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Current drive for Loudspeakers
Current drive for Loudspeakers
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Old 30th January 2015, 09:08 PM   #401
PMA is offline PMA  Europe
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Thank you, do you mean something like this?
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Old 30th January 2015, 09:23 PM   #402
kgrlee is offline kgrlee
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Quote:
Originally Posted by PMA View Post
Pavel, this is excellent work.

My own investigations in the 1980's & early 90's show similar results but I'd expect improvement even above 100Hz on most speakers

Last edited by kgrlee; 30th January 2015 at 09:37 PM.
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Old 31st January 2015, 08:04 AM   #403
PMA is offline PMA  Europe
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Quote:
Originally Posted by kgrlee View Post
Pavel, this is excellent work.

My own investigations in the 1980's & early 90's show similar results but I'd expect improvement even above 100Hz on most speakers
Thank you Richard, I believe that measurement with a driver without passive crossover (3-way box) would show improvement even above 100Hz, I am planning to make more measurements.
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Old 31st January 2015, 08:51 AM   #404
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Thank you Richard, I believe that measurement with a driver without passive crossover (3-way box) would show improvement even above 100Hz, I am planning to make more measurements.
My experiments were with a single drive unit in sealed box.

For ported boxes, other techniques are better for distortion reduction[*]. I've tried Erik Stahl's ACE with good results. This method is also good for sealed boxes. It's much more complicated

AES E-Library Synthesis of Loudspeaker Mechanical Parameters by Electrical Means: A new Method for Controlling Low-Frequency Loudspeaker Behaviour

[*]Current Drive is poor for ported boxes on several fronts. In particular, the frequency response becomes seriously wonky.
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Old 31st January 2015, 09:05 AM   #405
PMA is offline PMA  Europe
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Very good info, thank you!
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Old 31st January 2015, 01:31 PM   #406
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Here are the results I got with midwoofers: http://www.diyaudio.com/forums/vendo...ml#post3026510
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Last edited by pos; 31st January 2015 at 01:38 PM.
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Old 31st January 2015, 02:13 PM   #407
Soldermizer is offline Soldermizer  United States
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A moment of doubt...

I have been following this thread with interest. But now some doubts! Of course it is easy to be skeptical (I excel at it!) but here goes:

If current drive (or related ideas like negative impedance) is such a good idea, why has it not been experimented with and developed more fully?

The simplest answer I know is that it would complicate the design of a specific amplifer/speaker combination. Apparently each system must be tuned uniquely.

Does this type of feedback actually reduce distortion or improve the sound in an audible, or at least measurable way?

"Yes", according to some of the data posted here and other places. On the other hand, there are people who say it makes no difference and may even sound worse.

Despite all these doubts, I say "experiment as much as you like!" and I am slightly jealous that I don't have the equipment or the skills to join you.

P.S. My criticism notwithstanding, I have just ordered Merilšinen's book
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Old 31st January 2015, 02:16 PM   #408
vacuphile is offline vacuphile  Netherlands
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Current drive for Loudspeakers
As I showed in my #380, it also can improve distortion in tweeters. Enough so to warrant placing a resistor in front of a tweeter even in active speakers.
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Old 31st January 2015, 02:33 PM   #409
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Yes, it improves tweeter distortion as well. I will prepare further set of measurements.
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Old 31st January 2015, 03:11 PM   #410
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In France, my own findings (*), comparing voltage and current drive (inserting a resistor of a few tens of Ohm) at different frequencies with equal voltages across the voice coil to maintain identical SPL output, have shown a great disparity in the results. In no way, demonstrate systematic distortion reduction using current drive and often quite the contrary.

(*) Commande en courant des haut-parleurs
there are other investigations made by some fellows in the following posts, their conclusions do not differ from mine.


Speaker Dave shared his experience of current drive in some DiyAudio posts,
non exhaustively :

http://www.diyaudio.com/forums/multi...ml#post2430629

http://www.diyaudio.com/forums/multi...ml#post2432756

http://www.diyaudio.com/forums/multi...ml#post2465501

So if you intend to go current drive, you have to first check if the loudspeaker you're going to use will really benefit from it.
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