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Johnny5's four Pi build [message #81424] Wed, 01 July 2015 05:35 Go to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
New guy here Razz .

I'm building a a pair of 4pi's.
I see a lot people build these floor standing speakers with a rearward lean to them.
In other words, the front of the cabinet sits slightly higher than the rear.
Others also put them on stands.

Which should I do?
Can someone tell me why this is?
Why not just put them flat on the floor?
Re: Johnny5's four Pi build [message #81425 is a reply to message #81424] Wed, 01 July 2015 10:36 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18676
Registered: January 2001
Illuminati (33rd Degree)

Most people put speakers on stands to position them roughly at ear level. I generally recommend putting mains on stands and flanking them with subs. Study on flanking subs to learn more about that configuration.

The angle of the stands serves to "cradle" the speaker, because there is a back plate (or usually just a lip) that the speaker rests on. It doesn't take much tilt to allow gravity to hold them in place. The stands could be flat though, and the speaker could be secured in a different way.

The pattern is clean above and below the forward centerline +/-20° so some vertical tilt is OK. If the speaker is angled upwards, say 5°, then the vertical nulls would be positioned 25° above and 15° below.

Re: Johnny5's four Pi build [message #81426 is a reply to message #81424] Wed, 01 July 2015 14:27 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
Thanks Wayne.

Another question- Whats the deal with some builders putting "putty"
or caulking all over the back of the waveguides Shocked .

I've seen some builds with this,and it would be easy enough to do before installing the waveguides, if it is indeed something I need to/should do.
Re: Johnny5's four Pi build [message #81427 is a reply to message #81426] Wed, 01 July 2015 14:51 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18676
Registered: January 2001
Illuminati (33rd Degree)

I cannot detect an improvement either by ear or by measurement from adding damping material like putty to the outside of the waveguide. But it doesn't hurt anything either. Some people swear by the stuff and say it reduces bell resonance.

Re: Johnny5's four Pi build [message #81428 is a reply to message #81424] Wed, 01 July 2015 18:39 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
I'm also considering trying a tube amp with these eventually (currently running an Adcom-555).
Any suggestions? Perhaps mono-blocks that don't cost a fortune Razz ?
Re: Johnny5's four Pi build [message #81430 is a reply to message #81428] Thu, 02 July 2015 10:24 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18676
Registered: January 2001
Illuminati (33rd Degree)

I think you'll really enjoy that.

I personally own an Audio Note SET amp, an Image SET amp and a Heart Audio UL amp. The Audio Note amp is all tubes, and the other two have tubes in the signal path, but have solid state rectifiers in their power supplies. I use each amp several hours a day.

Re: Johnny5's four Pi build [message #81432 is a reply to message #81424] Thu, 02 July 2015 14:56 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
Funny you should mention Audio Note.

As a first choice, I have been considering their single ended triode amp, the 300B Kit 1 standard version.

Secondly, the Odd Watt Odd blocks as a somewhat cheaper alternative, but I like the idea of all tube.

The problem is I am a tube amp newbie, and I am just unsure if it is powerful enough for these 4pi's?
Re: Johnny5's four Pi build [message #81435 is a reply to message #81432] Sun, 05 July 2015 10:54 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18676
Registered: January 2001
Illuminati (33rd Degree)

They're perfect, both Audio Note and Oddwatt. In fact, those are my choices of amplifiers at trade shows, when demonstrating my loudspeakers.

Re: Johnny5's four Pi build [message #81440 is a reply to message #81424] Tue, 07 July 2015 16:52 Go to previous messageGo to next message
johnnycamp5 is currently offline  johnnycamp5
Messages: 354
Registered: June 2015
Location: NJ
Grand Master
Can the 4pi's be placed in corners like the corner horns, or are they better placed more out in the room and away from the corners?

The room in question is 25' long x 15' wide x 8' tall.
They will be oriented on the short (15') wall facing the length (25')of the room.

Re: Johnny5's four Pi build [message #81441 is a reply to message #81440] Wed, 08 July 2015 08:47 Go to previous messageGo to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18676
Registered: January 2001
Illuminati (33rd Degree)

If you have two good corners, I'd suggest building constant directivity cornerhorns to take advantage of them. They are designed for that placement, and maintain acoustic proximity to the boundaries appropriate for the wavelengths involved. The bass bin and mid horn both work to achieve this goal.

Otherwise, use flanking subs to mitigate the anomalies that invariably arise from placement near boundaries. That's the next best thing, because you cannot get any other kind of speaker acoustically close to the boundaries, and most times, you can't get them far enough away either. So the use of DI-matched waveguide mains with flanking subs are the best option.

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