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ClaudeJ1

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

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Out of curiosity, if you used a 16 inch driver instead of 15 wouldn't the throat need to be modified because of the larger driver?

Depends on if you want a little more bass or a little more treble. It would be OK as is in case another, more standard, true 15" driver was used later. The length and flare of the horn have a greater effect than wiggling the throat or back chamber. Again because the room response wipe out any minor differences when you listen or measure. this is why many of us use room correction, which is mostly in the frequencies where the Qpie is doing it's job.

Edited by ClaudeJ1

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" wouldn't the throat need to be modified because of the larger driver?"

 

Only the frame is larger, it is still a 15" (nominal) woofer.

 

In my mind the best reason to try an Altec is they are an underhung design, better linearity.

 

The JBL E145 is also underhung.

Edited by djk

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" wouldn't the throat need to be modified because of the larger driver?"

 

Only the frame is larger, it is still a 15" (nominal) woofer.

 

In my mind the best reason to try an Altec is they are an underhung design, better linearity.

 

The JBL E145 is also underhung.

Agreed. This is what makes these classic drivers so good in horns, where, like a Khorn, it's only about 1/16th of an inch peak movement under normal home loud levels. The reason to horn load in the first place.......minimize cone motion and distortion. I used to drive my Quarter pies and Peavy FH-1's to normal and loud levels with a $25 T-amp and a Radio shack 12v power supply. Less than 10W/ch. but I only needed about 25 Milliwatts for normal listening. Maybe 10 milliwatts on the mid/treble. Hard to believe, I know, but I measured it, so it's true.

Edited by ClaudeJ1

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It would be interesting to hear these in a QP cabinet. I have K33 in my front three and EV 15L in the side two. I really don't hear much if any difference in the sound in the 50 to 400 HZ band I use them in.

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It would be interesting to hear these in a QP cabinet. I have K33 in my front three and EV 15L in the side two. I really don't hear much if any difference in the sound in the 50 to 400 HZ band I use them in.

You are the king of Quarter Pies...........so far. I only had 2. You have 5!

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It would be interesting to hear these in a QP cabinet. I have K33 in my front three and EV 15L in the side two. I really don't hear much if any difference in the sound in the 50 to 400 HZ band I use them in.

You are the king of Quarter Pies...........so far. I only had 2. You have 5!

 

 

Some day I might build two more for rears. I would have to mount them to the ceiling though.  ;)

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It would be interesting to hear these in a QP cabinet. I have K33 in my front three and EV 15L in the side two. I really don't hear much if any difference in the sound in the 50 to 400 HZ band I use them in.

You are the king of Quarter Pies...........so far. I only had 2. You have 5!

 

 

Some day I might build two more for rears. I would have to mount them to the ceiling though.  ;)

 

Well, I did say "easy to build" so you proved me correct with how fast you built 3, so 2 more should be no problem for you.

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I have a few Altec 416 8c woofers, would these work with the stock dimensions? Also, are they appropriate?

You have to make sure to clear the max dimension of the driver, so make the cab 16 1/4 " tall instead of 15 3/4. You cut sheet layout will be different, but so what? Very good woofer if you are not looking to cross at 600 hz because it favors the low end rather than the top end, like a Klipsch K-33

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It would be interesting to hear these in a QP cabinet. I have K33 in my front three and EV 15L in the side two. I really don't hear much if any difference in the sound in the 50 to 400 HZ band I use them in.

You are the king of Quarter Pies...........so far. I only had 2. You have 5!

 

 

Some day I might build two more for rears. I would have to mount them to the ceiling though.  ;)

 

Well, I did say "easy to build" so you proved me correct with how fast you built 3, so 2 more should be no problem for you.

 

 

Super easy to build. The biggest thing stopping me from building another pair is the expense of the mid horns and crossovers. I had that already for the first five.

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I also have a few Emilar EH-520 horns that might work but I cannot find tests of them. So crossover point unknown.

You should be ok to cross at 500 Hz.

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" wouldn't the throat need to be modified because of the larger driver?"

 

Only the frame is larger, it is still a 15" (nominal) woofer.

 

In my mind the best reason to try an Altec is they are an underhung design, better linearity.

 

The JBL E145 is also underhung.

Agreed. This is what makes these classic drivers so good in horns, where, like a Khorn, it's only about 1/16th of an inch peak movement under normal home loud levels. The reason to horn load in the first place.......minimize cone motion and distortion. I used to drive my Quarter pies and Peavy FH-1's to normal and loud levels with a $25 T-amp and a Radio shack 12v power supply. Less than 10W/ch. but I only needed about 25 Milliwatts for normal listening. Maybe 10 milliwatts on the mid/treble. Hard to believe, I know, but I measured it, so it's true.

 

What t-chip amp did you use? Were you using a T-chip amp for the 1/4 pies, and another for the horns? 

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What t-chip amp did you use? Were you using a T-chip amp for the 1/4 pies, and another for the horns? 
It was a Tripath 2020 chip on the woofer after going through an active Xover with a 50-320 Hz. band pass, the K402 mid and tweet had just one capacitor at their cutoff and those were driven by my Onkyo 818 receiver with Audyssey XT/32

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Hi Claude

                                  I just wanted to let you know that after reading your full lengthy thread on the Quarter Pie bass horn topic ,  I have decided to build a pair as well for myself . I am currently listening to 1991 Klipschorns for music only ( FM-tuner , CD player , and Turntable ) , and have a pair of 1981 La Scalas  not being used , but presently holding in reserve  . I just acquired  a  pair of Klipsch  K402 horns , a pair of Klipsch 1133 drivers , a pair of K510 horns , and a pair of 69A drivers  for the project . Even though I  got the K510 horns and 69A drivers , I was thinking of only using the K402 horns with the 1133 drivers for this project and maybe doing what you did , and use the same QSC Waveguides  with B&C DE-250 tweeters  that you used  , are yours still available by chance , or did you all ready sell them ?   

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are yours still available by chance , or did you all ready sell them ?   

 

 

Still have them. I'll give you a good price if you want them. I also have passive networks, but I do recommend the Mini DSP with tri amping for best sound. Have that for sale as well including a 12 channel amp. The simpliciy of those bass horns is partially why they sound so good. You can't beat the K402/K1133 combo. Tried and true since they were designed for each other. PM me is you have further interest in more details.

Edited by ClaudeJ1

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Hey Claude,

I have most of the parts now for the final rear pair for my 7.2 setup (tweeters and mid horns, and one extra EV 15L). If I want to build yet another pair of QPs for that how small can I make them. They will have to be suspended from the ceiling and the smaller the better.

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Leaving the "core section" the same (back chamber, throat, expansion, etc.) you can change anything you want after the corner reflector. So instead of 48" in that dimension you can make it 24." this will yield about a 3 1/2 foot horn instead of the full 5 1/2 foot horn, with an 80 Hz. cutoff. instead of 50 hz. for the full Qpie.

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Leaving the "core section" the same (back chamber, throat, expansion, etc.) you can change anything you want after the corner reflector. So instead of 48" in that dimension you can make it 24." this will yield about a 3 1/2 foot horn instead of the full 5 1/2 foot horn, with an 80 Hz. cutoff. instead of 50 hz. for the full Qpie.

If you take the side you cut off and mount to the ceiling, it will, effectively, give you back some of the length you lost by using the ceiling as a substitute for what you cut off. If you can mount them in rear corners, you will get back what you lost anyhow, since the existing structure will effectively/partially replace what you cut off.

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What if instead of having a bend I made it a straight horn?  Would it work if If pieces #7 and 8 of the flare were extended by 24 inches or so and the top and bottom were cut to match that new flare profile. I would wind up with a horn 54 or 55 inches long including the back chamber. Length in my location is better than width. I don't really care about much below 80 to 100 HZ since I have that so well covered elsewhere. What I want is the clean bass that I have elsewhere.

I am just exploring options. I will not be in any position to build anything until June/July.

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