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Spinorama! (also known as CTA/CEA 2034 but that sounds dull, apparently)

QMuse

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@amirm Per the discussion in this thread and how you said the Klippel calculated the ER curves, I decided to check for myself and use the klippels own data to calculate the ER curves manually using the process described by Todd Welti above. I had noticed that the klippel-generated ER and ERDI curves looked usually a fair bit smoother than the Harman ones around the crossover, and this shows why.

Here is the M16 ER and ERDI curves as generated by Klippel (white) vs the process used by HATS(blue) mentioned by Todd Welti above:

View attachment 56561

Not too much of a difference, but you can see the notch/bumps in the blue curves are worse and match Harman's a little more closely than the klippels.
View attachment 56562

Now on the Revel F35:


View attachment 56566

A more prominent crossover issue, and once again, closer to the HATS result:View attachment 56567
The bump on the ERDI curves are now nearly identical.

While probably not something worth going back to fix, it's something to perhaps keep in mind with measurements going forward, and that I hope klippel is informed of. Once again, it could be the difference between a good and great DI curve, especially on a speaker with particularly egregious vertical problems. And it would be good for the CTA-2034A to process to actually be used as, you know, a standard:)

As an interesting contrast, while almost every speaker I've tested gets worse with the HATS process, the Harbeth actually seems to get better. It has less of a tilt in the ER and smoother directivity. The vertical and horizontal dips actually do a better job of balancing out with this interpretation.
View attachment 56563

But of course Harbeth was the one that got better. It's only purpose is to serve as a universal exception for all rules! :D
 

napilopez

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But of course Harbeth was the one that got better. It's only purpose is to serve as a universal exception for all rules! :D

Haha I was thinking the same. It does seem like the focus was on balancing various nulls for a smoother in room response.
 

tuga

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thewas

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napilopez

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803D3 fares very well in terms of ER- and SP-DI.

I wish that these plots include Estimated In-Room response...

A shortcut is to just look at the Early Reflections curve with a little crick in your neck. :) The estimated in-room response is almost always nearly identical to the early reflections curve in shape - it just tilts down a dB or two more. In his book Dr Toole also often used the ER as an analog for the PIR.
 

hardisj

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Have you guys noticed this in the ANSI/CTA-2034-A R-2020 spec?

4.1 General Test Setup and Conditions
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.
.

If a small loudspeaker (satellite, bookshelf, etc.) without a manufacturer-specified filter network is being tested then a two pole Butterworth 80 Hz high pass filter network shall be used.

I don't plan on implementing this, personally. But, I found it interesting.
 

edechamps

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Have you guys noticed this in the ANSI/CTA-2034-A R-2020 spec?

That's… really weird, and I'm having trouble making sense of such a recommendation. I would certainly like to see an explanation on this. Looks like no-one follows that guidance and intuitively I'd think that's a good thing! Maybe add that to the pile of stuff that should be revisited/clarified in CTA-2034…
 

Juhazi

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These CTA ER curves are anyway just calculated sums of some x/y-axis measurements. Quite irrelevant which is "right" , but for comparisons sake we must stick to a standard way of measuring/calculating - differencies between "good" speakers are small.
 

napilopez

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These CTA ER curves are anyway just calculated sums of some x/y-axis measurements. Quite irrelevant which is "right" , but for comparisons sake we must stick to a standard way of measuring/calculating - differencies between "good" speakers are small.

I definitely agree about the differences between good speakers being small, so being consistent matters when comparing across sources.

But also, aside from keeping the standard a standard, the 'wrong' method significantly masks the influence of vertical reflections on timbre and in my experience seems to be noticeably worse at predicting the in-room response because of it. Not huge, but enough to probably make an audible difference when EQing

Especially given how we tend to evaluate speakers based on small differences around these parts. In the 'proper' ER method the vertical components make up 40 percent of the final curve. Put another way, the 6 'ceiling' and 'floor' angles count for as much as the full 17 curves in the front horizontal hemisphere.

Meanwhile in the 'wrong' method, the vertical portion only accounts for 23 percent of the ER, with each direction counting for the same. The rear hemisphere also only accounts for 11 percent of the wrong method vs 20 percent in the correct one, so it would rear its head more with omnidirectional speakers and such.
 
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napilopez

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Thank you for this!

So, what make and model is that $1800 loudspeaker that they measured in the video at 1:03? :)

Someone in another forum mentioned they thought is was an infinity il50. Can't find specific spins for it though
 

Xyrium

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Someone in another forum mentioned they thought is was an infinity il50. Can't find specific spins for it though
Wow. I believe it. That's a nice design.
 
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