Transition area vs steady state

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Dahlberg
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Transition area vs steady state

Post by Dahlberg » 24 Nov 2020 11:52

I have moved my subs some to get rid of an anoying dip in frequency response and then found myself in bit of a problem. Between midbass and tweeters it was possible to acchive opposite polarity in the transition area and to align to a steady state. Here you can see the sub / midbass position.

Perfect opposite polarity in the transition area and steady state totaly of.
Image

Polarity changed for the sub. Nothing else done.
Image

This is what I'm using now. No change in polarity but rotation by -334 samples for the sub.
Image

Maybe I would be better of with another placement of the subs in the room. To acchive both the transition
area and steady state at the same time seems hard to do as they are placed now.

And at last, is there a ranking order that would say that either of the two aspects are more important over the other ?
Best regards. Bengt
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Uli
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Re: Transition area vs steady state

Post by Uli » 24 Nov 2020 13:49

From first picture I would conclude that sub and midbass start at the same time, they are correctly in opposite at the early beginning of the transition area.
But for some reason the phase of the black curve suddenly changes and now the drivers are in opposite polarity.

The polarity switch heals the phase shift without changing the time. But now, if e.g. the black curve belongs to the midbass, it is necessary to check how the driver behaves at the tweeter XO frequency. So it might be not a good idea to switch the polarity.

The rotation also corrects the phases but it also changes the timing.

So whatever you do it will solve a problem and create another one. I truly wonder how other programs promise an automatic time alignment.
The best solution would be to find a reason for the behaviour of the black curve and to fix it.
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Dahlberg
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Re: Transition area vs steady state

Post by Dahlberg » 24 Nov 2020 13:59

I'm a bit short for time :oops: but as soon as possible I will try to relocate the subs to another possition to see if
that will create another situation. Midbass / tweeter is perfect.
Best regards. Bengt
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Dahlberg
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Re: Transition area vs steady state

Post by Dahlberg » 24 Nov 2020 16:17

The black curve belongs to the subs forgot that.
Best regards. Bengt
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UliBru
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Re: Transition area vs steady state

Post by UliBru » 24 Nov 2020 18:28

Bengt,

you can also measure the sub close-up to see if the transient behaviour is caused by the sub or by some reflection.

BTW if you post pictures it would be nice if you can keep them alive. Otherwise the complete thread does not make sense.
Stay well tuned
Uli

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Acourate system: JRiver/Roon -> AcourateConvolver -> miniDSP U-DIO8 -> TacT M/S2150 amps -> DIY horn speakers
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Dahlberg
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Re: Transition area vs steady state

Post by Dahlberg » 25 Nov 2020 08:17

The pictures are working just fine here :?
Best regards. Bengt
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Dahlberg
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Re: Transition area vs steady state

Post by Dahlberg » 25 Nov 2020 10:47

Tried it with Crome / MS edge (PC) and with Crome on my phone. Same there, works just fine :?
Best regards. Bengt
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Dahlberg
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Re: Transition area vs steady state

Post by Dahlberg » 25 Nov 2020 11:19

Subwoofers relocated to a position ~70cm's further away and rotated +34 samples :)
Image
Best regards. Bengt
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UliBru
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Re: Transition area vs steady state

Post by UliBru » 25 Nov 2020 11:39

This looks much better.
Stay well tuned
Uli

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Acourate system: JRiver/Roon -> AcourateConvolver -> miniDSP U-DIO8 -> TacT M/S2150 amps -> DIY horn speakers
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Dahlberg
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Re: Transition area vs steady state

Post by Dahlberg » 25 Nov 2020 11:51

:D :-:

Are there still problems with the pictures ?
Best regards. Bengt
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