Well... I'm now an XR-55 owner...

[Eddie]

Another theory I've heard has to do with impedance swings.

http://forum.ecoustics.com/bbs/messages/1/179531.html

scroll down to Jan Vigne's postings starting on Friday, December 09, 2005 - 11:12 am. Be forewarned, if you are a stranger to that forum: it's virtually unmoderated, unruly and highly digressive!

[Asliang]

Eddie - (although I haven't read the post yet, I will in a bit) actually I think we are talking about the same thing!

Impedence swings from poor damping leads to overload, which leads to THD spikes, and if its higher odd order distortion, it's going to be be some shrill/harshness to the sound.

[Eddie]

Eddie - (although I haven't read the post yet, I will in a bit) actually I think we are talking about the same thing!

Impedence swings from poor damping leads to overload, which leads to THD spikes, and if its higher odd order distortion, it's going to be be some shrill/harshness to the sound.

To be honest I don't really understand the technical aspects of this theory myself...what can you expect from a Lit major after all?

[Asliang]

To be honest I don't really understand the technical aspects of this theory myself...what can you expect from a Lit major after all?

Well the simple way to say is, impedence swing = harder for amp to drive in a certain frequency range (overload).

When amps overload, they give off an individual type of distortion. Tube amps give off even (pleasant, warm) order distortion, solid state give off odd (not so pleasant, harsh) distortion. I believe in if the orders are higher (say fifth vs third), it becomes more annoying even if the THD% isn't any higher. If the Panny has a really high order distortion, this might be the cause of the harshness, even though it only measures at 0.03% at 1W input.

[einsteinjb]

Well the simple way to say is, impedence swing = harder for amp to drive in a certain frequency range (overload).

When amps overload, they give off an individual type of distortion. Tube amps give off even (pleasant, warm) order distortion, solid state give off odd (not so pleasant, harsh) distortion. I believe in if the orders are higher (say fifth vs third), it becomes more annoying even if the THD% isn't any higher. If the Panny has a really high order distortion, this might be the cause of the harshness, even though it only measures at 0.03% at 1W input.

OK so if I'm reading this right, and if that is indeed the cause of these comments, then wouldn't it be accurate to say that the Panny should only sound harsh/too bright at high enough volumes that the amps are overloading?

Which leads to my next question: To the XR55 owners who say it's too bright, do you feel this way only at high enough volumes to possibly cause some distortion, or at all volumes?

(Don't have my own XR55 yet so I can't test it meself...)

[bikeman]

(Don't have my own XR55 yet so I can't test it meself...)

I do and I have tested all these problems myself. If the problems were with the design of the Panny, all the units would exhibit the problems. They don't. Go figure.

David

[Asliang]

OK so if I'm reading this right, and if that is indeed the cause of these comments, then wouldn't it be accurate to say that the Panny should only sound harsh/too bright at high enough volumes that the amps are overloading?

Which leads to my next question: To the XR55 owners who say it's too bright, do you feel this way only at high enough volumes to possibly cause some distortion, or at all volumes?

(Don't have my own XR55 yet so I can't test it meself...)

There are two scenarios. They aren't mutually exclusive, so it makes it even more confusing 1) Amp Overload with high harmonic distortion 2) Crossover distortion

A lot of people seem to have varying conditions for their "brightness" concerns. I myself do feel it sounds a little harsh when you turn it up on music, but it's impossible to tell if it's the speakers (cone breakup) or amp-related overload. Considering people with all kinds of speakers have mentioned the brightness thing, I don't think its speaker-limited.

If it is 1) then you are right, the higher you turn it up, the worse it will sound.

If it is 2) Then theoretically the opposite would happen; the higher you turn it up, the better it would sound (the music would drown out the crossover distortion).

Given it's a digital amp, it could be BOTH, and while crossover distortion is audible, not all people are as sensitive (or sensitive to the same order) harmonic distortions. Thus if the amp exhibits BOTH problems, then all sorts of people with different hearing sensitivities complaining about brightness could be describing two seperate things, or in a worse case scenario, both.

Anyway, I wan't to put in a disclaimer that I've taken 0 audio theory classes, have no experience in DIY, and most of what I have learned is from people in the DIY community and online audio white papers. My knowledge base could be flawed, AND since I am mostly postulating, it's all idle speculation anyway. I could be wrong on all accounts.

[Beuby]

OK so if I'm reading this right, and if that is indeed the cause of these comments, then wouldn't it be accurate to say that the Panny should only sound harsh/too bright at high enough volumes that the amps are overloading?

Which leads to my next question: To the XR55 owners who say it's too bright, do you feel this way only at high enough volumes to possibly cause some distortion, or at all volumes?

(Don't have my own XR55 yet so I can't test it meself...)

I would have to describe the sound as consistently bright; this impression has been magnified by my switch from 170 classics to 340SEs. Only David could speak of the technical differences/improvements of the new tweeter design but (again, to my ears) the pairing of the XR55 and and the 340SEs isn't as neutral/natural as I'd hoped. It would appear that the 340SEs "smoke out" the XR55's limitations...

[Eddie]

I do and I have tested all these problems myself. If the problems were with the design of the Panny, all the units would exhibit the problems. They don't. Go figure.

Are you saying that the Panny sounded bright with some speakers but not with others? Which models specifically?

I tend to also believe that it depends mainly on the speakers.

[Grayson73]

Did any of you own the XR50 previously? If so, is it worth the upgrade to the XR55?