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Old 1st May 2009, 12:14 PM   #1
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Default Speaker impedance linearisation

Just bringing this subject up to this forum department from "Solid State" about how to work a 3-way passive speaker impedance linearisation for all type of amps(+/-). Thanks.
3-way passive speaker impedance linearisation
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Old 2nd May 2009, 06:06 PM   #2
pointy is offline pointy  United Kingdom
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i don't do X overs but to me

the mid range would have a 32uf for the 40uf
and the 900mH on the bass would be more like 600mH

as i said i don't do X overs i also don't know your speaker drivers
and i used this

<http://books.google.co.uk/books?id=1...esult#PPA80,M1>

sorry i can't help
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Old 3rd May 2009, 02:42 PM   #3
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Thanks pointy,
I have another xover design just like what you said, that looks very good on paper.
My question comes more, about, in line with what Joe Rasmussen (Diy) is saying here
Quote:
As can be seen, the impedance stays well within the 12-6 Ohm envelope. The lowest phase angle is -10 degrees just above 2Khz where Z is 8 Ohm. As stated before, it's when a low phase angle coincides with low Z at the same frequency, this is where amplifier demands become unacceptable. What we have here is a benign load and good system efficiency and sensitivity above 90dB.
http://www.diyaudio.com/forums/showt...13#post1144413

and here by John Kreskovsky (Diy john k...)
http://www.diyaudio.com/forums/showt...20#post1584420

and here by JR
Quote:
This is the rule I follow: It is where the two coincide, low Z (say four and lower) and significant neg phase angle (say well above -30) at the same frequency, this must be avoided (but conjugates are still an important tool). But coming back to the example where I used series 5" mids, it helps when they are a high 16 Ohm Z and you have that XT25 tweeter, that series element helped overcoming the XT25 by avoiding that coincidence. When phase was bad the combined Z was still above 8R. I could have use a conjugate but ended up with 4R? The improvement in the phase was offset, so no real gain. In other instances your suggestion would have to be considered.
http://www.diyaudio.com/forums/showt...46#post1585346

...and so on from john k...
Quote:
Consider Z out = 0.1 ohm and 3 ohms (you mentioned 3 ohms). with 0.1 = Zout, the speaker will perform basically the same with and w/o a conjugate network. But when Zout= 3 the speaker w/o the conjugate network would show a rise in the response centered around 3k of about 1.3 dB with Q = about 0.5 (relative to the midrange level).
Quote:
I'm not trying to be critical here, but I think you might look at that conjugate network. I realize it will draw more current from the amp, but assuming the amp can handle it I think it would make the speaker more "tube friendly".
Notes:
a) The use of 9mH inductors by JR here http://www.diyaudio.com/forums/showt...24#post1446624

b) There's nothing to do with the posts on The "Elsinore Project" Thread, just the motivation of learning how amps work.

c) This one I'm going to read next: Examination of crossover induced transient distortion.
http://www.musicanddesign.com/Speake..._Analysis.html

"Funny" by JR
Quote:
The amps we typically use are typically 30 Watts or less and the current amps we make/sell to clients are 18 Watt (Vacuum State DPA-300B @ $16,000 built and $10,000 kit).
(Let's go party...)
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Old 4th May 2009, 01:11 AM   #4
pointy is offline pointy  United Kingdom
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way out of my league i'm still looking for some output transformers for about 50 2nd hand
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Old 8th May 2009, 02:46 AM   #5
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Default on Kef crossovers (Kef 107)

Just to add some insightful information from a KEF insider on the impedance compensation (conjugates).

By AndrewJ, diyaudio.com
http://www.diyaudio.com/forums/showt...35#post1766135
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