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

[davewantsmoore 30]

So it will be a bit like this?

 

I came very close to building a horn like Martins (the one in your picture).

 

It just didn't fit very well in my space....   I guess it depends strongly if you want to utilise a little more floor space, or more space above the horn.       (Obviously, as I went for a QP-like design) I really like the idea of laying the folded path down on the ground.

 

 

When CJ said "L shaped" .... I always imagined it was meant like shown in post #872

[davewantsmoore 30]

I would love to see a DIY of the Danley SH-50.

 

I tried  (well, a two way version).    Without a CNC, or a some really nice shop tools, it is the biggest PITA that could be imagined.

 

When some other guys nearby in southern Australia offered up a team to work on a plastic (moulded) horn using similar ideas .... I jumped at the chance, and stopped having nightmare about making 13.7 degree angles using my handheld circular saw.

 

http://redspade-audio.blogspot.com.au/2012/12/s3-prototype-complete_7808.html

[Mariusz_ 61]

 I want to try and built a bass only version with two 15" drivers. It's an amazingly small horn for what it does. I want to match a pair of K-402's with an upsized verion of  that bottom before I do another Quarter Pie as it will be more challenging and interesting.

 

Claude, what do you think about this modification?

By top loading and lenghtening the tube we could go down to 35-40Hz and still reach 350Hz.

I made a simple model and simulation (Kappa 15C in regular and extended top-loaded QP).

[ClaudeJ1 1690]

Claude, what do you think about this modification? By top loading and lenghtening the tube we could go down to 35-40Hz and still reach 350Hz. I made a simple model and simulation (Kappa 15C in regular and extended top-loaded QP).

 

Very Nice. It would leave room for a treble section on top and in front of rearmost section and probably negate a subwoofer for most music. Plus you could make any size rear chamber for any woofer. You are very clever. 

Edited January 4, 2016 by ClaudeJ1

[Mariusz_ 61]

I have just calculated expansion curve for Kappa 15C and flare 35Hz. The best height of the horn is about 25 inches. It does not look so cool as flat QP but gives nice response.

 

For other woofers with smaller optimal throat area

expansion curve may fit to 17 inch tall QP (like Precision Devices PD.153 ER which I modelled also).

 

Anyway, 100 inches long horn sounds appealing. I think I will make one and check it with ears :-)

 

 

black: top-loaded tall QP with Kappa 15C (25 inches)

grey: top-loaded flat QP with Kappa 15C (17 inches)

Edited January 4, 2016 by Mariusz_

[ClaudeJ1 1690]

I have just calculated expansion curve for Kappa 15C and flare 35Hz. The best height of the horn is about 25 inches. It does not look so cool as flat QP but gives nice response.

 

For other woofers with smaller optimal throat area

expansion curve may fit to 17 inch tall QP (like Precision Devices PD.153 ER which I modelled also).

 

Anyway, 100 inches long horn sounds appealing. I think I will make one and check it with ears :-)

 

 

black: top-loaded tall QP with Kappa 15C (25 inches)

grey: top-loaded flat QP with Kappa 15C (17 inches)

Nice work. The "cool" look of the Quarter Pie, was somewhat accidental, since all I did was radius the wood to create an effectively longer horn path down the center and create less wasted lumber. I had a double stacked MWMs, which became a single stack without audible penalty in the bass. So the idea of the Quarter Pie was to not waste any floor space and only losing 6" or horn length. The results speak for themselves.

 

I'm glad to have inspired some variations and experimentation (isn't Hornresp fun!) in the quest for better bass, which is the most expensive and difficult part of sound reproduction.

 

I really like what you are doing as it would eliminate a subwoofer. My sub setup is flat to below 20 Hz.in the current room, but for music, diminishing returns set up quickly below 35 Hz., and your design would take you down to below that (33.74 in quarter wave terms to -3 db)

 

Like Einstein said, things should be as simple as possible.

Edited January 5, 2016 by ClaudeJ1

[ClaudeJ1 1690]

I would love to see a DIY of the Danley SH-50.

 

I'm thinking a 40x40" mouth (basically scaled up from 28x28 of the SH-50). Using either 4 Twelves instead of two, or two fifteens. We shall see. Have to build do a Xover for the TAd 4002's first. Bass only for the Danley derived cabinet..

Edited January 10, 2016 by ClaudeJ1

[Chris A 2579]

I'm amazed at the 40 Hz. bass from Danley SH-50 synergy horns. Audyssey crosses mine at 40 Hz. to subs. Probably because room simulations show a peak at that frequency. The Danleys have too much bass in my room and must be EQ'd down...

 

...I want to try and built a bass only version with two 15" drivers. It's an amazingly small horn for what it does. I want to match a pair of K-402's with an up-sized version of  that bottom before I do another Quarter Pie as it will be more challenging and interesting.

 

I've got some insight to this-first hand..and with data.  I think you will be surprised if you do that. 

 

If you're interested in that discussion, you can start another thread on that particular topic (K-402s and 15" woofers in a multiple entry configuration), or you can PM me.  It's pretty interesting.  I think you've got over-EQ issues that Danley put into their passive crossovers for half-space or full-space use.

 

Chris

[Ron E 571]

 

I'm amazed at the 40 Hz. bass from Danley SH-50 synergy horns. Audyssey crosses mine at 40 Hz. to subs. Probably because room simulations show a peak at that frequency. The Danleys have too much bass in my room and must be EQ'd down...

 

...I want to try and built a bass only version with two 15" drivers. It's an amazingly small horn for what it does. I want to match a pair of K-402's with an up-sized version of  that bottom before I do another Quarter Pie as it will be more challenging and interesting.

 

I've got some insight to this-first hand..and with data.  I think you will be surprised if you do that. 

 

If you're interested in that discussion, you can start another thread on that particular topic (K-402s and 15" woofers in a multiple entry configuration), or you can PM me.  It's pretty interesting.  I think you've got over-EQ issues that Danley put into their passive crossovers for half-space or full-space use.

 

Chris

 

I think it would be nice to hear what you have to say about this Chris. I am not as technical as most others, but I would love to know more about this.

[Chris A 2579]

I'll start a new thread under the Technical/Modifications subforum since that subject is really off topic for this one.  I need to think about how to approach the topic a little, since it has a lot of potential to challenge conventional logic about horn-loaded loudspeakers.

 

Chris

[ClaudeJ1 1690]

A full horn load like the Quarter Pie gives about 104 db/watt, just like a Khorn or LaScala.

[ClaudeJ1 1690]

So, Mariusz, will you be building your new horn prototype?

[Mariusz_ 61]

I will, but now I am still comparing different ideas switching among Hornresp, my spreadsheet for horn equations and SketchUp trying to avoid 180 degree folds. On the other hand the bottom end of my project is that I am very glad of my current setup of QP+THT. There is simply not too much marginal return to achieve.

[ClaudeJ1 1690]

I will, but now I am still comparing different ideas switching among Hornresp, my spreadsheet for horn equations and SketchUp trying to avoid 180 degree folds. On the other hand the bottom end of my project is that I am very glad of my current setup of QP+THT. There is simply not too much marginal return to achieve.

I know, it's hard to beat. My current Synergy horns and tapped horn subs are simply a little bit more wonderful in a smaller package, but if your throw the money spent into the equation, what you have now is a much better VALUE in terms of sound per dollar at low distortion and high dynamics.

Edited January 26, 2016 by ClaudeJ1

[gavaets 0]

I have just calculated expansion curve for Kappa 15C and flare 35Hz. The best height of the horn is about 25 inches. It does not look so cool as flat QP but gives nice response.

 

For other woofers with smaller optimal throat area

expansion curve may fit to 17 inch tall QP (like Precision Devices PD.153 ER which I modelled also).

 

Anyway, 100 inches long horn sounds appealing. I think I will make one and check it with ears :-)

 

 

black: top-loaded tall QP with Kappa 15C (25 inches)

grey: top-loaded flat QP with Kappa 15C (17 inches)

Hi guys.

First of all would like to thank Claude for his amazing work and sharing with us his knowledge and experience. I was looking for bass horn under my Synergy PSE144 for about six months and have build quiet numbers of BPH, FLH, RLH, Scoops, PPSL, Karlson 12 and 15, Altec 7 etc, Including EXTRO, Cubo, hybrids and others.

 

As for now, under 350hz., I use double Hypex 70, but comparing to Altec 7, there are some compression and missing passages. I don't want to use 12" anymore, I feel 15" will do the work much, much better. Maybe even some 18" like those JBL2240 in Inlow sound 80hz horn.

I was sure that I have to use separate midbass horn with lowest knee possible and was lucky to find Claude horn.

But now, reading Mariusz post about the 35-350hz horn, I'm begining to believe in magic again. So, as soon as there are gonna be measurements, I gonna built one!

 

P.S. There is a question: -  it's more than 3 octave horn, should we consider a high Xmax woofer? Like 7-9mm? 

Thank you, guys!

Edited January 30, 2016 by gavaets

[davewantsmoore 30]

Wow.  You have built lots of boxes.

 

With my PSE144 I have only tried a normal sealed box 15", and a QP-style horn  (it is very good).

 

 

P.S. There is a question: -  it's more than 3 octave horn, should we consider a high Xmax woofer? Like 7-9mm? 

Thank you, guys!

 

I don't think so, unless you need to play very loud.    I use a 6mm driver, but < 2 would be more than enough.

[Mariusz_ 61]

The above showed were my first simple calculations.

 

Now, to be more formal, for Kappa 15C it looks like this:

 

St=72 inches

Fo=37Hz

m=0.52

Sm=1325 sq inches (corner placement)

Vb=40 litres

 

So expansion area is:

 

x      Area

0      72,0

10    87,9

20    111,2

30    144,6

40    192,2

50    259,7

60    355,2

65    416,8

80    680,5

90    949,3

100 1328,7

In Hornresp it returns nice freq and SPL <chart 1>.

 

And now the most difficult task: folding. This part is still under development :-). One of the trials is showed below. When simulated in Hornresp it returns <chart 2>. Still not bad but Hornresp knows nothing about 180 degree fold. 

 

The other way is to build a "chimney". It would be simpler, for me to make it, for air to move through only one 90 degree fold. The height including back chamber is 100 inches.  

Edited January 30, 2016 by Mariusz_

[Coytee 2292]

Currently working on a symmetrical "L" version of the Qpie

 

Nice, so Qutie Pie is going to have a big sister, Lillie Pie!!

 

    

[ClaudeJ1 1690]

The other way is to build a "chimney". It would be simpler, for me to make it, for air to move through only one 90 degree fold. The height including back chamber is 100 inches.   Attached Thumbnails

 

What you call the "chimney" was to be my "L-horn" and that would be my simpler/preferred solution. I still prefer a subwoofer below 40-80 Hz. to get down to the high teens or 20 Hz. The lower you go, the more expensive it gets. I spent roughly HALF of my HT system money to get lots of cubic feet of TH cabs, large excustion drivers, and kilowatts of amplifier power to those house shaking note to play right. So keeping it to Quarter Pie length was all I needed to do and separate the super low stuff, the way you did also.

 

Although instead of your chimney I still would have made the core section identical to the Quarter Pie/Klipsch MWM and simply create a symmetrical 90 degree fold, which is what you have done. That way, the higher frequencies remain symmetrical in their dispersion while they don't matter much in the lower octaves. 

Edited January 30, 2016 by ClaudeJ1

[ClaudeJ1 1690]

P.S. There is a question: -  it's more than 3 octave horn, should we consider a high Xmax woofer? Like 7-9mm?  Thank you, guys!

 

 

You are welcome. BUT, I prefer low Qts 15's and subs below 60 hz. it's a much better sounding approach. This was the original design intent and it was realized in the simplest way possible at the time.

Edited January 30, 2016 by ClaudeJ1