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PostPosted: Fri Mar 07, 2014 5:25 pm 
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Cow

Joined: Mon Feb 09, 2009 2:36 am
Posts: 149
Just saw this:

http://www.customanalogue.com/tlcl_speaker.htm

by Joe Rasmussen

Over at the other place:

http://www.diyaudio.com/forums/multi-wa ... eaker.html

I remember T played with current drive for a bit and I tried some current chipamps. Looks like the (missing) crossover is just compensating for the impedance peaks of the loudspeaker system.

I've seen some good debate about the actual benefits of current drive.

What thinks you?
Are there any other drivers (maybe full range) that have a smooth impedance that's good for driving with a current amp?

Thanks,
Jeff

PS

Here's Joe Rasmussen's paper, part 1 (part 2 starts on the Lin Current Speaker page):

The Mystery of the Current Mode Amplifier - Custom Analogue Audio
http://www.customanalogue.com/various/C ... cation.pdf


Here's Nelson's good starter papers:

Current Source Amplifiers and Full Range Drivers
http://www.firstwatt.com/pdf/art_cs_amps.pdf

Current Source Crossovers
http://www.firstwatt.com/pdf/art_cs_xvrs.pdf

from:
http://www.firstwatt.com/articles.html


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PostPosted: Fri Mar 07, 2014 6:54 pm 
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Board jester
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Posts: 2042
Sorry I don't grasp the idea.
Can you explain in very simple terms? Eventually current must flow through the voice-coil of the speaker....

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PostPosted: Tue Mar 11, 2014 6:10 pm 
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Muriel
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Elso,

Elso Kwak wrote:
Sorry I don't grasp the idea.


http://en.wikipedia.org/wiki/Thiele/Small

Ciao T

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PostPosted: Thu Mar 13, 2014 1:28 pm 
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Goat

Joined: Thu Jan 13, 2005 7:11 pm
Posts: 534
Elso Kwak wrote:
Sorry I don't grasp the idea.
Can you explain in very simple terms?


http://www.enjoythemusic.com/magazine/e ... wattf1.htm


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PostPosted: Fri Mar 14, 2014 7:43 pm 
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Cow

Joined: Tue Jan 15, 2008 12:09 am
Posts: 280
Too complicated approach to a no-existent problem - heating of speaker coils.
Sure the coils heat up and resistance increase. But that's a linear process, does not introduce any distortions. It's enough to turn the volume up if that's an issue.
Anyway, for the small levels of power that "first watt" advocates, the heating effect is insignificant.


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PostPosted: Sat Mar 15, 2014 5:44 pm 
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Muriel
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Hi,

SoNic wrote:
Too complicated approach to a no-existent problem - heating of speaker coils.


Hardly non-existent.

http://www.soundonsound.com/sos/jul02/articles/monitors2.asp

SoNic wrote:
Sure the coils heat up and resistance increase. But that's a linear process, does not introduce any distortions. It's enough to turn the volume up if that's an issue.


Only if you are listening to sinewaves. As music (especially anything that is not heavily compressed pop) has a very wide dynamic range only loud passages will cause appreciable heating, compressing them, while the inevitable slow recovery will attenuate anything directly after the peaks... Upping Driver efficiency goes a long way to reduce the issues.

However, current drive deals with other issues I consider more important. Namely one of the main distortion sources in dynamic speakers driven by a low impedance (Eddy Current distortion). Of course there are other ways to deal with this (all the speakers I currently use have this on the midrange), but they have become a little more common only recently and of course again, reducing current by increasing efficiency again works also quite well.

A happy middle ground are above average sensitivity speakers with additional measures taken to reduce eddy current distortion.

Ciao T

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