Post ringing

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UliBru
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Re: Post ringing

Post by UliBru » 13 Sep 2021 22:07

Ok, thanks. Please send me the pulse responses.
Stay well tuned
Uli

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Acourate system: JRiver/Roon -> AcourateConvolver -> miniDSP U-DIO8 -> TacT M/S2150 amps -> DIY horn speakers
PhilActiveAudio
Posts: 55
Joined: 21 Jan 2021 21:51

Re: Post ringing

Post by PhilActiveAudio » 14 Sep 2021 19:12

Here are the Left and Right pulses.
Attachments
Pulse48.zip
Left and right pulses
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exaSound e68 DAC ==> class D / Accuphase / class D ==> Jensen Supravox / Arai Radian / Fostex
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UliBru
Posts: 433
Joined: 19 Oct 2019 13:58

Re: Post ringing

Post by UliBru » 15 Sep 2021 12:34

Hello Phil,

do you use a Umik-1 microphone?
The zoomed pulse response looks like
Time.png
Time.png (49.13 KiB) Viewed 1706 times
This is not normal. It is not caused by a brickwall filter.
Please do a recording of the tweeter in nearfield (about 40 cm at tweeter axis), you can simply run e.g. a sweep from 5 kHz to 24 kHz even without XO. Select the proper recording channel and the low frequency according to the tweeter specs. A sweep time of 10 sec is enough. In addition you can also check the Dirac option in the recorder if you use a Umik-1 or USB mic.
Please send me then the file Logsweep48_rec.wav to ulrich.brueggemann@audiovero.de
Stay well tuned
Uli

Moderator
Acourate system: JRiver/Roon -> AcourateConvolver -> miniDSP U-DIO8 -> TacT M/S2150 amps -> DIY horn speakers
PhilActiveAudio
Posts: 55
Joined: 21 Jan 2021 21:51

Re: Post ringing

Post by PhilActiveAudio » 15 Sep 2021 13:55

Hi Uli,

No, I use a Earthworks DM23 mic and a RME Fireface UCX card for the mic input and the 6 outputs.

These measurements are 3 ways with a basic XO setup (NT-1 550 5500) with no delay correction neither voice optimisation.
In my setup, the low voice is physically in first position, then the tweeter and finally the mid voice which is the most distant driver.
To protect drivers, I had installed Mundorf capacitors before the mid and tweeter.

I will measure the tweeter at 40cm this evening.
I already send you a tweeter on axis measurement at 100cm, 2.5 to 30 kHz (96 kHz).
exaSound e68 DAC ==> class D / Accuphase / class D ==> Jensen Supravox / Arai Radian / Fostex
PhilActiveAudio
Posts: 55
Joined: 21 Jan 2021 21:51

Re: Post ringing

Post by PhilActiveAudio » 15 Sep 2021 19:26

I've made some new measurements of the tweeter this evening, on-axis 40 cm and found several things.

1) The physical position of the tweeter was probably not good: the tweeter was originally located on the back side of the Arai mid driver horn and was probably generating reverb on the pulse. Once relocated on the front of the Arai horn, reverb was less important.
2) The measurement of the range 2,5 kHz to 30 kHz shows oscillations that are highly corrected when measuring starting from 5 kHz. Is this can have an impact of the original problem, knowing that the measured filter was set at 5500 Hz between mid and tweeter? I probably need to set a new filter at 6,5 kHz or 7 kHz.

Tweeter in back of the horn, on-axis 40 cm, 2,5 kHz to 30 kHz
Tweeter avant.jpg
Tweeter avant.jpg (360.86 KiB) Viewed 1695 times
Tweeter in front of the horn, on-axis 40cm, 5 kHz to 30 kHz
Tweeter après.jpg
Tweeter après.jpg (363.89 KiB) Viewed 1695 times
exaSound e68 DAC ==> class D / Accuphase / class D ==> Jensen Supravox / Arai Radian / Fostex
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UliBru
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Re: Post ringing

Post by UliBru » 16 Sep 2021 10:28

This looks much better. How about a tweeter measurement up to 24 kHz with 48 kHz samplerate?
Stay well tuned
Uli

Moderator
Acourate system: JRiver/Roon -> AcourateConvolver -> miniDSP U-DIO8 -> TacT M/S2150 amps -> DIY horn speakers
PhilActiveAudio
Posts: 55
Joined: 21 Jan 2021 21:51

Re: Post ringing

Post by PhilActiveAudio » 16 Sep 2021 21:27

I will perform new measurements this WE with the new positioning.
The last measure at 48 kHz samplerate was before I found the problem and move to 96 khz to see if if was equal and then proceed with optimisation.
exaSound e68 DAC ==> class D / Accuphase / class D ==> Jensen Supravox / Arai Radian / Fostex
PhilActiveAudio
Posts: 55
Joined: 21 Jan 2021 21:51

Re: Post ringing

Post by PhilActiveAudio » 20 Sep 2021 19:49

Here are the new 48 kHz measurements on axis at 40 cm. The tweeter is now located in front of the Arai horn so no possible early reflections except the room:
> Red curve is 5 kHz to 24 kHz.
> Green curve is 7 kHz to 24 kHz.
Pulse 48kHz.JPG
Pulse 48kHz.JPG (341.39 KiB) Viewed 1639 times

The pulse still looks weird to me. I was not able to remove the oscillations as I managed to to with my early post but I don't know how (except that the recording was done at 96 kHz from 7 khz to 30 kHz).
exaSound e68 DAC ==> class D / Accuphase / class D ==> Jensen Supravox / Arai Radian / Fostex
PhilActiveAudio
Posts: 55
Joined: 21 Jan 2021 21:51

Re: Post ringing

Post by PhilActiveAudio » 03 Oct 2021 18:53

I did some more measurements and found that there are oscillations when I measure the tweeter above 20 kHz at 48 kHz and above 40 kHz at 96 kHz.
I did a RME Fireface UCX II loopback measurement and found that I have the same oscillations but with limited effects.
Can these oscillations be related to the card?
I don't know and would appreciate some feedback from other users.

However, I have good results when measuring at maximum 20 kHz at 48 kHz.
Here is the tweeter pulse at 3,5m distance (listening position).
Good enough to build a first "real" filter (UB jPol11 2nd order) with corrected delays for each driver.
Sound very good!
Left tweeter pulse at 3.50m.JPG
Left tweeter pulse at 3.50m.JPG (71.08 KiB) Viewed 1572 times
exaSound e68 DAC ==> class D / Accuphase / class D ==> Jensen Supravox / Arai Radian / Fostex
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