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4 PI by Andy [message #74018]

Wed, 03 October 2012 07:48

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

Here we go!

Crossovers are built

Attachment: P1030089.jpg
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Attachment: P1030090.jpg
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Re: 4 PI by Andy [message #74022 is a reply to message #74018]

Wed, 03 October 2012 08:04

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

These are built on a 12" X 13" board.

I sort of mixed up on what I went $$$ on and what I went cheaper

I used Meniscus Audio 14ga air core inducers so I splurged a bit with these

I used Dayton caps. I used the standard 250V Poly on the 20uf and 10uf and I used the better new Dayton precision grade 250V Poly on the 6.8 and .047.

On the resistors I used the Dayton Precision Audio Grade Resistor line

I probably should have stood up the .6mH Inducer up. I hope this won't be a problem.

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Re: 4 PI by Andy [message #74027 is a reply to message #74018]

Wed, 03 October 2012 12:48

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

I thought I'd add my plan on these 4PI speakers. I'm going to build something similar to what a user Nicol1997 on this forum did on this thread (http://audioroundtable.com/forum/index.php?t=msg&goto=61737&#msg_61737)

• I would use the same 4PI crossover exact to Wayne's plan.
• I would space the 290 horn from the woofer exact to the 4PI plan only center the horn.
• I would have the speaker stand 7" taller. I plan to use two 4" Ports at 9-1/4" length on ea speaker. These are at the bottom of the speaker. I plan to run a lower internal brace at the point where the bottom board would normally be on a to plan 4PI. I'm thinking to run the router on this brace to cut holes in a variety pattern.. some 2" and some 3"... To allow for sound down to below this brace where the ports will run. I'll have the ports run down in the lower chamber and stuff that with the R13 and then lay a layer of R13 on top of the lower brace. I have these in mind (This is the outer piece of the tube that has a taper and the tube would be cut to attach to this )-

http://www.psp-inc.com/Graphics/PSP-4DOFH.jpeg

I used these on a subwoofer and I like the look and they work well.
• speaker box - 7" taller. trim one inch in width (17-1/2" instead of 18-1/2"). Add ¾" to the depth (15" instead of 14-1/4")
• Each speaker will have an upper brace which will be a criss cross of boards per speaker. Again, to the plan of a normal 4PI

I am planning to use Baltic Birch and I'm looking for the best grade I can get. Right now I have a line on 5' X 5' sheets. The speaker boxes are big and getting all the wood I'll need out of 2 sheets is a bit tight.... So I drew up some cut plans.

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Re: 4 PI by Andy [message #74028 is a reply to message #74027]

Wed, 03 October 2012 13:14

Wayne Parham
Messages: 18675
Registered: January 2001

Illuminati (33rd Degree)

I'm not able to see some of your pictures. Looks like they're uploaded to a private area on the internet somewhere that you can see (probably because you're logged in) but the rest of us cannot see. I suggest uploading them as an attachment here, to make sure they are visible to everyone reading.

As for the mods, I'll have to make the standard disclaimer that if you don't measure the cabinet, you can't be sure the internal standing waves aren't going to make an anomaly in the lower midrange. So if you don't have the equipment and time to do acoustic measurements, then I would suggest sticking with the plans as shown, or with a mod that you know has been tested. Don't deviate blindly, even if what you plan to do appears to be a trivial change. It's just not worth it, to risk messing up the midrange when the plans as drawn are tested and optimized. We discussed this in the thread you linked above, so I think you understand.

Now that we're through with the "standard disclaimer", notice that I said "I would suggest sticking with the plans as shown, or with a mod that you know has been tested." Nick's mod has been tested, so if you go with his cabinet, you'll be good to go. You can center the tweeter but don't change the positions or sizes of the woofer or port(s). If you change position or size, you'll need to do some testing to verify the midrange.

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Re: 4 PI by Andy [message #74033 is a reply to message #74028]

Wed, 03 October 2012 15:56

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

How do my crossovers look? Newbie... I'll try using something else to post update photos

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Re: 4 PI by Andy [message #74034 is a reply to message #74033]

Wed, 03 October 2012 16:22

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

I hear ya Wayne... I'll have to think about going more with exactly what Nichol1997 did... I feel ok doing what he did as the outcome of his test looked pretty good and close to a spec 4PI build.

Here are the attachments I had.

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Re: 4 PI by Andy [message #74035 is a reply to message #74034]

Wed, 03 October 2012 16:35

Wayne Parham
Messages: 18675
Registered: January 2001

Illuminati (33rd Degree)

I agree - Probably best to duplicate what Nick did, since we know that worked well. You can center the tweeter, but don't change the ports.

As for the pictures, what I see is, "Your client does not have permission to get URL". Can you save the images on your computer and then upload them here, as an attachment in your posts?

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Re: 4 PI by Andy [message #74037 is a reply to message #74035]

Wed, 03 October 2012 17:52

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

Google Images...

Lets try this!

Thanks again for any help/feedback. I totally understand the disclaimer as well.

Attachment: 4PI_Face_Mod.jpg
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Attachment: 5X5 sheetcuts_4PIMOD Page1.jpg
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Attachment: 5X5 sheetcuts_4PIMOD Page2.jpg
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Re: 4 PI by Andy [message #74039 is a reply to message #74037]

Wed, 03 October 2012 17:55

Wayne Parham
Messages: 18675
Registered: January 2001

Illuminati (33rd Degree)

There you go, excellent!

Just remember on those cut sheets that there will be some material loss from the cutting blade. But you have some room at the edges to make up for it, so I think you're good.

Looks like you're going to have some killer speakers before long!

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Re: 4 PI by Andy [message #74040 is a reply to message #74037]

Wed, 03 October 2012 18:00

mantha3
Messages: 72
Registered: May 2012
Location: Lino Lakes, MN

Viscount

Some really ugly crossovers

The .5 and 1.5 Inducer are close to one another... They are far enough away from the 1.0 that I'm not too worried about that.

I thought you just didn't want to "see" another Inducer looking thru the hole of an Inducer.. the .5 is close to the 1.0 but the 1.0 is a good 3in from the 1.5.

index.php?t=getfile&id=879&private=0