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#16527 - 02/09/2000 18:44 4 channels vs. 5 channels
borislav
addict

Registered: 30/04/2000
Posts: 420
Loc: Sunnyvale, CA, USA
I'm looking at the amp section at Crutchfield and the price of the 5 channel ones makes me wonder. The cheapest one they have is Clarion Pro Audio at $250, all the others are $400+. On the other hand the 4 channel US Acoustics USX-4065
is only $180 and it looks like a much better amp.

So I'm thinking maybe I can get a 4 channel amp, bridge two channels for the sub and run two speakers in parallel on each of the remaining two. Would that work? I guess the main thing I'm losing is the ability to control front and back separately. I'll be installing this in a 1990 Volvo 740 with four door-mounted speakers, so I don't really have high hopes for proper soundstaging anyway...

Any thoughts?

Thanks,
Borislav
(how many posts do you need before you stop being a stranger, anyway?)


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#16528 - 02/09/2000 22:18 Re: 4 channels vs. 5 channels [Re: borislav]
alear
enthusiast

Registered: 05/07/2000
Posts: 301
Loc: Montana, USA, Bozeman
I have that that clarion amplifier. It works perfect and will feed your speakers just fine. It also provides plenty of power to the subwoofer channel. I have never been disappointed. Good filter (crossover) options too.


You could do that USAcoustics amplifier in the configuration that you mentioned. It would drop the equivalent impedance down to 2 ohms but the USAccoustics amplifier should handle that just fine. I doubt the USAccoustics has a low pass filter for your subwoofer channels though. You could tweak the EQ for those channels in the empeg. Not the best way to do it but it would probably work OK and save money from buying an external filter. Of course you lose fader control but you could look at it the other way around and say you gained subwoofer level control

Alex Lear
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Alex Lear

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#16529 - 02/09/2000 23:06 Re: 4 channels vs. 5 channels [Re: borislav]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
So I'm thinking maybe I can get a 4 channel amp, bridge two channels for the sub and run two speakers in parallel on each of the remaining two. Would that work?

It would work but only if:

a) The amp in question can have the rear channels bridged for a sub like that, and it has enough power to properly drive your chosen subwoofer in that configuration. Not all amps are bridgeable, and not all amps are good for running subwoofers that way. If you're not careful about matching the sub to the amp, damage to either the amp or the sub can result.

b) The front channels can handle a 2-ohm load.

c) The front speakers can operate correctly in parallel.

Another option would be to get a relatively inexpensive 4-channel amp (say, 30w RMS per speaker) and then add a self-powered subwoofer (for about $300). That's the way I had things going in my VW before the stereo and the subwoofer got stolen. It sounded great.

___________
Tony Fabris
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Tony Fabris

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#16530 - 03/09/2000 01:19 Re: 4 channels vs. 5 channels [Re: alear]
borislav
addict

Registered: 30/04/2000
Posts: 420
Loc: Sunnyvale, CA, USA
I have that that clarion amplifier. It works perfect and will feed your speakers just fine. It also provides plenty of power to the subwoofer channel. I have never been disappointed. Good filter (crossover) options too.

Cool. I was just a bit wary since it was by far the cheapest one.

I doubt the USAccoustics has a low pass filter for your subwoofer channels though.

It does - 40-200 Hz, 24 dB per octave. Not bad at all.

Of course you lose fader control but you could look at it the other way around and say you gained subwoofer level control

Haven't thought of it this way!

Thanks,
Borislav


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#16531 - 03/09/2000 01:44 Re: 4 channels vs. 5 channels [Re: tfabris]
borislav
addict

Registered: 30/04/2000
Posts: 420
Loc: Sunnyvale, CA, USA
a) The amp in question can have the rear channels bridged for a sub like that, and it has enough power to properly drive your chosen subwoofer in that configuration. Not all amps are bridgeable, and not all amps are good for running subwoofers that way. If you're not careful about matching the sub to the amp, damage to either the amp or the sub can result.

In the spec sheet it says "Bridged Power (Watts x Channels) - 160x2" so it sounds like it would work. I'll have to ask specifically.

b) The front channels can handle a 2-ohm load.

Yup.

c) The front speakers can operate correctly in parallel.

Didn't consider that but I'll have it in mind (haven't chosen speakers yet). BTW, if I want to drive two speakers in parallel at say 30W each, does that mean I need 60W output at the amp? Highschool physics was a while ago.

I think I'll give Crutchfield a call next time I'm awake during their business hours.

Thanks,
Borislav


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#16532 - 11/09/2000 17:58 Re: 4 channels vs. 5 channels [Re: borislav]
fvgestel
old hand

Registered: 12/08/2000
Posts: 702
Loc: Netherlands
Take a look at Caliber : http://www.caliber.nl
I bought the CA 80.5 and am very pleased about it
Specs :

Maximum Power Output :
4 x 80W or 2 x 160W Bridged
1 x 200W Subwoofer output

Continuous Power output :
4 x 40W or 2 x 80W Bridged
1 x 120W Subwoofer output

seperate variable input level : front, back and subwoofer
front and rear have high-pass/low-pass filter
sub has variable crossover 40Hz-400Hz

The Amp costs around 600 guilders in holland, which makes it about $250; don't know about availability in your country


Frank van Gestel
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Frank van Gestel

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#16533 - 11/09/2000 23:36 Re: 4 channels vs. 5 channels [Re: fvgestel]
teemcbee
addict

Registered: 04/02/2000
Posts: 687
I've made the experience that a low-cost amp usually doesn't have a very good high/low-pass filter. It just gives about 6db off in comparision to a high quality amp which gives about 18db off. That's a big difference in sound quality.

I had a low-cost 5 channel Gelhard with max 4x150 W and 1x300W Sub and continous 4x 75W and 1x 150W Sub. But at a higher volume it started to clip the sound and even though it were 150W on the Sub it was not very powerful.
Then I bought a high quality 4 channel amp (some american brand) with 4x 80 W (or 2x 160W) continous. I run all speakers on the left side on one channel, all speakers on the right side on another channel and the sub over 2 bridged channels now. The only thing I can't do is fading - but I don't really need it - it sounds perfect that way.
The highpass/lowpass filter is perfect and just lets the adjusted frequencies to the speakers (as this hasn't been in the cheap amp) and so the speakers just get the frequencies they are made for. (Of course the tweeters have a separate lowpass filter).

I'd recommend to make the following installation steps:

- install all the cables (and speakers!) and prepare the connection of an amp.
- install the empeg
- then go to a car-audio dealer and ask if you could try some amps. In a good store they will let you test some amps. Then you'll hear the difference.
Have a thought about spending some more money on your system - it's not THAT big difference if you buy a 250 $ amp or if you buy a 400-500 $ amp. You've spend > 1000$ for the Mk2! So some bucks more for a good amp won't be too much to have a really good sound!

If you want a low-cost amp - I have one for you - A 5 channel Gelhard with the spec's I've given above. I gave 250$ for it - used it about 4 weeks. I would let it for 150$...
But I wouldn't tell you to prefer this amp..


TeeMcBee
Got my Mk2! # 080000143
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TeeMcBee
[orange]Mk2, # 080000143, 40+30 GB, Tuner, Peugeot stalk hookup</font color=orange>

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