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TPCH with an Alpine SWR8D2
TPCH with an Alpine SWR8D2
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Old 30th March 2018, 08:26 PM   #31
Circlomanen is offline Circlomanen  Sweden
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THD and Group Delay.

I know some people strive for less GD, but I don´t. This is just the way I want it.

I hope I can post more tomorrow after we have used it our car where it is supposed to be used.
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Old 31st March 2018, 04:50 PM   #32
Circlomanen is offline Circlomanen  Sweden
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On our way to a spl comp a 2 hour drive from here disaster struck. We were playing a wide verity of 80ies pop music with some Deadmau5 thrown in the mix, when our amp suddenly died. We can turn on the amp but the very second it gets some kind of signal the amp shuts down into some kind of protection mode while simultaneously drawing enough current to cause a 1,5 v voltage drop from our car battery.

No measurements or impression today...
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Old 31st March 2018, 05:03 PM   #33
Brian Steele is offline Brian Steele  Grenada
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THD and Group Delay.

I know some people strive for less GD, but I don´t. This is just the way I want it.
Wow, the equivalent of basically 84ms at 58 Hz, the equivalent of almost 5 cycles of delay...

I'm thinking that yes, that would probably be very audible.
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Old 31st March 2018, 05:12 PM   #34
Brian Steele is offline Brian Steele  Grenada
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Originally Posted by Circlomanen View Post
On our way to a spl comp a 2 hour drive from here disaster struck. We were playing a wide verity of 80ies pop music with some Deadmau5 thrown in the mix, when our amp suddenly died. We can turn on the amp but the very second it gets some kind of signal the amp shuts down into some kind of protection mode while simultaneously drawing enough current to cause a 1,5 v voltage drop from our car battery.

No measurements or impression today...
Sure it's the amp? Perhaps it's a shorted coil on the driver.
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Old 3rd April 2018, 02:26 PM   #35
Circlomanen is offline Circlomanen  Sweden
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Quote:
that would probably be very audible
I am sure the audibility of the GD drowns in the intense buzzing and rattling noise from the interior of the car when subjected to a short burst of 145+ dB in a spl-comp situation.

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Sure it's the amp?
Yes. We measured the dcr of the voice coils and it was 1.9 ohm per coil.
We have a new amp and the bass is ferocious.
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Old 3rd April 2018, 02:50 PM   #36
Brian Steele is offline Brian Steele  Grenada
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I am sure the audibility of the GD drowns in the intense buzzing and rattling noise from the interior of the car when subjected to a short burst of 145+ dB in a spl-comp situation.
Oh, I'm sure that the box meets the "one-note" SPL box requirements, and GD is considerably less of a concern there, as is the ability to be listenable when playing actual music ;-)

But for playing music at a reasonable level (i.e. NOT at an interior-buzzing 145+dB)? I think that huge group delay peak will be audible, yes.

Many years ago I helped design such one-note wonder. A vented box designed to achieve peak output at the car's cabin resonance frequency. It blew the rear glass off of the SUV during the last SPL test (more a sign of the age of the SUV than the SPL achieved, but still). Great fun. Good for listening? Probably not, make that definitely not, but I did design the box to allow it to be "detuned" for normal listening by blocking a few of the vents. Best of both worlds. I'm sure I have a picture of the install hanging around somewhere, but can't find it at the moment.
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Old 3rd April 2018, 05:31 PM   #37
Circlomanen is offline Circlomanen  Sweden
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In-car measurement 2 cm from the front windshield on the right side where we measured 135 dB from the Paraflex a few weeks ago. Taken at 1.0 volts with the two voice coils in series for a 4 ohm load.

I added a Hornresp sim at 0,5 pi as a comparison.

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Oh, I'm sure that the box meets the "one-note" SPL box requirements, and GD is considerably less of a concern there
I had a hunch that this would happen.

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It seems like the semi-closed car cabin damps the Q of the resonator enough to flatten the GD substantially. Even the broad wide band peak indicates a lower Q then the simulation predicts.
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Old 3rd April 2018, 06:37 PM   #38
BP1Fanatic is offline BP1Fanatic  United States
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Nice!

Post that pic Brian!
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Old 16th April 2018, 12:29 PM   #39
USRFobiwan is offline USRFobiwan
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TPCH with an Alpine SWR8D2
All the Circloman images are blocked because of 'phishing attacks'. Better find a trustworthy host. Why don't you use the build in diy audio gallery?
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Last edited by USRFobiwan; 16th April 2018 at 12:31 PM.
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Old 17th April 2018, 02:28 PM   #40
BP1Fanatic is offline BP1Fanatic  United States
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Shoot, why can't you upload from your hard drive or phone?
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