Best curve for my twin 12 inch subwoofers

[toffkanda]

Hello,
I'm a new member on this forum and am about to work on a pair of tall standing slot ported 2cuft subs using the Epik 12" drivers which I ordered because I love very low bass extension. On modelling with WinISD, it appears the driver may not be so efficient as the spl substantially falls away at mid to low frequencies . I want to choose from two curves (see images) the pink one is 2 cuft tuned to 20.4hz ( port 12.5 by 1.75) having less sub20hz extension spl, better mid 20s prominence but potentially worrisome group delay. The white curve is 2.187 cuft tuned to 18hz (port 12.5 by 1.5) same external box size, having more sub20 extension but less spl between 20 and 50hz yet a more tolerable group delay. I intend to use an old Grundig digital Subwoofer nr line audio amplifier/receiver and am hoping I can compensate the 6 to 9db spl deficit at these frequencies by using the available bass management system it has. Which curve do you think I should use and how do I practically set up a high pass filter for this? Also does anyone know if this receiver (which BTW has powered sub output for passive subs which is what I want to make)has any variable crossover settings . Thanks for any advice on this project.

 

[TheWarrior]

Whether you are referring to Epik, or TC Sounds Epic, you are building a box that is too small. The T/S Parameters define all of your goals, including port dimensions. It appears you are trying to build this by selecting the frequency you want, rather than letting the driver tell you what frequency is best in what type of enclosure. Try again!

 

[toffkanda]

Strangely enough when you key in the T/S parameters of this driver into WinISD you get a recommendation for a ridiculously small box with an impossibly long port and fairly high Fb. I have read about the anatomy of the sentinel which uses the same driver and volume of box and it has good reviews in terms of low extension but audible group delay. When I input bigger box volumes I get a hump around the 20hz area of the frequency response and a valley in the 30-40 region rather than a flatter response. It may indeed be a strange driver or my mistake for choosing it. In the country I am in, it is socially strange to have massive speaker boxes in your sitting room, but very much appreciated to hear low (rather than loud) extension from relatively small boxes. Really Large and loud boxes are left for PA systems. I'd rather fall back on room gain, multiple boxes and amplification for lower frequency emphasis but I would still appreciate any advice I can get as it concerns this my plan.

 

[KEW]

You may want to check out the DIY subforum and post there.
http://forums.audioholics.com/forums/audio/diy-corner-tips-techniques.22/

 

[TheWarrior]

Strangely enough when you key in the T/S parameters of this driver into WinISD you get a recommendation for a ridiculously small box with an impossibly long port and fairly high Fb. I have read about the anatomy of the sentinel which uses the same driver and volume of box and it has good reviews in terms of low extension but audible group delay. When I input bigger box volumes I get a hump around the 20hz area of the frequency response and a valley in the 30-40 region rather than a flatter response. It may indeed be a strange driver or my mistake for choosing it. In the country I am in, it is socially strange to have massive speaker boxes in your sitting room, but very much appreciated to hear low (rather than loud) extension from relatively small boxes. Really Large and loud boxes are left for PA systems. I'd rather fall back on room gain, multiple boxes and amplification for lower frequency emphasis but I would still appreciate any advice I can get as it concerns this my plan.

On Parts Express http://www.parts-express.com/tc-sounds-epic-12-dvc-subwoofer--293-650 they indicate suggested box sizes... assuming this is the correct driver.

Only thing I can think of is that VAS is listed in feet, not liters, could that be what fouled up the results?

 

[BoredSysAdmin]

optimized vented box F3 is shown as 30hz... not what I would call very low extension.... but then , 2.26ft3 is a tiny box
Maybe it's worth starting from scratch with different driver....
but then again, What do i know..

 

[toffkanda]

Thanks for all the suggestions. This is not the TC sounds driver. Check
http://www.ebay.com/itm/NEW-Epik-12-Aluminum-Subwoofer-Driver-Woofer-for-Car-Audio-HT-Home-Theater-/281613507683. This is the driver that was used in the Epik sentinel and vanquish subs, The "built like a tank" driver. General info on this driver is scarce.