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Discussion Starter · #1 · (Edited)
Had Dan over my house to run REW on my system. But we got these strange readings with my KEF Q900 fronts. So why is it taking a nose dive around 2k but my NHT rear looks flat thanks. :help:
 

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Hi John,

That looks like the Q900 tweeters are disconnected (or non-functional). I'm surprised you wouldn't have heard this out of the box when listening initially. There are biamp terminals on the back with twist knobs for (dis)engaging, should allow you to test the tweeters separately to see if functional.

cheers,
 

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Had Dan over my house to run REW on my system. But we got these strange readings with my KEF Q900 fronts. So why is it taking a nose dive around 2k but my NHT rear looks flat thanks. :help:
Hard to say without knowing more about the mic orientation (0-90), calibration file in use (ditto), mic axis in relation to the speakers in question, etc. I doubt it’s inoperable tweeters, however; you’d be seeing a much stiffer rollout above 2 kHz than that, and that 8k spike wouldn’t be there for sure.

Regards,
Wayne
 

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Discussion Starter · #5 ·
I'm new to all this stuff and just trying to understand what's going on. Why is it the NHT looks good but not the KEF's.
 

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Hard to say without knowing more about the mic orientation (0-90), calibration file in use (ditto), mic axis in relation to the speakers in question, etc. I doubt it’s inoperable tweeters, however; you’d be seeing a much stiffer rollout above 2 kHz than that, and that 8k spike wouldn’t be there for sure.

Regards,
Wayne
Mic is a UMIK-1. Each speaker was measured separately on axis with 0 deg cal file. I measured his surrounds to make sure there wasn't anything wrong with my equipment(although I had just used it the night before and it worked fine). All of his surrounds stayed flat out to around 15-17khz(Audessy ON) as expected.

Also it's important to note that the tweeter attenuation is clearly audible during the sweep,.I can hear all the way to 22khz on a good day and i lost track of his mains well before that where as I was able to hear his NHT surrounds complete the sweep.
 

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I doubt it’s inoperable tweeters, however; you’d be seeing a much stiffer rollout above 2 kHz than that, and that 8k spike wouldn’t be there for sure.
Regards,
Wayne


So you're thinking that Robs measurement showing 15db-ish drop from 2k to 5k-ish and spike at 8khz, exactly matching the Stereophile graph above, is just coincidence?
I don't. :)

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My guess is only the bottom posts are being powered.

I think ajinfla is onto something with those graphs, they look very similar to the measurements we got. I thought his tweeter was busted right away at first, but when all 3 speakers did it that seemed unlikely.
 

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Ok gents.
Step 1: twist the center knobs into the "open" position.
Step 2: Connect speaker wires to the bottom terminals, play music, hear sound (probably same as now)
Step 3: Connect speaker wires to the top terminals, play music, hear.....
 

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Discussion Starter · #18 ·
I got my terminals connect to the bottom of all speakers. I removed the terminals from my left speaker. Twist the center knobs to open and connect the terminals to top and no sound coming from the left speaker the others are working with connection to the bottom.
 

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So you're thinking that Robs measurement showing 15db-ish drop from 2k to 5k-ish and spike at 8khz, exactly matching the Stereophile graph above, is just coincidence?
I don't. :)
Why would you assume that I’ve ever seen that graph before?

And John's graph doesn't "exactly" match. Despite Stereophile’s impressive ability to measure SPL in negative dB values, assuming the green trace is low freq drivers only, they show the drop from 2-5 kHz to be more than 25 dB, not the 15 dB John’s graph shows, which supports my contention that the tweeters aren’t dead (hey thanks for backing me up :) ), but for some reason down in level more than they should be.

Or maybe not. Assuming the Sterohile graph (which shows relatively flat high-end response) is near-field, we can naturally expect to see a droop in high freq measurements taken at the listening-position, so John’s graph really isn’t off the mark.

So to answer the original question...
But we got these strange readings with my KEF Q900 fronts. So why is it taking a nose dive around 2k but my NHT rear looks flat thanks. :help:
...apparently these speakers are merely softer on the high end than the NHTs are.

Speaking of, the response of those NHTs is pretty impressive! Do they sound as good as they measure?

Regards,
Wayne
 

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Discussion Starter · #20 · (Edited)
OK I went and did all three the center is the only one working per your steps. The NHT speakers are the VT & VS 1.2 line from 1999 I think. I had the Full line up in my system the Towers and rears with VS-2a as center. Give the towers and center to my friend and got the KEF"s.
 
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