yes, that's another option that can work, if he has the drivers at hand.
one my experiments a couple of years back was using 4 Pyle ppa15 drivers (one pair per channel) in a linkwitz style W baffle
unfortunately, they were much too large, inefficient (in my case) and Xmax limited to work with the hi eff mains, pretty clean bass down to 35 hz. the good thing about this approach is that large high qts drivers are often inexpensive
one my experiments a couple of years back was using 4 Pyle ppa15 drivers (one pair per channel) in a linkwitz style W baffle
unfortunately, they were much too large, inefficient (in my case) and Xmax limited to work with the hi eff mains, pretty clean bass down to 35 hz. the good thing about this approach is that large high qts drivers are often inexpensive
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Zobsky, I think we have a misunderstanding, I want to build two enclosures with one driver in each. That way they will be in stereo and each will be smaller. I'm in the process of rebuilding the 2.7's (both frames and crossovers) which won't be cheap.These will be to supplement the lower end because with the rebuilt Maggies they should have much better bass. I'm not expecting them to go as low as the huge SDA-SRS 2.3tl's in my theater but the 2.7's have unreal clarity and accuracy just a little light in the lower end. I've got a diy vented passive using my old SVS 12" driver which is being driven by one of the 565 monoblocks which has clean deep bass but I need to figure how to increase the lfe signal coming from my avr because even at the max setting it is not pushing the sub hard. I'll try and work up some sketches and I'm sure I'll have more questions- here's one now! Any pics of these builds in progress and then completed? Thx Dean
In that case, halve S1 and S4 (length remains the same ) and adjust the design accordingly. Increasing the overall length (and maybe the cross sectional area) gets you lower bass, at the expense of a larger box. Hornresp sims will tell you the rest of the story. It shuoldn't be hard to install and work with on a windows XP , vista or 7 machine.
Can you direct me on how to get hornresp? I downloaded it and unzipped it but cannot find it! Please bear with me, I'm a retired/disabled FF and most of my lumbar spine is bolted together so I can't sit for very long before my legs go numb. I'd much rather be working than sitting, I need to just get to where I can draw up something like this.
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Indeed, I simmed this driver the other day since its specs looked good on paper and its low Xmax doesn't necessarily make it a non-starter for HIFI/HT apps. A single driver hits 'close enough' to DD/DTS/THX's 115 dB reference to ~30 Hz in ~7.2 ft^3 net/1 pi space on a measly Xmax limited 32 W and from 20 Hz-up in ~21 ft^3 net/64 W, so while not exactly petite by most folks standards it can be folded up like a DSL SPUD for a 'pancake' positioning or split in two and folded up into a 'stereo' tower pair.
After seeing zobsky's T-TQWT though, guess I need to look at a small room variant too.
Were the THs internally damped? This would be required AFAIK if not acoustically large enough to not need any for best blend to ribbons, electrostats, planar, or other highly damped alignment.
GM
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After unzipping it, browse to the unzipped folder and you should see a hornresp.exe binary somewhere in there. Double click and the application should launch.
Here's a guide on how to double fold a tapped horn, if that's what you want to do. http://www.volvotreter.de/downloads/Folding_a_Tapped_Horn.pdf
GM: I don't remember if I stuffed my T-TQWT prototype. I remember playing with it, but may have taken it out when I sealed it up. Could you explain how to determine the usable SPL. In all my T-TQWT, as soon as I increase the power handling to 1W or more in the TH wizard, the response goes to hell. This doesn't match reality.
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Bummer, I've a mostly fused cervical and lumbar spine, so know your problem well.
Anyway, HR downloads to wherever 'you' tell it to and auto unzips to C: HORNRESP unless you tell it otherwise, so assuming you didn't, look for its folder on drive C. In the folder, click on 'hornresp.exe' to open the program and to create a shortcut to click on in the future to save going to the folder each time and maybe accidentally screwing something up that keeps it from working properly or worse.
GM
Oops! Didn't see your HR response.
Hmm, I haven't used the Wizard to find Xmax limited power handling, but in trying it just now it does look ugly since it's calculating by frequency without the smoothing a typical box program does for simplicity's sake, so you'll have to trace it out mentally/manually to find its average peak response.
GM
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I found it and was able to get a shortcut to my desktop! But it is all greek to me! I have have never used this type of software. I read threw the help section and realize its way over my head! Give me a drawing or picture to scale and my tools and I can build pretty much anything. Thx again Db
Hornresp can be pretty complicated, but it is by far the best tool I have found for modeling these enclosures.
I don't really have the time to go into a detailed lesson here, but it can be broken down pretty simply. Once you have a model you can translate it to the real world pretty quickly.
For the simplest tapped horn/TTQWT, we are worried about areas in a tapered enclosure at four places and the lengths between those areas.
S1 = Throat (small end in a TH, large end in a TTQWT)
S2 = Driver entry 1 (Center of the driver cutout in the baffle)
S3 = Driver entry 2 (Center of the driver cutout on the other side of the baffle)
S4 = Mouth (Large end of a TH, small end of a TTQWT)
L12 = length from throat to center of driver
L23 = length from driver center to driver center
L34 = length from center of driver to mouth
In hornresp, numbers are metric - square cm for areas, cm for distances.
What I do for a single fold layout:
Divide L23 in half, then add the larger of L12 or L34, this is your total baffle length.
Set the width of the baffle to a convenient number (large enough to fit the drivers width-wise, small enough to fit the drivers depth -wise)
With this internal width - I determine the cabinet width and establish the layout of the tapered path. Though not exact, the rate of expansion for a conical enclosure is closely approximated with a simple slanted baffle in a rectangular enclosure, certainly close enough for our needs. I lay things out full scale on one of the cabinet sides (usually takes me several tries).
Then- it is simply a matter of cutting out the parts, cutting the driver holes, and putting it all together. Bracing is a good idea when panels are wider than a foot or so, especially with 1/2 inch material.
I don't really have the time to go into a detailed lesson here, but it can be broken down pretty simply. Once you have a model you can translate it to the real world pretty quickly.
For the simplest tapped horn/TTQWT, we are worried about areas in a tapered enclosure at four places and the lengths between those areas.
S1 = Throat (small end in a TH, large end in a TTQWT)
S2 = Driver entry 1 (Center of the driver cutout in the baffle)
S3 = Driver entry 2 (Center of the driver cutout on the other side of the baffle)
S4 = Mouth (Large end of a TH, small end of a TTQWT)
L12 = length from throat to center of driver
L23 = length from driver center to driver center
L34 = length from center of driver to mouth
In hornresp, numbers are metric - square cm for areas, cm for distances.
What I do for a single fold layout:
Divide L23 in half, then add the larger of L12 or L34, this is your total baffle length.
Set the width of the baffle to a convenient number (large enough to fit the drivers width-wise, small enough to fit the drivers depth -wise)
With this internal width - I determine the cabinet width and establish the layout of the tapered path. Though not exact, the rate of expansion for a conical enclosure is closely approximated with a simple slanted baffle in a rectangular enclosure, certainly close enough for our needs. I lay things out full scale on one of the cabinet sides (usually takes me several tries).
Then- it is simply a matter of cutting out the parts, cutting the driver holes, and putting it all together. Bracing is a good idea when panels are wider than a foot or so, especially with 1/2 inch material.
If I recall - the hornresp Maximum SPL plot is a constant power plot, where voltage is varied according to impedance at a specific frequency, making the wattage constant (not how I test), whereas the the standard hornresp SPL plot holds voltage constant and allows the wattage to vary according to the impedance (how I test).
To determine usable power limits in a simulation, I simply increase Eg in the model until I reach excursion levels I am concerned with. For these drivers in a TTWQT enclosure similar to what you've simulated, there are excursion problems at low frequencies (below 25 Hz) once power levels above 50W into a pair are reached. Corner loaded, 50 watts into two drivers will make 120 dB in the TTQWT, about 125 in the TH, more than enough for most music listening (even mine...
). As it takes 500 W to get to 130 dB, and displacement at 500 W into 4 ohms is only 15 mm, I think things will be OK. Honestly, 15 mm is not that much movement for current subwoofer drivers. Response may not be linear, but we're not listening to a 25 Hz sine wave either. Typical drivers flop back and forth this far during free-air break-in. Realistically, I would not worry too much, as excursion and power handling should not be limiting factors for music use with these drivers in either type of enclosure, as excursion for either type is similar to what is seen in a closed box for these drivers. Most music does not have significant sub-25 Hz sine-wave content, just turn things down a notch on stuff that does. I would be concerned with home theater use causing the drivers to bottom out audibly, as the LFE in current movies can really move woofers.
I'm not that sure that xmax matters all that much in the non pro-sound world. The mechanical excursion limits (and how the driver behaves as it approaches those limits) is certainly more of a concern for me. My drivers in my current home theater "subs" (the temporary ones I slapped together 2 years ago....before I learned all about tapped horns and horns in general) only have a stated xmax of 4 mm. I have only bottomed them out during movies during explosions and scenes that have significant content below the horn tuning frequency. Things have to be LOUD to bottom them out. Loud like THX reference level. New sub drivers have been purchased, cool tapped horn enclosures have been designed, all I need to do now is make some sawdust.
Good point, ... which is why what I designed for his app is meant for music, not 15 - 30 Hz HT performance
I need help!! I tried playing around with hornresp and just got frustrated! In the meantime I picked up an active crossover to drive the amps off of my tube preamp and I've got lots of MDF just "know" plans. I've tried the box subs,SVS,Energy,Rythmic and am not happy with how they sound with my 2 channel setup. Acoustic Elegance is trying to get me to use their drivers (at 250.00 each X4) to make two open baffle towers but I don't have that kind of coin right now.
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