am fairly certain that is exactly how it works j0ey


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## [email protected] (Nov 7, 2010)

Then, does it seem funny to think that speakers are built with built in distortion (a big inductor to move it)? lol..


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## Patrick Bateman (Sep 11, 2006)

[email protected] said:


> Then, does it seem funny to think that speakers are built with built in distortion (a big inductor to move it)? lol..


And that's the reason that speakers with high power handling and big voice coils aren't always the best choices. If you *need* to dump 500 watts into a driver, then you might need a 4" voice coil.

But if you don't, there are a lot of good reasons to opt for a smaller/cheaper voice coil.

Speaking of cheap, check out the diyaudio thread - I have the Beolab lenses working today. Sounds great.


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## Patrick Bateman (Sep 11, 2006)

Sausalito audio works lens (diy) - YouTube

Here's a video of the Lens playing 'Christian Sands' by Tricky.
After making the vid I realized it's a bit of a silly choice for a demo video, because the singers voice is completely distorted in the mix 
I should probably get me some audiophile approved recordings one of these days. (I mostly listen to electronic music, movies, and podcasts. Not a lot of audiophile recordings here.)


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## hurrication (Dec 19, 2011)

[email protected] said:


> So, cliffnotes, it reduces both?
> 
> Does it reduce distortion through reduced inductance?


The change in inductance over stroke contributes to distortion, so controlling the inductance as the coil moves will reduce distortion. IMO, this is more important than having a low Le at rest. Pole caps reduce inductance on the outward stroke but there will still be inductance on the inward stroke. Magnet Id and pole sleeves do a great job of controlling the inward inductance and yielding a flatter Le curve.

Image c/o Sundown Audio:


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