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ClaudeJ1

Quarter Pie Bass Horn: Measured FR, How2Build, and Hornresp

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By experience, measurment, and ownership, and looking at these curves, the EVM12L (Klipsch K42) would give the best high end response. This is why I used an EVM15L in my original design. The EV's have Fs ratings of about 50 hz. and a Qts of about .25, which give them a higher rolloff. But in practive, I found the 15C to be a better woofer because it is 4 ohms and also has better bass.

Edited by ClaudeJ1

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So Mr. Stevenarrow, are you smelling the sawdust yet? How is the build going?

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So Mr. Stevenarrow, are you smelling the sawdust yet? How is the build going?

 

Work has been busy. I have two weeks off at the end of the month. Stay tuned.

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So Mr. Stevenarrow, are you smelling the sawdust yet? How is the build going?

 

Work has been busy. I have two weeks off at the end of the month. Stay tuned.

 

 

I've been singing that tune for the last 6 or 7 months. But next week I swear I'm going to start the back 2!  :rolleyes:

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I've been singing that tune for the last 6 or 7 months. But next week I swear I'm going to start the back 2! 

 

You are still the King of Quarter pies with 5 of them. Two more will probably maintain your world dominance for years to come!.....................unless of course someone build an 11.4 Atmos theater with a Qpie for each channel, but I doubt that would ever happen. 

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Claude -- What would be specific parameters to look for in the woofer for these? I'm looking at using a 12 inch, but the same length as your QPie  for the initial flair. I want to place them vertically and truncate the mouth similar to the Baby QPie, maybe leave a little more on the mouth. Other than cost, these might just fit the bill.

 

EDIT: Actually, would like to lengthen the main expansion (make system taller), to get a bit lower extension. A 32 inch taper rate should get to 25 Hz.. If this could get to 30-35 it would be great.

 

Bruce

 

Fs: 26.7Hz
Qms: 3.72
Vas: 160 L
Cms: 88.6 g
Rms: 4 kg/S
Xmax: 14 mm(peak)
Xmech: 18 mm(peak)
Sd: 530 sqcm
Vd: 1.48L (p-p)
Qes: .25
Re: 6.5 ohm
Le: .3 mH
Z: 8 ohm
Bl: 19.7 T/m
Pe: 500W (cont.)
Qts: .23
1WSPL: 92.9 dB
2.83V: 93.77 dB

Edited by Marvel

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Bought three sheets of plywood today and have laid out the cuts. I will start cutting this weekend!

 

QP VS.jpg

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Cutting has begun, again working in a friends shop. He has an amazing setup, day job is a GE engineer.

 

post-26564-0-20800000-1450824849_thumb.j

post-26564-0-30240000-1450825063_thumb.j

Edited by tromprof
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Dry fitting the pieces. Will glue it together probably after Christmas.

 

 

 

 

post-26564-0-34160000-1450824941_thumb.j

post-26564-0-23360000-1450824950_thumb.j

post-26564-0-17200000-1450824969_thumb.j

post-26564-0-68320000-1450824981_thumb.j

Edited by tromprof
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Cutting has begun, again working in a friends shop. He has an amazing setup, day job is a GE engineer.

I wish my shop looked 1/2 that good. What are the specifics of this build? Sorry if I missed it, but this is a long thread. (purpose, placement, frequency response and driver)

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Cutting has begun, again working in a friends shop. He has an amazing setup, day job is a GE engineer.

I wish my shop looked 1/2 that good. What are the specifics of this build? Sorry if I missed it, but this is a long thread. (purpose, placement, frequency response and driver)

 

It's a shorter, straight version of the Quarter Pie. Should go to about 80 Hz.

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Cutting has begun, again working in a friends shop. He has an amazing setup, day job is a GE engineer.

I wish my shop looked 1/2 that good. What are the specifics of this build? Sorry if I missed it, but this is a long thread. (purpose, placement, frequency response and driver)

It's a shorter, straight version of the Quarter Pie. Should go to about 80 Hz.

So this is not the pie version but just a straight horn? It looks pure conical, right?

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Cutting has begun, again working in a friends shop. He has an amazing setup, day job is a GE engineer.

I wish my shop looked 1/2 that good. What are the specifics of this build? Sorry if I missed it, but this is a long thread. (purpose, placement, frequency response and driver)

 

 

As Claude said, this is a straight version of a QP, just a bit shorter.  The purpose is to expand the basement theater from 5.2 to 7.2 surround sound. I had that previous to building the QPs but my back channel speakers just mucked up the sound of the 5 QPs, so they got ejected.  I wanted to build another pair of QPs for the back, but there is not enough floor space, the area behind the theater is a workout area with a treadmill, elliptical, squat rack...  My solution is to build a somewhat smaller slimmer horn based on the QP design that could be hung from the ceiling. Since it is for the back low bass is not a priority, just good clean sound like the rest of the speakers. I have two different drivers on hand, an EV15L, and a Kappa 15C.  I am going to try one in each and see which I like better.  

Edited by tromprof
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n EV15L, and a Kappa 15C.  I am going to try one in each and see which I like better.  

 

The EV is a bit more efficient and has better high frequencies, so depending on your Xover to mid horn.............the Kappa 15C will be slightly bassier with a tamer top end. It will also put out about 2 db more with the same voltage drive as the EV's 8 ohms, since it's 4 ohms. Normally, the difference would be 3 db, but, like I said, the EV is about 1 db more efficient. Both are good choices. Let your ears and measurements decide. It's a question of nominal balance with passive networks, which gets over ridden by the room EQ in your receiver. But it's good to start off as right as possible acoustically before EQ.

Edited by ClaudeJ1

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So this is not the pie version but just a straight horn? It looks pure conical, right?

 

The first 21" or so is identical to the Quarter Pie or Klipsch MWM. After that first portion, this, the QP, and the MWM are all diffent lengths, flares, and mouth sizes.

 

Yes this one is conical, but does not exactly adhere to a "pure" conical formula. Most bass horns, including those by Klipsch, are conical segments that approximate what would be a continuous curve. It is not critical in the bass/midbass frequencies and very critical in the mid to treble area.

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They (EVM 15L and Kappa 15C) should look like this: 

<see chart>

 

Notice:

Voltage to EVM and Kappa is different in my model to show differences in frequency response and not in efficiency (chart 1). When crossed passively Kappa is louder by 2-2.5dB (chart 2).

 

Black:Kappa 15C

Gray: EVM 15L

post-60882-0-54320000-1450887683_thumb.j

post-60882-0-21640000-1450888092_thumb.j

Edited by Mariusz_
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Voltage to EVM and Kappa is different in my model to show differences in frequency response and not in efficiency (chart 1). When crossed passively Kappa is louder by 2-2.5dB (chart 2).  

 

Thanks for the backup data. Much better than just my words. 

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They (EVM 15L and Kappa 15C) should look like this: 

<see chart>

 

Notice:

Voltage to EVM and Kappa is different in my model to show differences in frequency response and not in efficiency (chart 1). When crossed passively Kappa is louder by 2-2.5dB (chart 2).

 

Black:Kappa 15C

Gray: EVM 15L

 

Thanks for the hard data.  I will pass along my subjective impression in a few days.

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Can the Quarter Pie be used in upright position instead of having it flat on the floor?

Yes it can. But like any asymmetrical horn, the dispersion angle will change, but it's not as critical in the lower frequencies. Also, you will lose the floor reflection, which adds a few Hz at the bottom by effectively doubling the mouth size. In my situation, with a K-402 horn on top, raised up the tweeter to a desirable ear level, so it worked perfectly on the floor.

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