is underpowering subs bad?

jetas · Post by **jetas** » Sat Aug 30, 2008 12:54 pm

Alright so heres the deal ive been looking for a new sub and im trying to find one that i can properly run with my amp. My amps pushing out about 260RMS. Ive found alot of subs that handle 250 RMS. but my buddy keeps tellin me to just get one thats able to take 300RMS or more. I tell him it will sound like crap because ive seen/heard it done before but he says underpowering a sub wont do shit to it.

So my question is, Will underpowering a sub fuck it up? i kno it wont sound as it should.

And is it bad to run a Dual 2ohm sub wired in series?

jT · Post by jT » Sun Aug 31, 2008 5:58 am

an under powered sub isnt going to sound any different than a normally powered sub, other than it wont be as loud... but its not going to sound like crap per se, such as an overpowered sub would sound like (stressed, cracking, popping, blowing out).

youd probably be alright with a decent sub that is 250 RMS.. since 10w over isnt a huge amount. most people will argue that a quality sub can handle more than its rated for anyways.

as for wiring in series, do you mean Dual as in the brand name, or as in dual voice coil.. either way i think it depends on if the sub can handle the impedance of what it would end up being in series.. and also if the amp can stably provide that impedance rating

jetas · Post by **jetas** » Sun Aug 31, 2008 12:14 pm

Yea i did mean a DVC sub. Cuz if im not mistaken a Dual 2 Ohm sub wired in series comes out to be a 4 ohm load. and thats basically wat my amp is stable at. Correct wat i just said if im wrong

TheRandom1 · Post by **TheRandom1** » Sun Aug 31, 2008 12:54 pm

Everything I have heard says underpowering a speaker will do the exact same damage as overpowering it.

jetas · Post by **jetas** » Sun Aug 31, 2008 1:20 pm

I actually read something like that on this forum. I really wna kno the answer to this.

evilneon02 · Post by **evilneon02** » Sun Aug 31, 2008 7:13 pm

under power and over power will damage the sub but 10w wont hurt anything im 100w under and it still holding but im not tryn to win and comps and yes you can wire in series if you have a 4ohm amp

jetas · Post by **jetas** » Sun Aug 31, 2008 11:47 pm

Alright so myirst question hos been answered. And will wiring the DVC sub in series affect the perfomance at all??

Anonymous User · Post by **Anonymous User** » Mon Sep 01, 2008 1:19 am

underpowering a speaker wont do any damage UNLESS you turn your gain up to high & clip the amp to were you are sending the sub a "dirty" signal.

overpowering the sub will damage the sub, like over excursion it, bottom out the suspension, make the former hit the bottom plate, etc.

NiteHawk · Post by **NiteHawk** » Mon Sep 01, 2008 1:24 am

between underpowering and overpowering...overpowering is better.

the problem with them both is this...

when you underpower a subwoofer or speaker, you're going to push the amplifier harder to get the sound you want. pushing the amplifier harder than its meant to go is going to cause distortion and clipping. while the clipping and distortion wont damage a speaker or sub directly, the clipping CAN damage a speaker or sub because that short duration when the waveform is flat, the coil is not moving, creating more heat, which can eventually cause perminant damage to the coil.

overpowering is less risky because you can back the amplifier down so that you dont end up overpowering. but, because when you overpower a speaker or subwoofer, the waveform is still smooth and is not clipping, a speaker or subwoofer WONT overheat nearly as easily as when being underpowered.

all in all, its better to overpower, than to underpower.

now, to answer your question about how you wire things up.

depending on the stable ohm rating of the amplifier you're using, you will wire it according to that. if you have a subwoofer with 2 4ohm voice coils, and you have an amplifier that's only 2ohm stable when wired in mono, you're not going to be able to wire that in parallel. yes, 2 4ohm coils in parallel gives you 2ohm load, but when you take 2 channels on an amplifier and bridge them, you're already creating a lower ohm load. for instance.....

2 channel amplifier, 2ohm mono stable. 2 4ohm voice coils, wired in parellel, you'll have a 2ohm speaker load, but a 1ohm amplifier load.

same setup, but now wiring the voice coils in series. 2 4ohm coils in series, gives you an 8 ohm load, but a 4ohm amplifier load.

series or parallel makes no difference as far as performance is concerned, you will just get less power output with the series setup as opposed to the parallel setup.

i hope this helps.

jetas · Post by **jetas** » Mon Sep 01, 2008 1:06 pm

NiteHawk wrote: same setup, but now wiring the voice coils in series. 2 4ohm coils in series, gives you an 8 ohm load, but a 4ohm amplifier load.

Arite well this part of ur post applies to my current setup. Im running my amp bridged and its 4 ohm stable. And ur saying i can run a dual 4 in series wit no issues?

evilneon02 · Post by **evilneon02** » Mon Sep 01, 2008 4:35 pm

i think he is saying if you run your sub in parallel it will go from 4ohm to 2ohm and with your amp 4ohm bridged to 2ohm you will be good

jetas · Post by **jetas** » Mon Sep 01, 2008 6:55 pm

evilneon02 wrote:i think he is saying if you run your sub in parallel it will go from 4ohm to 2ohm and with your amp 4ohm bridged to 2ohm you will be good

huh

NiteHawk · Post by **NiteHawk** » Mon Sep 01, 2008 7:34 pm

if your amp is 4ohm stable when bridged, and you wire the coils in series, yeah, you will be fine.

jetas · Post by **jetas** » Mon Sep 01, 2008 11:05 pm

But wont the wattage going to the sub be cut in half because the sub is wired at 8 ohms?

nineball · Post by **nineball** » Mon Sep 01, 2008 11:48 pm

let's make this simple. what brand and model amp and sub are you using?

jetas · Post by **jetas** » Tue Sep 02, 2008 12:53 am

Its an Almani 2 channel. I forgot the model Number. And for now i have no sub. Thats y i wana see what I can and cant run. Im guna most likely end up running a 12 inch Memphis PR

nineball · Post by **nineball** » Tue Sep 02, 2008 1:45 am

NiteHawk wrote:depending on the stable ohm rating of the amplifier you're using, you will wire it according to that. if you have a subwoofer with 2 4ohm voice coils, and you have an amplifier that's only 2ohm stable when wired in mono, you're not going to be able to wire that in parallel. yes, 2 4ohm coils in parallel gives you 2ohm load, but when you take 2 channels on an amplifier and bridge them, you're already creating a lower ohm load. for instance.....

2 channel amplifier, 2ohm mono stable. 2 4ohm voice coils, wired in parellel, you'll have a 2ohm speaker load, but a 1ohm amplifier load.

same setup, but now wiring the voice coils in series. 2 4ohm coils in series, gives you an 8 ohm load, but a 4ohm amplifier load.

series or parallel makes no difference as far as performance is concerned, you will just get less power output with the series setup as opposed to the parallel setup.

i hope this helps.

the final ohm load of any amp is dependant on the speaker and what / how the voice coils are wired. it doesn't matter if you have a 4 channel amp bridged down to 2 channels or a mono amp running a single channel. almost any amp that is available in a retail marketplace has different outputs based on the load that is has to drive, which is decided by the speakers. if an amp is 2ohm mono stable you can most certainly wire a 4ohm dvc speaker in parallel to achieve a single 2ohm load to the amp.

just to explain a bit here are some specs taken from a mono amp to show anyone the difference that ohm loads can cause:

4 Ohm RMS Power: 1 x 275 Watts @ 13.8 Volts
2 Ohm RMS Power: 1 x 375 Watts @ 13.8 Volts
1 Ohm RMS Power: 1 x 600 Watts @ 13.8 Volts

as the onm load gets smaller the 'power' of the amplifier gets bigger. the amp does not know if there is a single speaker or 100 wired in any combination of series of parallel, it only knows what the final load is it has to drive.

using your examples to keep the comparison the same -

if i have a dvc 4 ohm sub and wire it parallel this will result in a 2 ohm load to the amp, not a 1 ohm load. it is not physically possible to have a single 4ohm dvc speaker have a 1ohm final load. with 2 of them it is but not with a single speaker. the only factor that changes is the power ability of the amp at a given ohm load.

i have a 4 channel amplifier that will do the following:

150rms x 4 @ 4ohms
300rms x 4 @ 2ohms
600rms x 2 @ 4ohms

currently the amp is wired in the last setting with two 2ohm dvc subs, each wired in series to present a final ohm load of 4ohms per channel to the amp, NOT a 2ohm load (per your math). the amp is not capable of sustaining a 2 channel 2ohm stereo load as your math would have someone believing. if this were the case the amp would have been 'fried' long ago.

NiteHawk wrote:if your amp is 4ohm stable when bridged, and you wire the coils in series, yeah, you will be fine.

yes, this will work in the end but again you will only be presenting an 8ohm load to the amp, NOT a 4ohm load.

like anything else in life you have to plan ahead. find out what the limitations of the amplifier are and then buy your sub accordingly.

if anyone has any further questions about car audio and wiring of amps / subs / speakers check out http://www.bcae1.com/ it is quite possibly the best site available to break things down to their simplest forms, and has lost of pictures for those who are still learning. scroll down to #57 and #58 to learn all you ever wanted to know about wiring speakers, be they single or dual voice coils, of any ohm load.

mattern248 · Post by **mattern248** » Tue Sep 02, 2008 2:52 am

o disagree about underpowering a sub i have an amp that is only a peak of 800 watts and a sub thats peaks at 1500 and the amp is at full load but really close, trunk gets to hot do to livin in az and black car, but i have ran this same setup for two years with many long trips back and forth from pheonix wich is a good hour in a alf away and not a single problem with quality infact i get compliments from every one i know on how well it sounds for being so low in power. but that my 2 cents lol

NiteHawk · Post by **NiteHawk** » Tue Sep 02, 2008 7:37 am

nineball: i've worked for a mobile electronics company, i've worked with their engineer's, trust me...an 8ohm speaker load on a bridged amplifier is a 4ohm load at the amp...very few people know that...

mattern, good for you. underpowering is still bad for your subwoofer and amplifier.

nineball · Post by **nineball** » Tue Sep 02, 2008 10:06 am

nitehawk: i find is strange that in my 20+ years of working in audio, both mobile and professional, you are the only person who has ever made that statement. i will believe what i know is true and follow the manufacturer's specs. just as you believe the information you have given out is correct i believe it is incorrect. we can agree to disagree but based on your statements people (like the OP) will be making incorrect decisions when purchasing equipment.

NiteHawk · Post by **NiteHawk** » Tue Sep 02, 2008 4:40 pm

we can agree to disagree, thats fine...

my only quesion is have you worked with the actual factory's engineers, or is your experience just in the retail end of things?

nineball · Post by **nineball** » Tue Sep 02, 2008 5:12 pm

more engineers than i care to admit, from radio to internet radio to mobile audio to professional concert clubs to recording studios.

if you (and by you i mean anyone reading this thread) have an amp, read the specs. whomever built the amp will know what it can do, bridged or not.

jetas · Post by **jetas** » Tue Sep 02, 2008 5:33 pm

Ok so Nineball n NiteHawk, So would it be safe and not a waste of money to run a DVC? wether it be a dual 2 or dual 4

nineball · Post by **nineball** » Tue Sep 02, 2008 10:19 pm

you have to find out the model of the amp, or at a minimum the specs. there is nothing safer about a svc vs a dvc.

jetas · Post by **jetas** » Wed Sep 03, 2008 2:12 am

Almani AL-CH550 I forgot i put the model # on the my garage feature thing

nineball · Post by **nineball** » Wed Sep 03, 2008 10:34 am

275 WATTS X 2 CH @2OHM
BRIDGED MONO:
550 WATTS X 1CH @4 OHM

those are the specs of that amp so buy your sub accordingly. we all know i am partial to alpine, so my suggestion would be to get a 10" or 12" dvc 2ohm sub, wire it to 4ohm and run the amp bridged to it.

Craz1000 · Post by **Craz1000** » Wed Sep 03, 2008 10:43 am

given this amp hes looking for a dual 2ohm. the type-r is a good choice for the money

SWR-1222D

HOWEVER these are the published specs of the amp which we all know 90% of the time are BS. if you want me to give you the real world specs i need to know 2 things. how old is your alternator and how many fuses are on the amp itself and what color are they

jetas · Post by **jetas** » Wed Sep 03, 2008 12:26 pm

Craz to answer ur question, The alt is the stock piece. idk if its been changed before as ive only had the car for a year. But i do kno that at idle the voltage at the battery is ~13.8 And i believe it has 1 40A fuse on it. A friend of mine did some wierd math came up sayin that the amp was pushing about 260 RMS.

Craz1000 · Post by **Craz1000** » Wed Sep 03, 2008 1:54 pm

13.8V*40A=552w max that amp can produse

now you get that 552w and use the efficency precentage to get the real world wattage.

so avarage nowadays is 85% so

552w*.85=469w briged @ 4ohms

so assuming its 85% your amp is putting out 469w RMS real world, thats pretty descent out of a 2 channel... and itll keep any good quality sub nice and happy. to get even more out of that amp look for a sub that has a high sensitivity percentage.

jetas · Post by **jetas** » Thu Sep 04, 2008 12:33 am

Craz wouldnt that be 469W Max?