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Old 26th July 2013, 01:25 PM   #1
3GGG is online now 3GGG  Australia
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Default 9ms time delay not enough

Is it possible to reconfigure the software to increase the time delay on the minidsp 2x8? On large horn based systems, 9ms is insufficient.

Last edited by 3GGG; 27th July 2013 at 05:53 AM.
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Old 5th November 2013, 08:42 PM   #2
Henkjan is offline Henkjan  Netherlands
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old thread, but I'll answer anyway: if you can live with the 48kHz sample frequency, using the 10x10 plugin will give you double the delay

btw: what kind of horn is larger than 10ft? because that's the distance equivalence of 9ms
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Old 7th November 2013, 10:47 AM   #3
3GGG is online now 3GGG  Australia
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Originally Posted by Henkjan View Post
old thread, but I'll answer anyway: if you can live with the 48kHz sample frequency, using the 10x10 plugin will give you double the delay


btw: what kind of horn is larger than 10ft? because that's the distance equivalence of 9ms
Thanks, I am not keen to reduce down to 48kHz

A 16Hz Le Cleach bass horn
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Old 17th November 2013, 03:28 PM   #4
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A 16Hz Le Cleach bass horn
A good question, answer, and retort!

As a Klipschorn bass owner, I wonder about this too.

Esp. with the Klipsch being in a corner and the sound coming from two mouths at different distances from the listener! And from both of the other mids!! which makes 6 possible distances needing 6 different time corrections, eh.

The correction isn't about wave-length per se but about the physical construction of the horn. A straight horn, rare for bass, is a straight-forward analysis. But what about a folded horn, as most are?

The alignment ultimately is about getting phase right. Phase is a matter of wave-length and varies with frequency. It is conceivable you could be, say, 360-degrees off and that would be a reasonable alignment. But the correction would be right only for one frequency. Of course, for subs, they generally handle only one octave, so that helps.

Also helping is the fact that 20 Hz is about 50 feet long. So you could improve the alignment from 10 feet (fully out of phase at 20 Hz) to 3, feet and consider that an improvement.

Having pondered all of this, I am not sure bass alignment is all too important... and I do favour sharp rumble filters to limit cones flopping around and needlessly producing Doppler distortion.
Ben
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Last edited by bentoronto; 17th November 2013 at 03:32 PM.
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Old 20th November 2013, 03:27 PM   #5
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Shouldn't two miniDSP 2x4 boards wired digitally in series provide double the time delay for the mids/tweets and still have enough outputs for a stereo tri-amped system? Shouldn't remaining digital (in series) avoid signal degradation?

Are there good reasons to avoid say a miniDSP 2x4 in series with a miniDSP 2x8, should those be the units you have sitting around?

BTW, I aligned speakers by playing a sine wave at the nominal crossover frequency and adjusting for peak loudness at the listening position. You could also readily adjust for tweeter beaming with the same setup, albeit at 10kHz.

Ben
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Old 22nd November 2013, 03:18 PM   #6
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Originally Posted by bentoronto View Post
BTW, I aligned speakers by playing a sine wave at the nominal crossover frequency and adjusting for peak loudness at the listening position. You could also readily adjust for tweeter beaming with the same setup, albeit at 10kHz.

Ben
As long as the peak isn't being added to by room reflections this would indeed work fine. It is similar to aligning a 3 crt projector. The blue is the most difficult to setup as you can't clearly see blue (front or rear screen projection) to focus properly, especially so if you are by yourself. What works is adjusting the blue focus for max brightness. When done this way it is properly focused.
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Old 28th November 2013, 03:41 AM   #7
minidsp is offline minidsp  Hong Kong
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Dear All,

Sorry for the delay. Note that an alternative if you really want very long delay is to use an OpenDRC-AN. On the Sharc module + external DDR we can do very long delays. (up to 3s). Hoping 100meters is enough for your time alignment. :-)

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