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Old 12th November 2014, 05:05 AM   #1
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Join Date: Aug 2014
Default SMALL 15 for Light PA use

Hey everyone!

So after some field experience with my LAB12 in a ported box (let me tell you what doesn't make for a loud bottom end) I've finally decided to build the PAL12 TH as it's response looks noticeably nicer than the Tuba45 the driver was originally meant for (not digging that huge 10dB rise to 100Hz)

Sorry if this post looks similar to my previous one about the aforementioned ported 12, I promise I'm going somewhere useful!

I'm super interested in this project;

Q15 Compact 15" Bass bin

And here in 'Murica the BMS driver might be tricky to come around but THIS ISN'T!

PRV Audio 15SW2000 15" High Power Pro Audio Subwoofer 8 Ohms

(Slightly baffled as to why the unsatisfied buyer had used a Subwoofer as a midrange)

Those Q15 subs had gotten some great reviews and the PRV driver while only 1dB down on sensitivity has it beat on several specs like Xmax and Pe which to a noob like me, seem to be all that matters in a BR! (I'm trying to learn!) However, will this PRV driver's .46 Qts mess up the response compared to the BMS's .32?

So, the question is, can I place this PRV Audio driver in the Q15 box and use the B6 assisted alignment with similar results? the designer claims strong bass down to ~40 Hz with fairly good SPL. (potential iron law fault)

This would be for those occasions where 1 corner loaded sub and 1 top is all I need for house parties and such. I do love my Bass-Happy house music (EDM if you will) and TRAP, but with a PAL12 TH on the horizon I can wait for the full effect!

So any tips would be wonderfully appreciated. Would I be better off with a build like this?

Ultra compact ported 15" Dayton Ref HO

I thought I could be sneaky and pop this driver in a proven box and be happy!

P.S. Someone will have to explain how this B6 alignment works (something about .707 of a normal F3 for this size box?) and how it is achieved on my DriveRack...

THANK YOU!
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Old 12th November 2014, 07:02 AM   #2
sine143 is offline sine143  United States
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Use the Dayton pa 385 instead of the pvr in a vented box.
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Old 12th November 2014, 01:31 PM   #3
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Is the Dayton a better choice due to the lower Qts? I tried simming it in WinISD and I guess none of these small boxes are going to have flattering curves without EQ. How does that B6 EQ not just kill your headroom?

This quote is from the Q15 thread:

"The response does tail off quite quickly below 40Hz as could be expected given the enclosure size and the processor settings. High pass at 41Hz Butterworth 12dB/oct with 8.7dB Parametric EQ at 41Hz (B6 alignment). Excursion seems to be well controlled and I've not had any issues running them one either side of a 1000W/ch into 8ohms amp."
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Old 17th November 2014, 05:32 PM   #4
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Quote:
Originally Posted by sine143 View Post
Use the Dayton pa 385 instead of the pvr in a vented box.

I have been aging around on WinISD lately with this idea. With the additional 20-40 liters of box volume and Fb at 40Hz, It looks to have very nice output; up to 10dB more than my LAB12 reflex at 100Hz (where I cross with my OTop) but only 3-4dB on the low end (35-40Hz)

Back to the B6 alignment questions, what kind of negative impacts are there with boosting EQ at excursion minima? I'm not looking for flat to 35 performance from a small portable party sub, but a boost at 40Hz seems like it would be perfect for a smaller box.


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Old 17th November 2014, 06:44 PM   #5
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I now have B&C drivers in my subs. Happy with how they turned out.
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Old 17th November 2014, 07:21 PM   #6
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Default SMALL 15 for Light PA use

Quote:
Originally Posted by turbodawg View Post
I now have B&C drivers in my subs. Happy with how they turned out.

Are these the same B&C's that the Dayton's look like they copied? I can sim in WinISD but how do you like the low end performance of them? Have you ever used EQ for a boost?


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Last edited by chips and palsa; 17th November 2014 at 07:45 PM.
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Old 17th November 2014, 09:11 PM   #7
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In my opinion Lab 12 are strictly horn drivers for PA use. The cone is too weighty for efficient bass reflex enclosures - it's built more like a car subwoofer than a bass reflex PA subwoofer, thus it will drink power and not give much sound in return. On top of that it's optimised for lower tuning e.g. 25-30Hz in home cinema.

Excursion minima are usually impedance minima. Too much power around there could heat things up.

As for Tuba 45 boundary loading should bring the lower bass up on par with the upper bass. Look at absolute numbers though too (although the Tuba 30 and 24 seem to have sub-par efficiencies in the bottom of the range, the horn looks designed for V-Plating due to the sudden flare that allows a long horn in a small box) the Tuba 45 seems to be more efficient at the lower bass judging by the graph and it has a bigger effective mouth size built into the cab.

I've been playing around with the T/S parameters of the B&C 18SW115 in a 6th order bandpass and got a theoretical 133dB from 40/45-100Hz with 110V (2Pi.
Chamber 1 is 135L + 500cm^2 * 45cm port (total 157.5L) for ~41 Hz tuning. Chamber 2 is 50L + 500cm^2 * 28cm port (Total 64L) for ~82Hz tuning. Sensitivity is between 100-102dB from 42-104Hz. (This is about 4dB more than the Bass reflex). I wonder how this would compare to sine143's mini tapped horn with the same driver.
Precision devices 15BR40 seems to sim equally well, although with less maximum power output.

Last edited by TimLewis; 17th November 2014 at 09:14 PM.
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Old 17th November 2014, 09:15 PM   #8
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Quote:
Originally Posted by chips and palsa View Post
Are these the same B&C's that the Dayton's look like they copied? I can sim in WinISD but how do you like the low end performance of them? Have you ever used EQ for a boost?


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I've got the B&C 15TBW100-4. They are much more sensitive in kick frequencies than the Dayton HO, and the low bass rolls off much quicker. Such that I lowered the highpass, and adjusted the lowpass to cut the kick. PEQ sometimes, but I start with the high and low pass. I use the DSP in my amp and just tune by ear (I have a pretty good ear).

I would rather still have the daytons, but they couldn't take the heat.

Last edited by turbodawg; 17th November 2014 at 09:19 PM.
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Old 17th November 2014, 11:16 PM   #9
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Quote:
Originally Posted by TimLewis View Post
In my opinion Lab 12 are strictly horn drivers for PA use. The cone is too weighty for efficient bass reflex enclosures - it's built more like a car subwoofer than a bass reflex PA subwoofer, thus it will drink power and not give much sound in return. On top of that it's optimised for lower tuning e.g. 25-30Hz in home cinema.
Hell yeah to that, the according to the sim, the box helps bump the low bass to a better level than the rest of the inefficient passband. Then again, I wasnt hoping for much, just needed something to run with my top on a Halloween party!

Now that I plan on building this PAL12 however, its time to build a proper BassReflex.

I was first intrigued by the possibility boosting EQ at excursion minima, but after reading Art Welter's replies to rated power and sine waves (I do love me some EDM and 808-laden trap/hip-hop), it really seems like I'm going to barbecue a a driver if I'm trying to play 40Hz sine waves while boosting that frequency despite the 1000Watt Pe. Can anyone validate/refute that assumption?

Again, I'm not looking to get PA levels out of a single 15 BR, I just know I can go louder than a LAB12 in a similarly small package (running 60 Liters now) and REASONABLY as low (would probably settle for a 40Hz F3)
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Old 18th November 2014, 02:40 AM   #10
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Join Date: Dec 2012
Quote:
Originally Posted by chips and palsa View Post
Hey everyone!

So after some field experience with my LAB12 in a ported box (let me tell you what doesn't make for a loud bottom end) I've finally decided to build the PAL12 TH as it's response looks noticeably nicer than the Tuba45 the driver was originally meant for (not digging that huge 10dB rise to 100Hz)

Sorry if this post looks similar to my previous one about the aforementioned ported 12, I promise I'm going somewhere useful!

I'm super interested in this project;

Q15 Compact 15" Bass bin

And here in 'Murica the BMS driver might be tricky to come around but THIS ISN'T!

PRV Audio 15SW2000 15" High Power Pro Audio Subwoofer 8 Ohms

(Slightly baffled as to why the unsatisfied buyer had used a Subwoofer as a midrange)

Those Q15 subs had gotten some great reviews and the PRV driver while only 1dB down on sensitivity has it beat on several specs like Xmax and Pe which to a noob like me, seem to be all that matters in a BR! (I'm trying to learn!) However, will this PRV driver's .46 Qts mess up the response compared to the BMS's .32?

So, the question is, can I place this PRV Audio driver in the Q15 box and use the B6 assisted alignment with similar results? the designer claims strong bass down to ~40 Hz with fairly good SPL. (potential iron law fault)

This would be for those occasions where 1 corner loaded sub and 1 top is all I need for house parties and such. I do love my Bass-Happy house music (EDM if you will) and TRAP, but with a PAL12 TH on the horizon I can wait for the full effect!

So any tips would be wonderfully appreciated. Would I be better off with a build like this?

Ultra compact ported 15" Dayton Ref HO

I thought I could be sneaky and pop this driver in a proven box and be happy!

P.S. Someone will have to explain how this B6 alignment works (something about .707 of a normal F3 for this size box?) and how it is achieved on my DriveRack...

THANK YOU!
I have a couple BFM subs and often in room it flattens out (corner), I have the T60 which is reasonably close to the t45 response curve. If the high sensitivity in the upper range looks like a bad thing you're not fond of using your EQ... it saves you power up high and all you need is 1 wide parametric filter -3dB or so at 80 Hz to get it flat, assuming you don't low pass at 80 (I lp everything at 80). 1 T45 will be silly loud, but the TH will go louder with a cutoff tradeoff, good luck! At 35 Hz the t45 is still pretty sensitive.

Last edited by sabaspeed521; 18th November 2014 at 02:49 AM.
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