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drboar

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Everything posted by drboar

  1. I had à horn very similar to LS "kuben " . In this horn thr effect of splitter and corner reflectors varied with the used driver,the same probably holds true for LS. I used double sided tape for the splitter and reflectors.
  2. Regarding reflectors I had a horn similar to LS Using a Beyma G320 driver adding corner reflectors did not to much in the 250-500 Hz range Adding a reflector at the horn split did nothing at all The effect of having both a splitter and corner reflectors was less than corner relectors alone! Using an other driver adding splitter did do a difference And having both splitter and corner reflectors added som dB from 250 to 800 Hz. These findings suggest that adding corner reflectors does not mean that you can take frequency response improvements for granted. At the time I did not have equipment to measure time domain response, now I would have done that if I had the horns still in my possesion.
  3. With such short horns and rellatively low upper cutoff horn flare really does not matter that much. I have been playing around with LS in Hornresponse and with set mouth, throat and length the horn is mosty set response wise. Flare, driver and backchamber do change it a bit but not much.
  4. I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical. The baffle will improve the low end loading of the midhorn and also work as vibration sink for the horn. If that does not work out, then go to other horns.
  5. 1. Crossbraces doghouse to sidewalls would be the first I would do. 2. Getting a flare in the cutout for the tweeter The do other things
  6. I did some measurements on adding reflectors on "Kuben" a vintage horn similar to the La Scala. 1. Bisecting reflector= minor changes 2. Reflectors at the corners= +12 dB above 1500 Hz. 3: Both bisecting reflector and corner reflectors =Back to minor changes. I also discovered that the results were inconsistent between different drivers. So the result you get with your corners and driver may not be the same as other drivers or corners. Some mesurements would be nice...
  7. I built the corner horns with the boards as straight 90 degree cuts. All compound angles with hand saw and file. Some angles not so pretty but out of sight! Used a Phyle MHC600 15" woofer. I really liked the slam and effortlessness of the horns but they really need proper corners. Concrete walls works well flimsy plaster board walls does not.
  8. Measurements were 50 cm in front of the horn with the same voltage applied to all drivers. Kuben was constructed in Sweden in the 70s with no knowledge of La Scala.
  9. If corner reflectors improve the high end response has to be tried by trial and error. Cone breakup causes the upper range to be hard to model. Below is a measurement of 3 different drivers (gamma LA1232 30 Hz Q about 0.4 and Vas 300 L and a proper PA Horn driver from Beyma. They still both work to about 1000 Hz even if he gamma should have a mass rolloff above 150 Hz... Kuben is similar but not indentical to the LS, even the 150 Hz peak is there
  10. I measured the response of a driver with a theoretical mass roll off in the 150 Hz range in horn "kuben" quite similar to LS. It worked well up to 1200 Hz at least level vise! I assume that the mass roll off stipulates that the cone works as a rigid piston and cone breakup alters the response. One way to get the LS to go a bit deeper would be to have an additional horn section extending 20-30 cm into the doghouse. Byusing two 10" driver per cabinet as drivers they would fit in a narrower part of the doghouse.
  11. The basic frequency response of the LS is determined by horn lenght (bass depth ) and mouth size (evenness). Driver chamber and throat size/flare makes minor changes. The LS will at most go down to 55-60 Hz. Depending on driver and chamber you can get the LS to start to slope below 100 Hz gently towards the cutoff or be flatter in that last octave. Download HornResponse and fiddle around with different options to simulate.
  12. Speakon connectors has been around for a long time in the pro market, there really are no reason to use anything else. That is from an engineering point of wiev but marketing like large banana post covered in blingy gold.
  13. 1. Unplug all drivers from both crossovers (remember to take note on polarity) 2.turn on the music and connect any widerange driver, old car speaker or what you have, to one crossover driver connection one by one. My guess is that one of the serial components such as the paper in oil caps has failed. You can find out wich one by simply bypassing each cap with a short cable. That also seriously afffect the working of he crossover so it is no cure for failing components! If I was you I would keep the old crossover as is (for resale value of orignial state for vintage nuts) I would also invest in a modern crossover
  14. The shortcoming of the LS is the horn length. In the Ciare B1 design the horn can be extended into the chamber by perhaps 150 mm, not much but for such a short horn everything helps. With the LS there really is not much space to do this but most of the section of the doghouse with no flare this can be done. How this section is made can affect the upper working range as well due to differences in path lengths and shape of the throat.
  15. Agree about the walls. The measurements was on Klipsch clones and the annotation is the other way around. In a proper corner with both walls concrete the horn kept going to 40-50 Hz. With the outer wall still concrete but the backwall in flimsy plaster the response below 80 Hz or so lost 5 dB. Mesurements were made 30 years ago using a Technics SH-8000.
  16. The curves below are from "Kuben" a horn similar to the La Scala horn but in this case using 12" drivers. The measurements was with the horn on a table and on axis on about one meters distance. Upper trace is Beyma PA driver Fr about 60 Hz and Qes of 0.2 a typical good horn driver. The lower trace is a Bulgarian Gamma Gamma 1231 driver, light cone very soft suspension and quite high Q (25 Hz 0.42 Qts and 340 L Vas) so the mass corner frequency is about 100 Hz. For PA use the beyma is far better more output by far for the same voltage and greater powerhandling as well. For domestic use a trade off between relative bass output and sensitivity might be scewed in the oposite direction. I am not claiming that frequency responses are everything, they have to sound good as well.
  17. I have been playing around witha LS type bass horn. The throat extends into the dog house and the driver is a 12" But it is still a short bass horn with the same mouth area as a LS. In my horn at least the basic response is set by horn lenght and mouth area. Different flares and chamber sizes does not make a big difference. These things can be used to change the knee above the high pass drop off.
  18. That is cool looking horns, I have some plans to build curved La Scala type horns, I do not know if the sound will differ but as modeled in HornResponse, the actual horn shape (within reason) have minor effects on the modeled response. So with a set lengths mouth size and throat then changing the curvature and chamber size mostly change the roundness of the knee at the high pass frequeny. BTW, do you have any ideas why 4 x 8" sounds cleaner than one 15"?
  19. Cleaning up the seals and also add some crossbraces to the side walls as per Volti http://www.klipschupgrades.com/lascalaupgrades2.shtml That horn slam is addictive
  20. Regarding corner reflectors. I did some experiments on vintage horn "Kuben" very similar to but not inspired by the LaScala. I tested a slew of drivers and adding corner reflectors (attached by double sided tape) was beneficial to some driver, harmful for some and, did nothing for others. Above 300Hz cone breakup causes different effective pathdifferences for different drivers (I assume) and the complex bouncing around can either add up or substract with or without those reflectors. An optical reflector like a mirror is easy to grasp but accoustic reflectors does not behave in quite the same manner. Vibrations in the sidewalls is a problem If I was to build them with no braces I would work with laminating two different materials rather than doing brute force things like 30mm MDF.
  21. Have you seen this crossover update? http://www.troelsgravesen.dk/JBL_L100.htm
  22. Calculate 1.the chamber volume 2. Horn lengh 3. Mouth area 4. Throat area Play around in horn response and you will discover that flare does little to change the bass. Parabolic section, conical, exponential or hyperbolic change some few dB and the roundness of the high pass knee. The chamber volume changes that roundness to. The low pass frequency is determined mainly by lenght of the horn and the unevenness/"peakyness" of the response is set by mouth area and radiation angle. Curvature and implementations of slots and bends will affect the real life low pass response but will do little in the bass response.
  23. Bruce Edgar studied the "rubber throat" of the Klipsch and concluded that the throat constriction was changing path lengths for the driver-horn start and that this benefical for the output in the upper range of the horn. If that still holds true and how driver dependent that is I have no idea.
  24. Braces like these http://www.voltiaudio.com/newsletter/NL8.shtml
  25. I tried out corner reflectors (Kuben in diyaudio forum) and the result varied with different drivers. I expeced the reflectors to allways improve things but it did not. My guess is that there was different breakup pattern in different drivers so different phase shift was introduced already on the way into the horn. The shift in phase beaviour with the added reflectors could then be benefial or harmful interference.
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