Tuning Freq. for DD 2512's

[Drunken.Swagger]

I'm designing a box for my 2 DD 2512's and I'm reading all the info I can find, but I'm hoping someone on here has experience and can tell me:

Would a 30Hz tuning frequency have a noticeably lower extension than a box tuned to 40Hz for these subs?

DD says that the subs can play well below the box loading point, but I want to know how true that is. This is going to be a daily driver and I love really low bass so I want to know from someone with experience what the best tuning frequency would be.

Thanks,
-Ryan

[bones22]

with most DD stuff stay between 38-42hz
myy 99z was tuned at 36hz and i wish i had gone with 40

[Drunken.Swagger]

I'm going to go with the largest box recommendation on DD's site at 5 cubes, so should I just use the 80sq x 18 inch port that they recommend as well?

[madmat]

Yeah, just build it according to their recommendations. DD are SPL woofers, they wouldn't know SQ if it bit them on the face so trying to run one of their subs in a box tuned below 40hz is pointless. They even admit it on their site.

[Drunken.Swagger]

Yeah, just build it according to their recommendations. DD are SPL woofers, they wouldn't know SQ if it bit them on the face so trying to run one of their subs in a box tuned below 40hz is pointless. They even admit it on their site.

Have you ever used a DD sub?

[madmat]

No but a SQ sub will have a FS way lower than 38hz and the MFG will recommend tuning the box under 40hz. 38hz FS and 40hz tuning = SPL sub plain and simple.

Go onto DD's site and every box they recommend is tuned to 40hz and sealed boxes are warned against. Now, you tell me if they build SQ subs.

[Drunken.Swagger]

No but a SQ sub will have a FS way lower than 38hz and the MFG will recommend tuning the box under 40hz. 38hz FS and 40hz tuning = SPL sub plain and simple.

Go onto DD's site and every box they recommend is tuned to 40hz and sealed boxes are warned against. Now, you tell me if they build SQ subs.

They aren't true SQ subs in the sense that they don't go very low, but they are very accurate in sound reproduction. They have great transient response and have a tight, punchy sound. If you read why they have the boxes tuned to 40Hz it's because the suspension is tight enough to remain loaded below box tuning, past 30Hz. I simply wanted confirmation of this by someone that has had experience.

I will agree that they aren't made for SQ but saying they are only for SPL when you've never heard one is ludicrous.

[madmat]

If it's not a SQ sub it's an SPL sub. It's either fish or fowl, it can't be both. Well, with the exception of stuff like Volfenhag and Visonik which aren't either, they're just garbage.

Look at it like this, if a sub cannot produce usable bass below 30hz it's not a SQ sub. If a sub is made for competition (which the DD subs are) and can't compete in SQ because they won't play below 30hz then what are they classed as? SPL or bassrace which is essentially an offshoot of SPL competing.

I don't have to hear a duck to know that it quacks.

[Drunken.Swagger]

I'll download some test tracks and get back to you later today because I don't have exact numbers on where my subs roll off. I do know that it is below 30Hz though.

[madmat]

Ideally, for SQ, true SQ mind you, you should have flat response from 20hz all the way up to the filter frequency of the sub amp. I can tell you right now that a sub in a box tuned to 40hz won't be flat. There will be a large hump in the response curve centered around 50-60hz. I've plotted my fair share of enclosures.

Have you got the T/S parameters for your subs? I'll be happy to plot them and show you what I'm talking about. I'd also like to see if there's anything to DD's claims that their subs won't work well with lower tunings.

[madmat]

By the by, this is directly from DD's site which reinforces what I was saying about their focus being on SPL>SQ.

The DD design philosophy of low moving mass, well controlled suspension and strong, linear magnetic systems allow the user many design applications never realized with traditional speakers. The growing popularity of the SPL competitions has led to new engineering requirements for an audio system. DD subs are ideally suited for both all out SPL vehicles and daily driver vehicles where high SPL and good sounds are required. The problem lies in the fact that the frequencies where a vehicles peak SPL may occur rarely ever coincide with a tuning frequency that promotes utmost sound quality. The peak SPL frequency is usually somewhat higher that the tuning frequency for sound quality.