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Differences between Pi Speakers [message #37756]

Sun, 11 August 2002 10:16

Erik Johansson
Messages: 65
Registered: May 2009

Viscount

What are the differences are between the Theater Series 3 Pi and 4 Pi speakers?

Also, I would like to build this next pair of speakers out of plywood. I´ve had enough of veneering for now and I´ve seen a few Pi Speakers made out plywood so I suppose it would be ok right? Do I need to add any material thickness compared to MDF? I plan to use berch plywood like that in the picture. (They sell 18mm, 21mm and here. BIG (!) price differences betweem them!).

/Erik

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I meant birch plywood (nt) [message #37757 is a reply to message #37756]

Sun, 11 August 2002 10:46

Erik Johansson
Messages: 65
Registered: May 2009

Viscount

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Strengths and weaknesses [message #37760 is a reply to message #37757]

Sun, 11 August 2002 12:01

Wayne Parham
Messages: 18772
Registered: January 2001

Illuminati (33rd Degree)

The three π is smaller but has higher peak impedance making it harder to drive for flea-power SET amps. The four π is much larger but any amp can drive it. Other than that, they're pretty similar sounding speakers.

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Begging the question, Wayne [message #37765 is a reply to message #37760]

Sun, 11 August 2002 16:27

BillEpstein
Messages: 886
Registered: May 2009

Illuminati (2nd Degree)

Several different posts today about lowered output (which we are aware of) with the Theatre 4 above 10,000 Hz.Which little super horn would work to augment, preferably without crossover or just a few extra parts?
How different, or similar is this issue with the JBL horns?

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JBL 2405 and KSN 1038 [message #37770 is a reply to message #37765]

Sun, 11 August 2002 18:44

Wayne Parham
Messages: 18772
Registered: January 2001

Illuminati (33rd Degree)

I've used both the Motorla KSN 1038 and the JBL 2405 quite a bit over the years for the top two octaves. Naturally, the 2405 is used in more expensive systems, and it's truly excellent. The KSN 1038 is a great part for its cost, so I tend to prefer it in smaller bang-for-the buck systems.

One problem with using a super-tweeter is it throws constant-directivity out the window. There is no way to crossover to a super-tweeter without interference notches at narrow vertical angles near the forward axis. The distances are too large and the wavelengths too short. So what you get is a speaker that is only right straight-on axis, and any movement causes all sorts of response anomalies. I'm not sure that's a compromise I would make.

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Re: JBL 2405 and KSN 1038 [message #37771 is a reply to message #37770]

Sun, 11 August 2002 19:39

BillEpstein
Messages: 886
Registered: May 2009

Illuminati (2nd Degree)

I could hook up the KSN to the tweet output of the 3677 crossover in addition to the horn? Just to see? Before the attenuation? In parallel?

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Re: JBL 2405 and KSN 1038 [message #37772 is a reply to message #37771]

Sun, 11 August 2002 20:04

Wayne Parham
Messages: 18772
Registered: January 2001

Illuminati (33rd Degree)

Use a 1uF capacitor in series, then a 16 ohm resistor in parallel, then a 2.2uF capacitor in series and a 20 ohm resistor in parallel across the KSN 1038 tweeter. Disconnect the 0.47uF C1 capacitor from the compensation circuit on the compression horn when you're installing this top octave tweeter subsystem.

Let us know how you like it!

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Re: Strengths and weaknesses [message #37773 is a reply to message #37760]

Mon, 12 August 2002 02:24

Erik Johansson
Messages: 65
Registered: May 2009

Viscount

Is there any alternative for the PSD-2002 + H-290? It's a quite expensive part... Could it be build with something like two KSN-1038 next to each other until I could afford the PSD-2002 + H-290 (I could just open up the two round holes to a single rectangular hole of the right size)?

/Erik

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