Impedance vs. channels situation

[96civ 10+ year member]

OK I'm starting to plan out a few things for a home audio setup I will make by the end of the summer.

The first question I have is about impedance with receivers. I see a lot of receivers with a spec list having the RMS wattage listed in 8 ohms, but nowhere does it mention the stable impedance. Can I just assume that it is 8 ohm stable or will I be able to go down to 4ohms? Maybe I'd have to ask the manufacturer of the receiver, but until then I'm asking the real professionals, you guys //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif.

The second question I have is about amplifier gains. Say I get a receiver rated at 125wRMS x 6 @ 8ohms and I want to push a 8ohm speaker rated at 50wRMS. In most receivers, will I be able to set the gain for each individual channel or am I SOL at this point? IF I am SOL at this point, would it be practical to attach a resistor in series with the speaker so that the channel outputs 50wRMS at that specific resistance load?

This might be hard to follow, but any help is appreciated.

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[thylantyr 10+ year member]

The general rule is that receivers with multichannel ability will never be as good

as a dedicated amplifier driving lower impedances. Each brand will make claims

but who knows what each specific model does unless you get some 3rd party

tested data. If you buy a good brand, no less than 6 ohms is a safe bet. After

that, it's a crap shoot unless you do more detailed homework on the specific

model of interest.

You are better off getting the lowest cost receiver {buy it used} that has

preouts to allow an upgrade path later to external amplification. Make sure

the lower end receiver has other features that you really plan to use as many

have stuff you will never use.

As time passes, collect good amplifiers and they will stay with you for a long

time. As time passes, technology advances and it's time for a new receiver again

because it may have a feature you want. Since your have your amps, you don't

need the higher end receiver to get the higher power ratings - unless of course

that feature you really want only comes in the high end model. Manufacturers like

to scam that way alot to rape customers.

Another strategy is to use the receiver to power the weaker speakers in

your system, lets say some rear surrounds, maybe a center channel. Lets

say you build or bought some monster towers that are lower impedance, difficult

for the receiver to drive, well then just get a 2 channel amp to drive those two

and the receiver to drive the other speakers. Just make sure you have some

RCA preouts to allow an upgrade path.

Don't worry about speaker power ratings and trying to match it to the receiver

or power amplifier's power ratings. Connect your 50w speakers to a 500w

amp, realistically there is no issue unless you do something dumb.

 

[joetama 5,000+ posts]

The second question I have is about amplifier gains. Say I get a receiver rated at 125wRMS x 6 @ 8ohms and I want to push a 8ohm speaker rated at 50wRMS. In most receivers, will I be able to set the gain for each individual channel or am I SOL at this point? IF I am SOL at this point, would it be practical to attach a resistor in series with the speaker so that the channel outputs 50wRMS at that specific resistance load?
This might be hard to follow, but any help is appreciated.

Ok, well, usually they will play to 4 ohms fine. However, overheating could be an issue if you play them at loud volumes for long periods of time. I think now is appropriate to ask what 4 ohm speaker you are running and if you know the min ohmage of them?

You can't think about this as car audio. There really is no "setting of the gains" other than adjusting the volume of your surround speakers/center channel and what not. It's usually a good place to start with a receiver that has automated volume and delay features, check out Yamaha RX-V series. But you usually play the volume level to where you like it and it shouldn't be over driven, if it is you need different speakers.

 

[96civ 10+ year member]

As time passes, collect good amplifiers and they will stay with you for a long

time. As time passes, technology advances and it's time for a new receiver again

because it may have a feature you want. Since your have your amps, you don't

need the higher end receiver to get the higher power ratings - unless of course

that feature you really want only comes in the high end model. Manufacturers like

to scam that way alot to rape customers.

It seems that buying dedicated amplifiers is EXPENSIVE for getting the desired power. For instance this amplifier, http://www.partsexpress.com/pe/pshowdetl.cfm?PartNumber=302-610&raid=27&rak=302-610, only pushes 100w @ 4 ohms into one channel? That means for $128.50+ I'm only going to be able to push 100w out of all my speakers?

I just think that's crazy. Would it be better to invest in some corporate home audio products, like Sony, Pioneer, Yamaha, etc... or to DIY it? I want the biggest bang for the buck and hopefully some good output, for this setup is going to be used for playing some music at parties (frat room) or for tv.

 

[thylantyr 10+ year member]

Why not audition receivers in the store to get baseline performance data?

Bring some familiar tunes and crank it in the store and see which receivers

performs well for you. If they don't perform up to expectations, then you

may need external amplification. It cost more but some folks buy proamps to get

more watt per dollar vs. dedicated HT home amps. Buying used lowers your cost.

 

[96civ 10+ year member]

Why not audition receivers in the store to get baseline performance data?Bring some familiar tunes and crank it in the store and see which receivers

performs well for you. If they don't perform up to expectations, then you

may need external amplification. It cost more but some folks buy proamps to get

more watt per dollar vs. dedicated HT home amps. Buying used lowers your cost.

Yeah I might just do that... for the record, what do you think would be a good speaker combo for a quad-frat-room (partying, watching tv, gaming)... like I'm thinking a 1" tweeter, 5" mid, 7" woofer on each tower, and then have either a 10" or 12" subwoofer... would that work well?

 

[96civ 10+ year member]

You can't think about this as car audio. There really is no "setting of the gains" other than adjusting the volume of your surround speakers/center channel and what not. It's usually a good place to start with a receiver that has automated volume and delay features, check out Yamaha RX-V series. But you usually play the volume level to where you like it and it shouldn't be over driven, if it is you need different speakers.

Ok I checked some of the Rx-V's and it seems like the speakers got **** loud before starting to distort. So I'm thinking about making a semi-d'appolito tower setup like PV while pushing those speakers with a 6-channel receiver (either new or used, whatever I can find). I would then use a plate amp to push the sub(s) I want later on after I've saved more. This would probably be a permanent setup unless I wanted to add satellites around the room where I would buy another receiver and power those with that. Is that a logical approach or should I buy a receiver as a temp. thing?

 

[thylantyr 10+ year member]

Yeah I might just do that... for the record, what do you think would be a good speaker combo for a quad-frat-room (partying, watching tv, gaming)... like I'm thinking a 1" tweeter, 5" mid, 7" woofer on each tower, and then have either a 10" or 12" subwoofer... would that work well?

Frat room speakers for a party, TV, gaming.....

One idea if you can DIY.

http://www.partsexpress.com/projectshowcase/magna/index.html

~ $200 for drivers.

You may not need a dedicated subwoofer for music playback as you

have four decent 12" woofers in a ported box.

Later, if you want a sub, get a 15" woofer and a plate amp,

but you may annoy your neighbors. hehehe

 

[joetama 5,000+ posts]

That would be a decent kit for parties or frats....