Tom Danley wrote on Tue, 06 September 2005 14:38 |
Hi The only Tapped Horn comparable in size to the Lab sub is the Vortex, also a Tapped horn which is a little smaller (42 by 42 by 22 ½ in). Multiple Vortex’s in a 2X2 , 2X3, 3X3 array would have forward directivity due to the frontal area BUT requires a crossover below 90-100 Hz due to the spacing between outlets. |
Tom Danley wrote on Tue, 06 September 2005 21:38 |
Hi The TH115 is a very modestly sized bass enclosure, which uses a 15” driver in a new type of low frequency horn I developed called a Tapped Horn. Your observation about the mouth area being small is correct, the advantage of the Tapped horn is that it allows a significantly smaller horn to be used than normal. How you ask? AS you make the horn mouth smaller, one finds ripples in the frequency response, which inversely coincide with peaks and dips in the impedance curve. These reflect a greatly changing acoustic load on the driver. With the Tapped Horn, the driver source impedance to the horn is made to change with frequency also, in a way that can largely adapt to the changing horn load, at least over the bass range. This is done by having both sides of the driver, driving the horn but from different points on its length. You will notice that even with one TH115, the normal ripple one would expect in a horn that small is not present. A more extreme case is the PB-12 which has a Teeny Tiny mouth but still lacks the traditional ripple pattern. So far as the LabSub, it was pretty much as much as I could get out of that size box and cutoff, going as far as seemed safe with driver parameters. Even now some years later, the Lab 12 driver is one beefy driver. The only Tapped Horn comparable in size to the Lab sub is the Vortex, also a Tapped horn which is a little smaller (42 by 42 by 22 ½ in). I couldn’t find the measurements someone sent me of their single Lab @ 1meter but one for one the Vortex would have less ripple and greater sensitivity. Once you had say 6 Labs (where the mouth is big) then they would be about 50% efficient and would be hard to beat electroacoustically. Multiple Vortex’s in a 2X2 , 2X3, 3X3 array would have forward directivity due to the frontal area BUT requires a crossover below 90-100 Hz due to the spacing between outlets. A 2X2 array would have about 10 dB of apparent gain on axis added to the sensitivity mid band in addition to a higher over all efficiency. We do not have measurements for that case yet however. In another thread there here is a discussion about spec’s. The curves on our web site are TEF measurements, taken in a conservative way by driving the box in half space at 100W and at a microphone distance of 10 meters. This removes the errors present if one measures a large speaker up close at 1 meter and the 10 meter distance is –20DB from 1 Meter but the 100W level is + 20dB from 1 Watt so the result is a conservative 1 Watt equivalent. These are what anyone else will measure if they do the same test, no magic or BS. Numbers are for designing so they should be accurate but listening is what really matters, I think you would be impressed with the sensitivity, sound quality, output and weight of the TH115….but how else could I feel ha ha.. Your best bet is to call Mike and see about getting some demo’s, nothing beats first hand comparisons. Hope that helps Tom Danley |
Walt wrote on Thu, 15 September 2005 04:46 |
No, The Funktion One Infrabass is a fourth order bandpass. It has two closed chamers for the 18" woofers. The middle chamber works both as a chamber as port. In all Funktion One products the back of the driver is contained in a closed volume. Off course there is a reason to do that. Best regards, Walt |
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BP4 lends itself to average sensitivity |
Johan wrote on Thu, 15 September 2005 09:41 | ||
With BP 4th (and 6th) order you can choose between an average sensitivity with large bandwith and high sensitivity with a small bandwith. It probably uses two costumdrivers with low fs and high Vas. With the frequency band optimised between 30 and 60 Hz. Still it's quite much. Mvg Johan |
snowflake wrote on Tue, 20 September 2005 08:03 |
I have been trying to figure out what is happening inside the tapped horn designs for a while. On a few of the pictures you can see either where one side of the driver is mounted near the mouth or where there is an access panel which presumably gives access to one or other side of the driver. I can't see any relation between the distance of the back of the driver from the mouth and the frequency response or impedance chart. In some of the designs the back side of the driver is so near the mouth it can't be horn loaded and its output must be insignificant compared to what is coming down the horn. I have seen a design where the back chamber has a port that enters the horn further back than the driver http://www.audioasylum.com/forums/hug/messages/87962.html but Tom Danley replied to that thread suggesting that it is difficult to load a vent with a horn because of the frequency dependent loading of a horn. Perhaps you could use several ports all loading over a very small frequency range. Perhaps the tapped horn uses several small apertures to form the horn throat. I'm not sure if it is viable but could the size of the apertures be used to offset the low impedance presented by the horn at certain frequencies? Phil |
Tom Danley wrote on Wed, 21 September 2005 12:16 |
Hi guys The PB-12 tower for example has a measured group delay which hovers around “zero” down to about 30 Hz. A vented box with the same low cutoff would already have about 10 –12 ms GD at 30 Hz. One can picture the effect of GD more clearly when you recall that this is like moving your speaker to the rear in time at a rate of 13.5 inches per millisecond of delay. |
chmed wrote on Tue, 27 September 2005 22:49 |
Perhap I'm not fluent enough in group delay but I don't understand how it can "hover around zero" when measured outside the enclosure. Isn't there some delay at least based on the distance of the driver from the mouth? |
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Does the Karlson design actually help improve sound quality. It looks like it was able to improve impedance a little. I noticed Ivan Beaver Had a few of those in his sound system back a few year ago. Anyone take any sweeps of those things??? |
Antone Atmarama Bajor wrote on Fri, 18 November 2005 14:18 |
My father was telling me about another company that was making compression driver lenses with a similar slot expansion in it. Antone- |
Ivan Beaver wrote on Fri, 18 November 2005 19:52 | ||
It was called "The tube" and came out in the late 70's. It was a horn driver with "the Tube" attached to it and it faced straight up. The tube was like a plane wave tube with a slot "looked like the carlson" cut into it. I think they didn't take off because of the lack of sensitivity. I only heard them once in a very small room with a lunatic guitar player. I don't remember how they sounded-the show caught my attention. |
Iain Macdonald wrote on Sun, 20 November 2005 00:42 |
Hi all. Now I feeling really old. My late friend Bill Kelsey used the Tube in his C System design for TFA ElectroSound here in the UK in the late 70's/early 80's. It was a 2 box system, bass and mid + Tubes. The bass had 4 x 15 reflex loaded. The top box (same size as bass) had 4x12ins and 4 Karlson Tubes with 1 inch compression drivers. The tubes were arranged alongside the 12's, vertically in two pairs with the tube ends in each pair touching at something like a 45 deg angle. The idea was to have a vertical line of bass and a vertical line of mid/hi. Yes, a line array in 1980! To me, when set up properly, it was the most hi-fi system that I have ever heard until my experience with planar/ribbon hf systems. Of course TFA had people like Ted Nugent as customers, so volume not Hi Fi was the order of the day. The only problem as I recall, was that it used EV drivers, which at the time were not the power monsters we have today. Also people would insist on stacking mid/hf cabs side by side. The dispersion of the tubes was about 100 degrees, so you can imagine what the comb filtering was like. Had to be heard to believed. Just ask Mick Whelan (EV). In the mid 80's I worked with Bill on developing a 2inch tube, but we had insufficient funds to go anywhere. Just like the compressed air powered bass cab and our early line array. A familiar tale to many, I guess. Iain. |