Car audio amps, dual 500W or 700W ?

[audioguru]

I saw the equalizer for a fairly expensive Bose speaker. It was a "happy face" with the bass boosted and the treble boosted. No response below 100hz and none above 10kHz. Same for their home systems with little 2" satellite speakers and a 4" "sub-woofer".

 

[tcmtech]

Now quit posting stuff about Bose home junk! I cant argue with anyone about it. I am completely defenseless.

I do love the sound of the high end gear they make but I too think they should get out of the home audio business. Or at least drop the price by about five times!

All I can say is that I used to experiment with car audio for hours on end and I did find some wierd consepts out there that did work well, even though they went against conventional views!
I often ran with modified or reworked equipment and just let my ears tell me if it was good or not. I never cared what other people thought about how I had it hooked up. If they liked the sound too that was always good enough for me!
And I still dont care what other people think! If it works well and I am happy with it thats all I need!

 

[ParkingLotLust]

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

In the world of Car Audio, we call this Bi-amping (having one amp for tweeters and one amp for woofers) or Tri-amping (you can just guess )

What stuff are you running? I am just curious.

2 JL 500/1v2's and 2 12W6v2's

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?

Certain amps are made to be ran in a master-slave configuration, but if you have to ask, the answer is no, you cannot hook two amps to one sub. You would rather have a single, large amp than two small amps as, from an installer standpoint, it is easier to tune a single amp and sub than a pair.

/thread

 

[Nigel Goodwin]

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

No, by ten.

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

And you would be wrong!

 

[Cobalt60]

I guess what Im asking is, as far as sound quality is concerned, is one ohm rating better than the other? With this amp, I can run dual 2ohm 350W or a single 4ohm 700W. So far I sort of got an answer saying dual would be better simply to have more surface area. But nothing as far as which ohm rating would be better. I also seemed to learn that dual 350W would probably be equal in loudness to a single 700W, but Im sure whatever I get will be more than loud enough for me. So Im just looking to get the best quality sound.

And if anyone wants to recommend a size thatd be welcome. Im thinking 12"

 

[tcmtech]

I am not sure what to say. Last time I got shot up for advice based on what was popular when I was into the car audio back in my day.

A 2 ohm speaker has less resistance so it will alow more amperage to flow through it at a lower voltage.

20 volts at 2 ohms will flow 10 amps. 20v * 10a = 200 watts.
20 volts at 4 ohms will flow 5 amps. 20v * 5a = 100 watts.

Two 4 owm speakers in parallel equal a 2 ohm load.
Two 2 ohm speakers in series equal a 4 owm load.

Given your amp is rated for two 2 ohm per channel at 350 watts I would go with the 2 subs myself. Bridging it and running them in series will still give you 350 watts each.
I dont care what any one says two 12 inch at 350 watts each will move more air than one 12 inch at 700 watts.

Plus with two subs you can always add a second amplifier when you get one!

If any one says you dont need that much power tell them, Piss off! Your too old!

And you can quote me on that even though I am almost 35 years old.

Make loud noise, Live care free, And play nice with the girls, or you will regret not having done it later! I promise!

The amps I had were rated to run 2 ohms per channel or 4 ohms bridgeable. They were what was called at the time a three channel configurable design. that is, in stereo mode they could run a four ohm load at each channel but still run a single 4 ohm sub across the bridge connection. Two input channels three output channels.
The negative of one channel shared a common internal connetion with the positive of the other channel.
When I ran 2 matching subs on one amplifier the center connection point to the amplifier could be disconected and there was no change in the sound. It only needed that connection for stereo sound. Mono mode did not care. Exspecialy at the low frequency end.

I still say the subs in series do work.


Just do what your ears tell you sounds right! You will be much happier, pick up more girls, and the other guys will be a bit more envious!

Isnt that what this is all about anyway?

 

[audioguru]

Never connect speakers in series. It destroys the good damping on the speakers from the extremely low output impedance of the amplifier. Good damping stops the resonances of the speakers.
GEETAR speakers are connected in series for the added boomy "effect".

 

[Cobalt60]

Why does everyone recommend I bridge them? Is there a reason not to just use each channel independently, at 2ohms? I think this would mean the subs are not connected in series or in parallel, they would be independent of each other.

I did do some research and found that 4ohm was recommended over 2ohm. So in that case, I could bridge to achieve 4ohm, and then what? Run 2 12s in parallel? And if I did that, then I would be looking for 4ohm speakers?

Thanks

 

[audioguru]

Two 2 ohm speakers in parallel makes 1 ohm, not 4 ohms. 1 ohm is like a short circuit and might blow up the amplifier.

You don't need two sub-woofers. Very low frequencies are in mono, not stereo. Just mix the two channels together and use a lowpass filter to feed a single amplifier driving a single sub-woofer. The amplifier might have the mixer and lowpass filter built-in. Usually the amplifier is bridged so it has high power into 4 ohms.

If you have two 2 ohm sub-woofers then you should use them with a stereo amplifier that can drive 2 ohms per channel. Then do not bridge the amplifier.

 

[ParkingLotLust]

Bridging it and running them in series will still give you 350 watts each.
I dont care what any one says two 12 inch at 350 watts each will move more air than one 12 inch at 700 watts.

With the exact same subwoofers, yes, 2 12" have more cone area than 1 12".

I guess what Im asking is, as far as sound quality is concerned, is one ohm rating better than the other? With this amp, I can run dual 2ohm 350W or a single 4ohm 700W. So far I sort of got an answer saying dual would be better simply to have more surface area. But nothing as far as which ohm rating would be better. I also seemed to learn that dual 350W would probably be equal in loudness to a single 700W, but Im sure whatever I get will be more than loud enough for me. So Im just looking to get the best quality sound.

And if anyone wants to recommend a size thatd be welcome. Im thinking 12"

Again, it depends what you have now. Use what you have. If youre going out and buying, personally I would recommend the single more powerful sub, as this gives you room to expand, and gives you better sound because it is much easier to tune a single amp vs two amps.

The size depends what youre looking for - if youre looking for tight, fast bass, get an 8" or a 10". If youre looking for deep, thumpy bass (if youre more into Rap or R&B) get a 12"

 

[Cobalt60]

OK so you are saying I could just bridge it and run 1 sub. Any recommended size? Id like to be able to hit some of the lower frequencies, so I think Id want bigger than a 10. A lot of people tell me to stay away from 15" but Id like to hear your opinion. Loudness plays basically no role in my decision.

FYI, since I like to calculate surface areas of circles, a 15" has approximately the same surface area as 2 10s.

 

[ParkingLotLust]

A 15 is too boomy for my tastes, I bought JL equipment as Im more into SQ vs SPL. Do you have the amp model # and sub model # handy? You have to be sure the amplifier supports bridging, and that the impedance you bridge to matches the sub.

 

[tcmtech]

I tend to agree with what parkinglotlust had to say. I checked in with an old buddy of mine that does the higher end installs for offices, high end custom home theater, and bar and theater sound sytems, not the honkie tonk "geetar" bars either!

His opinion was that if you want good sound run a pair of sub woofers. 10 or 12 inch are what he recomends for good car sound. bigger does have more bass but two smaller subs will do the same job and will be able to fit better if space is a problem.

Also his recomendation was to run the subs either with a pair of amplifiers with an RMS rating equal to or greater than the rating of the sub woofer or one big amplifier with per channel ratings of equal or greater size than the sub woofers.
A bigger amp will have less chance of clipping and can keep the speaker under control better. It actualy has less chance of damaging the speaker even though it has more watts rating than the speaker itself.

His opinion was that running two matching subs in series with an amplifier of equal or greater total RMS rating than the combined speakers will give you the same sound as if they are ran separately. Its often done to bring the ohms and power ratings closer together on the big systems when a customer wants a particular amplifier or already has one but wants different speaker setups.
Very commonly done, and works well according to him.

However if the amplifiers or the speakers are of lower quality the sound will not be as tight at high volumes.

His opinion was that what you do is your business. What sounds good to you is what matters. Take others opinions with an open mind but still do your research. The ones who call themselves experts but wont tell you what they work with, where they work with it, how long ago they worked with it, or where they get there information are not the ones to listen too!

Talk to people that have something like what you are looking for. Find out first hand if thats what you want and if that setup works the way you want it to. Get honest opinions about its good and bad points.

Also do your homework on the stuff you want. Not all the big name stuff is good, nor is all of the unheard of stuff junk either. Look for honest ratings and try to match you numbers on everything. Ohms to ohms, Watts to watts.

And above all we are just a bunch of strangers sitting behind computer screens. Most of use are honest and truthful, but some are fakes just getting a sick thrill, or stroking their fragile egos by claiming to be experts and then giving false answers or bad advice based on half truths and bad information from unreliable sources!

I hope this helps.

Get junk or take bad advice and your the one that pays for it!

 

[unclejed613]

I can't remember what it is called but it has many benefits like a smaller enclosure.

Isobaric...

"I'm in Artillery..... I don't care what you play, as long as you play it LOUD!!!!" Robin Williams, "Good Morning Vietnam"

i had a friend who had a pair of 95db/1W/1m studio monitors in the back seat of his Mustang. that simple setup was plenty loud at 50W/ch and didn't require an aftermarket alternator.

 

[Sceadwian]

It's all about one word. Fidelity.

 

[unclejed613]

the 50W/ch amp wasn't clipped, the speakers weren't experiencing overexcursion, so it sounded good. only problem is, you really can't do much about channel separation in a car.

 

[mneary]

Were there any lost posts in this thread between March 27, 2009 and March 30, 2010?

 

[Sceadwian]

I think there are.

 

[unclejed613]

sorry, my fault.... i think i replied to this thread thinking it was a current thread, not noticing it was a year (within a couple of days) old. so , sorry i played Dr Frankenstein to a dead thread...."I've done it Igor.... It's alive....."

 

[Aaron28]

just need abit of help if any one can help me i have a 700w ampifier and 2 600w speakers how meny people is that ok for in a pub like in events plz