Hello All,
The Tower of Power caught my eye, the band is my favorite (get well soon Rocko). The white paper Rob posted reminded me of an article I read many years ago about a system a guy built in his basement with 5 channels, 3 across the front an 2 on the sides that fired toward the back of the room. The figure 5 is the one that sparked my memory. If this rings a bell with anyone let me know. I think I say a reprint on the internet once but I can't find it now.
The Tower of Power caught my eye, the band is my favorite (get well soon Rocko). The white paper Rob posted reminded me of an article I read many years ago about a system a guy built in his basement with 5 channels, 3 across the front an 2 on the sides that fired toward the back of the room. The figure 5 is the one that sparked my memory. If this rings a bell with anyone let me know. I think I say a reprint on the internet once but I can't find it now.
TAP design....
had a look at Walt's design and had a few thoughts/questions. The TAP looks very similar to a BIB except that the driver is inside the line loading both sides of the horn at two different points (throat and mouth). Both designs would appear to be conical 1/4 wave horns. The significant differences that I see (physical) are that the TAP has a definate end plate (wave reflection) which would define the length of the horn and also that the mouth of the horn is on the side (at the end) rather than directly at the end of the horn. The mouth of the TAP is small only a little bigger than the Sd of the driver by the looks of it. I am wondeing if the combination of the side firing mouth and the small mouth size are not at all unlike the configuration of the B-DEAP design? Is Tom using the nonlinear action of air to expand upon the small mouth or exit as he refers to it in the TAP also.
Thoughts and comments would be welcome. Regards Moray James.
had a look at Walt's design and had a few thoughts/questions. The TAP looks very similar to a BIB except that the driver is inside the line loading both sides of the horn at two different points (throat and mouth). Both designs would appear to be conical 1/4 wave horns. The significant differences that I see (physical) are that the TAP has a definate end plate (wave reflection) which would define the length of the horn and also that the mouth of the horn is on the side (at the end) rather than directly at the end of the horn. The mouth of the TAP is small only a little bigger than the Sd of the driver by the looks of it. I am wondeing if the combination of the side firing mouth and the small mouth size are not at all unlike the configuration of the B-DEAP design? Is Tom using the nonlinear action of air to expand upon the small mouth or exit as he refers to it in the TAP also.
Thoughts and comments would be welcome. Regards Moray James.
a couple of good links...
this is for a dual driver Jensen Transflex bass cabinet which is very similar to both the BIB and the Tapped Horn
http://translate.google.com/transla...n&u=http://www.caninialtoparlanti.it/sub1.htm
this link is for a version of the Tapped Horn
http://www.speakerstore.nl/index.php?l=en&pg=11&c=61
The Tapped horn and the BIB both would appear to be 1/4 wave conical horns which would account for tha added gain while the Transflex is a straight sided tube and so would behave more like a transmission line.
The BIB is a folded 1/4 horn with a mouth that is open at the end of the 1/4 wave distance which fires into either a wall/ceiling interface when positioned on a side wall or when positioned in a corner it has the added benefit of the extra reflective surface. So with the BIB the intent would seem to be to have a fairly compact conical horn that then uses room boundries to expand upon the flairto enlarge the overall size of the horn.
The Tapped horn would seem to differ (from the BIB) in that it has a perdetermined length which is set by the fact that the end of the horn is blocked by a solid plate and the mouth (or exit vent) is positioned on the side wall of the horn. So while the Tapped horn has a mouth it is not in the normal plane that one finds in most all horns. The Side position will allow for wave reflections from the mouth to the throat. I suspect (but could well be wrong) that this arrangement may have to do with controlling ripple in the horn response. Your comments would be welcome. Regards Moray James.
this is for a dual driver Jensen Transflex bass cabinet which is very similar to both the BIB and the Tapped Horn
http://translate.google.com/transla...n&u=http://www.caninialtoparlanti.it/sub1.htm
this link is for a version of the Tapped Horn
http://www.speakerstore.nl/index.php?l=en&pg=11&c=61
The Tapped horn and the BIB both would appear to be 1/4 wave conical horns which would account for tha added gain while the Transflex is a straight sided tube and so would behave more like a transmission line.
The BIB is a folded 1/4 horn with a mouth that is open at the end of the 1/4 wave distance which fires into either a wall/ceiling interface when positioned on a side wall or when positioned in a corner it has the added benefit of the extra reflective surface. So with the BIB the intent would seem to be to have a fairly compact conical horn that then uses room boundries to expand upon the flairto enlarge the overall size of the horn.
The Tapped horn would seem to differ (from the BIB) in that it has a perdetermined length which is set by the fact that the end of the horn is blocked by a solid plate and the mouth (or exit vent) is positioned on the side wall of the horn. So while the Tapped horn has a mouth it is not in the normal plane that one finds in most all horns. The Side position will allow for wave reflections from the mouth to the throat. I suspect (but could well be wrong) that this arrangement may have to do with controlling ripple in the horn response. Your comments would be welcome. Regards Moray James.
Re: a couple of good links...
Greets!
If the terminus's area is the same as the end plate's, then it's acoustically transparent in the sub's intended BW. If larger, then it represents an expansion, tuning it higher, ergo smaller is mass loading it, tuning it lower.
WRT the B-DEAP, I haven't seen spec drawings of it, so don't know whether its terminus is appropriate for the expansion or not, but in my own experience with acoustically small horns is that mass loading is your friend. Altec certainly thought so, just look at the A7 cab, which is a crude BLH that was used with/without two different size vent boards for a certain amount of tuning flexibility.
The Transflex, TOP, are effectively 6th order BPs, and the Karlson K-15 is a series of resonant couplers that mimics a Transflex in a smaller package.
GM
Greets!
If the terminus's area is the same as the end plate's, then it's acoustically transparent in the sub's intended BW. If larger, then it represents an expansion, tuning it higher, ergo smaller is mass loading it, tuning it lower.
WRT the B-DEAP, I haven't seen spec drawings of it, so don't know whether its terminus is appropriate for the expansion or not, but in my own experience with acoustically small horns is that mass loading is your friend. Altec certainly thought so, just look at the A7 cab, which is a crude BLH that was used with/without two different size vent boards for a certain amount of tuning flexibility.
The Transflex, TOP, are effectively 6th order BPs, and the Karlson K-15 is a series of resonant couplers that mimics a Transflex in a smaller package.
GM
GM said:Greets!
All the more reason to 'disagree' if I'm not clear enough, not to mention I'm hardly infallible, so I can be clearly wrong.
GM
If it's a driver in some kind of box, I doubt it. Now if you want to talk about OB's, I'm sure I'll come up with something to disagree about like I do with everyone else. That's only because the theory isn't well understood, and how it applies in the real world can be a totally different animal because the room is your box. I guess OBs are really just big tapped horns, but our listening position is inside the box.
Geez I hate it when I guess wrong...
GM thanks for the response. man I really thought that a plate covering the end of a horn would have some kind or reflective impact. Now I find out that it is transparent. I guess that is just a little too counter intuitive for me. So enough whining. This is as a result of the wave being so long that it just does not see a difference between end and side? Why then do I read about reflections back from the mouth of a horn being responsible for all manner of grief? Is that only when the mouth is fore shortened?
So the mouth of the Transflex is also being used as a vent to tune (load) the line? Since it is smaller than the full cross section area of the pipe it will add load to the line.
Quote: If the terminus's area is the same as the end plate's, then it's acoustically transparent in the sub's intended BW. If larger, then it represents an expansion, tuning it higher, end Quote. Can you please explain how the terminus can be made larger than the full size of the horns mouth? or am I miss reading what you have said?
I would also appreciate a more discriptive explaination of the TAP and Transflex as Bandpass devices.
I am wondering about the flair rate in a TAP horn and have thought that a hyperbolic flair would give a greater load to the driver than a conical one. Does that make sense? Would it really make a difference in a 1/4 wavelength horm? Enough questions for the moment. Thanks for helping to explain things. Regards Moray James.
GM thanks for the response. man I really thought that a plate covering the end of a horn would have some kind or reflective impact. Now I find out that it is transparent. I guess that is just a little too counter intuitive for me. So enough whining. This is as a result of the wave being so long that it just does not see a difference between end and side? Why then do I read about reflections back from the mouth of a horn being responsible for all manner of grief? Is that only when the mouth is fore shortened?
So the mouth of the Transflex is also being used as a vent to tune (load) the line? Since it is smaller than the full cross section area of the pipe it will add load to the line.
Quote: If the terminus's area is the same as the end plate's, then it's acoustically transparent in the sub's intended BW. If larger, then it represents an expansion, tuning it higher, end Quote. Can you please explain how the terminus can be made larger than the full size of the horns mouth? or am I miss reading what you have said?
I would also appreciate a more discriptive explaination of the TAP and Transflex as Bandpass devices.
I am wondering about the flair rate in a TAP horn and have thought that a hyperbolic flair would give a greater load to the driver than a conical one. Does that make sense? Would it really make a difference in a 1/4 wavelength horm? Enough questions for the moment. Thanks for helping to explain things. Regards Moray James.
johninCR said:
If it's a driver in some kind of box, I doubt it. Now if you want to talk about OB's, I'm sure I'll come up with something to disagree about like I do with everyone else. That's only because the theory isn't well understood, and how it applies in the real world can be a totally different animal because the room is your box. I guess OBs are really just big tapped horns, but our listening position is inside the box.
Greets!
Well, I feel like I have a 'good enough' understanding of what effects a box has on a driver at some intuitive level from my own and other's experiments, but Ron E. MJK, TD, etc., understand it at the particle physics level, which makes me, well, not sure what it makes me, but certainly not in their league.
Anyway, not sure I agree with this since the early mechanical and electrical engineers left precious few 'stones unturned' in their quest for understanding virtually all aspects of sound and its transmission/reproduction, but they had little use for dipoles, so not much documentation exists AFAIK beyond early console/table radio, and TV cabinet design.
Hmm, seems to me that dipoles are the exact opposite of a BP since any loading on one side is annulled on the other and what gives it such a natural sonic signature. It's just another form of box though since it modifies the driver's point source BW. Dipole radiation and room dynamics are understood 'well enough' IMO, but their interactions are so numerous in a typical room that calcing accurate wide BW plots are probably a 'pipe dream' for now and why for this and other reasons I prefer horns and large drivers to get the room out of the way, so to speak, as much as practical.
GM
qi said:
Here's my take on the tapped horn.
Tom Danley has said that his Unity horn inspired the tapped horn. I threw together three images in Visio, based on what he's saying. Or at least what I *believe* he's alluding to! Check 'em out here:
Is a tapped horn a unity horn?
In the meantime I'm building one! I'll post some pix once it's finished. The project is one of those "wtf will this work?" things, because I have no idea if it will.
:: PB ::
moray james said:
Greets!
You're welcome!
It will act as a reflector at frequencies that are around its size or smaller. Since the math describing airflow is for the most part literally Greek to me, I visualize a soap bubble traveling along to ~'see' how various things affect it's shape/motion, so a bubble that's been forced into a small pipe with some portion of it still hanging out isn't going to notice how it's shaped until it shrinks in size as it nears its apex (rising frequency) and increasingly 'feels' the effects of its surroundings.
A gross oversimplifation of course, but it at least gives you an idea of what's going on. To fine tune it a bit, as you wave the bubble wand/membrane back and forth it expands forwards and backwards (compression/rarefaction), so the very apex? of this spherical expansion is its highest frequency, ergo since the larger the bubble's circumference (WL) is in all directions defined by its oscillation, the wider its BW.
This vibrating horn/duct/pipe/whatever air plug mass extends beyond the mouth's boundary somewhat, so any sharp edges, etc. will deform it, causing a harmonically rich shockwave back to the throat, modulating whatever is coming down the line at all these later points in time. If real estate value is location, location, location, then high SQ wide BW horn design is termination, termination, termination, so foreshortening in and of itself isn't a factor.
Right, the Transflex is a BP that's duct loaded on both sides.
If I seal off a horn/duct/pipe/whatever's terminus of 'x' CSA, can I not cut a larger terminus of 'x+' CSA along one or more of its sides?
I have no 'insider' knowledge of the TOP, only how I would design/build a proof-of-concept', and just confident enough in my opinion that it will work well that I prefer not to elaborate while it's patent pending. Someone locally offered to build/test one during his summer break, but teens being teens, unfortunately it didn't happen.
GM
GM, I have seen a lot of your posts and I can't remember a single sentence in any of them that I did not believe. (I'm not smart enough to always know, but it always seems to make sense.) But the transflex as a bandpass I am having difficulty with. I am not saying you are wrong, in fact I am pretty sure I am wrong and I just don't know why yet. I realize you are hesitant to talk theory until the patent passes and so I won't be offended in the least if you do not reply to this at all, but here are my thoughts.
The "as built" MJK sim you did for me corresponds so closely (especially in the low end before the upper harmonics start) to the actual (unmeasured) output of the sub that without a meter and some slow, accurate test sweeps you might think the sim was done taking the tap into consideration, with tl software that could do that.
Although I have not actually done this, if the transflex is a bandpass I should be able to simulate its performance with WinISD. From what I know about bandpass boxes, if the front chamber gets as close in volume to the back chamber (as would be the case with the transflex) you would end up with a super boom box. I would describe the sounds coming from my box as powerful, but certainly not boomy.
Although I am most certainly wrong about this whole bandpass thing, I would be much more comfortable evaluating driver suitability for a transflex with tl software than bandpass software. The sims you did for me were right on the money.
The "as built" MJK sim you did for me corresponds so closely (especially in the low end before the upper harmonics start) to the actual (unmeasured) output of the sub that without a meter and some slow, accurate test sweeps you might think the sim was done taking the tap into consideration, with tl software that could do that.
Although I have not actually done this, if the transflex is a bandpass I should be able to simulate its performance with WinISD. From what I know about bandpass boxes, if the front chamber gets as close in volume to the back chamber (as would be the case with the transflex) you would end up with a super boom box. I would describe the sounds coming from my box as powerful, but certainly not boomy.
Although I am most certainly wrong about this whole bandpass thing, I would be much more comfortable evaluating driver suitability for a transflex with tl software than bandpass software. The sims you did for me were right on the money.
Greets!
Well, let's hope they were all true then!
All speaker systems are BP, just the BW and/or Q changes, so I can't ever be wrong using such a general statement. It's like saying all liquids are fluid. Regardless, we normally define a BP as an alignment with both a fixed low and high cut-off by acoustically loading both sides of the driver, which the Transflex has by virtue of having both a compression and filter chamber. The fact that it's one long duct serving both functions is irrelevant.
Sorry, I've done so many designs I don't recall yours, so please refresh my memory.
You can't sim the Transflex with any program I'm familiar with per se since you can't factor in the duct's TL resonances and changing phase shift, though you can use a TL program to sim the two combinations and sum them for a 'close enough' sim AFAIK.
GM
Well, let's hope they were all true then!
All speaker systems are BP, just the BW and/or Q changes, so I can't ever be wrong using such a general statement. It's like saying all liquids are fluid.
Regardless, we normally define a BP as an alignment with both a fixed low and high cut-off by acoustically loading both sides of the driver, which the Transflex has by virtue of having both a compression and filter chamber. The fact that it's one long duct serving both functions is irrelevant.Sorry, I've done so many designs I don't recall yours, so please refresh my memory.
You can't sim the Transflex with any program I'm familiar with per se since you can't factor in the duct's TL resonances and changing phase shift, though you can use a TL program to sim the two combinations and sum them for a 'close enough' sim AFAIK.
GM
Earlier this year I made a modified transflex/TOP with a 2:1 taper. The "tap" does not work as Danley's does, as the taper should be 1:2. I have been hesitant to reverse my taper, although it will only take a few minutes, because I love the low end extension but I have to cross over low to avoid the higher harmonics. When I change the taper it should function very close to the PB12. Remember now?
Although I have been enjoying it, I don't consider it to be finished until I change the taper to benefit from the "tap". I might even break down and add a bit of stuffing if it needs it. But I will be building a Graham Holliman Infrabass Speaker in the next few weeks to take over the lows, at which time I intend to reverse the taper which will raise the tuning to nicely match where the Holliman box should roll off.
I started a thread here, "5 - 25 hz" to discuss the Holliman box if you have any interest in reading or commenting on this strange design. I find it fascinating, so I have to try it.
Although I have been enjoying it, I don't consider it to be finished until I change the taper to benefit from the "tap". I might even break down and add a bit of stuffing if it needs it. But I will be building a Graham Holliman Infrabass Speaker in the next few weeks to take over the lows, at which time I intend to reverse the taper which will raise the tuning to nicely match where the Holliman box should roll off.
I started a thread here, "5 - 25 hz" to discuss the Holliman box if you have any interest in reading or commenting on this strange design. I find it fascinating, so I have to try it.
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