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post #1 of 10 Old 02-02-17, 10:16 PM Thread Starter
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LWTransform for Dipole Subs?

Hi

I have modeled response for, designed and made an enclosure for one sub. I'm familiar with how to apply LWTransform in winISD. The sub is built but the circuit not yet. In the foreseeable future its likely I will stick another identical driver on the end of the enclosure to form dipole to even out room modes. I'd like to model this first as well before I pull trigger on the parts to build the first LWT circuit.

So how does one model 'pole-shifted' dipoles in winISD? (EDIT I meant Bipoles)
Maybe divide by two either the default response, fo, Qo, or the transformed response fp, Qp?.

Thanks in advance

Onward, bassheads

Last edited by giro1991; 06-07-17 at 03:04 PM.
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post #2 of 10 Old 02-02-17, 10:25 PM
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Re: LWTransform for Dipole Subs?

I'm not sure what you mean by pole shifted dipole, or how to model that.

Cheers and good luck!


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post #3 of 10 Old 02-02-17, 10:58 PM Thread Starter
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Re: LWTransform for Dipole Subs?

LinkWitz Transform is a pole-shifter.
Dipole, iirc is two loudspeakers mounted in opposite phase.
Bipole is the same but they move in harmony (in phase).

In my OP Dipole or Bipole doesn't matter as long as it's two drivers in a box.
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post #4 of 10 Old 02-02-17, 11:14 PM
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Re: LWTransform for Dipole Subs?

Two drivers in one box is a piece of cake in WinISD, and so is a Linkwitz Transform. Dipole cannot be modeled, AFIK. What is your question exactly?


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post #5 of 10 Old 02-02-17, 11:17 PM
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Re: LWTransform for Dipole Subs?

Confused on what your even asking. A Bipole design speaker is a speaker design in which the drivers radiate generally on opposite faces.(in phase) Dipole the drivers are generally on opposite faces but radiating the same direction so out of phase is another way to look at it. Here is a picture:



And your poleshifter comment I havent a clue what your trying to say there.

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post #6 of 10 Old 02-02-17, 11:29 PM Thread Starter
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Re: LWTransform for Dipole Subs?

Well isn't this thread going swimmingly.
Linkwitz transform is a pole shifter. Thats what it does, it shifts electrical poles, virtually according to what I've read.
I know the difference between Di and BiPole thanks.

I would like to know how to model a two speaker enclosure in WinISD and include the Linkwitz Transform EQ feature.
See attachment and perhaps re-read OP which I did my best to write clearly.
thanks.
Attached Thumbnails
LWTransform for Dipole Subs?-untitled.jpg  


Last edited by giro1991; 02-02-17 at 11:38 PM.
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post #7 of 10 Old 02-02-17, 11:48 PM
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Re: LWTransform for Dipole Subs?

I think you're doing it correctly. Just go to the driver tab and change it to 2 drivers, which would model them wired in-phase.


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post #8 of 10 Old 02-02-17, 11:55 PM Thread Starter
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Re: LWTransform for Dipole Subs?

Yes, 2 Drivers.
However the performance works out worse then, even with the LWT circuit patched in. It inclines one to build another box in light of this fact, granted two boxes will help eliminate room modes more if dotted about the room, but...

I was thinking if there was another way, that involved perhaps two circuits and one box, if you see. (Currently its 78Litre, quite big to have two)

(Keep in mind, that if the drivers are in-phase, theoretically the volume remains the same, providing the signals fed to each driver are 'identical'...)

Very odd concept I know. Perhaps two enclosures it is then...

Last edited by giro1991; 02-03-17 at 12:03 AM.
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post #9 of 10 Old 06-07-17, 12:19 PM
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Re: LWTransform for Dipole Subs?

This is super old, but I just saw it now, and I'm going to post anyway. Giro, I think what you're looking to build is a dual opposed enclosure, right? It is essentially bipole, but DO is how it's commonly referred to in terms of subwoofers, as far as I know.

So you're on the right track, and @fusseli was right about entering 2 drivers into the program. The questions remaining are how much power are the drivers going to get, and have you accounted for the volume of the enclosure when changing from 1 to 2 drivers?

If you have modeled an optimal enclosure for 1 driver, and then just add a 2nd to the program, it will no longer be optimal. Now you have 2 subs competing for space, and each one receiving half the power. Try increasing the volume of the enclosure and see if it looks better. Now regarding power... will each sub be powered by its own amp (or its own channel from the same amp)? If so, you'll need to double the power input number. On the other hand, if you're wiring them up together to the same single amp (or channel) you'll have to see what that new load does in terms of impedance and what that, in turn, does to the amp you're using. In either case, your model will be underpowered.

Hope that helps, and sorry it's 4 months late.

- OJ -

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post #10 of 10 Old 06-07-17, 02:38 PM Thread Starter
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Re: LWTransform for Dipole Subs?

My OP is a bit dumb. Power is OK. Volume of spider surround is accounted for too.

Working backwards
Take two commercial subs already equalised, put them back to back.
Whats better acoustically speaking, Dipole or Bipole?
I know two subs eliminate standing waves.
What matters is the timing discrepancy that a distance between two subs adds, di or bi-pole being irrelevant (I think)

Some subs have switches others dials for this. I think there is a misunderstanding among designers as to which 'phase to use'
because there are two types, one is azimuthul, a delay. The other is just a 180 flip. The Former can still be adjusted to 180 though,

With bipole the WinISD would work like normal because the volume would remain constant (EDIT actually thats complete rubbish thinking about it! - I'm not dumb afterall!!)

Two signals via two individual circuits in the same enclosure sharing the same space as per OP > overthinking.
LWT was designed for infinite baffle closed box.

I'm unsure if I should split the box and try full stereo which also requires two circuits.
A mono signal is probably sufficient though; as always it depends on source material.

FWIW In the article where Siegfried Linkwitz originally describes the LWT, he says that with LPs, when the two LR signals are summed, the signals that are 180 out of phase cancel out when summed to mono to go though the circuit. IIRC it was a 2.1 system.

I doubt winISD can simulate this btw, regardless of signal type.
My best bet would be to ask Mr Linkwitz himself... anyone have his number at hand? Haha

Last edited by giro1991; 06-07-17 at 03:42 PM.
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