I'm not sure, but I doubt that it would be much. Bear in mind that the output of the KS is influenced significantly by the shape, size and location of the mouth, which can't be modelled effectively in Hornresp.
119 pages? OMG. That "PPSL" thread was bad enough!
I'd like to consider A 12" or 15" Keystone design. (The 18" is way too large for my use.)
I assume they are in this thread, somewhere.
Does anyone have that data, already copied & "collated" & can repost it? Just the basic data, with whatever drivers were used:
Dimensions & weight, frequency response, & efficiency? - plus what post #'s are involved.
I'd like to consider A 12" or 15" Keystone design. (The 18" is way too large for my use.)
I assume they are in this thread, somewhere.
Does anyone have that data, already copied & "collated" & can repost it? Just the basic data, with whatever drivers were used:
Dimensions & weight, frequency response, & efficiency? - plus what post #'s are involved.
Skimming through a little bit, I REALLY like the fact that the removable waveguides can be added for an extra 3 dB or so.
This is a very nice feature for guys like me, where sometimes space is limited. Having them as options, and being able to transport them in a separate space, is a HUGE deal.
I'm still leaning towards PPSL, though.
This is a very nice feature for guys like me, where sometimes space is limited. Having them as options, and being able to transport them in a separate space, is a HUGE deal.
I'm still leaning towards PPSL, though.
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1) Unlike that thread, this one has actual frequency, phase and distortion measurements.
2) All the Keystone (other than the B-Low) measurements for 2x12" and 15" drivers used the same 45" x 25.5" x 22.5" cabinet. It could be made "thinner" for the smaller drivers with a loss of output.
There are smaller TH available that would fit any size you want.
3) The OP has reference to other posts of interest to the OP and readers ;^).
4) All those details can be found in the OP and references to the pertinent posts.
5) "Waveguides" or "Barn Doors" will increase level in front of any bass cabinet you decide on.
Large road cases can work well as "Waveguides" or "Barn Doors" too. Leave no turn unstoned..
6) The Keystone has a bit more output level than a PPSL bass reflex containing double the drivers using twice the power occupying the same trailer space.
The PPSL would have a few % less THD than the Keystone, as would a standard BR. That said, if not driven past Xmax, I doubt any sound engineer I've met in the last 42 years would notice that the even order distortion had been reduced and the odd order went up in comparison of the two.
However, that 6 dB sensitivity gain requires only 1/4 the power to achieve the same sound level, and in typical "plug the amp in the wall" situations, that four times the power demand can result in voltage drop that severely limits the potential of the less efficient system.
80% of the sound engineers I've met would notice the drop in SPL between the two systems under "brown out", the other 20% would be too effed up to care.
And anyone paying for twice the drivers and amplifiers will notice a difference..
Cheers,
Art
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No, just in the "B-Low" version.
There are comparative SPL and power estimates with the various drivers in the OP.
Well, I'm near giving up, as I can't for the life of me figure out what design is best.
The problem with so many of these threads si that the original designer doesn't always explain the pros & cons of the design. That should almost be a requirement.
Also, size and weight of the finished product, once it has actually been built.
And frequency response, of course.
---------------------------------------------------
So Art, here's where I'm at:
I know you think this is the ultimate design for me, but despite your huge amount of correspondance & info (which I am grateful for) you nevver once said WHY this was the right design.
have 2 problems with it.
1: A bit too large, and I assume too heavy. (I can't find the weight listed anywhere, but it must be at least 150 lbs.)
2: I really want to build PP, if possible, to minimize even distortion. Granted, some high-end drivers already do minimize this *using phase plugs or whatever) so who knows.... This is a big problem when building something you can't actually hear first.
As best I can figure, the main advantage of this Keystone design is efficiency. That's great, no doubt, but I don't need the MOST efficient boxes possible, for a given size. I just need a few db more than I was getting with my old sealed Bag End 18's. (2 per side.)
That's not exactly hard to accomplish.
I also don't need these to be near flat at 30 Hz. Reasonably flat to around 38 - 40 Hz is probably more than I need. I'm more concerned with tightness, cleanliness, intelligibility, integration with the tops, etc. I therefore don't see why a 15" version needs to be the same dimensions as the 18" version. Unless I'm missing something. (Always a strong possibility.)
============================
So, WHAT I MIGHT BE ABLE TO USE:
You mentioned a slimmer version. THAT could work. I mainly need something not too deep, as I cluster them in the center and stage space is often a problem. (Also, some managers etc freak out if the subs are too large. Tall, wide, and shallow doesn't "appear" as big as it actually is.
And finally, tall but shallow makes it much easier to move the subs around, and especially to flip them into my pickup truck.
I can deal with 45" high, in fact in some ways that's ideal. 26.5" wide can also work, though that's getting onto the "scare the manager" territory. - But maximum depth is limited by the wheel well in my Tacoma, which is about 42.5", and I'd need about 1/2" for the covers. so 21" deep, absolutely the most.
If that can be done, mayb with a 15" or dual 12", then I would consider this strongly (although I still lean towards some kind of a push pull concept) However, even at 45" x 26.5" x 21", and using expensive neo drivers, I fear these will be awfully heavy.
The problem with so many of these threads si that the original designer doesn't always explain the pros & cons of the design. That should almost be a requirement.
Also, size and weight of the finished product, once it has actually been built.
And frequency response, of course.
---------------------------------------------------
So Art, here's where I'm at:
I know you think this is the ultimate design for me, but despite your huge amount of correspondance & info (which I am grateful for) you nevver once said WHY this was the right design.
have 2 problems with it.
1: A bit too large, and I assume too heavy. (I can't find the weight listed anywhere, but it must be at least 150 lbs.)
2: I really want to build PP, if possible, to minimize even distortion. Granted, some high-end drivers already do minimize this *using phase plugs or whatever) so who knows.... This is a big problem when building something you can't actually hear first.
As best I can figure, the main advantage of this Keystone design is efficiency. That's great, no doubt, but I don't need the MOST efficient boxes possible, for a given size. I just need a few db more than I was getting with my old sealed Bag End 18's. (2 per side.)
That's not exactly hard to accomplish.
I also don't need these to be near flat at 30 Hz. Reasonably flat to around 38 - 40 Hz is probably more than I need. I'm more concerned with tightness, cleanliness, intelligibility, integration with the tops, etc. I therefore don't see why a 15" version needs to be the same dimensions as the 18" version. Unless I'm missing something. (Always a strong possibility.)
============================
So, WHAT I MIGHT BE ABLE TO USE:
You mentioned a slimmer version. THAT could work. I mainly need something not too deep, as I cluster them in the center and stage space is often a problem. (Also, some managers etc freak out if the subs are too large. Tall, wide, and shallow doesn't "appear" as big as it actually is.
And finally, tall but shallow makes it much easier to move the subs around, and especially to flip them into my pickup truck.
I can deal with 45" high, in fact in some ways that's ideal. 26.5" wide can also work, though that's getting onto the "scare the manager" territory. - But maximum depth is limited by the wheel well in my Tacoma, which is about 42.5", and I'd need about 1/2" for the covers. so 21" deep, absolutely the most.
If that can be done, mayb with a 15" or dual 12", then I would consider this strongly (although I still lean towards some kind of a push pull concept) However, even at 45" x 26.5" x 21", and using expensive neo drivers, I fear these will be awfully heavy.
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Since the Keystone is almost the same size as any double 18 used around the world. I do not know why you are trivial about size and weight. For small gigs use small speakers, for big gigs use large speakers. (or a combination) It's that simple.
Also you worries about distortion, I say what distortion? You only distort TH's if you push it TOO hard or use a driver not suited for the design. In my own experience TH designs are exceptional clean in output. Build many (12 or more) and you never ever have to worry about distortion, you can play it at moderate amp settings, you're probably not want to play it louder or else you're bringing down the building.
You don't need to be flat to 30...So crossover it at 31,31,33,.. 50, 60.. whatever rocks your boot.
It seems like you have strong 'feelings' for a PP design.
Why don't you build a prototype of both the Keystone and any PP from cheap ply or MDF. and test it. And then decide. Both are relative simple builds.
Also you worries about distortion, I say what distortion? You only distort TH's if you push it TOO hard or use a driver not suited for the design. In my own experience TH designs are exceptional clean in output. Build many (12 or more) and you never ever have to worry about distortion, you can play it at moderate amp settings, you're probably not want to play it louder or else you're bringing down the building.
You don't need to be flat to 30...So crossover it at 31,31,33,.. 50, 60.. whatever rocks your boot.
It seems like you have strong 'feelings' for a PP design.
Why don't you build a prototype of both the Keystone and any PP from cheap ply or MDF. and test it. And then decide. Both are relative simple builds.
A) I have never claimed any design is the "ultimate" for anyone.
You primarily have complained about distortion.
I have explained many times that distortion is related to three things:
1) Driver design. (phase plugs have nothing to do with LF driver design..) Good designs have little distortion below Xmax, bad designs can have far more distortion even well below Xmax.
2) Driver excursion. More excursion=more SPL and more distortion.
3) Cabinet efficiency-a more efficient design requires less excursion for a given output.
1: Depending on the drivers and type of plywood used, 150 pounds is a reasonable estimate. More weight if Baltic Birch and ceramic magnets are used.
2: If you look in post #758 of "A Thread for those interested in PPSL enclosures", (or on ProSoundWeb), you will note that Mark 100's tests using the his slot load cabinet in both push-push and push pull demonstrates that the BMS 18N862 speaker design using triple shorting rings is not only very low distortion, but also has a very linear suspension and motor in terms of deviation between "push" and "pull".
The even order differences between the "push" and "pull" stroke are cancelled in PP mounting, but lacking that difference, either way of mounting works basically the same, with the exception of the suspension and coil vent noise more audible with a "reversed" driver.
In other words, don't expect push pull to "improve" good drivers.
3: You say you don't need "much more" efficiency , but complain of distortion at low volume in your 2x12", and not enough output in your 18". See "A".
4: Any version of the Keystone could be made thinner (reducing the 26.5" dimension) without affecting the basic frequency response, just reducing efficiency. Reducing depth would reduce path length, which would reduce LF output. The Keystone Response drops below 37 Hz.
5:Get a trailer!
OK, since you won't do that, you could cut the Keystone in half making two cabinets using 12"
drivers, exterior dimensions 45" x 22.5" x 13.75", go three wide and one sideways on the tail. The Keystone exit was done empirically to get the optimum blend between LF output and upper smoothness, that process would be required again for the thinner cabinet, though reducing the width of the exit by 50% and retaining the same aspect ratio would be a good starting point.
6: A pair of the "split" Keystones would be about 1/2 sheet heavier than one due to the extra side-wall wood, but would come in under 100 pounds each.
Cheers,
Art
I have, thanks.
I could still only fit two of those, and I'm worried that two would not be loud enough for some situations, despite the horn being more efficient at lower frequencies.
What would possibly be ideal (if I could find the perfect driver) would be a TH using TWO 12". Something like Danley's design. Same basic size as the single 12, only a little bit heavier, but MUCH more output across the entire usable frequency range.
So, your limitations are box dimensions? What exactly are the limitations that you're working with?
I'm not really a fan of dual-driver enclosures. While they may save a little on weight, failure of one driver usually leaves the entire cabinet useless, and they are larger and heavier to move around.
Art, this is VERY intriguing. Actually, if the specs panned out, this could be amazing. (Also if there's a quality 12" with the same low distortion design as that 18" you mentioned.)
I still could only load three of these (I have a lot of other gear) but that might be OK.
Could I even go a bit deep and wider, so as to maximize efficiency & bass extension, based on my truck and "at gig" limitations? (or use 15's)
If so, how do I do this?
(Maybe I could pay you to do it?)
Could you possibly run a quick simulation, using the best possible driver, and estimate LF response and efficiency?
I'm thinking the 18 Sound 12NLW9300 or possibly the B&C 12BG100. - The 12NLW9300 is lighter and much more efficient, but I as yet don't understand what other parameters make a driver suited for this design.
My guess is that a LOT of guys would be interested in such a shallow design, for the same reasons as me. Even forgetting the small truck bed, it's the idea of being able to center-group subs in front of a band or DJ rig, and not stick out too far. (Often a problem in smallish rooms.)
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There is no best.
All designs are compromises. What matters is which compromise(s) you choose to accept in order to design a product you want to use.
For instance, a tapped horn is a way of using a bigger cabinet to get more output than a ported box with the same driver. Sealed boxes can be smaller than ported boxes, but you lose a lot of output.
A pair of sealed 18"s with 7mm Xmax (about right, IIRC, for the drivers in those Bag End subs) will manage 116.3dB at 40Hz.
A single Tiny15" will manage 121dB at 40Hz with 1KW input, in a box that's 440x440x650mm, and weighs somewhere around 50lb. I haven't weighed them, but I weigh around 160lb and can move them one-handed.
A Keystone sub loaded with a good 18" would match up with 3x Tiny15"s, while using around half the power. The Keystone would be larger (you don't get the extra sensitivity for free) while also digging a few Hz lower.
For larger events, I'd pick a couple of Keystones over moving 6+ Tiny15"s.
Chris
1)The LAB12 had low distortion in the Keystone, but there are certainly lower distortion drivers now available, though I have not tested them.
2) Designing enclosures to maximize space available in a small vehicle is a challenge.
Explaining how to do it would take days, and is beyond the scope of this thread, which is about a specific TH design that does not fit into a "quick simulation".
Hornresp inputs that approximate the Keystone design are available in post #96 and 130 if you'd like to plug different drivers in for comparison, though simulations won't tell you anything about distortion...
As far as "best possible driver", as Chris said, there is no "best", just compromises you are willing to accept over a multiplicity of parameters.
I am available for design consultation for pay, you have my number.
3)Shallow cabinet depth does not seem indicative of what "a LOT of guys would be interested in", at only 22.5" deep the Keystone has less depth but far fewer views than several other popular TH design threads ;^).
Cheers,
Art
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Well I am getting ready to build some more Keystone 18sw115's. It is still my favorite sub so far. Anyways, I have noticed some very rare "ringing" (at least I think thats the correct description) in the upper bass range. The bass guitar on Chris Stapletons "Say Something" seems to "ring". Higher frequency sound than is actually in the song and a humm sound thats louder than it should be. I was wondering if any sort of fill or sound absorbing mat on the flat surfaces 90 deg to the folds would help. I very rarely notice it, but figured I would pick everyones brain before I build more. I am running a 100hz LR 24db low pass right now. I will try to analyze it with my microphone and find out exactly what frequency it is. Any one else have similar issues?
Thanks,
Thanks,
1) "Ringing" is also called "overhang", most easily heard with very short duration transients, like a noise-gated kick drum hit.
2) That particular track has the bass line join with a percussive upward pitch sweep.
3) Fill could reduce "ringing, but will also reduce output level.
4) You may want to use EQ to flatten the upper peaks in the response of the Keystone if you are not already doing so.
5) There are many that complain about resonant behavior, but a 1/4 wave resonator cabinet won't work without it. Can't make an omelette without breaking some eggs ;^)
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