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Re: 4PI Plans Request [message #91270 is a reply to message #91268] Mon, 16 December 2019 09:48 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
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Registered: January 2001
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mathiasb wrote on Sun, 15 December 2019 22:12
I'm having difficulty finding a good high pass for the mains. Considering they'll be getting a full range signal I want to protect them. The tuning is around 50Hz. With a sub LPF of BU2 100Hz, is BU4/BU3 HPF at 50-60Hz a good start for the mains? After that - there's the playing around with the delays to get the sub and speaker to integrate, before even looking at EQ.

High-pass at 50Hz fourth-order is fine.

As for the delay, please remember that what we're doing with flanking subs actually requires some delay. The modal range is caused by a multitude of phase interactions from reflected signals. There are multiple reflectors and therefore multiple delays. Each wall, the floor and the ceiling is a different distance and creates a signal with a different delay. So the application of multisubs - flanking subs and distributed subs alike - is to create dense interference, not to create in-phase summing. The purpose is to make the modal field act more like the statistical field, having dense interference to smooth the region.
Re: 4PI Plans Request [message #91271 is a reply to message #91266] Mon, 16 December 2019 09:51 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

Valentino Beach wrote on Sun, 15 December 2019 21:12
Have been following your 4PI design with great interest for over a year now.
Finally I have purchased a pair of 2226H JBL drivers for this project.
Can you please send me a set of plans to build these speakers.

You've got mail!
Re: 4PI Plans Request [message #91272 is a reply to message #91270] Mon, 16 December 2019 10:07 Go to previous messageGo to next message
mathiasb is currently offline  mathiasb
Messages: 6
Registered: December 2019
Location: WA
Esquire

Wayne Parham wrote on Mon, 16 December 2019 09:48

mathiasb wrote on Sun, 15 December 2019 22:12
I'm having difficulty finding a good high pass for the mains. Considering they'll be getting a full range signal I want to protect them. The tuning is around 50Hz. With a sub LPF of BU2 100Hz, is BU4/BU3 HPF at 50-60Hz a good start for the mains? After that - there's the playing around with the delays to get the sub and speaker to integrate, before even looking at EQ.

High-pass at 50Hz fourth-order is fine.

As for the delay, please remember that what we're doing with flanking subs actually requires some delay. The modal range is caused by a multitude of phase interactions from reflected signals. There are multiple reflectors and therefore multiple delays. Each wall, the floor and the ceiling is a different distance and creates a signal with a different delay. So the application of multisubs - flanking subs and distributed subs alike - is to create dense interference, not to create in-phase summing. The purpose is to make the modal field act more like the statistical field, having dense interference to smooth the region.

Thanks, I'll try that.

To paraphrase - we don't want to add to the speaker's existing response (say, by adjusting delay so the impulse response is matched), but rather complement it where there might be nulls/dips (room) or a natural roll off (below tuning / HPF).
Re: 4PI Plans Request [message #91287 is a reply to message #81341] Fri, 27 December 2019 13:47 Go to previous messageGo to next message
Damkel is currently offline  Damkel
Messages: 2
Registered: February 2019
Esquire
Hi

Could I please ask for the plans again I somehow lost/deleted the mail.
Thank you very much Smile
Re: 4PI Plans Request [message #91288 is a reply to message #91287] Fri, 27 December 2019 17:32 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

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Re: 4PI Plans Request [message #91289 is a reply to message #91288] Sun, 29 December 2019 22:43 Go to previous messageGo to next message
Birdman is currently offline  Birdman
Messages: 1
Registered: December 2019
Esquire
Hello Wayne,

May I request a copy of the 4-pi plans?

Hope you had a Happy holidays and are looking forward to the new year,
Ian S.

PS: Do you appreciate a build log for modified speakers? (I may increase the volume without making too many changes to the front baffle, I have read your comments on taller cabinets having pipe resonances among other things... I can perform measurements. actively crossover with an Audia Flex...)
Re: 4PI Plans Request [message #91290 is a reply to message #91289] Mon, 30 December 2019 11:11 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

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We all love to see build threads. So please create one and post often!

As for the mods you are considering, I am glad you understand the potential for anomalies from standing wave modes in large full-range cabinets. That knowledge will push you towards diligence in this regard.

For crossover information, please see the following thread:
Watch the video in that thread too, because it shows you how to find the position of the vertical nulls. The forward lobe is between the nulls.

I also encourage you to look at the concept of flanking subs. They work hand-in-hand with the three Pi and four Pi cabinets, meaning that they increase bass extension and conjugate lower rolloff both from cabinet alignment and from baffle step. In addition, each flanking sub mitigates SBIR from nearest boundaries and it smoothes higher frequency room modes.

By making the cabinets larger, you not only change the position and frequency of internal standing wave modes but you also change the bass alignment and possibly the frequency where baffle step occurs. This might change the overall synergy between the mains and their flanking subs.

So keep these things in mind as you incorporate your changes.
Re: 4PI Plans Request [message #91348 is a reply to message #91290] Thu, 16 January 2020 19:49 Go to previous messageGo to next message
brad n is currently offline  brad n
Messages: 1
Registered: January 2020
Esquire
Hi, Wayne.
I'd like to request the plans for the Four. I'm considering this project and would like to get a sense of the woodwork involved. I'll also be perusing the various build threads here.
Many thanks!
Brad
Re: 4PI Plans Request [message #91350 is a reply to message #91348] Fri, 17 January 2020 10:24 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

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