Question on the AMPS...

[nicholtl]

I, as many others here, own one of the Halo 2 channel and 5 channel amps. I have the A51 and A21, like I know Chris, Goldear, Netarc, and others do.

My question is: is the 2 channel amp supposed to drive the FRONT MAIN speakers, or the REAR SURROUND speakers? I've always had them driving the rears, but only recently did I think about giving the font mains the exclusive power. But since both amps are rated at exactly the same watts x channel, would it make any difference whatsoever?

[Chris D]

I've debated about this one, too. I don't think there's one correct answer.

If I use the A21 for the rear speakers, I can leave it turned off when I'm not listening to a full 7.1 source. I see the benefit here as being heat production out of the A21, really.

If I use the A21 for the front mains, I can leave the A51 off when I'm listening to stereo music only. While I do this, it would actually happen not all that often. And I know what you're saying about intuitively it seems to make sense to dedicate the exclusive power of the A21 to just the front mains, even watching movies. But then I wonder how beneficial that would REALLY be, since with movies the VAST majority of sound put out really goes to the center channel, not the front mains. (hmmm... if I use two speakers for my center channel, driven by the A21... or better yet, if I bridge the A21 to drive the center channel... oh yeah...) :D

I'd be interested to hear Parasound's suggestion on this.




CHRIS
http://www.htguide.com/bilder/images/199/C17gif.jpg Luke: "Hey, I'm not such a bad pilot myself, you know"

[Scarp]

The specs give away the answer:
A21: 1.2 kVA encapsulated toroid power transformer
A51: 2.2 kVA encapsulated toroid power transformer

So the A21 uses for two channels over half that of what the A51 uses for 5 channels.

Not that it says all, but a 2 channel amp is usually made for stereo usage, so better suited for the front speakers. The 5 channel is made for surround, although also a superb stereo amp.

[David Meek]

I'm a little unclear on the specs. For the A-51 it shows:2.2 kVA encapsulated toroid power transformer with independent secondary windings for each channel
Is the "for each channel" only referring to the secondary windings or does is refer to the power transformer, also?




David - HTGuide flunky
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[Scarp]

The number refers to the transformer. Each channel has secondary windings (at first I read wingdings (windows font) :)).

[nicholtl]

David, Scarp, could you guys explain what the 1.2 and 2.2 torrid transformers do? I am not nearly as knowledgable and I haven't the slightest how these specs translate into driving speakers?

[netarc]

Just jumping in - actually, I don't own a HALO amp :( (yet!)

But if I *did*, I'd definitely use the A21 for fronts, and A51 for center/surrounds/back.

[Scarp]

David, Scarp, could you guys explain what the 1.2 and 2.2 torrid transformers do? I am not nearly as knowledgable and I haven't the slightest how these specs translate into driving speakers?

I am not sure myself, but what I do know is that more is better in this case. These transformers is what powers the thing and they need to be big and have good quality (and make no noise). If you take a look at some big krell amps, they have huge transformers (making a stereo version weigh more than a 5 channel parasound).

Usually stereo amps are better performers in stereo usage. Since many people also use their system for stereo (cd, tv, etc) I recommend using a stereo amp for the fronts and surround amp for the rest. This is only in case both amps match eachother.

[audioslave]

An amplifier is made up of basically two parts, power supply and amplification section. The power supply’s job is to provide a stable clean dc power source for the amplification section. A good amplifier circuit with a bad power supply will still sound like crap.

The power supply is made up of three main components the transformer, rectifier and filter capacitors. The transformer changes the voltage of the incoming AC power from 120 v @ 60 Hz to something else that is still AC @ 60Hz. The AC power then enters the rectifier. The AC signal consists of a signal that oscillates from +V to a –V in a sine wave. The rectifier takes the negative portion of the signal and makes it positive. So out of the rectifier you get a lumpy all +V signal. The filter capacitors smooth the lumpy signal to produce a stable +V that is DC. (in actuality you end up with a stable +V and –V signal but that’s good enough to get an idea of what the tranny does)

The power rating of the transformer is a measure of the maximum amount of power that enter the amp on a continuous basis. Obviously more is better until you have enough for any conceivable output of the amp. The job of the power supply is to provide any amount of current the amplifier circuit demands without letting the voltage sag. The ability of the power supply to do that depends on both the power rating of the tranny and the amount of the filter capacitance.

BTW for any real E.E.s out there feel free to poke fun at my explanation. Especially since I have an M.E.
;)




mike