Valde

Hi, The woofer I will use is the same as I'm using now in my corner speaker, the JBL K-145. It has a very light diapragme and is able to go >400 Hz. The reason for trying other cabinets is also to flatten the response from 100 to 500 Hz as good as possible. I guess my woodwork is to claim for my current response [:$] Anyway what is the drawback if the flare rate is not maintained? My opinion is that the throat vs. mouth size is settled and then the "road" to the mouth is done as a exp. development so this is it or....? Anyway I will keep you updated in the building progress which should start within 30 days..... Regards Valde

Yes, that also what I belive would be the case. If I do the resizing it will still obey the exponential development and the benefit will be, that the horn will be some 15 to 20 cm longer (haven't done any cal. yet) and more interesting the mouth will be considerable biggere. As I understod the horn stuff the start and end area is of great importance (of course also the exp. dev. in the horn). I like the look the LS has and also the possibility to build in my midrange (WAF) I have done the Ascent V2 which is a design Dana Moore did for some 3 years ago (I have posted my construction of it in the diy area). A modified K-horn. Here the midrange is on top (low WAF).This horn, due to corner placement, hase a very powerfull lowend <45 Hz. For the LS what is the low end here? Reg. Valde

Hello, I have a question regarding the La Scala model. For the moment I'm using a JBL2350 mid horn (80cm wide) for my AscentV2 corner speaker (Dana Moore's). The La Scala model is around 60cm wide. Do the forum think that it will give a reasonable result if I do some scaling so the wide of my future La Scala cope with the 80cm wide mid horn. So to say I will "stretch" the numbers on the drawing, keeping the angle in the horn throat and just prolong the lines in hight and wide. The dept will I keep. Any thought about the fn of this "tweaking"? Regards Valde

Hi TC, I dont think your 2404 polarity is of any concern because the wave, from the mid's at crossover, had traveled several wavelength before it end up at the front of the mid horn. If you has placed the tweeter right here I think your ears should tell you what polarity you want. If the voice coil is placed side by side I guess it is another story [] Regards Valde

Maron, Thanks for your information regarding the smith horns. Yes the JBL way of doing the vanes is completely symmetrical. Although I do belive in that construction because the mathmatical "fail" compared to a true exponential development is very small. As I understand the horn performance is the way from straight, conical and (hyp)exponential only a matter of performance at the low end which means the so called roll off. JBL did do a kind of overhang and I think that this was done to compensate or improve the horn at the low end ;-) And yes I have "smoothed" the vanes as much as possible. I have the possibility to put them in a anechoic chamber and see how they will performe, when I'm finished with then. for now I will enjoy my rock music (the last half year I have been doing tweaking and listening in relation to the x-over filter). Can you post a picture of the wide horn you have, I'm very curious about it and I will also return when I do some progress with the Smith's [] Regards Valde

Hi, Yes my scaled version is on hold although I nearly has all the parts. No, the internal flares is done by me with a jig saw (stiksav) covering a radius of 104 cm. The ones from Martinelli is designet to fit to a replica of the Smith horn (JBL2397). I have scaled the horn 200 Hz below the original, that means the internal flares has a length of 34 cm instead of the 20,5 cm in the original. The horn will be to wide if I completely follow the overhang JBL has done (from the flares to the mouth of the horn) so I will make a compromise around 1m wide (overhang equals flare length/4 instead of flare length/2 as JBL did). Flemming

Did, by accident, post a replica of the previous ;-)

Happy newyear, There has been some progress in my project (Dana's V2 bas bin). The JBL2380 horn has been retired and the replacement is at the moment JBL2397. I wrote at the moment because I plan to do a scaled version of the JBL2397, which will go 200 Hz lower. But to the sound of my system. Just after newyear I did change my x-over filter from 750 Hz to 500 Hz. The sound did change dramaticlly. My very first impression was that the combined system was even more wider in the sound. I would say that the sound has now a very impressive spatial "body" which are completely in-line with my taste. Again, I would say that the bas bin is some of the best I had ever build in my 25 year's dedication to Hi-Fi. The low end is VERY powerfull and dynamic. This earlier mentioned "booming" I have written about is completely surpressed, I can't hear it and the only "noise" I have in the system is 50Hz from my valve amplifier and some notes due to the shape of my livingroom. Some of the notes is supressed by a notch designet to work at around 150 to 225 (4dB down) The result of the change to 500 Hz is a confirmation to Dana's theory about the mouth reflections and subtraction of higher frequencies, from the woofer, that end up in a so called "horn" sound, but it seem that I had to go through this hi-fi work myself (recognition of the ability, not to run to high in a front loaded enclosure) and do have a better understanding today ;-) Some people on the net claim that the mid horn (JBL2397) is not able of running at that low frequency but to my ears it sound very nice to me.The horn has a incredible spatial performance (140 degrees) and if you run over such a pair, buy them (they are easy to get rid of again!). They are very flat from 500 to 10000 Hz. So I'm a very happy Hi-Fi nut ;-) Best regards Flemming P.S I can't remember how to upload a picture of my mid's and high. Dana if you are able of uploadning the 10-12-06_1247.jpg picture in a earlier mail then feel free ;-)

Thanks, for you comments Armando [] I can understand that you are doing some horn construction/building and in relation to that I will ask if you have any construction plans, you will share, or know somebody who have plans for a midrange horn in the range of 700 - 7000 Hz using compression drivers? My midrange is "rolling" off at both ends! Flemming

Yes, the sidewall's is actually vibrating much more than I had expected! My experience with the enclosure is that it is very stable and do not vibrate in a way as a closed box cabinet. I forgot to add that these speakers ARE able of doing low end work. Dana say's the fc is 40 Hz, but in my living room I am happy to find output even lower than that (30 Hz with considerable output, tested both with music and testtones). Flemming

The next trial is ongoing now and is tweaking around with a notch filter with the center around 150 Hz. Simulations show that I can control the level of the band of interest (150 - 400 Hz) by some dB's (6 dB right now). I'm not finished with this yet but for K145 and the horn this has helped alot on the "booming". I have also heard that the K145 is a underhung voice coil speaker and this type has the tendency to do so ? I'm very happy with the construction and sound. Dana has done a great job here. This was a long "run" to put the pictures on the forum and I hope someone find it interesting. Later on I think more will be added when it come to my mind!! [] Flemming

So the sound is very tight and dynamic just as i want it. After some long listening I realized that there was some "booming" in the area of 150 - 400 Hz. I has made a CD with different test tones and has run through it. I did put some "Wannabe wool" inside the back chamber but this didn't help the problem.

Inside the Topbox:

The X-over is a linkwitz-reiley 24dB/oct. This picture show the schematic. The crossings is at 750 Hz and 7000 Hz.

And after another hard work a top box was designet to put in the mid horn and the tweeter. The plan is also to have the X-over located here.