cradeldorf Posted July 2, 2015 Share Posted July 2, 2015 (edited) Okay I have been toying around with a modified LaScala horn idea and I have a question. If a LaScala stops being a Horn at 104 hz is it because there is only one actual taper between the side wall and the doghouse? Heres my thought and correct me if I'm wrong but the distance from the side to the doghouse at the very mouth of the horn is only so many inches, But the distance between the top and bottom of the cabinet is a much larger difference so if you were to taper the top and bottom from nothing at the mouth to a smaller dimension at the back of the cabinet wouldn't it in essense be a larger horn which would then play lower? And, If the side and the doghouse create a horn then wouldn't the top and bottom also create a horn if they were tapered? And if the top and bottom taper at the back of the horn started at the same height as the side to doghouse left off at..... wouldn't it kinda work like a doubled up two horns in one? My plan is to use a Dayton Pa 380-8 15" pro woofer. I also have it designed to be a ported Doghouse where the the very point of the doghouse is sliced off leaving an open slot port the entire height of the doghouse. Here is a rough draft of where I'm at, It's not very informative at this point. The throat is still 3" wide by 13" tall. Doghouse is 18" wide by 18" tall by 18"deep. Edited July 2, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
Don Richard Posted July 2, 2015 Share Posted July 2, 2015 Okay I have been toying around with a modified LaScala horn idea and I have a question. If a LaScala stops being a Horn at 104 hz is it because there is only one actual taper between the side wall and the doghouse? Heres my thought and correct me if I'm wrong but the distance from the side to the doghouse at the very mouth of the horn is only so many inches, But the distance between the top and bottom of the cabinet is a much larger difference so if you were to taper the top and bottom from nothing at the mouth to a smaller dimension at the back of the cabinet wouldn't it in essense be a larger horn which would then play lower? And, If the side and the doghouse create a horn then wouldn't the top and bottom also create a horn if they were tapered? And if the top and bottom taper at the back of the horn started at the same height as the side to doghouse left off at..... wouldn't it kinda work like a doubled up two horns in one? My plan is to use a Dayton Pa 380-8 15" pro woofer. I also have it designed to be a ported Doghouse where the the very poin for exponential hornst of the doghouse is sliced off leaving an open slot port the entire height of the doghouse. Here is a rough draft of where I'm at, It's not very informative at this point. The throat is still 3" wide by 13" tall. Doghouse is 18" wide by 18" tall by 18"deep. A bass horn's low frequency response is determined by the throat size, taper rate (length to double cross sectional area for an exponential horn), horn length, and mouth size. Modifying a LaScala throat tapers as you have outlined won't lower bass response. You could port a LaScala to get it to go lower or add a subwoofer. 1 Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 2, 2015 Share Posted July 2, 2015 I have plans from Dana at Soniphase (the SL6), that uses a single 15, with the ports exiting in the horn. The cabinet is a tad wider than an LS, about the same height, for just the bass. This makes the horn mouth slightly larger, plus the porting, has am fc of 35Hz, depending on the driver. I really am as excited about building these asi am about finishing porting the beater pair of LS is have. Bruce 1 Quote Link to comment Share on other sites More sharing options...
Mariusz_ Posted July 2, 2015 Share Posted July 2, 2015 (edited) It is right discussion to ask about something. I am going to build a pair of La Scala bass bin. I have found a plan that is slightly different from LS 1 and LS 2. The most important difference is internal width dimension. It is 590mm instead of 565mm (23 1/4 instead of 22 1/4). Motorboard is also a bit wider (15 9/16 instead of 15 1/4). Will this changes be audible? I hope not because I want to get LS sound. The plan: http://www.mh-audio.nl/plans/other%20plans/La%20Scala%20Horn.pdf Edited July 2, 2015 by Mariusz_ 1 Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted July 2, 2015 Author Share Posted July 2, 2015 (edited) My assumption was that since the top of the cabinet and the bottom of the cabinet are Parallel they are not a horn... and from looking at actual LaScala plans theres a section of the horn that is not a horn as they are both Parallel. I'm speaking of the sides of the doghouse way in the back which are parallel to the sides of the cabinet. Edited July 2, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
djk Posted July 3, 2015 Share Posted July 3, 2015 The basic taper rate is 100hz or so, the area doubles in 8 inches. If you expect it to go lower, it has to expand slower, the Klipschorn is about 16 inches. . 1 Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted July 3, 2015 Author Share Posted July 3, 2015 (edited) Okay I get where your coming from, now if I tapered the top and bottom of the horn from 18" tall at the mouth to 13" tall at the throat then wouldn't it play lower because the taper is so much more shallower that the side to doghouse taper? If I drew a line down the center of the horn path in my design it would be approximately 28" long and would taper 5 inches in that 28" path. which should make it play lower? is that right? Also wouldn't the elimination of any parallel surfaces be a gain on sound as all they do is create the standing wave, boxy, tubey sound? By tubey I don't mean tube amp but paper tube when you talk through one. Edited July 3, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 3, 2015 Share Posted July 3, 2015 Will this changes be audible? I hope not because I want to get LS sound. I believe the difference will be negligible. Attached is a pdf of drawings made by a former Klipsch forum member. He took measurements from different LaScalas to make these drawings. You could also build the Peavey FH-1 cabinets for pretty much the same sound. The FH-1 drawings are in metric. Bruce LaScala.pdf peavey FH-1 plan drawing 3 April 2012.pdf 1 Quote Link to comment Share on other sites More sharing options...
Guest David H Posted July 3, 2015 Share Posted July 3, 2015 My assumption was that since the top of the cabinet and the bottom of the cabinet are Parallel they are not a horn That isn't the case. The area of expansion from throat to mouth makes it a horn. The rate of expansion determines the type of horn. (over simplified) Parallel surfaces can be a nuisance when building a horn, but acceptable. Check out Smith Horns. Dave 1 Quote Link to comment Share on other sites More sharing options...
Islander Posted July 3, 2015 Share Posted July 3, 2015 (edited) There's something you missed. The back part of the La Scala cabinet is not straight. There are inserts on the top and bottom of the back wall, called "chevrons". These form the tapered shape of the horn as soon as the wave reaches the back wall, and continue until they reach the sides of the doghouse. You can't see them directly from the front. Then the sound wave hits the straight part, and then passes through the second tapered part of the horn, the front vee. There's also a vertical wedge-shaped piece on the back wall facing the slot that directs the sound to the left and right. This picture of a La Scala II with the back wall removed shows the chevrons very clearly: Edited July 3, 2015 by Islander 1 Quote Link to comment Share on other sites More sharing options...
Islander Posted July 3, 2015 Share Posted July 3, 2015 My assumption was that since the top of the cabinet and the bottom of the cabinet are Parallel they are not a horn... and from looking at actual LaScala plans theres a section of the horn that is not a horn as they are both Parallel. I'm speaking of the sides of the doghouse way in the back which are parallel to the sides of the cabinet. If you look closely at the top left and bottom left diagrams in your 4:20 pm post, you can see the vertical wedge and the chevrons. In the bottom left diagram the chevrons are numbered 2 and the wedge is numbered 3. Quote Link to comment Share on other sites More sharing options...
drboar Posted July 3, 2015 Share Posted July 3, 2015 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. Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted July 4, 2015 Author Share Posted July 4, 2015 (edited) There's something you missed. The back part of the La Scala cabinet is not straight. There are inserts on the top and bottom of the back wall, called "chevrons". These form the tapered shape of the horn as soon as the wave reaches the back wall, and continue until they reach the sides of the doghouse. You can't see them directly from the front. Then the sound wave hits the straight part, and then passes through the second tapered part of the horn, the front vee. There's also a vertical wedge-shaped piece on the back wall facing the slot that directs the sound to the left and right. This picture of a La Scala II with the back wall removed shows the chevrons very clearly: mine will have the same things, that is a good picture though but after studying the original plans I figured out they were in there. I'm thinking of casting the top and bottom, back and sides in concrete. The only thing that will be wood will be the doghouse. Mainly because doing the taper on the top and bottom would be easiest that way. Also my design has a constant taper with no parallel sides anywhere in the horn path. Not sure if it a concern in the LaScala as the area's that are parallel are fairly close together. Not sure if standing waves would create a problem. Plus in the original Lascala plans you'll see 7.5 inches of nothing but straight sides with no taper to them after the sound rounds the corner and starts heading out the main horn. Hmmm I just realized my horn length is only 28" long where the original is 35" but if you subtract the 7.5 inches of no horn in the lascala they equal out.. Edited July 4, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted July 4, 2015 Author Share Posted July 4, 2015 (edited) 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. Even if the doghouse is ported out the front? I drew the port size to be equal in square inches to the throat size. Port size will be 18 tall by 2.170 wide Edited July 4, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
moray james Posted July 4, 2015 Share Posted July 4, 2015 the parallel section does no harm but it does add length so why would you intentionally make your horn shorter? That would be very counter productive.Standing waves excited by what at that frequency (given the dimensions) not the K33. Time for a cup of coffee. Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted July 4, 2015 Author Share Posted July 4, 2015 (edited) I was hoping to run my design up to 3000 hz before switching over to the HF. I'm planning on using a Dayton P380-8 driver in it. Edited July 4, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
djk Posted July 4, 2015 Share Posted July 4, 2015 "I was hoping to run my design up to 3000 hz before switching over to the HF." Not going to happen. The main limitations are the mass corner of the driver, and the cross-section of the bend. Quote Link to comment Share on other sites More sharing options...
Islander Posted July 4, 2015 Share Posted July 4, 2015 Bass notes go around corners without much difficulty, but fewer corners are better, thus the Jubilee bass section has fewer turns than the Klipschorn, and the MWM has fewer turns than the Jubilee. Not so with treble notes, which is why treble horns are always straight. Sending music in the 1000-3000 Hz range through the La Scala bass bin would probably not sound as good as you hope it would. Quote Link to comment Share on other sites More sharing options...
moray james Posted July 4, 2015 Share Posted July 4, 2015 http://www.audiokarma.org/forums/showthread.php?t=287479&page=8 Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 4, 2015 Share Posted July 4, 2015 (edited) Well, I can't agree with djk about a 100 Hz Fc. It is more like 62 Hz. I pointed this out in a previous post. https://community.klipsch.com/index.php?/topic/156947-exponential-horn-question/ Not mentioned there is the mouth size issue for the LS. At one time I looked at optimum mouth size as predicted by Don Keele. My calculation was that the four square feet was about optimum for placement in a corner. It seems to me that PWK must have designed for this. (Correction: I just recalculated this and find that optimum in a corner for a 62 Hz horn is 1496 square inches, but the LS has a mouth area of 576 square inches. Maybe I'll start with a fresh sheet of paper some time in the future and try again.) IMHO, the performance of the bass horn is very greatly influenced by the length and mouth size. Therefore, small changes in the profile along the path can't make things much better or worse. As I've said, "You can't make things better by solving a problem which does not exist." OTOH, we all welcome tinkering. WMcD Edited July 5, 2015 by William F. Gil McDermott 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.