Why not pick a 2-way with appropriate 15” and CD-horn combo? Spend a tad more on a good 15”, save on the 10” and X-over components and get better directivity of the system as a bonus. Seems a no-brained to me.
Yes, that's what folks wanting your money tend to do, though compared to the outright bald face lies (sadly some to a greater or lesser extent continue to this day) typical of when I got online in '96 and began browsing BBs specific to my various knowledge bases assuming it would be more a learning experience to quickly making it my ongoing goal to 'set straight' as many as possible and been kicked off more forums that many (most?) ever will participate on, so you can count on me and a relatively few kindred spirits to 'muddy the waters' on any forums we're active on.
T/S math explained and IME used by all speaker box design software programs since at least 1981; scroll down to n0 and SPL rating - efficiency
This site has all the info in total, calculators; in particular, SPL/Eff/Sens
Not by the physics of the situation, just that PE apparently caters mostly to the mobile audio crowd, the biggest DIY audio group AFAIK and where a vehicle's 'cabin' (room) gain Vs available speaker box net volume (Vb) is so extreme, which is why it's a poor choice for HIFI if not loaded OB, IB, (ML/vented) TL or ~ aperiodic.
Sure was for me by age 10 due to all the big speakers I was exposed to, but took me till age 18 before I could afford to DIY a quality system and being very horn 'centric' did a pair of Altec A7-500 made from 3/4" marine grade no void plywood.
As mentioned in Post #1, I've been building vented 2-ways with horns all my life. I totally agree they are the best value for the dollar, and the best sounding speakers ever when properly set up.
But as I also mentioned in post 1, the sole purpose of this build is my first ever 3-way. That may sound crazy, but that's the way it is.
I'm also a huge fan of Altec VOTT, and I know that despite all the math involved the results are far from ruler-flat but extremely pleasing to the ear. I expect the same applies to these modern drivers, and that results might be very good in spite of the divergence from their even more controversial math.
Aside from some very basic principles, I've never used modeling. I expected it to provide a consensus, but it appears to have only added confusion. As in the past, everyone still has their personal iron-clad do's and don'ts, and I really appreciate hearing them. I'm sure I'll develop my own as I move forward with this build.
But as I also mentioned in post 1, the sole purpose of this build is my first ever 3-way. That may sound crazy, but that's the way it is.
I'm also a huge fan of Altec VOTT, and I know that despite all the math involved the results are far from ruler-flat but extremely pleasing to the ear. I expect the same applies to these modern drivers, and that results might be very good in spite of the divergence from their even more controversial math.
Aside from some very basic principles, I've never used modeling. I expected it to provide a consensus, but it appears to have only added confusion. As in the past, everyone still has their personal iron-clad do's and don'ts, and I really appreciate hearing them. I'm sure I'll develop my own as I move forward with this build.
I wrote down the specs for the fifteen-inch PRV driver & plugged them into WinISD to simulate with those parameters given. Now we collectively seem to agree the advertised T/S parameters are NOT set-in-stone...apart from measuring these parameters directly with your own gear, considering them guidelines. As such, I got a WinISD resultant EBP (Efficiency bandwidth Product) rating of 57.3 ...the "rule of thumb" states, below a value of Fifty gets one a sealed preference, above a Fifty, points one towards a ported enclosure, at 57 this makes this driver "versatile" for either. Only by doing these simulations do we notice how good or poorly such drivers work in the sealed vs. ported situations. My personal preference holds Twelve-inch drivers at the maximum for sealed systems...this opinion coming from doing lots & lots of these sims...tweaking enclosure volumes, port sizes, Fb (box tuning frequencies)... I have found those drivers in the eighteen-inch sizes, rather useless & undisciplined...the fifteens being the best for the bottom end....the eight, ten, & some of the twelves like the sealed alignments.
In your choice of this specific PRV driver, WinISD wants a ported alignment of 1.1563 Liters of INTERNAL volumes, this alignment reaches all the way down to 20.15 hertz at a fallen rate of 3.09 Decibels worth. The very bottom of our human hearing threshold....more sensory vibrations felt than actual hearing. By using a sealed enclosure for this driver, all that big surface area is "wasted", never getting those impressive, window rattling, earthquake type frequencies.
Yes, the sealed system has the benefit of a so-called "reasonable" size, but at too high a cost for me. The ported version using my favorite dimension ratio gets you an INSIDE size of 1.321 Meters high, 1.049 Meters deep, 834.5 mm wide....and the drivers get mounted on the eight hundred thirty four mm wall.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
In your choice of this specific PRV driver, WinISD wants a ported alignment of 1.1563 Liters of INTERNAL volumes, this alignment reaches all the way down to 20.15 hertz at a fallen rate of 3.09 Decibels worth. The very bottom of our human hearing threshold....more sensory vibrations felt than actual hearing. By using a sealed enclosure for this driver, all that big surface area is "wasted", never getting those impressive, window rattling, earthquake type frequencies.
Yes, the sealed system has the benefit of a so-called "reasonable" size, but at too high a cost for me. The ported version using my favorite dimension ratio gets you an INSIDE size of 1.321 Meters high, 1.049 Meters deep, 834.5 mm wide....and the drivers get mounted on the eight hundred thirty four mm wall.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
I'm confused. You wrote 1.1563 litres of internal volume which is ridiculously small. But when I take your dimensions I get an internal volume of 1156.617 litres, which strikes me as ridiculously large.
I think that should be 1.1563m^3, not litres. In any event the box is indeed ridiculously large, over 40 cu ft!
If we take WinISD results seriously, this driver is basically unusable in any form.
If we take WinISD results seriously, this driver is basically unusable in any form.
If you have Excel, download Jeff Bagby'd WBCD (woofer box & circuit designer) and play with the numbers. Just Google Bagby WBCD.
My bad, yes, it is slightly larger than one cubic meter...you want the deeper values of frequencies?, BIB, (bigger is better). BTW, my wife is not opposed to such dimensions, particularly if it "sounds good", what's your excuse?...just how committed are you, really?
------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
Out of curiosity I modeled my current 2-way build, then measured with REW. The driver is a Visaton W250S. Mic is Dayton UMM-6, soundcard and mic are calibrated. These speakers have very audible response down to 30Hz as shown with REW, but you'd never think it possible if you trusted WinISD!
And yes, that boom at 70Hz is noticeable but not intrusive. And the dip at 350Hz is actually beneficial. 🙂
Additional info on the REW graph in Post #33: The high drivers are PRV D230TiB on Dayton H812 horns. Crossover is 12dB at 2k Hz.
Interesting page, an exercise in semantics really. Nothing I find crusade-worthy, particularly not to the point of bragging about being banned. The industry is not going to change their parameters to suit you, and the current 2.83v/1m standard is even better than 1w/1m since it now recognizes impedance.
Thanks for clarifying your position and goals though! 😉
No brag, just the fact of the times and if you'd come to any of the early established net forums with 'hat in hand' as you've done here you'd of been told to follow the manufacturers or their recommendations and none of what you've already received.
Considering all the naysayers here, I've assembled one of these enclosures for some preliminary testing. No extra bracing, no insulation, everything held together with just a few screws. I'm happy to say that it sounds and measures great! They will need some fine-tuning, but it is very clear that speaker sims are just that, simulators. They are an interesting starting place, but old time knowledge and intuition still works. And REW is your friend. 🙂
All assembled and doing some break-in. I wasn't happy with the compression drivers, so I changed to the PRV Audio D260My-B 1" Mylar. The 230's were struggling to keep up, but these 111dB mylar versions need a bit of attenuation and sound much more smooth. There's still a lot of finish work to do, but overall I'm extremely pleased with the results. The Chifi EL34 has no issues at all, and can be run much lower than I did for my prior 2-ways.
