SR124-DVC box building for sound quality

catch22atplay

I currently have almost everything in my signature below except i'm still waiting for the 2 amplifiers and IPOD touch to arrive. Nothing is installed yet except the new battery.

So i'm in the building stage you might say. Before i build my sub box i'd like some input. I like my bass tight and i prefer sound quality. So sealed boxes seem the best choice for me. I figure it might be helpful if i add some history and what i'm looking for.

I previously had 2 10" JL Audio subs that i bought 12 years ago and used in 2 previous vehicles. When i built that box i followed JL Audio's enclosure recommendations. I subtracted speaker displacement and wall thickness, etc to get an exact match of recommended internal volume. This sounded like MUD and i called JL Audio and got with their engineers. They then suggested a larger enclosure and i built it. This was a huge improvement in sound quality. Although i still felt it should sound better. Ended up using those subs for about 10 years in 2 vehicles and in fact i still own them. I can't believe they've survived this long.

OK I don't wish to repeat my previous box building failure due to bad box recommended sizes in the literature that comes with the subs. Why manufactures have to list the smallest size possible is beyond me. This manual says 0.88cu ft net free. As i've searched the forums and reviews of the SR124-DVC i see suggested sizes up to 1.5cu ft. I'd like to know if this puts Qtc at 0.700 or not. Figuring 0.700 as being non muddy sounding and more sound quality sounding.

Due to minimal Thiele+Small parameters in the manual it's difficult for me to actually know for certain what size box i need. Using WINISD it say 3.4cu ft for 0.704 qtc. Now that's 96.2 litres and VAS is 53 litres. So this doesn't seem correct. So i reentered the data and tried again. This time getting 0.704qtc and 3.217cu ft. Tried it again and got 0.704qtc and 2.868cu ft. This still seems way wrong. So either the Thiele+Small parameters are wrong, i inputted the parameters wrong or there just isn't enough info provided for me to use this software correctly. Then again i've never used WINISD so it could very well be me. Oh the above was for 1 sub btw. I figure i can accommodate up to 2.0cu ft per sub if needed.

So i gave up trying to figure this out myself. My choices are to either call Polk and talk to an engineer and pray he gives me real and true advice and hard numbers or get some feedback from some people using these subs. Feedback can be very helpful as you're the ones listening to the subs.

I listen to virtually everything, from classical on up. It all needs to sound good. I need extremely good bass extension and would like to forgo the use of the Bass Epicenter. Hoping i can get this bass extension without having to use it basically. I understand i'll loose max SPL as box size increases as there's less cone control and more excursion. I can live with that. But i also don't want to bottom out the voice coil and fry the sub. So this causes a conflict.

So i'm looking for some opinions on the matter before i build this box. Thanks.

Greg Peters

catch22atplay wrote: »

I currently have almost everything in my signature below except i'm still waiting for the 2 amplifiers and IPOD touch to arrive. Nothing is installed yet except the new battery.

So i'm in the building stage you might say. Before i build my sub box i'd like some input. I like my bass tight and i prefer sound quality. So sealed boxes seem the best choice for me. I figure it might be helpful if i add some history and what i'm looking for.

I previously had 2 10" JL Audio subs that i bought 12 years ago and used in 2 previous vehicles. When i built that box i followed JL Audio's enclosure recommendations. I subtracted speaker displacement and wall thickness, etc to get an exact match of recommended internal volume. This sounded like MUD and i called JL Audio and got with their engineers. They then suggested a larger enclosure and i built it. This was a huge improvement in sound quality. Although i still felt it should sound better. Ended up using those subs for about 10 years in 2 vehicles and in fact i still own them. I can't believe they've survived this long.

OK I don't wish to repeat my previous box building failure due to bad box recommended sizes in the literature that comes with the subs. Why manufactures have to list the smallest size possible is beyond me. This manual says 0.88cu ft net free. As i've searched the forums and reviews of the SR124-DVC i see suggested sizes up to 1.5cu ft. I'd like to know if this puts Qtc at 0.700 or not. Figuring 0.700 as being non muddy sounding and more sound quality sounding.

Due to minimal Thiele+Small parameters in the manual it's difficult for me to actually know for certain what size box i need. Using WINISD it say 3.4cu ft for 0.704 qtc. Now that's 96.2 litres and VAS is 53 litres. So this doesn't seem correct. So i reentered the data and tried again. This time getting 0.704qtc and 3.217cu ft. Tried it again and got 0.704qtc and 2.868cu ft. This still seems way wrong. So either the Thiele+Small parameters are wrong, i inputted the parameters wrong or there just isn't enough info provided for me to use this software correctly. Then again i've never used WINISD so it could very well be me. Oh the above was for 1 sub btw. I figure i can accommodate up to 2.0cu ft per sub if needed.

So i gave up trying to figure this out myself. My choices are to either call Polk and talk to an engineer and pray he gives me real and true advice and hard numbers or get some feedback from some people using these subs. Feedback can be very helpful as you're the ones listening to the subs.

I listen to virtually everything, from classical on up. It all needs to sound good. I need extremely good bass extension and would like to forgo the use of the Bass Epicenter. Hoping i can get this bass extension without having to use it basically. I understand i'll loose max SPL as box size increases as there's less cone control and more excursion. I can live with that. But i also don't want to bottom out the voice coil and fry the sub. So this causes a conflict.

So i'm looking for some opinions on the matter before i build this box. Thanks.

Are these the T/S parameters you input to your enclosure design software?

http://www.polkaudio.com/downloads/manuals/car/SRSubwoofersManual.pdf

catch22atplay

Yup, used those numbers. I did talk to a Polk guy. He suggested a few different sizes for sound quality. 1.4, 1.5 and max 1.57cu ft for close to a 0.700 Qtc. I'll probably go with the 1.57cu ft. I don't need to rattle and flex everything. Just want the best sound possible out of these fine subs. Can't wait to hear em. Should be quite a difference compared to my last pair. I'll update in a few weeks with the results. Although i'd still need time to burn em in properly.

How's yours sounding Greg? What size did you go with?

Dodge Ram 1500 SLT Quad Cab 2007. DCPOWERinc 260 Amp Alternator (200 Amps at idle), Odyssey AGM Battery PC-1500DT
Pioneer AVIC-Z110BT Head unit, IPOD Touch 64gb and G3 Blackberry, Audio Control Bass Epicenter (i've used this one for over 10 years now)
Rockford Fosgate T1000-4 4 channel amp, Rockford Fosgate T1500-1BD mono sub amp, Polk Audio SR5250 separates 2 pairs, Polk Audio SR124-DVC 2 total

catch22atplay

Oh btw anyone know of a grille that would fit these subs? Neither of the Polk grilles would be sufficient for me. Not enough coverage/protection. I'd probably damage the speaker cones. Need a mesh type grille. Searching online they don't give the depths. I'm mounting the subs from the outside of the box.

catch22atplay

OK i finally got 3 of these programs working correctly. All 3 sizes are great suggestions for sound quality. 1.5 i can see why i've seen posts to use up to this size. All around that's probably the best choice. But after playing around with these programs i may end up going with 1.67cu ft instead. Quite a bit against the norm. But for what i want it to do this may be best for me.

wheely1up

does anyone have any pics or diagrams of an enclosure for vented dual SR124? polk tech support is crap at best. they send me a box design for SPL and the vent dimension was longer than the inside dimension of the box where they reccommend placing it. doesn't make sense. i made the change from W6's to polk, but haven't been able to get accurate info. any help would be great.

chu

wheely1up wrote: »

does anyone have any pics or diagrams of an enclosure for vented dual SR124? polk tech support is crap at best. they send me a box design for SPL and the vent dimension was longer than the inside dimension of the box where they reccommend placing it. doesn't make sense. i made the change from W6's to polk, but haven't been able to get accurate info. any help would be great.

The measurements doesn't have to be exact, you're off by 2' big whoop. Just make the ported part of the box taller where your sub can vent out.

edit: dude, you're in sac? I built a couple ported enclosures for the sr124, and I think I still have one of them somewhere that you can have free of charge that if I can find it :X

Marvelous Marv

catch22atplay wrote: »

OK i finally got 3 of these programs working correctly. All 3 sizes are great suggestions for sound quality. 1.5 i can see why i've seen posts to use up to this size. All around that's probably the best choice. But after playing around with these programs i may end up going with 1.67cu ft instead. Quite a bit against the norm. But for what i want it to do this may be best for me.

So how is the SR's doing?Can you give me the name the programs you used for your specs?

Marvelous Marv

wheely1up wrote: »

does anyone have any pics or diagrams of an enclosure for vented dual SR124? polk tech support is crap at best. they send me a box design for SPL and the vent dimension was longer than the inside dimension of the box where they reccommend placing it. doesn't make sense. i made the change from W6's to polk, but haven't been able to get accurate info. any help would be great.

Did you ever complete your ported box design?Wondering because I was going to do the same thing until they kept saying made for a seal box

catch22atplay

WinISD beta, WinISD pro alpha, Linear X (demo). Numerous spreadsheets by Jeff Bagby, Paul Verdone, Charles Laub (woofer box model and circuit designer, response modeler, passive crossover designer, to name a few. Also online java aps. But their not very good.

I like winisd pro alpha but also the spreadsheets.

As i'm still working on an island and my ride is on the mainland i've still not built nor installed anything sadly.

And Marv the speaker parameters are right in the middle for sealed vs vented. It will work very good for either application. We say go sealed as sealed boxed have better cone control below the tuning freq. Also it will have more output at lower freqs and won't need a subsonic filter usually. Delay would be less as well. Basically sealed will be tight and controlled with a flat freq response.

Vital

22 - what size u went with?? Ho do u like it??

catch22atplay

I still have zero time. So hard to get anything done when i'm not home.

I've yet to install anything. And now my alarm is acting up and Dodge wants me to leave it with them for 2 days. I can't even do that.

evil ryu

catch22atplay wrote: »

WinISD beta, WinISD pro alpha, Linear X (demo). Numerous spreadsheets by Jeff Bagby, Paul Verdone, Charles Laub (woofer box model and circuit designer, response modeler, passive crossover designer, to name a few. Also online java aps. But their not very good.

I like winisd pro alpha but also the spreadsheets.

any idea where i can get these programs? i prefer a user noob friendly one...lol