drboar
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Posts posted by drboar
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Up to 80 Hz or so speed is not an issue. Volume displacment is a 6.5" cone van move at 20 Hz but Will have a hard time generating audiable output.
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With blue tooth headphones lossy compression is needed, but otherwise? My iPhone has 256 GB thats a lot of music even with just lossless compression.
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Two miniDSP HD?
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30 years ago I measured my DIY klipsch corner horns. In My first apartment I had proper concrete corners (walls floor and ceiling. In the next one of the walls was à light drywall that was à 6dB loss across the bass below 100 Hz or so.
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As far as simulations in HornResponse changing the flare has very minor effects on frequency response. With the driver filling the with of the doghouse thicker doghouse it will increase the horn path a little. Simulations does not tell the whole story but still.
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As I recall radiation angle affect the needed mouth area not horn length. There is some effect of the end correction that extend the accoustical lenght a bit in a corner compared free field.
Very nice video and a very nice kit where all the parts snaps together. As I live in Europe shipping a kit would be way to expensive so I will do my own interpretation if I build the horn, but that does not diminish the joy of looking at the video.
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Looking at the horns makes me wish that I had not reduced my collection of 12" drivers
On the other hand I have modeled the LaScala and other in HornResponse, there horn lenght is critical for where the high pass occurs. The JWC looks really short something like 50cm or so (thats 20" in imperial units) Then the horn should start dropping at 140 Hz or so??
The scientist in me wants to how the horn work to get down to 60 Hz!
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This is the response of Beyma, Fane and Eminence PA drivers a vintage Isophon and Gamma Bulgarian driver, the last one with a Fr of 28 Hz a Q around 0.4 and a Vas of 300 liter no less! All mounted in Kuben a La Scala look alike. they all reach to arund 1 kHz despite having mass roll offs way lower than that.
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Faital Pro LTH102 have a very good reputation and can be streched toward 600 Hz in a baffle and in a domestic setting. The larger LTH142 can go lower still. Both need some adaptors as the Selenium is a screw on driver. How well those adapors work I do not know.
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I would go for the active. But you could try some simple steps to cut out some midrange
Mechanics.
1.Add some space in front of driver by adding a baffle the front chamber will add some low pass.
2. Add som fiber wadding in front of driver
Crossover
3. Add a zobel link to the bass driver, it will improve the action of the coil
4. Add a cap to get a 12 dB action
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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.
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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.
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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.
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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.
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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
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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...
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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.
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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.
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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
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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.
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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.
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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.
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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
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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.
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JBL 2446H vs Selenium D4400ti
in Technical/Restorations
Posted
As far as smoothness goes it is strongly impacted by curves "in the nude" or smoothed curves. In my setup I can diplay cuves au naturel warts and all. smoothing over 1/12 octave all the way to smoothing to running averages over octave windows.
The overall response is then dependent on which horn that is used with the driver.