DiyMobileAudio.com Car Stereo Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
Ok, so I am totally new to car audio, but I'm working on putting together a system. I've got my heart pretty set on a single DIYMA12, but I'm trying to figure out how big of an amp to buy. I've read that doubling the power only gives an extra 3 dB. Is that true? It just doesn't seem right. That means that you could give a 200W sub straight HU power (25 watts) and it would still play at least half as loud?!?! On the DIYMA, would I even notice a difference going from say 500 W to 800 W?

I don't like to listen to my music TOO loud, but I am expecting to be able to "feel" the sub. How many watts would be enough? (It's going in a 2003 civic coupe)

Also, I have heard it recommended that the enclosure should be anywhere from 0.5 to 1.0 cu. ft. What are the differences between the two? Will one play louder than the other? Does the freq. response change?


I'm sorry for all the newbie questions, but I really want to be sure of what I'm getting before I buy. Thanks so much in advance for your help!
 

·
Registered
Joined
·
1,485 Posts
Theoretically, yes. 3dB is double power. Just wait til you want to get 10dB louder and have to increase your power 10x!!

The diyma12 will handle more power in a larger enclosure due to the very fragile cone. If you want to "pound", the DIYMA12 might not be your sub.

And here's a big scoop of Perry for you too: Basic Car Audio Electronics
 

·
Registered
Joined
·
2,384 Posts
I've read that doubling the power only gives an extra 3 dB. Is that true? It just doesn't seem right. That means that you could give a 200W sub straight HU power (25 watts) and it would still play at least half as loud?!?! On the DIYMA, would I even notice a difference going from say 500 W to 800 W?
Doubling the power does yield a 3 dB gain. A 3 dB gain is a noticable difference, but 10 dB is perceived as twice as loud. On our forum we had a good post about the difference between 750 watts and 500 watts where "GunForHire" responded with this:
No sound difference. How can I state that?

Open your Windows calculator (or Mac, or Linux).

Type 750 / 500. You get 1.5 right? Now press the "log" button, you get 0.17.

Now press * 10 - you get 1.7. There is 1.7 dB difference between those two amps. A level that you'll go "I think I hear it"... Get to 3 dB and you'll know there's a volume difference, but it won't be much. Get to 8 to 10 dB and you'll hear it as twice as loud.

Bottom line, unless you're talking about a ratio of 2 or more in terms of power, it's really not an issue. Go with the smaller amp (you'll have the same sonics), save the cash, space, weight, and power draw.
And to answer your question about throwing HU power (you said 25 wats, but most of the 'powerful' HU's bench at ~13 watts no matter what they claim to do) on a subwoofer, I highly advise against doing so. If you start with 13 watts and go up from there, 200 watts would gain you roughly 12 dB which would put it a LOT louder than powering it with a HU. Also keep in mind that not all power is the same. Even two amps rated for the exact same amount of power can sound completely different.
 

·
Registered
Joined
·
42 Posts
I have 2 in my trunk now (VW GLI) and I can feel them. They are in a sealed box, 1.0 cubic feet per sub. I'm not pushing them too hard either... Just guessing they are getting around 300-400 watts a piece.
 

·
Registered
Joined
·
172 Posts
I have a DIYMA 12 on the way and just picked up an Alpine PDX-6.100. My car audio knowledge is a bit rough but if I remember right you'd get more volume from 2 12's getting 300 watts each than you would with 1 12 getting 600 watts? Double subs gives you 6db increase correct? So it's almost always more efficient to have more subs than power for pure spl though the space is the issue.
 

·
Registered
Joined
·
2,384 Posts
Doubling your surface area gains you 3 dB. Transient response is better with two drivers though. :)
 

·
Registered
Joined
·
539 Posts
I have 2 in my trunk now (VW GLI) and I can feel them. They are in a sealed box, 1.0 cubic feet per sub. I'm not pushing them too hard either... Just guessing they are getting around 300-400 watts a piece.
I gotta get together with you and hear that setup.
 

·
Registered
Joined
·
172 Posts
Doubling your surface area gains you 3 dB. Transient response is better with two drivers though.
Actually I think that calculation was under the assumption that your 2nd sub had the same amount of power as the first. So if you doubled yours subs and the 2nd had equal power then it would be 6db. Told you I was a bit rusty but I'm catching back up.
 

·
Registered
Joined
·
2,241 Posts
Actually I think that calculation was under the assumption that your 2nd sub had the same amount of power as the first. So if you doubled yours subs and the 2nd had equal power then it would be 6db. Told you I was a bit rusty but I'm catching back up.
yea, but in the proposed setup it was 600w total in both scenarios.
 

·
Registered
Joined
·
1,245 Posts
Ok, so I am totally new to car audio, but I'm working on putting together a system. I've got my heart pretty set on a single DIYMA12, but I'm trying to figure out how big of an amp to buy. I've read that doubling the power only gives an extra 3 dB. Is that true? It just doesn't seem right. That means that you could give a 200W sub straight HU power (25 watts) and it would still play at least half as loud?!?! On the DIYMA, would I even notice a difference going from say 500 W to 800 W?

I don't like to listen to my music TOO loud, but I am expecting to be able to "feel" the sub. How many watts would be enough? (It's going in a 2003 civic coupe)

Also, I have heard it recommended that the enclosure should be anywhere from 0.5 to 1.0 cu. ft. What are the differences between the two? Will one play louder than the other? Does the freq. response change?


I'm sorry for all the newbie questions, but I really want to be sure of what I'm getting before I buy. Thanks so much in advance for your help!
Here's a good read for you:

http://www.diymobileaudio.com/forum...ported-ib-0-30-cft-sealed-0-5-cft-sealed.html

Who'd a thunk it, search DIYMA in the review section, and you get member reviews on the sub...
 

·
Registered
Joined
·
58 Posts
DIYMA is not the sub for you :(
I'd agree with this. The DIYMA is in a sense not meant to be felt from what people describe. Its supposed to be a transparent, moving your sound stage forward sort of a sub.
 

·
Registered
Joined
·
5,755 Posts
Well look, if the frequency is low enough, you'll feel it there's no way around that.

I ran a Diyma sub and you can certainly feel it. It just has it's limit on how much output you can get out of it and I end up destroying the cone on it trying to get more.

I ended up replacing it with an RE SE12. That sub could take a lot more "abuse" if that's what you want to call it. The Diyma had a slight edge over the SE12 as far as accuracy is concerned, but the SE had a lot more output. It depends on your true goal. I personally was willing to sacrifice a little accuracy for increased output.
 

·
Registered
Joined
·
2,384 Posts
Actually I think that calculation was under the assumption that your 2nd sub had the same amount of power as the first. So if you doubled yours subs and the 2nd had equal power then it would be 6db. Told you I was a bit rusty but I'm catching back up.
*edit* Yes, that is assuming that power stays the same. Ie, say you have an amplifier that produces 600 watts no matter what impedance it is given. When you from one 12" driver to two 12" drivers you gain 3 dB. Two 12's to four 12's you gain another 3 dB, etc.

However, if you double your surface area (one 12" to two 12's) AND double your power (600 watts total to 1200 watts total) you gain 6 dB.
 
1 - 16 of 16 Posts
Top