WuNgUn

I'm going 7.1 in my car...I was initially thinking two amps (2 channel + 5 channel), but maybe a 6 channel will work?
The center channel will be powered straight off the soundcard, and the amp will drive the front, side and rear channels...

Can I then bridge a single 10" sub on, say, the front channel (so I can still have subs while in 4 channel mode)?
Or will this give me too much power to the front (reducing the Ohms)?

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pancit175

I would not attempt such an action. Very few amps state in their manual that it is possible and how to perform such an install, but I would highly reccomend against that. Typically a sub requires more power than would be generated by trying to share the channels with interior speakers. And I believe supression or x-over filter/circuit (inclusion of capicators or inductors) would be required to do so. Check with your amp's manual first to see if it is something that stated they reccomend and if they have a diagram.

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pokki

First of all I would addrsss the issue of why you want 7.1?

99.5% of movies are still mixed in 5.1 or lower. Most 7.1 mixes you see on DVDs are matrixed mixes , i.e. the addition 2 channels are mathmatically created and do not reflect thr original source. So sticking with a 5.1 setup makes a lot of sense.

Or if it's to simply fill the car with sound then i'd recomend better quality over greater quantity.


This seems very odd to me.


Sounds fine to me.


Yes, most amps allow for tri-mode operation, you will however have to add suitable caps to your front speakers to act as a high pass filter, and a suiltable inductor on your sub to act as a low pass filter. Alternatively hunt down a phoenix gold xvr crossover which will do all this for you.


If your amp is tri-mode capable and designed to run down to at least 2ohm stero you should be fine as long as you stick with 4ohm speakers and sub.

PS you will loose discrete sub signal/control buy not running it of it's own channel.

krnpimpsta

If you really want 7.1 - and I really don't think you want 7.1. I think you want 5.1.

Lots of audiophiles actually just have regular stereo (2.1 - TWO CHANNELS), because the extra speakers just add sound interference and reduce the quality of the sound.

So given that very little content is 7.1 surround, I think you really want 5.1.

So given that, I think the a more reasonable way to do 7.1 would be:
1) get a 5 channel amp for your 4 corners + center
2) get a 2 channel amp for your 2 side speakers
3) get a 1 channel amp for your subwoofer.

Then again, I think most 5 channel amps are for 4 channel + sub, in which case you would just get a cheap mono amp for your center channel.

And then again, not to shoot your idea down, but I think 5.1 is a much better goal sound quality wise and.. just.. practicality wise. Sort of like why Gillette has a 5 blade razor, but they don't make a 10 blade razor. More is not always better..

RedGTiVR6

How exactly?

And I'm going to Echo the question of 7.1....why??

Why for all of the same reasons mentioned above...???

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WuNgUn

7.1 because the rear channel is going to be set up also for viewing the drop-down 22" widescreen from the hatch for tailgating
And for actual 7.1 surround content, well, why not? Sure it won't be used 99.5% of the time, but it's the .5% that matters.

I'm going with Boston Accoustic Pro60's front and side, and 5 1/4" MBQuart seperates(with passive crossovers) for the rear, so actual 'mode' of the amp is moot I think...
The Pro60's will be bi-wired thru their crossovers, so everything is covered except the sub...but I don't think it matters if full range goes to the sub. It won't hurt anything, right?
Amps will be 2 Ohm stables, yes...

Or I might go with a 2 channel amp for the rear, and a 5 channel for everything else...

My center channel is a powered Logitech mm28 flat NXT panel speaker...driven out of the Auzen Xplode, there is PLENTY of power for center channel use...why is that strange? What powers your desktop speakers?

Also, the sub runs from the center channel output from the soundcard, which is typical...
So maybe a two amp (2 channel/5 channel) would be better suited for my application...

WuNgUn

[QUOTE=krnpimpsta;1167989].

Then again, I think most 5 channel amps are for 4 channel + sub, in which case you would just get a cheap mono amp for your center channel.

QUOTE]

Center channel and sub channel are not discreet...they run off the same channel, unless, perhaps it's 5.1 DTS...

Felix509

The Sub Out or the .1 in the 5.1 or 7.1, is also known as the LFE(Low Frequency Effects) Channel.

It is completely seperate from the center channel and is digitally crossed over somewhere under 100Hz.(my home receiver has 3-4 frequencies to choose from)

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krnpimpsta

I found that strange because the only time I ever experienced passive speakers (powered by sound card) was when I got a pair for free with my first ISA sound card on my 386 (before PCI cards existed).

My current speakers? They're logitech branded and powered by a big amplifier in the subwoofer. Even at work, the cheapy freebie speakers are powered by external power.

The sound card outputs a "line level signal," as in this is basically just the signal - the data. Not enough power to actually create alot of sound, unless you are powering very small speakers or a pair of headphones.

I don't know what kind of flat panel speaker you have, but I don't know of any audio technology that is capable of creating sound volume that can rival even a crappy stock car audio setup with just a line level signal.

WuNgUn

Read a little closer...I said it's a Logitech mm28, and it's powered...
And it's capable of holding it's own in the car!

pokki

It will sound a bit *** though.


Consideering your install (last 2 channels being used with a flip down screen), playing a 7.1 source through such an install will sound worse than a proper 5.1 setup.


My desktop speaker have a built in amplifier and plug into the mains socket.


It shouldn't. The center/sub output is a stero out, not mono. One side (left) will be for sub, the other (right) will be for the center channel - may have this around the wrong way.

If it was me, and I wanted a setup similar to yours (surround sound in car + tailget system), I would set it up like so - presumign a limited budget.

5 channel amp for front, centre, rear. With the tailgate speakers wired in parallel to the front speaker with a switch over their speaker wires.

Match all the speaker to the same make/models - i.e. all boston pro's - vary the woofer size depending on install location, but that's all.

Then a mono amp to drive the sub.

So for in car listening set you PC to play in 5.1 mode. For tailgate listening set it to 2.1 and flick the switch to kill the fronts and activate the tailgate speakers (you could have this computer controlled but i'd keep it simple for now).

krnpimpsta

[QUOTE=WuNgUn;1168025]
What do you mean center and sub are not discrete? Then what you are talking about is 4.0 sound, not 7.1. The .1 means the sub is discrete.

The 7.1 standard defines 8 discrete channels. Two fronts, Two Sides, Two rears, a Center and a Low freq (sub).

I think what you are talking about is creating just a regular 4 channel setup but having 7 speakers? That is not 7.1. That is just 4.0 with more speakers. For example, my car has 8 speakers, stock. Two door woofers, 4 component front speakers, and two rear deck speakers. This is still 4.0. There are only four discrete channels.

WuNgUn

Again, your talking about digital out...I'm running 7.1 analogue out, and the center/sub channels are shared...not discreet. Call it 7 channel if you wish.
The only difference is the LFE channel thru analogue out...

To get true 7.1 (8 discreet channels) you need to run the digital signal out of the sound card thru coax or fiber optical into a digital decoder
that's able to handle Dobly Digital Surround-EX, Dolby ProLogicII-IIx and DTS-EX signals...for which my sound card is capable of producing...
My amps woudn't know what to do with that noise!! Hence the analogue out, combined center/sub channel...

krnpimpsta

Ok, I see that it is powered. I just checked it out: http://www.amazon.com/Logitech-97017.../dp/B000AM6QH4

I also noticed this:
Batteries: 4 AA batteries required.

If you got a 6 volt power source, I think that would work. But I think a much cleaner solution would be to leave all the amplifying to standalone amplifiers (not built-in-speaker-amplifiers).

How's this?

5 channel amp to power your 5 regular channels,
2 channel amp to power your rear tailgating speakers
mono amp to power your sub (I'm guessing you'll want alot of bass for people outside the car to be able to hear it)

Then you can run your 5.1 output from your soundcard to your 5 channel amp and mono amp. Hopefully the 5 channel amp will have a pass-through output where you can grab the front two channels and output it to your 2 channel amp - the reason I say do this instead of splitting the front channels before the amps, is because splitting will reduce the volume in only the front speakers..

pokki

No they;re not - see my post above.

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