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Discussion Starter #1
I am open to sealed or ported designs using a 12"-15" driver. I have a Bash 500 watt @ 4 ohm amplifier that will be powering this project. My media room is 13' wide and 17' long with a 10' ceiling. I have access to a decent wood shop and plan on building the enclosure myself. Please be as specific as possible about internal volume and port dimensions.

Thanks for your input,

James
 

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Discussion Starter #3
Yes, home theater application. I'm looking for the nice tight impact that makes you jump when it hits you in the chest. I had a Revel B15A several years ago and it reproduced impact like that. I currently have an Earthquake Kompressor S12 that's a decent sub, but I'd like to step it up a bit.

I actually need to build 2. I'd like to keep 1 of them around 5 cu.ft. if possible, the other could be 8 cu. ft., maybe a little bigger. Let me know what works best and I'll try to make it fit.

James
 

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Discussion Starter #5
I can afford 8 cu. ft. or maybe a little more for my theater. I also need to build one for my brother, but the WAF comes into play because his 5.1 system is in the family room. I could use a 12" sub in his application if it keeps the size mangeable. I'm hoping to find an relatively inexpensive(under $250) 15" that performs well in 7-9 cu. ft. and the 500 watt BASH amp has enough power to get the sub moving for my dedicated room.

The main reason I'm thinking $250 and under is because the more expensive($300-$600)subs need a lot more power to get them pumping.

These are my observations, but I have been known to be wrong. I'm open to other ideas if someone cares to show me the way.

Thanks again for your time.

James
 

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I can afford 8 cu. ft. or maybe a little more for my theater. I also need to build one for my brother, but the WAF comes into play because his 5.1 system is in the family room. I could use a 12" sub in his application if it keeps the size mangeable. I'm hoping to find an relatively inexpensive(under $250) 15" that performs well in 7-9 cu. ft. and the 500 watt BASH amp has enough power to get the sub moving for my dedicated room.

The main reason I'm thinking $250 and under is because the more expensive($300-$600)subs need a lot more power to get them pumping.

These are my observations, but I have been known to be wrong. I'm open to other ideas if someone cares to show me the way.

Thanks again for your time.

James
The AE AV15-X fits the bill. It is $250, and fairly efficient. 500 Watts would drive it to very high levels. It can take far more power, but it will produce very substantial output with 500 watts. In fact, the very high 1000W power rating for the driver means you will probably encounter very little thermal compression using a 500W amplifier.

http://aespeakers.com/shop/catalog/...id=68&osCsid=7677db0c60792fc7ab30062347d47413

As a rough example in 8 cubic feet, and for 500 watts input(with minimal air port velocity), a folded slot port that is 5" high x 12" wide and 56" long would tune the box to 18Hz. -3 around 18Hz, -6 around 15Hz. In room -3 would probably be 14-15 Hz.

The above is just an example based on the factory provided specifications for the driver.

-Chris
 

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For you I'd suggest the Mach 5 Audio IXL-15. $220 shipping included. In 6 cu.ft. net volume box tuned to 19 hz. Your Bash 500 amp would have to have the HPF changed to 14 hz. SPL would be over 111 db at 20 hz, plus the effects of room gain. Two 4 inch flared ports would keep the port air speed acceptable.

IXL15.JPG
 

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Overall, the AV15 will produce 40-60% more output with the same input power as compared to the Mach 5 based on your above graph. It is better suited to the low power amplifier that the OP states will be used.

Also, while I have not modeled the Mach 5 15", two 4" ports is likely going to not allow the 20Hz spl target you specified. If one is build a cabinet, there really is no reason or excuse to not use a folded slot port and have the device act as linear as possible through it's bandwidth. In addition, one also has to make allowance for thermal compression and BL loss at a specific excursion. Most drivers have rapidly falling BL after just 25% of their claimed xmax. Only the drivers with exceptional motor designs have a sort of flat BL curve for the majority of their xmax rating.

-Chris
 

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Discussion Starter #9
OK Chris,

I like what I'm hearing . Would you recommend building it to the factory specs you showed as an example, or should I look elsewhere for more info on getting the most out of it.

Does the 8 cu. ft. include the port volume and woofer displacement or do I need to add that to the internal volume measurements?

I grew up building tuned enclosures, but have been out of that loop for a while and don't have a clue as where to start.

I see a lot of the guys here using pro sound amplifiers to power their enormous subs. Is there a pro sound amp you would recommend to really rock the house using this sub, and who is the best source?

Thanks a million for the info,

James
 

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OK Chris,

I like what I'm hearing . Would you recommend building it to the factory specs you showed as an example, or should I look elsewhere for more info on getting the most out of it.
It would probably work fine using the factory T/S specs to model the unit to pick a cabinet tuning, as I did. But I like to break in and measure the T/S specs myself on any driver I use in ported cabinets to ensure the results are as I intend. However, you would have invest and additional $100 to buy the device to test the T/S parameters for yourself; you'll have to decide if it's worth it to you to get the measuring tool.

Does the 8 cu. ft. include the port volume and woofer displacement or do I need to add that to the internal volume measurements?
No, I only included net internal volume. The port will have to be compensated for in the volume.

I see a lot of the guys here using pro sound amplifiers to power their enormous subs. Is there a pro sound amp you would recommend to really rock the house using this sub, and who is the best source?
In your first post you expressed specifically that you had a 500 watt amplifier you intend to use. The specific driver I recommended will produce as much SPL as most high quality 15s will with 1000 watts, and that is one of the main reasons I specified this subwoofer for you. Now, I am not aware of the true linearity of this driver, nor many others, as I depend on credible 3rd party Klippel or Dumax BL and compliance linearity analysis, or accurate freefield or ground plane measurements showing SPL vs. THD and compression characteristics in order to estimate the quality of a driver or line of drivers based on others in it's lineage. But, seeing as you will not near the xmax of the driver and will only use 1/2 of it's rated continous thermal power rating, it is a pretty safe bet that you will get nearly perfect linear behaviour from this driver in your use, using a true 400-500 watt amplifier. If I was to suggest an easy to use practical amp for this driver, it would be the O Audio BASH500, because it has been measured/verified by credible 3rd party to perform superbly, it's made of very high quality parts(and in North America) and it has user adjustable subsonic filter, which is very important for safety to ported subwoofer systems if used for HT use. While I normally would specify at least 1000 watts as ideal for many 15" drivers, again, this one is much more sensitive, and you can use much more power on it if you really wan to, and perhaps get extremely high SPL('extreme' is a relative term; even at 500 watts, this driver will produce well over 120dB of output in the average sized room when corner loaded), assuming the motor remains linear at higher power(Again, I have no idea of knowing if is.).

-Chris
 

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Discussion Starter #11
Well Chris,

You hit the nail on the head. I ordered an OAudio BASH 500 watt amp a couple of days ago and was going to use it with a Dayton Titanic MKIII. After doing some research here and realizing I'd been out of touch for a while, I thought I would ask some of the members who have good experiences with subs I may not be familiar with.

Did you use an enclosure modeling program with the manufacturers specs to produce the example you posted earlier, or was that posted on their site?

As a rough example in 8 cubic feet, and for 500 watts input(with minimal air port velocity), a folded slot port that is 5" high x 12" wide and 56" long would tune the box to 18Hz. -3 around 18Hz, -6 around 15Hz. In room -3 would probably be 14-15 Hz.
Do you think I could use your example and my OAudio BASH 500 watt amp and get at least 90%-95% of it's potential?

I have a nice Fluke multimeter. What else would I need to test the T/S parameters, and what program would you recommend to model the enclosure after I have accurate measurements?

James
 

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Did you use an enclosure modeling program with the manufacturers specs to produce the example you posted earlier, or was that posted on their site?
I used the manufacturer provided T/S specifications in a modeling program (WinISD Pro). I observed excursion, vent air speed and made a generic assumption for BL vs. excursion strength and thermal compression dynamics. WinISD can not automatically model these factors, and to do so accurately, you need for example a full Klippel analysis report, but one can make some ballpark assumptions with enough experience. I always make these assumptions based on a worse case scenario as not to over-estimate performance.

Do you think I could use your example and my OAudio BASH 500 watt amp and get at least 90%-95% of it's potential?
What do you mean by potential? Potential SPL? To get full potential, you would probably need a 1500-2000 watt amplifier. But unless you have a huge effective room, I don't see where you need any more than the BASH amp can provide for this woofer. Is 120+ dB not sufficient(assuming a 2000 cubic foot room, corner loaded)?

I have a nice Fluke multimeter. What else would I need to test the T/S parameters, and what program would you recommend to model the enclosure after I have accurate measurements?
The Woofer Tester 3 from www.partsexpress.com is the device you need. It comes with, or did come with a digital scale that you also need to complete the measurements. In addition to this, you simply need some non-hardening modeling clay to use as added mass to calculate compliance.

Now, one can calculate T/S parameters using a multi-meter and a frequency generator. But uhm, this method requires a great deal of time invested and many steps to accomplish. I highly recommend against it.

-Chris
 

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Discussion Starter #13
What do you mean by potential? Potential SPL? To get full potential, you would probably need a 1500-2000 watt amplifier. But unless you have a huge effective room, I don't see where you need any more than the BASH amp can provide for this woofer. Is 120+ dB not sufficient(assuming a 2000 cubic foot room, corner loaded)?
I meant the potential of the woofer driven by the OAudio 500 watt BASH amp.

The WT3 looks like a pretty nifty device. I may have to look into picking one of those up. I'm sure I'll be obsessed by this for a while

James
 

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I used the manufacturer provided T/S specifications in a modeling program (WinISD Pro). I observed excursion, vent air speed and made a generic assumption for BL vs. excursion strength and thermal compression dynamics
Regarding the O-Audio amp, did you also model the boost that goes with the high pass filter and the effect of it on cone excursion and SPL?

The AX15-X definitely models better then the IXL-15, but I don't see a 40-60% increase in output. The AV15-X has a 3 db advantage from 30 to 80 hz. Both models are with 500 watts, no High pass filters.

AX15-X.JPG
 

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The AX15-X definitely models better then the IXL-15, but I don't see a 40-60% increase in output. The AV15-X has a 3 db advantage from 30 to 80 hz. Both models are with 500 watts, no High pass filters.
Yes, there is about a 3dB averaged increase in output with the same power using the AV15-X over the majority of the bass band. 3dB is a 50% increase in SPL amplitude. 6dB is a 100% increase in SPL amplitude. For example, it would require two equal drivers operating in phase to produce a 6dB gain (100%) in output. It is quite an increase. The AV15-X can produce overall the same output with a 500 watt amp on the AV15-X as a 1000 Watt amp would produce on the IXL-15. Or if you want to look at it another way, the AV15-X with the same power, is like 1 and 1/2 drivers. :)

-Chris
 

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Although your explanation is correct, a "40-60% increase" can be deceiving to the uninformed. A 3 db increase in volume has been stated as "barely noticeable".

Now back to the O-Audio amp. Of the 4 selectable high pass filter frequencies, only the 25 hz setting does not apply any boost. As tight lipped as O-Audio has been about the amount of boost in their amp, plus the difficulty in interpreting their published graph, it has been estimated that there is 4 db of boost at 20hz, 6 db at 16 hz, and 8 db at 12 hz. I'm having trouble modeling this in WinISD. what HPF setting would you recommend for the AV15-X in 8 cu.ft. tuned to 18hz?
 

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Although your explanation is correct, a "40-60% increase" can be deceiving to the uninformed. A 3 db increase in volume has been stated as "barely noticeable".

Now back to the O-Audio amp. Of the 4 selectable high pass filter frequencies, only the 25 hz setting does not apply any boost. As tight lipped as O-Audio has been about the amount of boost in their amp, plus the difficulty in interpreting their published graph, it has been estimated that there is 4 db of boost at 20hz, 6 db at 16 hz, and 8 db at 12 hz. I'm having trouble modeling this in WinISD. what HPF setting would you recommend for the AV15-X in 8 cu.ft. tuned to 18hz?
I would disagree. 3dB is very noticeable. Now, 1 dB is barely noticeable. And the ancient research into volume change vs. perceived level is obscure and only mentioned indirectly. So it's not even clear the exact methodology used in this research(which must have been from the early 1900s).

I will say, that to me, 6db sounds roughly like 2x the volume, and 3db sounds roughly like about 1/2 increase. But maybe that's my imagination...

I am going to set up a randomized blind test to submit to myself and others to come to a more defined conclusion. This issue is important.

As for the HPF subsonic filter, at the 18hz tune, and considering the low end boost inherent to the amp, I would probably set the amp to 20 or 25Hz based on the end result response curves indicated by O Audio. The O Audio specifications page clearly shows the various response curves of the amplifier, so there is no mystery to it's frequency response. You could use the parametric EQ to cancel the boost if you wanted. Since there really is no other use for the parametric EQ in a ported system, you could go ahead and do this.


-Chris
 

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I am going to set up a randomized blind test to submit to myself and others to come to a more defined conclusion. This issue is important.
Agreed. A more defined conclusion would be welcome. I tried increasing the volume of a sub by 3 db by using a SPL meter, I found it barely perceptible. But that could just be my personal hearing.
You could use the parametric EQ to cancel the boost if you wanted.
I was unaware this was possible. Strange that O-Audio support never mentioned it in the many emails sent regarding the amount of boost that is applied. Trying to get information from them is impossible.
 

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Any progress on this? I love seeing other people's subs. If you haven't bit the bullet yet, have you thought about the ED 19Ov.2? It's a great sub. 18", decent xmax, and not nearly as expensive as a lot of other subs out there. With that same 500w amp and a little bigger box (10 cubic ft tuned to ~19 hz) you'd get better spl from it than the other woofers mentioned. That's only if you can get a bigger box.
 
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