DB12 Dynamic Balance sub questions

Courtland

Hello all,

I'm new to the forums here. I liked the specs on the DB12 and it also looks like it has some of the same construction as my Polk RM7500 speakers in my HT which I love the sound of. The DB12 sub being delivered tomorrow and I have a few questions regarding it.

I plan on putting this sub in an existing sealed box I made that is 1.02cft. It currently has a 10" in it with just over 1/2lb of polyfill. The box is in a 2002 BMW 325i and it is sealed to the ski pass opening and pressurized to the cabin.

How much polyfill should I use in the box for the DB12 for a SQL application?
How does the SQ compare to say an IDQ?

Thanks,
Courtland

MacLeod

That box is going to be bigger than the recommended volume so I would use any polyfill at all.

Polyfilll slows the waves down inside the box so it acts as if the box is actually bigger. In your case youre box is too big so you dont want to slow the waves any more.

Jstas

Dude, you need .85 cubic feet for that dB12. I can tell you from experience too that they don't like big boxes at all. You can build the box smaller and they will live happily there but big boxes give them too much space to pressurize and they don't sound right.

Does the sound compare to an IDQ? Dude, these were widely considered the best sub on the market when they were new. They will stil compete with alot of other subs out there now. They aren't big boomer, power-house subs. They are high quality subs that, when put in the correctly sized box, are clean, tight and probably one of the most musical subs I have ever heard. I have yet to hear anyone state dissappointment when listening to my dB12 or my dB10 before it wore out. Then again, my sub is voice matched to my dB3065 components and dB6500 drivers so it blends well too.

Toxis

your sub is voice matched to your components??? I don't even want to go there.

Courtland

That was my next question. Is there anything in the current line that is matched to this sub?

Jstas

Toxis wrote:

your sub is voice matched to your components??? I don't even want to go there.

Go ahead, go there. Let's see what you have to say.

Toxis

are you serious? To say a sub is voice matched to your components is painfully funny to me. Mainly because I'm an ex-car audio junkie turned home audio junkie. There's nothing voice about a sub let alone to match to your speakers. Now I know you're gonna say that your sub has similar characteristics as your components but that's far from saying it's voice matched. So either you listen to a lot of old R&B with the sexy deep vocals or you're x-overs are set WAY off... so basically what I'm saying is you do not match your subs to your components, you match them to the style of music you listen to. There is a difference.

Jstas

Ah, ok. Just as I thought. Nothing of substance.

Let me ask a question. If I listen to literally all kinds of music except opera, how should I choose a sub? Please, enlighten us, the slobbering masses.

One more question. If you can't voice match a subwoofer then why do so many of them sound so different?

MacLeod

John's right. Maybe its not "voice" matching exactly but its the same principle.

Granted its not as important as matching center channels to the mains but you want a sub that sounds like an extension of the midrange speakers. To Joe Sixpack, a sub is a sub but to the more critical listener like us we will be able to pick out when a sub doesnt match up well with its midrange counterparts.

Toxis

they sound different because of design. If you have done any research on speaker design, you'd understand that every single piece on a subwoofer can and will effect the sound down to the tinsel leads and dust cap. THAT'S why they sound different, not because they're voice matched to something.

You choose a sub on your preference of sound quality. I know this is something highly overlooked in the car audio industry of today but looking at it from a home audio perspective, the sound is what you go off of not the matching capabilities. I honestly thought this was a given but I guess to many people get brand happy and think it must be the same brand and line sub otherwise it won't sound/look right.

Example, I prefer a very smooth and subtle tweeter, Aggressive yet detailed midrange, punchy midbass and a smooth with a slight punch sub for my car. So I'd find the equipment that will give me the sound that I like, whether it's the same brand/line or not.

neomagus00

cool, so we agree! yay! now we can stop right here, because everyone can be happy, before this degenerates into yet another argument where both participants are arguing for the same thing... whee!

Jstas

OK, so because you choose your speakers that way, that's the correct way? Oh, I get it now. Well thank you for enlightening us with your superior intellect. We shall all prostrate ourselves at your feet because your opinion is so much better than ours. We are obviously blithering idiiots and incapable of handling things by ourselves and need you to guide us through our miserable existence.

Courtland

What Polks would be a good fit for components up front and coax's in the back? I like the sound of the RM7500 speakers we have.

Thanks,

Courtland

MacLeod

No John, youve got it all wrong. Its because car audio guys dont understand subtleties of SQ like HA guys do.

Courtland - Depends on how much you want to spend bro. The Momo components are $300 where the DB run $200'ish. But the Momos will sound noticeably better plus theyll have a better crossover to boot.

1996blackmax

I have had some guys who are really into home audio sit in my car back when I had my older setup (Alpine CDA-7949, Alpine PXA-H600, Kicker Resolution Components-the really old ones, Kicker ZX460, Kicker DX700). They were blown away by it. Something like I did not know that music could sound so good in a car. I then told them if you think this is good, there are so many more cars with better equipment than me and better installations, so just imagine that . But I guess we car dudes do not understand the subtleties .

Toxis

Jstas wrote:

OK, so because you choose your speakers that way, that's the correct way? Oh, I get it now. Well thank you for enlightening us with your superior intellect. We shall all prostrate ourselves at your feet because your opinion is so much better than ours. We are obviously blithering idiiots and incapable of handling things by ourselves and need you to guide us through our miserable existence.

you know, all you would've had to say is "I have no answer here." It would've saved you a lot of time attempting to be a smart ****.

Obviously you didn't get what I was saying. I was telling you what I like and because of that, I pick my system by the sound I'm trying to achieve, not because they're "voice matched." If you picked your speakers because they all gave you the sound you want, perfect! If you picked them because they're "voice matched," well I already went down that road.

Mac... don't remember saying that car guys don't understand good sound. I'm actually a car guy turned home guy. So I'm very much on both sides of the fence and am not saying one side is greater than the other. Car audio has the morons who only want bass to bump their new Mike Jones cd while Home audio has the retards who love the sound of transister radios and buy HTiB's.

It's good to know nothing has changed around here. :rolleyes: :rolleyes: :rolleyes:

MacLeod

Toxis wrote:

Mac... don't remember saying that car guys don't understand good sound.

Toxis wrote:

You choose a sub on your preference of sound quality. I know this is something highly overlooked in the car audio industry

Hmmmmm.

Besides, I was kidding anyway. Notice the little -> ? Sheesh, lighten up.

Jstas

Toxis wrote:

your sub is voice matched to your components??? I don't even want to go there.

You posted the above before any other post. You also stated that you had some undeniable proof to backup the comment you made but refused to post it. You were asked to "go there" and when you did, all your post amounted to was personal opinion. Sure, my responding post to that was rude, ignorant and arrogant but hey, that's what I was met with so that's what I gave back. Cry me a frickin' river why don'tcha?

All this leads me to believe that you are foisting your personal opinion on the rest of the world as the defacto standard on how to choose a subwoofer.

To that I will call shenanigans.


I have two 8" Kenwood subs, two 12" JBL subs, two 10" Polk DX subs, a 10" JBL sub, a 12" DX sub, a 10 " Polk MOMO sub (MM104), a 10" Polk dB sub, a 12 inch Polk dB sub, a Polk C4 sub and two MTX Two's. None of them sound the same and the only ones that blend seamlessly with my dB components are the dB subs.

1996blackmax

My sub blends very nice with my DB's .


OK let's take a deep breath guys .

neomagus00

1996blackmax wrote:

OK let's take a deep breath guys .

HA! good luck with that...

Toxis

Claimed to have undeniable proof... interesting. I just reread every post of mine in here and once again, you're making stuff up. I'll let this thread get back on track now... I'm to busy trying to voice match my sound dampening material to my wires.

neomagus00

Toxis wrote:

I'm to busy trying to voice match my sound dampening material to my wires.

teehee... toxis made a funny...

MacLeod

Toxis wrote:

I'm to busy trying to voice match my sound dampening material to my wires.

Waaaaaaaaaaaaahahahaha!

Youre still the king of the one liners.....youre wrong, but youre still the king!

audiobliss

Man, that's hilarious. If you make a lot of those funny comments, I'll hafta go back and read all your posts, too!

PoweredByDodge

any driver, in theory, can be voice matched to any other driver intended for a different frequency range.

applies to car or home...

ie. you can voice match a tweeter and a midbass and you can voice match a midbass to a subwoofer. you can't however match a tweeter to a subwoofer (if there is no midbass). but, by matching the tweeter to the mid, and the mid to the sub, then the sub is matched to the tweet.

In short, yes a sub can and has been voice matched to a "highs" speaker.

The original DB's, i believe, were voice matched. No one, IMO has put out a speaker line of that quality before or since then.

So I'm with John... and for the principle of it... a subwoofer is no different than a midrange... if you think it is, then you're a complete idiot. And so, the tinsel leads do not affect the sound... they only way they have any affect is if they are too thin (read as 24 gauge on a 1,000 watt sub, they add resistance), and if they are not taken into account as far as length of the voice coil. Any coil has inductance, and the length of the tinsel leads, as being part of the voice coil, should be taken into account - the exact science of doing so I am not up to par on, but that's not the point.

---

IDQ versus DB vs DX...

The Image Dynamics IDQ is a speaker I became familiar with after looking for Polk DX replacements. The DX series was the replacement (a little inferior, but still a very nice speaker of which I am a personal fan) for the original DB line. As far as overall sound quality, roughly the same power handling, and even their affinity for small boxes, the IDQ and the DX are pretty much cousins in the audio subwoofer world.

The original Polk DB, however, surpasses both these subwoofers. Power handling is the same as the DX (which is about 20% higher than the IDQ's), but the overall sound quality beats out both the IDQ and the DX.

I think you will be very happy with a DB sub, but as John mentioned, they are 0.88 cubic feet (including dispalcement of speaker) friendly. NO LARGER. 0.88 with a smidge of poly fill and you're golden... 0.70 - 0.75 with half a pound and you can surpass the rated RMS power with ease (still be careful though, at no time do I advocate gross insanity with equipment).

Now... you CAN put it in that 1 cubic foot box... but here's the problem you're going to have...

1- woofer will lack proper suspension (the box works as a sort of "pull back" - sucking the cone backward - assuming the box is 100% sealed as it is supposed to be, and not leaking).

2- frequency response will be boomier than typical and will lack the nice "flat response curve" characteristic of the DB speakers and other good SQ speakers such as the IDQ. Boomy sucks.

3- becuase of the lack of proper suspension, you will have to cut back your power to the sub... you can run the damn thing free air on your floor in theory, but you could only put a piddily 50 watts to it... you would probably have to cut back power (just guessing here) by at least 150 watts.

A much better solution is to get some 2x4 pieces... small ones... and figure out how many chunks of 2x4 of a given length it would take to cut your box down to 0.88 (that is if you are totally against building a new box).


.... you know I had a 0.88 box here that was my "test box" for 12's... used to use it to test out DX's... I would've gave it to you but I tossed it when we cleaned out the garage.

PoweredByDodge

and toxis - go back to the friggin HA forums where you jackasses debate whether or not cables have to be "burnt in", and have a firm belief that 8 gauge solid core speaker wire is the way to go.

the whole idea of voice matching is that if you're mid has a virtually flat response curve at say 85 db's, then your sub will have a similarly flat curve at 85 db, and your tweeter as well... often tweeters have to be compensated for with resistors (yes i said resistors), but you judge the overall set once built, not the individual pieces.

the definition of "voice matched" is ... "similar tonal quality". what is tone... tone is a particular mixture of bass, mid, trebble frequencies... well speakers don't produce frequencies, they simply broadcast ones that are put into them... signal sources and amplifiers produce those frequencies (equalizers, etc)...

I do not recall the name - maybe whitnoise? - but there are test tone compilations that will play various frequencies within the audible range from down at 20 hertz up to 20k... the speakers in a system (lets say a 3 way - sub, mid, tweet - all crossed over properly, whether active or passive) can then be tested for their response. when you get virtually the same response, for virtually all frequencies, across all 3 speakers -- that's voice matched.

now go burn in some more cables ****.

exalted512

dude, cables do need to be burned in. I had a set of 3 yr old monsters in my 2-channel rig and i put a new set in there and it sounded awful, but after i put it through my $500 burn in machine i got off ebay, it sounded so much better...and added 2dB!

yea ok i lied
-Cody

Courtland

Thanks for the good info. My friend had the same recommendation for my box to make it 0.88^3 by **** and gluing a small piece of MDF inside.

I just picked up 2 more db 12"s on eBay for $20/ea. One will replace the Momo (pinch tear in the surround) in my car and the other will go into the home system with another db 12.

Here's the finished trunk on my car:



And the trunk on the wife's car:
She will be getting new amps whenever I finish her system one of these days.

The box is sealed to the back of the seat. When the trunk is open, it sounds no different outside the car than with it closed. All of the bass is going straight into the cabin.

The space behind the armrest has a grillcloth and frame to hide the sub from the cabin.