The Alexia's are HERE!

[steve williams]

Even worse Micro is the phase angle on the Alexia.
HifiNews measured impedance at 1.8ohms at 80Hz, that is tough but then considering phase angles the EPDR gives a practical figure of 0.9ohms at 65Hz.

Cheers
Orb

Orb

I plead dumb. Can you explain this

 

[microstrip]

Orb

I plead dumb. Can you explain this

Steve,
We have an excellent 2007 article by Keith Howard explaining the EPDR in Stereophile. It is available online :
http://www.stereophile.com/content/heavy-load-how-loudspeakers-torture-amplifiers

 

[Orb]

Thanks Micro.
EPDR is equivalent peak dissipation resistance.
At its simplest when you look at the measurement on Stereophile for impedance against frequency, you will also notice they show the line relating to the phase angle and this can affect the load-demand from amplifiers the further this moves away from 0 to 45.
Look at Fig 1 for the XLF:http://www.stereophile.com/content/wilson-audio-specialties-alexandria-xlf-loudspeaker-measurements
So in theory the worst demand for an amp would be a combination (the two lines at same frequency) of the lowest impedance (solid line) and also phase angle (dashed line) closest to 45; so 900Hz possibly the most demanding point for the XLF but this is still pretty reasonable.
The maths for it can be found-described as seen from Keith Howard article, and also Soundwest (I think).

Cheers
Orb

 

[Bruce B]

Thanks Micro and Orb.... I'll have to do some reading now.

 

[DonH50]

So, is EPDR simply calculating the power based upon the speaker's impedance (magnitude) vs. frequency?

 

[andromedaaudio]

Congrats bruce , nice loudspeaker .
I was supposed to hear them last weekend , but other things got in the way.

 

[LL21]

Tonight is my first "official" attended mastering session with the new Alexia's. I know they are not fully tweaked in, but I think I have a handle on what they are doing.

Congrats, Bruce. I have heard remarkably good things about this speaker. My local dealer is pining away for a pair for himself personally, and that says something to me. I have known him for 10 years and he rarely picks a favorite.

 

[Orb]

So, is EPDR simply calculating the power based upon the speaker's impedance (magnitude) vs. frequency?

Yes, taking both phase angle (which increases the load demand for amplifier dissipation due to its power factor) and impedance in consideration; so it considers the worst case load in the interraction between amp and speaker vs frequency.
Elliott Sounds describes it very well, just did a search for it as it is a good read:
http://sound.westhost.com/patd.htm

Regarding the 45degree number just notice he says:

The 'magic' figure of 45° is worst case with typical systems, where the transistors must dissipate double the normal peak power, while the load only receives half the power it would normally get. Note that the amplifier peak dissipation appears to fall after 45 degrees - this is only because of the increased impedance presented because of the reactance. While these figures are reasonably accurate, it must be understood that the situation varies depending on output power and supply voltage - there are a great many variables, and it is not practical to try to cover them all.

Cheers
Orb

 

[microstrip]

So, is EPDR simply calculating the power based upon the speaker's impedance (magnitude) vs. frequency?

Yes, it is why the phase measurement also becomes important. Some magazines, such as french Son et Image present this type of data in their reviews. See the "consumption curve" of an SoundLab electrostatic:

 

[DonH50]

Thanks guys. To me impedance always includes phase (and magnitude), or real and imaginary parts, however you want to express it. Just making sure I hadn't missed some new term invented by audiophiles. Of course, in my world of traveling waves, S-parameters are more often used, but Z is found everyone, too.

ESLs are essentially big capacitors so are an ugly low and reactive load at HF.


What is truly unfortunate for any speaker is when the amp driving it happens to be particularly unstable right at a speaker reactive peak (or impedance dip)... I have seen SS amps oscillate at HF (above the audio band) with ESLs.

 

[microstrip]

(...) ESLs are essentially big capacitors so are an ugly low and reactive load at HF. (...)

What is truly unfortunate for any speaker is when the amp driving it happens to be particularly unstable right at a speaker reactive peak (or impedance dip)... I have seen SS amps oscillate at HF (above the audio band) with ESLs.

Very true, but they can sound so good with appropriate amplifiers that audiophiles forgive them for being such a nasty load!

 

[NorthStar]

Yes, it is why the phase measurement also becomes important. Some magazines, such as french Son et Image present this type of data in their reviews. See the "consumption curve" of an SoundLab electrostatic:

---- Nicro, are you a subscriber to Son et Image audio mag?
...Just an online reader? ...You read French?

 

[microstrip]

---- Nicro, are you a subscriber to Son et Image audio mag?
...Just an online reader? ...You read French?

Non, mais j'ai fait le download de la critique des SoundLab M2 - c'est trés rare de voir des essais sur les SoundLab. Je ne suis pas un abonné, mais quelques fois j'achette sporadiquement des magazines de hi-end aux aeroports de Paris ou Lyon. Juste pour lire durant le vol ...

 

[steve williams]

Hey

even I understand that Micro

 

[microstrip]

Hey

even I understand that Micro

Est-ce qu'on va avoir un rapport sur la nouvelle salle bientôt?

 

[steve williams]

Oui

La Salle est complèt aujourd'hui

 

[LL21]

Est-ce qu'on va avoir un rapport sur la nouvelle salle bientôt?

Whew...scraped by on those translations, Micro! Thank goodness for high school French...il ya au moins vingt-cinque ans que j'ai etudie francais! Vraiment longtemps!

 

[NorthStar]

-- ...Hope Bruce's in a good "French" mode today.

 

[Bruce B]

-- ...Hope Bruce's in a good "French" mode today.

I don't know squat about French.... I took Spanish in HS and College....

 

[DonH50]

I'm an engineer, barely know English... How the speakers breaking in?