For whatever reason, getting a 404 error, so will add this in case it's not already listed elsewhere: What is Group Delay
GM
Thanks Freddi, somehow the whole household caught this bug.
It's hard to know what sort of sound you'll get, reading various folks reviews of various drivers/cabinets... You end up with a lot of contradictory statements. Push push vs. push pull, sealed vs ported. I'd like to experiment and try all the options, but there's a good chance I'll build a test box out of OSB and if it sounds "good enough" I'll just run with that.
Your memory of the Pyle PA cabinet doesn't sound promising.. they were actually the same drivers, the PPA15?
Scott, I've read that before, and it's a neat build. It certainly utilizes space in the right direction! That said, for the helper woofer in this case I'm using as a base for the full range box to sit on, so that its up at ear level and to minimize the total footprint. For a subwoofer, I'm still planning on an F20 or lilwrecker in a back corner somewhere for HT only.
FWIW, based on published specs, 'optimum' based on Vas is ~7.89 ft^3 [223.42 L]/driver and even then Qtc = ~1.05; plus Pyle is notorious for having much worse specs in reality, so Qt may be audibly high enough to need to 'bleed' some of it off via ~aperiodic loading, such as 'gapping' the driver off the baffle to 'taste' [fine tune with some damping material].
GM
Bummer! Sucks when everybody's sick and especially when 'down for the count' and can't take care of the kids without 3rd party to help.
Yeah, we hear the same, yet not so much, hence even with a number of folks in the same room it's not uncommon to get numerous different opinions of a system's performance and why only the individual can determine what's best overall for them for their intended app.
Still, there are basics that one should start with, which some of us have exposed you to, so not that much to sort through initially.
GM
GM, with box volume larger than 4 ft^3 per driver, the Xmax gets eaten up rather fast... In winISD I'm applying a full 80w signal to simulate full volume of the amp, then adjusting the box volume down if necessary to bring down the excursion curve. Truth be told, the maximum rms output is actually higher since two of these 15"s per channel would be a 4 ohm load.. On this driver, it doesn't seem to take much volume at all for it go down as low as I want.. Pretty sure I'm only at 4 ft^3 / driver in the graphs I posted, but they go down to an f3 of below 40 hz.
Specs being incorrect, well that's pretty lame... How can they outright lie or inflate the specs? Gapping the driver off the baffle, if its what I think you mean (like spacing it offset from baffle with washers/spacers under the basket @ screw points), that sounds.. terrible!
I understand that this makes it a relatively high Q alignment, but is that necessarily bad? How would you describe a Qt which is audibly too high (IE, what would this sound like)?
If it was 2x12" vs 1 x 18", I'd say the 18", even if xmax was higher on the 12's.
Just a gut feeling of better air pump (or lever).
But, yes, the qts on cheap drivers is usually much higher than published.
I'd stick with eminence.
I've stuffed my ports.
Tuned to 30hz (f3) was no slower than sealed f3 near 50 to 60hz.
Sealed just had less bass, like 6db, thats a lot !!!!!
But 27hz tuning was a deeper and smoother than a thunky 40hz tuning.
A ported is the same speed as a sealed at twice tuning frequency.
But porteds are usually double the size of a qtc .707
But an octave deeper is nothing to sneeze at either.
So, you are looking for a deep woofer or sub 80hz only ?
Where will you cross at ?
Just a gut feeling of better air pump (or lever).
But, yes, the qts on cheap drivers is usually much higher than published.
I'd stick with eminence.
I've stuffed my ports.
Tuned to 30hz (f3) was no slower than sealed f3 near 50 to 60hz.
Sealed just had less bass, like 6db, thats a lot !!!!!
But 27hz tuning was a deeper and smoother than a thunky 40hz tuning.
A ported is the same speed as a sealed at twice tuning frequency.
But porteds are usually double the size of a qtc .707
But an octave deeper is nothing to sneeze at either.
So, you are looking for a deep woofer or sub 80hz only ?
Where will you cross at ?
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Hey Norman, don't forget about those Fane 12"s 
Those Pyles get very peaky if you put them in a vented box, huge peaks around 60-70 I think it was... So if I got them, I'd pretty much be stuck with them in sealed boxes (or OB, I know, but lets not go there)
That 18" PRV, the 18sw1000, would at least work for either sealed OR vented...
I'm still planning on crossing around 150-750 hz... I'd prefer it lower to keep the vocals out of the woofers, but as you said things are much more punchy with it crossed up at 750. Electronic crossover will let me fiddle with it to see what sounds best to me.
Helper woofer then needs to handle, say 750 hz down to around 40 hz unassisted (music only; HT will be augmented with sub). Lower would be great, as there seems to be some pretty low content in music these days.
Those Pyles get very peaky if you put them in a vented box, huge peaks around 60-70 I think it was... So if I got them, I'd pretty much be stuck with them in sealed boxes (or OB, I know, but lets not go there)
That 18" PRV, the 18sw1000, would at least work for either sealed OR vented...
I'm still planning on crossing around 150-750 hz... I'd prefer it lower to keep the vocals out of the woofers, but as you said things are much more punchy with it crossed up at 750. Electronic crossover will let me fiddle with it to see what sounds best to me.
Helper woofer then needs to handle, say 750 hz down to around 40 hz unassisted (music only; HT will be augmented with sub). Lower would be great, as there seems to be some pretty low content in music these days.
here's a real rough 1pi kluge of a 0.91 scale 115bk with Kappa12a vs PPA15 in a 100 liter box - dunno if the little Karlson is really that hot (?)
for a vented box and pa310-8, I could not figure out how to invoke hornresp's active highpass with peaking (for 6th order assisted bass reflex case)
for a vented box and pa310-8, I could not figure out how to invoke hornresp's active highpass with peaking (for 6th order assisted bass reflex case)
here's a project I remember - they assumed it was a PPA15 Pyle of junk into pile of bass
for a vented box, those clearance P-Audio 15 should be a bargain.
for a vented box, those clearance P-Audio 15 should be a bargain.
Yeah I read that one... read all the ones I could find
The P Audio 15"s do look okay in a vented box (just not in a sealed box!)... With 8 ft^3 per woofer, I tuned the ports at 35 hz to get a nice looking curve, but then run out of xmax from 65-42 hz...
Hmm, 6.75 ft3 and 40 hz looks a little better, but still approaches 6mm at 55 hz.
Note that's with simming it at the full 80w rms that my little receiver will make... Seemed like good practice to make sure that Xmax couldn't be exceeded within the operating range of the woofer. But not sure if that's standard practice or not.
Edit -
Freddi, those bm15cxa woofers are still $100 ea. even on sale (and currently out of stock still) - for 100/driver, wouldn't I be better off with that Dayton PA460 or the PRV 18SW1000, 18" woofers?
The P Audio 15"s do look okay in a vented box (just not in a sealed box!)... With 8 ft^3 per woofer, I tuned the ports at 35 hz to get a nice looking curve, but then run out of xmax from 65-42 hz...
Hmm, 6.75 ft3 and 40 hz looks a little better, but still approaches 6mm at 55 hz.
Note that's with simming it at the full 80w rms that my little receiver will make... Seemed like good practice to make sure that Xmax couldn't be exceeded within the operating range of the woofer. But not sure if that's standard practice or not.
Edit -
Freddi, those bm15cxa woofers are still $100 ea. even on sale (and currently out of stock still) - for 100/driver, wouldn't I be better off with that Dayton PA460 or the PRV 18SW1000, 18" woofers?
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(I'd never give a midbass 15 ore than 4CF - like JBL with 2226 and 2035) - -
there seems to be two different sets of specs for that P-Audio 15 - one with Qts ~0.45 the other ~0.36 magnet weights
are different (~4 ounce vs ~8 ounce) - it would be nice if Loudspeakersplus could tell which one they have
if more like 0.45 - then could make a decent open baffle helper woofer for fullrange
http://www.paudioeurope.com/pdf/E15_350N.pdf
http://i45.tinypic.com/4g3ift.jpg
there seems to be two different sets of specs for that P-Audio 15 - one with Qts ~0.45 the other ~0.36 magnet weights
are different (~4 ounce vs ~8 ounce) - it would be nice if Loudspeakersplus could tell which one they have
if more like 0.45 - then could make a decent open baffle helper woofer for fullrange
http://www.paudioeurope.com/pdf/E15_350N.pdf
http://i45.tinypic.com/4g3ift.jpg
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Oh you mean That p audio 15, the neodymium one... that is a bit curious, the two different specs.. other things are different too. Maybe an older version? I simmed the paudioeurope one previously and it didnt look good, but i may have only tried it sealed enclosure... will check in a bit!
edit: i did that sim on a different pc.. but I know I used the Paudioeurope pdf when I assigned driver specs.
edit2: I poorly labeled the project names, so what I thought was the sim for the BM15CSA was actually the E15350N... oops! So then perhaps that driver is worth looking at... dpending on what the actual specs are. The one I simmed is the Paudio Europe one, .36 qts.
edit: i did that sim on a different pc.. but I know I used the Paudioeurope pdf when I assigned driver specs.
edit2: I poorly labeled the project names, so what I thought was the sim for the BM15CSA was actually the E15350N... oops! So then perhaps that driver is worth looking at... dpending on what the actual specs are. The one I simmed is the Paudio Europe one, .36 qts.
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