Sound from Under Powered sub?

[sirhk100]

What will an underpowered sub sound like? Say I have an amp that puts out 200 RMS and my Sub is rated at 500 RMS. What can I expect from it performance wise and sound quality?

 

[leenjen]

well, it depends on a lot of factors: the subwoofers sensitivity rating, the amps output @ voltage rating, and the enclosure type.

for example an Audiobahn AW1205X subwoofer handles 1000w rms. the sensitivity rating is 93db (2.83v@1meter). an Audiobahn A275HCX (amp)has a rated output of 600w mono @ 12volts.
since the subs sensitvity is so high and the amp is rated at a low voltage, they sound perfect together (better than all four of my 15's) in a large ported enclosure. they also sound good in a small sealed enclosure, but no where near the SPL of the ported.

now the opposite: a Rockford fosgate Power HX2 10" handles 1000w. the sensitvity rating is only 85db (2.83v@1meter). a Profile 800sx (amp) has a rated output of 600w mono@ 14.4volts. in this example, the sub has lower sensitvity and the amp can only achieve the power it claims at higher voltages. they might still soud ok in a ported box, but not even close to the first setup. a sealed box isn't as efficient, so the more power the better.


hope this helps. if your subwoofer is truly underpowered, it will do serious damage to the voice coil.

 

[sirhk100]

Leenjen,
Thanks for all of your help on this issue and others. What do you do? I saw your profile and it said audio for profession and hobby. Do you work at a shop or are you just into the stereo as a hobby and do install stuff on the side?

I'm sure you remember me asking about the Audiobahn subs. Here's some more detailed info on my amp. I would appreciate your opinion on a sub selection.

'96 model year, Punch 100x2. This info is out of the operators manual.

Mono into 4ohm Load measured at 14.4V: 400watts.

RMS power mono into 4ohm load at 12.6V: 200watts.

From the print out test sheet I got these numbers.
Test Voltage: 14.08
Test Impedance: 2ohm
Output Voltage: 21.2
Output Power: 225 Watts/Channel (this measurement of watts confuses me. Is this bridged? Max? RMS? It doesn't say.)

What's the difference between an Ecursion Woofer and a compression piston Sub? Soundwise? Function wise?

The guy at a local shop just tried to sell me an AW1200X for $160. He showed me a van that had 4 of them accross the back and it sounded insane. I found this same Sub online out of NY for about $115 to my door step. Would my amp be enough to push one of those? You recommended the AWP212X which I found in for about $105 to my door. You also recommended the AW120XS which I havn't found a price for. These subs all seem about the same price range so it's really just a matter of choosing the best one for me. I have a sealed box with 1.25 cu' of space built or a band pass box that both are built to mount a 12" sub in. I listen mostly to punk rock and music with a fast drum beat. I also listen to some rap and I'm getting into trance and jungle music.

Are these good prices? Which sub would you suggest from your experience/opinion? Which box would you recomend me use? I would assume the sealed since I'm looking for SQ and a tighter bass then a real booming bass although both would be awesome!! Can you get any hook ups in your area? Email me or respond here. THANKS FOR YOU TIME AND INFO, IT'S MUCH APPRECIATED AND VALUED!!

By the way, the shop I just went to had a PT Cruiser on 20" rims dropped on Air Bags. All custom white interior with a plexy Glass box in the rear and a single 18" alum. cone Audiobahn sub facing rearward. Insane!!!

 

[leenjen]

thanks for all the kind words. i just dont want to see anyone get ripped off, or spend too much on equipment that doesn't perform as expected. as far as occupation goes, i do installs and sell equipment locally but do not have a store yet. i'm working on that. first i want to move, then find the best place to set up shop.

the 1200X is a very good subwoofer, but i dont know if your amp will be compatable. the last 2 generations of rockford fosgate amps are all stable to 2ohms mono, but i dont know if yours is. if it is then they will probably work well together. the 1200X is a dual 4ohm voice coil subwoofer that handles 700 watts rms with a 93db sensitivity rating.

the AWP212X will probably work much better with your amp. it is a single 4ohm voice coil flat piston subwoofer. it handles 450w rms and has a sensitivity rating of 94db. the compression piston can handle tight accurate bass while still providing high spl.

the AW120XS is another good choice. single 4ohm voice coil. 500w rms. 93 db sensitvity.

so, with your punch amp i'd probably go with the AWP121X. if it can handle a higher current 2 ohm mono (and puts out enough power @2ohm mono), then the AW 1200X will be perfect.

 

[leenjen]

Originally posted by sirhk100
I listen mostly to punk rock and music with a fast drum beat. I also listen to some rap and I'm getting into trance and jungle music.
.......
Which box would you recomend me use? I would assume the sealed

i used to listen to mainly punk and ska in highschool, now lots of different music.

definitely go for the sealed over bandpass. i hate bandpass... such a narrow frequency range... it changes the music and makes it seem unnatural. when i do an install and someone asks about a bandpass box, i let them listen to music first in a bandpass, then a sealed or ported. they rarely opt for the bandpass. if you want you can get a 4" holesaw and drill the sealed box, throw in a 4"pvc pipe and it's now ported. it depends on what you prefer.
i do like many sealed enclosures, but personal preference in my vehicles is ported.

 

[sirhk100]

I've been out of the stereo scene for awhile now cause I just listen to what I have. How can I find out if my Amp is stable at 2 ohms? Will it generally say in the paper work somewhere or is it something I can test without killing the amp? For the electronically challenged and stereo lingo illiterate what did you mean by "if it can handle a HIGHER CURRENT 2 ohm mono(and puts out enough POWER @2ohm mono)" What's this asking or suggesting? I'm assuming Current=Volts and Power=Watts. Is this right? How can I check this. I've got the spec sheet provided for my indivual amp and the manual. Heck I could fax you a copy of it and maybe you can decipher what my amp's capable of. Also just for my curiosity and understanding could you describe (in idiots lingo) the difference between a compression piston sub and a Excursion sub? I've been searching through sounddomain.com and I'm confused because these guys are technical and assuming I have background knowledge when reading it. Right now I'm leaning towards the AWP212X based on your comments and opinions. (Don't worry, if I get it and it's not what I'm looking for I won't be all agressive and pissed at you, hell what can I do from SoCal!!) :~) I'm sorry for asking all these questions, just trying to widen my knowledge and like you said make a more informed and better purchase!! Thanks again for your time and info!!

 

[sirhk100]

As for ported vs. Sealed. I'm definately not going to use my band pass. It sounded better in my hatch back but doesn't sound good in the Explorer. I've been running the sealed box for a couple of weeks with my RFP-1412 sub that I toasted. It sounds good. The box is VERY well built and has outer dimensions of 14"x12"x19.75" with 3/4" MDF which is exactly what fosgate recomended for the RFP-1412 that I was using. What's the difference in sound going to be ported vs. sealed? How long of a tube and approximately where would I want it? Any experience sealed vs. ported in the back of an Ex. and also which orrientation. I have the sealed box firing towards the back right now which seems to be the best.
Thanks again for the help. I know this is repetative but I'm always blown away by the wealth of info you guys provide.

 

[leenjen]

well, current=amperes but that's not what we're really talking about here. Ohms=impedence or resistance, basically a simple explanation is slowing down the current. a 1ohm stable amp is considered high current (most amps are 4ohm mono stable) because it can handle being run at 1ohm where other amps would burn up. there is no safe way to test your amps capabilities (kinda like no safe way to test your airbags in your car) they do that at the factory. your best bet is to play it safe and go with a 4ohm single voice coil subwoofer like the AWP212X.

a high excursion subwoofer usually has a larger surround than most subs. more linear excursion moves more air, which provides higher spl. the compression pistons also move more air than a standard sub, but are more accurate than the high excursion subs.

 

[sirhk100]

Cool, thanks for the info. I don't think I'll test my amp since I don't really want to buy a new one. I've had it for 5 years now and it's always kicked ass and pounded hard. I'm actually surprised my Sub lasted as long as it did. I don't drive anywhere with my stereo quite!! I think I'm sold with the AWP212X. Thanks again!!

 

[leenjen]

with the box dimensions you gave, the internal volume of the enclosure is 1.386cuft. before you think about porting it, get the sub first and put it in. if you like how it sounds, do nothing. if you decide to port your box then do this.
get a 4" diameter holesaw and drill the box. get a 4" diameter pvc pipe and cut it to 14" long. this will give you a tuning frequency of 38Hz. this will give you more spl, without making it overly "boomy"

and rear facing is the best way to go IMO, it provides up to a +3db increase due to cabin gain. facing up works too, but rear facing still sounds better to most people.

 

[sirhk100]

I got the same volume as you so I'm glad I still know my math. Making the tube 14"s long it obviously has to mount the long direction. Not sure if you litterally meant 14"s though cause wouldn't that mean the tube was bottoming out in the box? How much clearance should there be from the inside of the box to the end of the tube? The length of the tube affects the deepness of the sound (Frequency) correct? Longer is deeper and shorter is higher? With a hole saw I'm guessing the port can just be pressed/glued in, correct? I feel like I'm in Subwoofer 101 but they didn't offer this at my college, at least there's no homework and the info is interesting and usefull!! I'll probably order the sub from the place in NY on Monday unless the local shop will match their price.

 

[sirhk100]

Do you know the difference between teh AWP212 and the AWP212X?

 

[sirhk100]

One more question, just tell me if you're getting sick of me but it seems like the local shops don't know as much as you do so I might as well grill you while I can. I was looking at the specs wor the AWP212X and it says " 2" 4-Layer ASV Voice Coil / Dual 4 ohm / 2 Ohm or 8 Ohm Operation". Does this mean it's a dual voice coil? And what ohms would my amp be running at if I have it bridged on mono? You said further up that it was a single voice coil but this sounds like 2 to me. How is it ran either 2 or 8 ohm?

 

[leenjen]

if you do decide to port it, then 14" is the correct length for a 4" diameter port tuned to 38Hz in a 1.386cuft enclosure. so, yes it woould have to go the long way. the distance between the back of the port and the inside wall of the box should be at least the diameter of the port away. so since your port is 4"dia, and the length is 14, it will be fine because the internal length of the box is 18.25"

a shorter length port will make the tuning frequency go up. this will cause higher spl, but not very good sound quality.

you might not even want to port the box. try it sealed first. usually a ported box is larger anyway (usually, not always though. i have a .88cuft ported enclosure designed for a 12" sub).
when it comes to subwoofer enclosures, bigger is better (to an extent), but yours should do fine.

 

[leenjen]

the AWP212 is last years model. the AWP212X is the 2001.
basically the same, but the 2001 models provide better cooling for the voice coils (which some day you will find is very important).

 

[sirhk100]

Bump, Leenjen please check out the post right above your last set of replys. Thanks again.

 

[leenjen]

WOW. i'm glad you noticed that. i was just looking at their stat sheet, and they misprinted it. it actually is a dual voice coil sub. well the AW120XS is still a single voice coil. i'm sorry i gave you the wrong info on the AWP212X, they must have changed it or something.

 

[leenjen]

they also have the AWC12X, which is another svc, but i never heard that model before. so i can't say how it performs.

it looks like your best bet is the AW120XS.

 

[sirhk100]

Maybe I don't understand how a dual voice coil speaker works but couldn't I just run both channels to the sub instead of bridging it to keep it up in the ohm range it needs to be in? If I did this wouldn't it be like running two 2ohm subs? The book for my amp says mono bridged into a 4ohm minimum but per channel into a 2ohm minimum. Running it like this though it looks like it's 200watts at 14.4volts and 100watts at 12.6 volts. That probably isn't enough or would it be since both channels are going to the same speaker? Or am I just trying to do something that shouldn't be done?

 

[leenjen]

if your amp was more powerful, i would highly recommend the AW1205X. but that's about double the price.

you could probably get the AW120XS for about $100