I'm trying to decide what box to put these in. I like the simplicity of a 260L vented box, the extension and the portability of them at this size. But, I've attempted to model them in Hornresp and I've seen the gains a good FLH or RLH (21 superscooper) can make while keeping extension fairly close to the BR alignment. But, the size and cost of materials goes way up. Any suggestions or ideas and opinions would be appreciated.
Sounds like you're caught in the middle of indecision trying to balance the inevitable compromises (size/weight, efficiency, simplicity).
I have one in a 310 liter box with 25Hz tuning. At the time I decided to build mine, I was considering something like an Othorn build. But I decided against that due to the weight of the thing. 240 lbs was not something I wanted to transport. Not sure if yours is for home or PA use and if portability is of concern. Mine is 125 lbs.
For horn use, I think it's a tad on the weak motor'd side of things based on BL^2/Re/Sd. Formula for optimal compression ratio suggests 3.0-3.3 which is a tad lower than you'd get with a LF21N551, or B&C 21SW152 or 21DS115. It's certainly not bad, but you might end up with a bigger horn (due to lower compression ratio) than with one of the above other drivers.
I have one in a 310 liter box with 25Hz tuning. At the time I decided to build mine, I was considering something like an Othorn build. But I decided against that due to the weight of the thing. 240 lbs was not something I wanted to transport. Not sure if yours is for home or PA use and if portability is of concern. Mine is 125 lbs.
For horn use, I think it's a tad on the weak motor'd side of things based on BL^2/Re/Sd. Formula for optimal compression ratio suggests 3.0-3.3 which is a tad lower than you'd get with a LF21N551, or B&C 21SW152 or 21DS115. It's certainly not bad, but you might end up with a bigger horn (due to lower compression ratio) than with one of the above other drivers.
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Yes, the weight is a little bit of a concern. I wouldn't be transporting them around much. Just for personal use. I like all types of music and a lot of the stuff I listen to can get down into the low 30's, even 20's. But, would I gain enough efficiency going to a tapped horn or rear loaded horn, to justify the size/weight difference? I'd definitely be interested in opinions on designs. I'm currently reading the Compound Loading 6th order thread. Very interesting stuff in there so far.
One thing for sure is, I need to learn Hornresp better.
One thing for sure is, I need to learn Hornresp better.
I'm sure they would, but performance wise, I think they would have less clean output and more ripple in the bandwidth. I'd try to simulate it, but I'm not good at translating drawings into hornresp input.
Anyone have any tips of deriving an actual plan from hornresp input? I'm having a hard time with attempting to fold a TH I've designed in hornresp. I actually have 5 of these 21" drivers, so I will make my 258L (internal) BR and then I'd like to try a tapped horn or 6th order compound loaded super planar (still need to figure out how to model it accurately).
What type of fold do you need? Single or dual-expansion?
Post a screenshot of the sim you came up with in Hornresp.
I'll screenshot my first quick go at it. I haven't touched it since, because I don't know if it will even translate into a feasible design. I don't know how strong the cone is on this driver, so I kept the ratio to 2:1 on s1 and s2. The rest I just attempted to hit my desired tuning points, 30Hz and 70Hz on the total path length. Then I adjusted the areas of each point to smooth the response.
For powering them, I have a NU12000DSP, which I measured with a peak hold feature on a RMS multimeter and a heater element resistor bank in a bucket of water at 8.78Ohms channel 1 and 8.654Ohms on channel 2. It supplied a constant 94Vac/Hz with a 20Hz tone for a couple of minutes and 146Vac/ch with a burst tone at 40Hz.
I, also have a Cerwin Vega CV-5000, which I haven't tested and they don't list the cross-over slope (12, 24, etc.).
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A few notes:
1. Let Hornresp auto-calculate S2 and S4. The driver will be mounted at those locations, which likely means no change in expansion at those points because the driver's baffle has to be flat
2. The expansion is close to a single expansion TH, so I modelled it in an MTH-30 type of fold and made some minor adjustments to get a similar response in a box with realistic dimensions. See attached. And yes, it's a big box
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Thanks, I'm interested in this design. I noticed towards the end, bracing was added. Is there an updated cut sheet? Would you be whiling to share the hornresp input for the updated version? I'll be breaking in one of mine soon and testing it with my DATS unit. I'd like to enter the results into an accurate model to see how it differs from the published data in this design. Thanks a bunch.
A few notes:
1. Let Hornresp auto-calculate S2 and S4. The driver will be mounted at those locations, which likely means no change in expansion at those points because the driver's baffle has to be flat
2. The expansion is close to a single expansion TH, so I modelled it in an MTH-30 type of fold and made some minor adjustments to get a similar response in a box with realistic dimensions. See attached. And yes, it's a big box
How Do I let Hornresp auto-calc S2 and S4?
Yes, 48 x 40 is huge! But, I plan on building one TH and one BR. Then I will see which sound I like best and if I can live with the hugeness of the TH. I do have 5 of these drivers, so if I don't do the TH's on all, I'll just toss that in the basement for my Home Theater build when I get around to that project.
In the "Loudspeaker" wizard, just double-click where it says "manual".
Another thing you might want to consider is enabling the "Lossy Le" option on the Schematic view of the Hornresp's "Loudspeaker Wizard", to see what the impact on the response might be like if tweak is applicable. JAG, who posts here regularly, can advise further.
A possible compromise between the BR and the TH might be an offset-MLTL. It should offer wider bandwidth, at the expense of some sensitivity.
here are hr inputs
ID=39.80
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Cir=0.19
S1=1245.00
S2=1245.00
Par=0.10
F12=0.00
S2=1245.00
S3=983.00
Par=38.70
F23=0.00
S3=983.00
S4=2348.00
Par=208.40
F34=0.00
S4=2348.00
S5=3295.00
Exp=40.00
F45=23.19
Sd=1730.00
Bl=34.50
Cms=8.79E-05
Rms=9.89
Mmd=278.85
Le=3.00
Re=5.60
TH=1
Vrc=0.00
Lrc=0.00
Ap1=0.00
Lp=0.00
Vtc=10000.00
Atc=857.30
Pmax=100
Xmax=5.0
Path=0.0
Mass=0.00
Fr1=0.00
Fr2=0.00
Fr3=0.00
Fr4=0.00
Tal1=100
Tal2=100
Tal3=100
Tal4=100
Comment=olsound 21" 7.3 beta lf21n451
not an easy bild tough
cut sheet pic was updated
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Thank you EPA. Greatly appreciate it.
Can someone, please explain the "lossy Le" feature in Hornresp and how it would be applicable for a large VC with a low Le? I'm currently building a 90L BR for my compact bass module using a surprisingly good driver, the Earthquake PRO-X128. I scored this woofer on Amazon when it went on sale for 98.00 USD. Even at 100-120 USD this would be a great woofer for a small BR, but it does have a very light weight cone.
Sorry to drag this up from the abyss, but I'm still in design phase trying to hash out something I can live with. I still plan on building a TH for my 5th driver, but I know that I want something different from a bass reflex.
I've been playing with hornresp and an 8th order bandpass. I've came up with a decent plant, critiques are welcome, but, have worries about the port velocities being audible through the final port (port 3). Please look over my design and tell me what you think. I've built an 8th order BP before and recall that the cuffing sound is not audible, until the velocities are closer to the mid-30 m/sec range with the inner ports and as long as the final port is within acceptable range. Let me know what you think, thanks.
I've been playing with hornresp and an 8th order bandpass. I've came up with a decent plant, critiques are welcome, but, have worries about the port velocities being audible through the final port (port 3). Please look over my design and tell me what you think. I've built an 8th order BP before and recall that the cuffing sound is not audible, until the velocities are closer to the mid-30 m/sec range with the inner ports and as long as the final port is within acceptable range. Let me know what you think, thanks.
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Quick Video Of My 5 - 21" RCF's Getting Some Break-in Action
Finally got some time in my house by myself, so I dragged out the 21's to do the first round of break-in time. Just low and moderate power with music was captured on video. Then I hit them with a 10Hz sinewave at around 68-70volts for a few hours. Had to cut it after the family came back home, my son thought it was fun sitting in the living room, because it sounded like a helicopter and it was like being in a message chair. LOL!
YouTube 1
YouTube 2
Finally got some time in my house by myself, so I dragged out the 21's to do the first round of break-in time. Just low and moderate power with music was captured on video. Then I hit them with a 10Hz sinewave at around 68-70volts for a few hours. Had to cut it after the family came back home, my son thought it was fun sitting in the living room, because it sounded like a helicopter and it was like being in a message chair. LOL!
YouTube 1
YouTube 2
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