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Speaker impedance patterns - how to read them?

I know this has probably been discussed ad nauseam, but here's my question. I'm grateful for any sensible opinion.

Premise.
A speaker system may have a complex impedance pattern that can vary from 3-ohms to 30-ohms depending on frequency. Some speaker systems with similar impedance patterns may be stated as being 8-ohm loads because the speaker is 8 ohm in an important part of its frequency response, but only there.
A tube amp, as a voltage amplifier, likes a regular impedance pattern. Almost no speaker system has a constant, regular impedance pattern. I am aware that solid state, powerful amps are built to compensate for modern speakers' complex impedance patterns, but there are tube amps around and people who love them. It's difficult to understand what average load a given speaker system will present to the amp.

Question.
When looking for suitable speakers for a tube amp - mine is a PrimaLuna EVO 100, 40w x 2 from EL34s - what must be looked at? How to best interpret the impedance pattern, whenever available? Assuming that one listens at normal levels in a medium-sized room, what are the criteria for matching speaker and amp?

Thanks for your views. M.
martinguitars
pedroeb
493 posts
 
Here's an interesting view on Understanding Speaker Sensitivity.

Higher sensitivity certainly makes life easier, but my main consideration is SQ and keeping well below limits so that peaks and fast attacks are handled with aplomb. The same goes with amplifiers.

The golden rule is never get even close to maximum specifications.
wolfie62
352 posts
 
Just get good SS and enjoy!

Thats why I dislike tubes. Way too temperamental.
martinguitars OP
23 posts
 
millercarbon,

are you talking about me? Because if it's so, the discussion ends here.

I shouldn't even have started it. The point of abuse has been reached soon..
And as far as you are concerned, the late Maurice Chevalier is reported to have said: Men choose a woman in such a dim light they'd never buy a dress in. I suppose this applies to you.
Well I prefer to know what I buy. Thanks to all, I am leaving the thread.
M.
noske
783 posts
 
All other things being equal (eg, ignoring things like actual level of sensitivity levels and type of amp, damping etc), I’d prefer a speaker with reasonably flat impedance and phase curves.

Goes to things like imaging and other issues of import. Get the first principles correct and you are sprinting off first base.

What is Asperger’s-level MDS and how is that relevant to this fairly focused discussion to a well considered question by the OP?
clearthinker's avatar
clearthinker
1,582 posts
 
@martinguitars              Hope you're back on thread.  Don't feel picked on by miller, he can't help it, he does it to everyone.  He will never reform, he thinks too much of himself.   Best to just ignore him like the rest of us do.


In almost all affected speakers, low impedances occur only across short frequency ranges.
Low impedance points  at bass frequencies causes amplifiers the most problems.

The phase angle at low impedance points should also be examined.  Where this is low, it should not cause the amp too much difficulty.  But a combination of low impedance and high phase angle at any point will mandate a more muscled amp.

Some of us remember the Apogee Scintilla that had an average impedance of pretty well 1 ohm.  In those times only big Krells could drive them.  Things are better now.
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