Subwoofer Experts or guys that know about them please help

[Guillermo]

short of designing a system for you, you're probably going to have a hard time understanding what anyone here is trying to tell you.

I would recommend reading this, and then asking questions. The answers will make a lot more sense, and you may not even have to ask!

http://www.eatel.net/~amptech/elecdisc/caraudio.htm

[TubeDriven]

Originally posted by Joe
I'll use my setup as an example to try to explain ohms, and how they change based on how you connect your subs:

I have 3 JL Audio 8W6 subs. They are Dual Voice Coil and are rated at 6-ohms.

Dual voice coil subs have 2 positives per sub and 2 negatives per sub.

With 3 DVC subs that are 6-ohm, a true parallel connection would be as follows: Take all positives and connect into the + on the amp when bridged. Do the same with all - 's. You better have a 1-ohm stable amp for this connection, or even lower. 1/2 ohm, etc.

A 75X2 @ 4 ohm amp (150X1 when bridged at 2 ohm) that is 1-ohm stable would provide 300 watts at 1-ohm. I used to have my subs hooked up like this with my Soundstream Reference 300 amplifer.


With 3 DVC subs that are 6-ohm, a true series connection would be as follows:
On one sub, connect one of the +'s and one of the -'s together with a small wire. Do the same on the other sub. Now take the remaining +'s and -'s and connect them to the amp. This would present the amplifier with almost a 4-ohm load exactly.

With this setup, your best bet would be to find a single-channel amp that is designed for subwoofer applications. An amp that can put out large numbers of wattage at 4-ohms. I have this setup, and use a Precision Power a600.2... ...it provides 600 watts at 4 ohm when bridged. There is no cleaner power than this.

With the parallel connection up top, your amplifer will run EXTREMELY hot, and isn't practical for long periods of listening.

I hope this answers a little bit of your questions about connections. It's hard to explain this concept without using examples of particular subs and amp ratings.

Remember that it's not all about huge power ratings in order to get good bass. I know a guy who has 70 watts going to a bandpass box in an E30 M3, and he has the bandpass box mounted up by the rear deck in the trunk with the port going through the rear deck.... ...and it sounds GREAT.

This is correct, but there is one more thing you must remember.

When an amp is wired mono, it actually sees half the ohm load of the speakers, no matter how they are wired. For example, if you were to wire (3)JL10w6 (dual 6 ohm voice coils) all in parallel, then they would be wired as a 1 ohm load. If you hook these up mono to an amplifer, the amp will see the load as 1/2 ohm. I learned this the hard way. If you take the same configuration and wire it to an amp in stereo, the amp will see the load as 1 ohm, just like you wired it.


So basically, make sure you purchase an amp and speakers that will work together well by getting the most power out of the amp without adding distortion. If you have any other questions just ask. I have close to 10k in audio in my car.

[Joe]

Originally posted by TubeDriven



This is correct, but there is one more thing you must remember.

When an amp is wired mono, it actually sees half the ohm load of the speakers, no matter how they are wired. For example, if you were to wire (3)JL10w6 (dual 6 ohm voice coils) all in parallel, then they would be wired as a 1 ohm load. If you hook these up mono to an amplifer, the amp will see the load as 1/2 ohm. I learned this the hard way. If you take the same configuration and wire it to an amp in stereo, the amp will see the load as 1 ohm, just like you wired it.


So basically, make sure you purchase an amp and speakers that will work together well by getting the most power out of the amp without adding distortion. If you have any other questions just ask. I have close to 10k in audio in my car.

You are right. I didn't clarify about the stereo / mono mode.

Stereo will be x ohms. Mono will be x/2 ohms. However, there are speciality sub amps for every possible situation. That is why I use an amp that when bridged puts out 600 watts RMS @ 4 ohm. Gotta love PPI.

[BMLRacer]

KAMIKADZE,

Thanks for the compliments. The boys at Polk Audio had the car for three months to do the install. I couldn't be happier with the quality of both the install and the sound. The credit really goes to Polk Audio, i'm just the nut behind the wheel. But, I can't say enough about the Polk/ Momo subs ability to take abuse.

You can see more of the car on my site, also, the car was featured in the Jan 2002 Eurotuner magazine. The article is also on my site.

Thanks again.
Brian

[Matt]

series or parallel.

this diagram might help you understand the difference, which is really not that hard, but if you mess it up

[Matt]

forgot the pic

[aus]

Speakers are all subjective. What sounds good to one person may not sound good to another, so go try some out. Most subz are damaged by dirty sound (alot of distortion) so the amp is really important and the amp is only as good as the sound source (ie head unit) and the cables are also important... so you get the point.

Some subz to consider would be ImageDynamics (IDQ), these are very clean and don't cost too much. They win sound offs regularly and are very efficient so they don't need alot of power. They can also be mounted in any type of box or infinite baffle (hanging of the rear deck without a box).
Audiomobile is also very good but more money.
Diamond Audio also makes some nice subz along with the other ones mentioned here.
Just remember, BMW truncks tend to be very tight and don't let too much bass in so you need alot of power or take out the rear speakers or use an infinite baffle mounting.
Also consider Class-D amps so you won't tax the electrical system too much. It just depends on how loud you want it to be.
Good luck

[RR BuGGz]

Originally posted by aus


Speakers are all subjective. What sounds good to one person may not sound good to another, so go try some out. Most subz are damaged by dirty sound (alot of distortion) so the amp is really important and the amp is only as good as the sound source (ie head unit) and the cables are also important...

This is so true. I have the Eclipse 12" titaniums and it puts out tight hard hitting bass while my g/f in her e46 has the Polk Momo which puts out a much sounding deeper bass. It all depends on what music you listen to and what kind of bass you like. The type of bass is also affected by the type of enclosure your sub is in. Sealed boxes tend to put out a tighter bass than ported boxes. But overall you will need to put a lot of power to your subs because BMW trunks are very tight. I would stay away from infinite baffe setups where the trunk is used as an enclosure I don't think too many people will like the bass it reproduces.

[elcoocool]

One thing that I've noticed in this thread is that people don't seem to realize much about amplifier circuitry. Espcially seeing statements like, "The lower the ohms, the more distorted signal you're going to get from the amplifier."

This is false. The THD rating, or Total Harmic Distortion is usually the same at ANY Rated load. Next, in most decent amplifiers, even class D which typically have a higher THD rating, the distortion levels at reasonable volumes are completely in-audible to human ears. Decent amplifiers usually have %.01 or lower THD ratings. For the most part, distortion typically is caused more by the users listening habits more so than the equipment. I can't even count on my hands how many people I've talked to who have the gains & bass boost up completely on their amps. Of course, they also have the bass & treble control completely up with it faded to the rear.

Also, the amplifier's circuitry just becomes more in-efficient when put under a lower ohm load. Almost always when an amp that is designed to run at 4 ohm mono is ran at 2 ohm mono, the power isn't exactly doubled. For example, an amplifier we carry called Synopsis Audio produces 322w RMS @ 4 ohms. At a 2 ohm mono load it produces 442w RMS.

Whoever was saying that when you run something at 2 ohm mono the amplifier actually sees it at 1 ohm, they have issues. When an amplifier is being ran at 4 ohm mono, there's only a few options to run it at 4 Ohm Mono. A, you have a 4 ohm sub. B, You have 2 8 ohm subs wired in parallel. C, you have 1 dual 2 Ohm sub wired in series. Etc, etc etc. Anyone who trys to tell you otherwise needs to just stay quiet and take a good hard look at Ohm's Law before they continue talking.

Mike

[elcoocool]

BTW, the guy who said that speakers are subjective, go listen to them is brilliant.

No one person on this board can predict how another prefers the sound of music. The only way for anyone to get an idea of what they like is to go to a sound board and go listen to speakers. Granted, they're not in the same application and of course they're going to sound different in your vehilce, but you'll at least get an idea of what they are going to sound like.

Personally I do like recommendations from people, but what I don't care for is the people who say "X brand is the best... I have them". Typically, take those recommendations for granted as those type of people usually don't much experience in the car audio industry. Sure, they may have spent a grip of cash on their system, but take in mind that they probably went off of the salesperson at circuit city saying this is the best... who is making a %15 commission..

[Axoman]

elcoocool is correct. The lower the ohm rating does not equal lower sound quality. Ohms are a measure of resistance. Also, whoever is saying that when you run an amp in mono, the load is different in stereo is wrong. If you have a 4 ohm load, no matter whether it is a single speaker or a combination of speakers, it will always be a 4 ohm load and the amp will see it as a 4 ohm load, regardless if the amp is bridged or not. This is a generalization because the speakers impedance will vary with frequency, but the point is that an amplifier will not magically lower the resistance of a load by a factor of 2 when going from stereo to bridged mono. Like it was said, go out and listen and figure out what sounds best to you.

[s--k]

Axo, I have to disagree. A "bridged mono" amplifier will see
half the ohms presented to it. If you have a 4 ohm sub the
"bridged mono" amp will see a 2 ohm load.

This is why many bridged amps will quickly shut down when given
a 2 ohm load vs. a 4 ohm.

[Axoman]

Ok, yeah, I was misreading what they were saying. I thought they were trying to say that when the going from stereo to mono, that the speaker's impedance will become half of what it was. But I misread it and agree as well. It's why a 2 ohm stereo stable amp is only stable into 4 ohm mono. I stand corrected.

[timers]

bump, ne more opinions on the momo subs?

[ChaseBmw]

A speakers impedence (ohms) is no indication of it's sound quality..it is a measurement for the average electrical resistance that its voice coil presents (more to it than that, but im not wrinting a paper)..that is all.....elcoocool is leading you in the right direction...go out and listen to the subs yourself, take your OWN music with you and listen..this is the best way. sound quality is very subjective...by the way the polks are a very nice sub, when applied correctly within your system, of course this can be said about any well made sub..remember high end car audio is 80% installation and adjustment and 20% equipment. a knowledgable installer can do wonders with even mediocre equipment.