Wilson Sabrina Review

[Dr Tone]

That's a measurement artifact; JA mentions to disregard it in several past reviews.

Because it's slightly a lower frequency this time he thought maybe not. But in all honesty if it's something he sees in the general area all the time, you have to think maybe it is the same measurement artifact.

You would have to believe Wilson would try to remove it even in their lowest model if it was easy to do. If it was really there.

 

[mauidan]

Question for Mike,

Why do have a speaker manufacturer on this forum making comments about another company's products?

 

[Vapor1]

Question for Mike,

Why do have a speaker manufacturer on this forum making comments about another company's products?

Someone asked me to comment on a tech question in another thread, so I did, then just happened to wander to this thread.

Since few care about tech, and it often ends up here - with someone getting their knickers in a twist, I'll just keep it to myself.

 

[the professor]

I personally like the different thoughts. As long as they are respectful.

Question for Mike,

Why do have a speaker manufacturer on this forum making comments about another company's products?

 

[a.wayne]

Seriously? If that's what you believe, you need to spend more time collecting and interpreting measurement data. I'm not trying to be a know-it-all, but your interpretation is off. That stored energy ridge is nasty, the only saving grace that would make it difficult to hear is high Q. Removing it could only have a positive effect.

Did you read both of my comments, i think not and yes i disagree with some of your assertions and will challenge if it's audible.

BTW, i have been gathering and interpreting loudspeaker measured data and their relevance for decades now, yep, even before there were PC data gathering nimrods who think they invented the loudspeaker. Feel free to Express your professional opinion, but recognize the limitation of doing so, as there's much more to designing a successful loudspeaker than to micro focus on such data, it shouts newbie because every-time you think you do , the audio gods will throw you a curve.


Regards..

 

[Mike]

I personally like the different thoughts. As long as they are respectful.

Agreed.

 

[Elberoth]

That's a measurement artifact; JA mentions to disregard it in several past reviews.

Indeed.

From KEF LS50 review:

'Ignore the black ridge of delayed energy just below 16kHz in this graph, which is due to interference from the computer's video-display circuitry.'

http://www.stereophile.com/content/kef-ls50-anniversary-model-loudspeaker-measurements#rFAhhKxhJ84h5v9M.97

 

[a.wayne]

That's a measurement artifact; JA mentions to disregard it in several past reviews.

I would be in agreement ...

Doubt that ...

Looking at the impedance mag/phase i really dont see any nasty resonance that would shine a light on the tweeter at 15K . A closer look at the FR measurements it looks to me more like baffle interference and or mic aberration, maybe a proximity effect due to it's narrow sharp response...

If it was tweeter resonance i would expect to see something in the Imp/mag/phase response and John's measurement test are not really meant to be complete or deep enuff to show all warts, since being only done at the 2.83V standard.

IMO, I would like to see the response avg with an increase in test voltage up to say 25 watts rms (worst case) ...

the Imp/Mag/Phase does tell alot ...



Regards..

If it was more obvious on the Imp/mag/phase graph i would be in agreement with Mr Vapor..

 

[FlexibleAudio]

Question for Mike,

Why do have a speaker manufacturer on this forum making comments about another company's products?

I like it too......a lot. I haven't heard any illogical proclamations marketing the Vapor line just pretty good science imo.

 

[Vapor1]

Did you read both of my comments, i think not and yes i disagree with some of your assertions and will challenge if it's audible.

BTW, i have been gathering and interpreting loudspeaker measured data and their relevance for decades now, yep, even before there were PC data gathering nimrods who think they invented the loudspeaker. Feel free to Express your professional opinion, but recognize the limitation of doing so, as there's much more to designing a successful loudspeaker than to micro focus on such data, it shouts newbie because every-time you think you do , the audio gods will throw you a curve.


Regards..

I suppose I'll continue the conversation, most seem cool with it.

So, let's assume the measurement shows a real anomaly. It appears to be a cavity resonance causing destructive interference with the in phase impulse. The question isn't whether it's audible, the question is under what conditions will it be audible. With distortion data we could tell if it propagates downward as odd order harmonics. It likely does, but silk domes being highly damped likely lessen it significantly. But if it does propagate downward to 5khz, and 3khz as distortion spikes, how could you possibly discard it as inaudible? If you've collected so much data, certainly you realize that resonances result in odd order harmonics as well, not just the fundamental seen in FR data.

The second question is why, knowing that a problem is there, would a manufacturer not do something about it? I've seen tweeters show cavity resonances very similar to this before, and assuming that's what it is, they're pretty simple to alleviate. Dave Wilson might have a perfectly reasonable answer, I don't know, I'm going on a lot of assumptions here. But it seems to me it would be like shipping a pair of speakers that have a flaw in the finish and saying "that's not visible". I don't argue that the issue is small, and for most listeners under most conditions would be very close to inaudible. It might equate to .1% of the total value for the speakers sound, but I also think most here would rather have that .1% back than not.

 

[a.wayne]

Since there's no THD plot to support your hypothesis , Im pretty confident if it was cavity resonance it would show up on the impedance graph..

So i'm in Agreement with JA take on it ..

BTW Dave Wilson voices his drivers when selecting and more specifically voices in the final sound of his speakers the same. The measurements reflects the voicing , not the other way around ....


Regards

 

[Vapor1]

Since there's no THD plot to support your hypothesis , Im pretty confident if it was cavity resonance it would show up on the impedance graph..

So i'm in Agreement with JA take on it ..

Incorrect, I even explained to you earlier why tweeter resonances don't often show on an impedance graph and you're still sticking with it? And a cavity resonance is even more likely NOT to show, because it's not the dome itself resonating, so even LESS likely to produce a wobble in the voice coil. If you're as technically proficient as you claim, that should be easy to grasp ... but here's proof.

This is a tweeter that shows almost the EXACT same cavity resonance behavior. On axis there's a suckout that turns into a ridge of stored energy. But will you look at that, narry a blip in the Imp trace. And look at the Distortion graph too, oh gee maybe I'm not a noob, there are spikes in 3rd and 5th order at 5khz and 3khz just as I expected.

BTW Dave Wilson voices his drivers when selecting and more specifically voices in the final sound of his speakers the same. The measurements reflects the voicing , not the other way around ....

I'm pretty sure that how almost everybody does it. But there's no way anybody intentionally voices in a 15khz cavity resonance.

 

[a.wayne]

I have to disagree ( regretfully ) as Suggested before it will show if it's that aggressive as in the wilson, ( unless tamed in the xover) and surely when testing the raw driver, you do know what causes the wrinkles in impedance graphs and you will see it in the FR.

Maybe Atkinson and I are wrong on this , but it does appear not to be driver related, is this where i post a graph showing the opposite , then what ..?

 

[a.wayne]

BTW: I do appreciate the graphs and the discussion , but i find the resolution poor on your imp graph , it would be hard to see wrinkle traces from that graph, nor am I saying its impossible that it won't show or one cant find a situation where it does not show, I'm saying its unlikely in the situation as presented by Stereophile .

Was That FR done with a baffle ..?

 

[Vapor1]

For the 3rd time now, cavity resonances in soft dome tweeters DO NOT show in impedance traces. It should be pretty obvious for the reasons I spelled out before why that's the case. Maybe if you 10x zoomed into just that area, you might see a hint of a wiggle. Instead of knee jerk defending your position, please take a step back and reevaluate.

Also the FR anomaly and correlating CSD energy storage of the tweeter I posted are essentially identical to the Sabrina tweeter, the graphs I posted couldn't be a more perfect analogy. Yet just as I predicted, neither shows a blip in impedance. Also just as predicted, there is odd order distortion spikes propagating downward ... and further as I predicted, those spikes are significantly damped because of the nature of silk dome tweeters. Having seen that type of behavior first hand many times, I know that it's very likely it could be eliminated with just a small wad of damping/stuffing inserted into the pole or rear chamber.

And no, you cannot 'tame' a high Q resonance like that in the crossover. #1 it's too narrow to target, #2 it's a suckout and not a peak, and #3 passive components cannot change the geometry inside the pole/chamber to prevent standing wave formation.

 

[a.wayne]

Mr Vapor ,

I'm trying and yes your graphs do mimic what you discuss , our discrepancy is if it would show in the impedance graph , could you Measure that tweeter again with LMS ( better resolution ) and if you could let us see what else changes when you stick that wad in , or did you believe in 50 yrs you were the first to do so...

 

[a.wayne]

BTW,


I never said or meant to say you could tame it (FR) i said, tame it in the Imp graph , the xover could mask it.

You did not answer my baffle question , did you measure with a baffle ..?

 

[Bruce]

For the 3rd time now, cavity resonances in soft dome tweeters DO NOT show in impedance traces. It should be pretty obvious for the reasons I spelled out before why that's the case. Maybe if you 10x zoomed into just that area, you might see a hint of a wiggle. Instead of knee jerk defending your position, please take a step back and reevaluate.

Also the FR anomaly and correlating CSD energy storage of the tweeter I posted are essentially identical to the Sabrina tweeter, the graphs I posted couldn't be a more perfect analogy. Yet just as I predicted, neither shows a blip in impedance. Also just as predicted, there is odd order distortion spikes propagating downward ... and further as I predicted, those spikes are significantly damped because of the nature of silk dome tweeters. Having seen that type of behavior first hand many times, I know that it's very likely it could be eliminated with just a small wad of damping/stuffing inserted into the pole or rear chamber.

And no, you cannot 'tame' a high Q resonance like that in the crossover. #1 it's too narrow to target, #2 it's a suckout and not a peak, and #3 passive components cannot change the geometry inside the pole/chamber to prevent standing wave formation.

Interesting re the Damping/stuffing you mention--the original WaTT Focal Tweet had Tube trap arrangement inserted in the pole piece/magnet assembly-it was if I recall a short length of Clear hosing encasing shot pellets with cork plug

Should we presume this is this was the early answer to your "damping/etc" quote--and possibly similar could be applied in this case?

Good thread

Bruce

 

[a.wayne]

For the 3rd time now, cavity resonances in soft dome tweeters DO NOT show in impedance traces. It should be pretty obvious for the reasons I spelled out before why that's the case. Maybe if you 10x zoomed into just that area, you might see a hint of a wiggle. Instead of knee jerk defending your position, please take a step back and reevaluate.

Also the FR anomaly and correlating CSD energy storage of the tweeter I posted are essentially identical to the Sabrina tweeter, the graphs I posted couldn't be a more perfect analogy. Yet just as I predicted, neither shows a blip in impedance. Also just as predicted, there is odd order distortion spikes propagating downward ... and further as I predicted, those spikes are significantly damped because of the nature of silk dome tweeters. Having seen that type of behavior first hand many times, I know that it's very likely it could be eliminated with just a small wad of damping/stuffing inserted into the pole or rear chamber.

And no, you cannot 'tame' a high Q resonance like that in the crossover. #1 it's too narrow to target, #2 it's a suckout and not a peak, and #3 passive components cannot change the geometry inside the pole/chamber to prevent standing wave formation.

Mr Vapor,

To iterate , I'm suggesting resonances will show up in the impedance Graph when seen in the FR graph and is also confirmed by the CSD plot ...

Cabinet interaction and or mic proximity errors may not show in the Impedance graph,

BTW, may i suggest a different software, the graph you posted had poor resolution and may have shown the error , but i could not tell .

How did the tweeter FR change after damping as you suggest, what about adding mass, ever tried, as BL changes the effect ..


Regards..

 

[a.wayne]

BTW,

I Thought you might find this interesting .....