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Car audio amps, dual 500W or 700W ?

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Cobalt60

New Member
I currently am in possession of a 700W car audio amplifier. Someone wants to trade me a matching pair of 500W amps for it. Now lets assume all of these amps work (which Im not sure of yet), which would I rather have? Can I hook up 2 amps to one sub, and would 2 x 500W amps be equal to a single 1000W?

Thanks
 

Sceadwian

Banned
Something is funny with that deal. Provide details of the exact model number and brand of the amps you're looking at.
 

Cobalt60

New Member
My "700W" amp is an MA audio M600XE competition series. I found some specs:

# 2 x 175W RMS @ 4 Ohm Stereo
# 2 x 350W RMS @ 2 Ohm Stereo
# 1 x 700W MAX @ 4 Ohm Bridged
# Variable High/Low Pass Crossover 50-250Hz
# Variable Bass Boost 0-18db @ 45hz
# 3-Way Protection Circuitry
# Full MOSFET circuitry
# 2-Ohm stereo stable
# High/Low level inputs
# Low level outputs

And I see on eBay you can certainly get one for $90 shipped. I have no idea the specs on the dual 500W, but I will find out tomorrow. But youre basically saying, dual 500W is better than a single 700W?

Actually its funny that I find out this unit is really a dual 350W capable of bridging to itself for 700W. But now I have to ask , its capable of half the wattage at half the ohms. So what would be the reason to use it at 2ohm? Better sound quality? So maybe it would even be a better idea to run 2 x 2ohm 350W speakers than a single 4ohm 700W speaker?

Well, im a complete newbie to the finer details of audio I guess, so thanks for any info.
 
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audioguru

Well-Known Member
Most Helpful Member
You will not hear the very small difference in volume between 700W and 1000W. Double the power is just a little louder.

Few speakers are only 2 ohms so maybe you will need two 4 ohm speakers in parallel for each channel or else the power is half.

I don't know if you have a single 700W speaker that the amp can drive it bridged.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Actually its funny that I find out this unit is really a dual 350W capable of bridging to itself for 700W. But now I have to ask , its capable of half the wattage at half the ohms. So what would be the reason to use it at 2ohm? Better sound quality? So maybe it would even be a better idea to run 2 x 2ohm 350W speakers than a single 4ohm 700W speaker?
Bridging doesn't give you any more power, it just allows you the same amount of power in a higher impedance load.

Your amplifer is specified as RMS - this is VERY rare for car amplifiers - assuming you want to do the swap, then check VERY carefully that the other amplifier is as well. Otherwise it's probably going to be a MUCH smaller amplifier.

As AG says, it's a waste of time swapping anyway, the minimum change you can hear is double the power (ten times the power is twice as loud), so 700W to 1000W is too small to tell any difference.
 

Sceadwian

Banned
Also note the 700watts MAX, not RMS. Once you get past a couple hundred watts of power the rest is just pointless unless you're in a concert hall or you're trying to blow your eardrums or windows.
 

tcmtech

Banned
Most Helpful Member
That power depends on where you put it. My brother owns a DJ business. They run several thousand watts of rms power. The main speakers that handle the voice range and up are only running a few hundered watts each. But the difference between 500 and a 1000 in a sub woofer is easily noticable. both in sound quality and feel.

Car audio is similar to that as well. I used to run over 1000 watts rms in a car. The rear dash had only ablut 120 watts per speaker from 120hz up the front dash had about 40 watts each from 180 hz up. All the rest of the power was in the pair of 12 insh subs.
You could easily tell the difference between a 300 watt, a 400 and a 500 watt RMS sub woofer amplifier.

The overal sound quality I had was very good. Very loud but not distorted.
Audio wattage depends greatly on where you put it.
A 1000 watts put in the tweeters just makes your teeth itch.
 

Sceadwian

Banned
Considering energy increases with frequency 1000 watts into tweeters might deafen someone standing near it.
 
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audioguru

Well-Known Member
Most Helpful Member
Does anybody turn up the volume in a car so that the amplifier is actually producing 1000W?? A 1000W amp plays 30W perfectly.

The sub-woofer in "the boot" of my car is 10". It has an amplifier that is 100W RMS. I had it turned up to clipping and it vibrates everything in and near the car and it is deafening. The sound from the sub-woofer goes through the rear seats and back shelf like they are transparent.
The other four amplifiers are 36W RMS each. Their speakers are 2 ohms each. They are also deafening when the volume is turned up.
There are two dome tweeters in the front. I don't know if they have their own amps or if they use a passive crossover with the front speakers in the doors.
 

Sceadwian

Banned
I don't think I've ever heard of someone using separate amps for tweeters. Passive crossovers work fine.
 

Cobalt60

New Member
First of all, my amp is indeed rated at 700W RMS. Anyway, yeah my chain was being pulled so Im keeping the amp. While were on the subject, what would a good setup be? I could do a pair of 350W 2ohm subs, or a single 700W 4ohm, which would be better?

Thanks

-Chris P
 

Nigel Goodwin

Super Moderator
Most Helpful Member
First of all, my amp is indeed rated at 700W RMS. Anyway, yeah my chain was being pulled so Im keeping the amp. While were on the subject, what would a good setup be? I could do a pair of 350W 2ohm subs, or a single 700W 4ohm, which would be better?
There's no point in bridging if you don't use a single speaker.
 

Hero999

Banned
ten times the power is twice as loud
I'm no expert but don't you have to multiply the power by 4 (not 10) for it to sound twice as loud?

Somehow, I doubt our ears work in log to the base 10.

At that much power you'll be deafened anyway - the chances are your huge amplifier and speakers will only produce 50W of real sound energy.
 

tcmtech

Banned
Most Helpful Member
Personaly I would Bridge it and run the pair of 350 watt subs in series. most likely your combined speaker surface areas will be bigger than a single sub giving you a slightly better low end air displacement.

Its sort of a phantom super sub concept. By using several smaller speakers of matching design you can cheat to get higher wattage and volume capability with out having to use one massive speaker. Four 10 inch 250 watt subs = One 20 inch 1000 watt sub. But can be separated and will fit in a average size car far more easily.

And If you ever looked the SPL rating on smaller speakers is higher too.

A 100 watt 90 dB rated speaker is just as loud as a 93 dB rated speaker at 50 watts or a 96 dB rated speaker at 25 watts.

Every 3 dB increase takes twice as much power. Several smaller but more efficient speakers will sound louder and cleaner than just one big one.

Watts are good but how you use them is what makes all the difference!

My brothers DJ speakers are this way on the voice and high range units. They use 9 smaller but higher efficiency speakers in each box instead of one bigger one.

Also his subs use two 12 inch running face to face with one 180 degrees out of phase from the other. its the equivilent of having a 12 inch sub but can run double the wattage capability.

you now know the secrets to having great quality and loud sound at the same time.

Use it wisely!
 

audioguru

Well-Known Member
Most Helpful Member
Personaly I would Bridge it and run the pair of 350 watt subs in series.
Then lose the excellent damping of resonances from the extremely low output impedance of the amplifier.
Old geetar speakers sound boomy because they are connected in series.

By using several smaller speakers of matching design you can cheat to get higher wattage and volume capability with out having to use one massive speaker. Four 10 inch 250 watt subs = One 20 inch 1000 watt sub. But can be separated and will fit in a average size car far more easily.
Many years ago, an electronics magazine published The Sweet Sixteen Speaker project. It used sixteen cheap little speakers that were all different. The displacement of all the cones was huge.
The idea was that their irregular frequency responses would cancel.

But it sounded horrible like many cheap little speakers. No bass and just a loud shriek. Also it was extremely directional.

And If you ever looked the SPL rating on smaller speakers is higher too.
No.

Several smaller but more efficient speakers will sound louder and cleaner than just one big one.
No.
Big speakers are more efficient than little speakers, have a lower resonant frequency and more cone movement for better bass.

Also his subs use two 12 inch running face to face with one 180 degrees out of phase from the other. its the equivilent of having a 12 inch sub but can run double the wattage capability.
I can't remember what it is called but it has many benefits like a smaller enclosure.
 

tcmtech

Banned
Most Helpful Member
Do I have to post every single detail about everything! man! I got jumped for not mentioning a LM317 needed a heatsink at 7.2 watts disipation yesterday! :mad:

I just took a dump so do I need to mention I wiped top to bottom too? :confused:

Far as the multi speaker concept, all I can say is talk to Bose Audio research dept. I believe they know what they are doing! Its what my brothers DJ systems run. And I know they are not the least bit directional as far as the frontal sound field is conserned. I dont know what they do but they only have 2 wires in and they sound great! :)

And yes if you use mismatched speakers they will sound bad. They all have to be the same. Sorry I did not clarify better. :p

And most of my catalogs show the good quality speakers are more efficient in the smaller and mid sizes than the big ones as far as SPL rating go.
But yes not all. Speaker design has been changing little by little over the years I am aware of that. :)
When I played with that stuff a good midrange speaker was around 93 dB SPL and a good sub was around 87 dB. I see some brands are now in the 99 dB and 93 dB respectively. A few claiming even higher.

What stuff are you running? I am just curious. :)

post some realivant info and prove your right and I will admit I am wrong.
I am alway willing to learn new things and I can easily handle being wrong.
I cant learn if no one tells me any:thing. :(

I have been out of the audio business for some time now. I got tired of having to defend myself from every dumbass dickhead that thought he knew something because he worked at a local electronics shop for a summer job and felt that brand X speaker or brand Y amplifier was the best. :mad:

The guys that can back up a claim with proof, I will aways respect them. :)

You have been here far longer than me so I will take you word for it but still There are a few people with screen names and avatars that dont exactly fit them too! :D

Hope your not one of them! :)
 

audioguru

Well-Known Member
Most Helpful Member
A small tweeter has an extremely lightweight dome that moves a very small amount and therefore is very sensitive.
A woofer has a heavy cone that moves far and therefore is not sensitive.

A big full range speaker is sensitive.
A little full range speaker is not sensitive.

A cheap PA speaker is very sensitive because the gap between the magnet and the voice coil is small and they don't care if they scrape.

Look at Bose Bashers in Google. Many people say that they make overpriced junk.
 

tcmtech

Banned
Most Helpful Member
I got to agree with the over priced part! But they do sound good! sorry if I cam across sounding pissy. I did not mean to. I was just grouchy for some reason. sorry about that.
I guess it means I am one of those posters that goes off on something dumb too!

Darn.
 
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