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Old 13th December 2010, 08:45 PM   #1
ahl395 is offline ahl395  United States
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Default Amplifier Questions

Hi everyone, im not sure if this is the right section or not... but i have a few questions.

For #1, does a Surround sound home theatre receiver have crossovers built into the receiver that filter out bass from the main connections? or is the crossover in the speakers themselves like normal?

My bigger question is the following...

Im looking at buying an amplifier. But i have mulitple speakers that are different ohms. and im not sure how to calculate how much power i actually need.
I have two 75watt 8 Ohms, two 100 watt 6 Ohms, and three 180 watt 16 Ohm speakers.

I know its not good to mix up different Ohms into one receiver, although im doing it now with the 8's and 6's and it is working fine... so im not to worried about that.

How much total power do i need to get in an amplifier to make it work right?

Thanks in advance.
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Old 13th December 2010, 09:11 PM   #2
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Some have an internal crossover but most just sum the channels or take the sub out from the center channel.

Different ohm speakers shouldent be a problem as long as you go below the minimum ohm rating for the speaker outputs.
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Old 13th December 2010, 09:19 PM   #3
ahl395 is offline ahl395  United States
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Quote:
Originally Posted by Tekko View Post
Some have an internal crossover but most just sum the channels or take the sub out from the center channel.

Different ohm speakers shouldent be a problem as long as you go below the minimum ohm rating for the speaker outputs.
ok... im trying to convert and figure out how much i need but i cant really seem to lol.

i have the following...

Two 100W 6 Ohms
Two 75W 8 Ohms
Three 180W 16 Ohms. (although i can cut that down to only two if i need to)

Would THIS amplifier be sufficient?
It says 3000W Peak...
2 x 800 watts @ 2 ohms
2 x 550 watts @ 4 ohms
2 x 300 watts @ 8 ohms
(Also to note, it is 4 channel. so i guess you would have to split those in half to get the per hookup output.)
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Old 13th December 2010, 09:34 PM   #4
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Quote:
Originally Posted by ahl395 View Post
For #1, does a Surround sound home theatre receiver have crossovers built into the receiver that filter out bass from the main connections? or is the crossover in the speakers themselves like normal?
Most modern 5.1 and 7.1 AVRs have bass management built into them and can be set by their internal menu system - ie - it is usually a selection something like this - select for each pair of speakers (FR/FL, BR/BL, SR/SL) either Larger or Small - if you select the small setting the AVR will not pass any Freq below 100Hx to that pair but will instead send it to the LFE/Sub channel instead.

Quote:
My bigger question is the following...

Im looking at buying an amplifier. But i have mulitple speakers that are different ohms. and im not sure how to calculate how much power i actually need. I have two 75watt 8 Ohms, two 100 watt 6 Ohms, and three 180 watt 16 Ohm speakers.

I know its not good to mix up different Ohms into one receiver, although im doing it now with the 8's and 6's and it is working fine... so im not to worried about that.

How much total power do i need to get in an amplifier to make it work right?

Thanks in advance.
That is a difficult question to answer.
- First what you would need to know is what speakers you want to use for each of the surround locations and then what is the Sensitivity rating for each of those speakers - ie if I put one(1) watt into that speaker how much sound do I get out in dbs.
- Second what is the size LxWxH of the room for this surround system and how loud do you normally like to play things ???

at THX reference levels ?

or something that won't scare pets and small children....
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Old 13th December 2010, 09:37 PM   #5
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A normal home cinema receiver will power your speakers to way beyond deafening levels. The smallest speakers would be the rears and the two biggest the two main channels.

The ratings on the speakers is the peak they can take for a few milliseconds before the coil melts, the cones would be on the other side of the room way before then.

Unless your setting up a home theatre for movies, your better off getting a good 2 channel amplifier for the main channels and a few hundred watt plate amp for the sub.
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Old 13th December 2010, 09:44 PM   #6
ahl395 is offline ahl395  United States
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Quote:
\Most modern 5.1 and 7.1 AVRs have bass management built into them and can be set by their internal menu system - ie - it is usually a selection something like this - select for each pair of speakers (FR/FL, BR/BL, SR/SL) either Larger or Small - if you select the small setting the AVR will not pass any Freq below 100Hx to that pair but will instead send it to the LFE/Sub channel instead.
Quote:
Originally Posted by Tekko View Post
A normal home cinema receiver will power your speakers to way beyond deafening levels. The smallest speakers would be the rears and the two biggest the two main channels.

The ratings on the speakers is the peak they can take for a few milliseconds before the coil melts, the cones would be on the other side of the room way before then.

Unless your setting up a home theatre for movies, your better off getting a good 2 channel amplifier for the main channels and a few hundred watt plate amp for the sub.

Ah ok, thanks.

Well the reason i ask is because its easier to find higher wattage in home theater system amps. so i was thinking about buying one of those and using it for all my speakers. but if it has built in crossovers for the main left/right speakers, etc. then it wouldnt work out too good for the speakers i wanna connect to it that have woofers
Quote:
That is a difficult question to answer.
- First what you would need to know is what speakers you want to use for each of the surround locations and then what is the Sensitivity rating for each of those speakers - ie if I put one(1) watt into that speaker how much sound do I get out in dbs.
- Second what is the size LxWxH of the room for this surround system and how loud do you normally like to play things ???

at THX reference levels ?

or something that won't scare pets and small children....
Hmm... ok.

-The two 100W 6 Ohms would be Rear Left and Right.
-The two 75W 8 Ohms would be Front Left and Right
-The two 180W 16 Ohms would be... "Center Left and Right". if you know what i mean by that. Front Left and right would be fine.

-The one other 180W 16 Ohm is a subwoofer. Which i could either get a crossover for, or just not use at all, since i dont really need it. Not a big deal at all.

Also, I dont think it really matters which are front and rear... because it will just be 2 channels anyway. and im only listening to music on it, so "surround sound" doesnt matter.

Im not sure what THX Reference levels are...

I like to play things pretty loud.......... lol

My room is actually pretty small lol... i call it the speaker room
I belive its about 10' x 11' although it could be a little bigger im not sure.

Last edited by ahl395; 13th December 2010 at 09:50 PM.
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Old 14th December 2010, 05:21 AM   #7
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Quote:
Originally Posted by ahl395 View Post
Well the reason i ask is because its easier to find higher wattage in home theater system amps. so i was thinking about buying one of those and using it for all my speakers. but if it has built in crossovers for the main left/right speakers, etc. then it wouldnt work out too good for the speakers i wanna connect to it that have woofers
I tend to agree, there are a lot of good sales on right now - personally I have always be partial to Pioneer gear such as this one on sale at PE. Even if you never use the HT capabilities of this unit some of the goodies like
Digital audio connections, bass management with direct Subwoofer output, DSP sound field simulation, etc are really thrown in for virtually free.

There are other good 5.1 units out there from Harmon and Okyno as well - just shop around for the best price feature set combination for your needs.

Basically for your size room 100W of clean power per channel will be more than enough. Once you have settled and gotten the amp just play arround with using different sets of speakers as you mains and your rears until you find a combo that make you smile

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Old 14th December 2010, 07:35 PM   #8
ahl395 is offline ahl395  United States
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Quote:
Originally Posted by Cokewithlime View Post
I tend to agree, there are a lot of good sales on right now - personally I have always be partial to Pioneer gear such as this one on sale at PE. Even if you never use the HT capabilities of this unit some of the goodies like Digital audio connections, bass management with direct Subwoofer output, DSP sound field simulation, etc are really thrown in for virtually free.

There are other good 5.1 units out there from Harmon and Okyno as well - just shop around for the best price feature set combination for your needs.

Basically for your size room 100W of clean power per channel will be more than enough. Once you have settled and gotten the amp just play arround with using different sets of speakers as you mains and your rears until you find a combo that make you smile

Well the other thing is i need it under $200... even close to $200 is stretching it lol, i was hoping for $150-$180.

Ill look around a bit though.

100W on what Ohm?

Also, 100W is going to underpower the 180W speakers alot, which are an important part of my setup.

Somethings making me think the amp i posted would be better lol, but i guess not

Also to note, im only playing music on this. which will be two channels. So i dont really need the home theater. just an option.
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Old 14th December 2010, 08:42 PM   #9
ahl395 is offline ahl395  United States
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Edit to the above...

I think my 16 Ohm speakers are just too high... Any amp that can power them is way to expensive. And not many amps even list 16 Ohm. I dont think theres any way for me to do this without replacing those speakers unfortunately.
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Old 14th December 2010, 09:51 PM   #10
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Any amp can drive 16 ohm no problem, though it will not give much power and will clip sooner as it hits the rails, but even with 16 ohms it'll be deafeningly loud way before that.
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