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ClaudeJ1

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

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3 hours ago, Ray_pierrewit said:

I figure I might try the Q-Pie instead. I love the idea of a fully horn loaded bass design and now have the room for it. My question for Claude is, how close to the KHorn is a Lascala with Q-Pie? I haven't reread the entire thread, so is there a new or modified design I should be looking at? Do I need to modify the crossover at all if I use my current woofers? I won't be building a sub any time soon, the bass as is with the bin is sufficient for my listening needs.

 

Are there any other Q-Pie builders that would like to chime in on their experience with this build and it's performance?

 

Thanks all!

Daniel

Looking at the first pair of curves should tell you all you need to know about how superior the Q-Pie is the the LaScala (mine was an FH-1, which is, essentially, the same thing), which you can still use the LaScala cabinet as a mid/tweet "spacer" after you pull the woofer and put in the Q-pie instead of the LS bass bin. You can use the same Xover, just run the woofer section wire to the Qpie and you're basically done. Ruler flat to 50 Hz. and useable down to below 40, but I still recommend a sub for "subterranean" bass (HT), although for just music, it's not really necessary. You'll be real happy with the Q-Pie, I promise. Even with Jubilees in my possession currently, I'm thinking about building another pair of Q-Pies for myself since it was the best horn bass I've ever had in my old Indy living room and I now have a similar space. Please post words of your success here after you are done!

 

If you wish to eliminate my bias from the equation, try a Personal Message to Tromprof on this site. He's a professional musician and the current "king of the Quarter Pies." He bought my originals and built 5 more for a total of 7. He can tell you better than I can.

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Man cave melancholy :- hi Claude , firstly thanks for offering your interesting design free to diy'ers. Would you be kind enough to consider if i have a workable option.

The problem is my new listning room. It really is a cave. 7ft 5 wide , 8 high , 10ft 5 long. I have sketched ( horribly ) a few possible orientations .

Width ways on the floor would mean trimming a few inches of the tips of the mouth. Any issues here with each channel essentially firing directly into the other one ? ( would a central divider/reflector make any sense? )

Below the q pie operating range im looking at either bill fitz table tuba ls in corners or the lab12 design you have posted.

Above will be a fane studio8m in the pi midhorn and an altec 288 in a tractrix.

I've altec 604 to use in the qpie or if its not practical in my room a set of karlson k15's as i do likw that karlson kick.

These are all parts i have to hand. Just wish i had a bigger room

Regards

Gary

Good idea. All of them are workable option. It's just deciding how high of a cutoff you want above 50 Hz. The original QP gets to about 50 Hz. so making it shorter works up to about 80 Hz. where subwoofers can take over without making their location known.
30417b7fbb45efc020578501ba5e8438.jpg

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12 hours ago, gazzamongo said:

Man cave melancholy :- hi Claude , firstly thanks for offering your interesting design free to diy'ers. Would you be kind enough to consider if i have a workable option.

The problem is my new listning room. It really is a cave. 7ft 5 wide , 8 high , 10ft 5 long. I have sketched ( horribly ) a few possible orientations .

Width ways on the floor would mean trimming a few inches of the tips of the mouth. Any issues here with each channel essentially firing directly into the other one ? ( would a central divider/reflector make any sense? )

Below the q pie operating range im looking at either bill fitz table tuba ls in corners or the lab12 design you have posted.

Above will be a fane studio8m in the pi midhorn and an altec 288 in a tractrix.

I've altec 604 to use in the qpie or if its not practical in my room a set of karlson k15's as i do likw that karlson kick.

These are all parts i have to hand. Just wish i had a bigger room

Regards

Gary



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I vote for A. You can trim off the extra 3" on each Quarter Pie you won't need since you don't have a full 96" width (90"=7.5 ft.). Since the profile remains low, you can put whatever you want on top. I would straddle a single Lab12, 60" across the two Q's and still leave room for your mid and treble horn drivers in the corners.

QpieConfig.jpg

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16 hours ago, gazzamongo said:

I LIKE it :) . thanks Claude , appreciate the input.

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Also, the best sounding (can be purchased new from Parts Express) woofer AND best for the money is the Eminence Kappa 15C for the Quarter Pie.

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Also, the best sounding (can be purchased new from Parts Express) woofer AND best for the money is the Eminence Kappa 15C for the Quarter Pie.
Better than an altec 604-8g? ( which i already have) ( i can sure make something else with those if so )



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11 minutes ago, gazzamongo said:

Better than an altec 604-8g? ( which i already have) ( i can sure make something else with those if so )



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I have not simulated or measured an Altec 604, since it would have to be severely modified for use in a bass horn (like cutting out the tweeter). So yes, you can sell them for $1,000-3,000 each on Ebay, and spend only about $220 for 15C's to have the optimum woofer for the Qpie. Or just use the 604's in bass reflex boxes, which is what they were designed for (heard a pair about 36 years ago with McIntosh tubes electronics).

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I have not simulated or measured an Altec 604, since it would have to be severely modified for use in a bass horn (like cutting out the tweeter). So yes, you can sell them for $1,000-3,000 each on Ebay, and spend only about $220 for 15C's to have the optimum woofer for the Qpie. Or just use the 604's in bass reflex boxes, which is what they were designed for (heard a pair about 36 years ago with McIntosh tubes electronics).
Interesting post. I guess i could run them in a smallish box or open baffle above the qpies while im fashioning the other horns i mentioned. Wouldn't sell. Im in the u.k so its that bit harder to come across items like them again. The eminence driver you mention is easily and cheaply available so im happy to follow your suggestion there ( i did once ring eminence and at the time they were happy to sell me k33's too ) thanks.

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27 minutes ago, gazzamongo said:

Interesting post. I guess i could run them in a smallish box or open baffle above the qpies while im fashioning the other horns i mentioned. Wouldn't sell. Im in the u.k so its that bit harder to come across items like them again. The eminence driver you mention is easily and cheaply available so im happy to follow your suggestion there ( i did once ring eminence and at the time they were happy to sell me k33's too ) thanks.

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The original MWM's were designed for K33's, according to a conversation I had with Gary Gillum, the co patent holder and former Klipsch chief engineer. THe reason they went to k43's was to handle more power for PA use. However, the 15C has about 3-4 db more output at 400 Hz. where it "meets the midrange." Plus they cost less, so I'd go with those.

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On 10/1/2018 at 12:41 PM, gazzamongo said:

Wish i had lovely cabinet making skills. Anything i make is going to look 'budget p.a' :s

 


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Building Quarter Pies is VERY easy for anyone who's willing to try. Tops and bottoms are from a 4x8 foot sheet of plywood cut in half, the radius comes later if you wish. All the other pieces are rip cuts on a table saw set to 15 3/4" which are then chopped up to different required lengths. The trim work on the initial section requires resetting the Table Saw to an 11 degree angle for 2 x 2 cuts (wood held at different orientations. PL glues expand to make sure there are no leaks (very important) after screwing them together. It's a very simple build with very few steps and very little lumber is leftover.

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19 hours ago, davewantsmoore said:

Don't do B or C.

I still really like your "Velvet Sledgehammer" name for the Quarter Pie SOUND. Very accurate description and totally COOL!

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Why not C ?  I thought standing on side was one of the suggested choices for setup.

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44 minutes ago, muel said:

Why not C ?  I thought standing on side was one of the suggested choices for setup.

I was asked for the BEST choice. C might raise the mid and tweeter too high, though it would still work.

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I've had the wood rough cut and sitting her for a couple of years now waiting for me.  I'll show you my idea for mid and tweeter placement as soon as I finally get back to this project.    Well, I can describe it... I'd set the access door side up.  The tweeter would be above this at the front of the flat portion and the mid horn (Eliptrac 400) would be placed forward and below with mouth resting on curved edge of Qpie.  The tweeter and mid drivers would be vertically aligned and the tweeter would be at or about the perfect height for me.   I'm thinking the mid horn would not be blocking the Qpie in any significant way?

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Building Quarter Pies is VERY easy for anyone who's willing to try. Tops and bottoms are from a 4x8 foot sheet of plywood cut in half, the radius comes later if you wish. All the other pieces are rip cuts on a table saw set to 15 5/8" which are then chopped up to different required lengths. The trim work on the initial section requires resetting the Table Saw to an 11 degree angle for 2 x 2 cuts (wood held at different orientations. PL glues expand to make sure there are no leaks (very important) after screwing them together. It's a very simple build with very few steps and very little lumber is leftover.

Thats definately a big attraction of the design* ( in conjunction with the expected performance ) . what is the go to method for a nice neat curve on the mouth section? Router on a 4 ft radius arm ? default_smile.png

 

 

 

 

 

* though about making a university classic dean. But it doesn't seem to measure better and then there's so much opportunity for failiure with all those angles to cut ( and sketchy plans )

 

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For the curve I found my center, ran a string for the radius and drew a curve with a pencil.  Followed with a cordless jigsaw (take it slow).  Not perfect but sander cleaned it up. 

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1 hour ago, gazzamongo said:

Thats definately a big attraction of the design* ( in conjunction with the expected performance ) . what is the go to method for a nice neat curve on the mouth section? Router on a 4 ft radius arm ? default_smile.png

 

 

 

 

 

* though about making a university classic dean. But it doesn't seem to measure better and then there's so much opportunity for failiure with all those angles to cut ( and sketchy plans )

 

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Yes. With about a 2-3 inch offset from the corner pivot point. Use a strong screw and don't worry if you puncture thought since it's behind the corner reflector.

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