REW Beta Release HF roll-off where none should exist!?

Robbie010

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Main Amp
Fusion FA123
Other Amp
Pro-ject Phono Box RS
Streaming Equipment
Bluesound Vault
Front Speakers
Klipsch La Scala
Other Equipment
Turntable
I’m in the middle of setting up DIY 3 way speakers in an active setup. According to the manufacturer, the tweeters (Visaton TL16-H) measure flat well beyond 20khz, however, both are measuring as though drastically rolling-off the HF from around 12khz. Both tweeters measure identically regardless of SPL, microphone distance etc.

I’ve played around with sample rates, that makes no difference, I’ve changed power amp and tried measuring without the crossover/DSP unit connected, nothing changes.

Setup is:

Eversolo DMP-A6 Streamer/Pre-amp -> Active Crossover/DSP -> (Hypex based) KJF Audio MA-01 Power Amps -> Speaker Drivers

Measurements taken with Umik 2, correct calibration file installed, using REW on both laptop and Mac.

As mentioned, I tried measuring without the DSP in the system, I’ve tried a different power amp, every setting I can think of tweaking and nothing helps. I even reached out to Visaton, their only suggestion, other than assuming that my measurements were at fault, was that the drivers are damaged. However, I find it highly unlikely that both drivers would be damaged or develop a fault in an identical manner yet still function perfectly and still measure identically!

Two things I’ve not tried are a different streamer /pre-amp and a different mic.

Has anyone come across this issue before and can make any recommendations or suggestions, other than buying a different streamer / pre-amp and a new Umik mic!?

Help!!!
 
I would try to replace it for a while.

I’ve already tried measuring the tweeter with a different (class-d) power amp, a Fosi Audio V3 mono. No difference.
 
One thing that does strike me is how well the roll off matches the microphone calibration curve:

roll off.jpg
 
Make sure the calibration file and mic orientation are the same – 0-degree file for aimed-at-speaker measurement, or 90-degree for upright mic orientation.

Regards,
Wayne
 
I have measured the tweeter every-which way…… and yes, correct calibration file for orientation is installed.

IMG_0389.jpeg
 
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