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DIY Waveguide loudspeaker kit

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well, there's no doubt in my mind that the worst distortion comes from crossover malfunction

I'm not sure what you mean here? Do you mean crossover distortion in a split supply amplifier? If so then yes, this is the most insidious type of distortion. I am rather surprised that you are not familiar with our work in this area. You should read it as it will answer your questions about measureing it etc.

But amplifier distortion is beyond the scope of this thread since we are talking about loudspeakers. In loudspeakers there are no types of distortion that are significant - unless the speaker is broken. Amps can have highly audible forms of distortion, but thats a topic for an amplifier thread.
 
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I have a funny analogy describing how we may have to look at it

when looking for planets in orbit around a star/sun they can't see the planet because it radiated no energy or light, or too little to make it visible on such distances

but they fund that the gravity relation between a planet and its sun causes a small imballance
this imballance makes the light fluctuate
and when they see fluctuating light from a star, they know there is planet in orbit around it

what we want to find may be invisible
but its effect on other parts of the system may well be more visible
that is, if we know what we are looking fore
 
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let me show you my xo, to illustrate what I found

changing a resistor from 12ohm to 15ohm made a huge impact on the whole system, and the sound
almost like night and day
 

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That is a completely linear situation, its not nonlinear distortion and not at all what I was talking about. You changed the frequency response of the crossover, of course you will hear that. Generally when people use the term "distortion" they mean "nonlinear distortion". Thats what everyone is going to assume you meant, thats what I mean. You can say "linear distortion" and it would be clear, but just "distortion" is going to be assumed to mean "nonlinear".
 
I do resistance values in inductor legs to tenths of an ohm and include the actual inductors resistance, again in tenths of an ohm. So would three ohms make a difference? Heck yes. I suspect that it changed the Q of the highpass on that section by as much as several dB, maybe more. And yes these kinds of subtle things can make a lot of difference in just the frequency response. Certainly until you can rule out that explaination you can't offer up anything else since that is the most likely.
 
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And yes these kinds of subtle things can make a lot of difference in just the frequency response. Certainly until you can rule out that explaination you can't offer up anything else since that is the most likely.

I surely can :usd:
FR response changes are there, ofcourse
but its just a minor sideeffect
ofcourse it has to be considered too, in overall balance
but the phase variations have much more impact
I believe thats a fact

but why it can cause distortion I still don't know
or how to measure that kind of distortion
as said, it can be severe with xo malfunction
or less with better xo function
but you can trust me on this, it is there
 
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Tinitus,

I believe I understand the feeling you are describing. I've often had this experience with changes of a similar magnitude.

Incidentally, I can see the risk of falling into the subjectivist trap with these posts but this is the basis for this post for me. It frustrated me that I couldn't put it into numbers (or explainable phenomena or whatever).

I do suspect this....that some changes in frequency response will mask or enhance parts of the spectrum. Most often I think, when you remove an offending region it lets others stand out. On the other hand, I know that I've added, oh let's say midrange, and found the bass now stands out as it is better supported. It can sound deceptively as if you've changed a woofer when you only touched a tweeter.

Taking this to another level...phase changes can cause some interesting frequency response effects. On axis can change (say, reduce...), whilst the in room power reponse can be increasing in level. This, by the way, I suspect (and pretty much blame) for the subjective difference with my earlier measurement procedures between what I saw and what I heard.
 
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