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Discussion Starter · #1 ·
I am looking at a couple of 7.1 Amplifiers and trying to decide if it worth it to buy 200 watts per channel or just stick to 100 watts. I do like things loud providing my wife isn't in the house, but is 100 enough or is there something besides volume I am not considering here. Any help would be appreciated.


Kurt
 

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There are tons of other things to consider besides the number they print in the AD 100 or 200W.


If you gave us some detalis about the amps we might be able to help more. Are you comparing within the same Brand for Example a Rotel 100 W vs a Rotel 200w? Or are you comparing a cheaper 200 W amp to a more expensive 100W.


I won't go into too much detail but but anyone can put a sticker on that says 200W but is it at 1% distortion which is unlistenable? is it at 4 ohms vs 8? is it 200 W with 7 ch driven or just one? Lots of questions before I cpould give an answer.
 

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Kurt,


It depends on the speakers you use. Low sensitivity or low impedance speakers usually do better with more power. The down side to higher power is that at low output, there is usually more noise output.


Not all 100 watt amps are the same. Some will put out 150 watts into 4 ohm loads while others will put out 200 watts when the impedance drops from 8 to 4 ohms. Speaker impedances vary as frequency varies.


The size of your listening room will also have an effect on the amount of power that you need. Bigger rooms need more sensitive speakers and more power. In many cases, the added power provides "headroom." For each 3 db increase in sound pressure, you must double the power input. Headroom will provide sufficient power for dynamic peaks that can be ten to twenty times higher than the average program level.


Bill
 

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Quote:
Originally posted by KurtONeill
I am looking at a couple of 7.1 Amplifiers and trying to decide if it worth it to buy 200 watts per channel or just stick to 100 watts. I do like things loud providing my wife isn't in the house, but is 100 enough or is there something besides volume I am not considering here. Any help would be appreciated.


Kurt
Output Power ratings are one thing, some brands tend to hype these more than others but here stay with the quality audio brands. Also you should consider room size, speaker type/impedance, favorite music and average playback level..
 

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If you discover the amps are truly rated as specified, 200w vrs 100w is only a 3db change not twice the loudness, its also a matter of how loud do you want to play the audio. Unless your speakers are very inefficient and you have an extremely large room the 100w should work fine.
 

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Hey Kurt,


Headroom is always good. What speakers will you be using? What's your budget? I use two amplifiers to power a 7.1 rig. A B&K Reference 200.5 and a B&K Reference 200.2 amp. Both dig deep when going below 8ohm's. Both are rated at 200WPC. I run PSB speakers.. my main's are Stratus Silveri's which are 4ohm. I use the Ref200.2 to power them @ 4ohm. The Ref200.2 can put out 350WPC @ 4ohm's, while the Ref200.5 can dig to 375WPC @ 4ohm's. Dynamic peaks, no problem.. Headroom, plenty.. This is in a basement HT i built from scratch with dimensions of: 21' 6" x 15' x 7' 7" ceiling. There's a seperate foyer/entrance area of roughly 6' x 5' and computer area of 6' x 4'..roughly 350 square feet or roughly 2650 cubic feet. It kicks HARD whenever i call on it. :cool:


ps. My main's are fairly efficient at 91 db. Here's a couple links to info on the amps i use:

http://www.bkcomp.com/ref200_audispecs.asp

http://www.bkcomp.com/ref200_57.asp



I don't listen all that loud most of the time. Sometimes...when company comes over and they want to see what my setup can do...well, let's just say jaws hit the floor and usually stay there for a while.. hahahaha...


Happy hunting! It's half the fun.. :)
 

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Discussion Starter · #7 ·
Thanks for all your replies. Here are more details. I was looking at the Adcom's because I owned a GFA-7500 and a GTP-750 previously but recently sold them. I have been looking hard and read some nice reviews about Outlawaudio's 950 PRe-amp and then I am trying to decide between their 100 watt 7100 or 200 watt 770 Amp. The details are on their web site at www.outlawaudio.com. It is in a 1000 square foot basement with a low ceiling. My speakers are B&W 7CSE's for the mains and then matching center and rear speakers. I also power stereo speakers by my pool and deck. I am trying to buy quality at a reasonable price and this Outlawaudio product seems to fit that bill. I am putting my money into the 70inch WEGA Sony LCD 950 TV. The 200 watt amp is $800 more and I am not convinced it is worth it.


I hope that helps. Again thanks for your guidance.


Kurt
 

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Well Kurt, the Outlaw is alot cheaper than mine but i gotta tell ya, i have a buddy who has the 200wpc x 5 outlaw amp hooked up to an Integra 6.2 receiver and it sounds great with plenty of headroom! I would not've considered Outlaw myself but, since hearing it first hand.. i like it. I don't know the spec's on it.
 

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IMO any time you can double the power available to your speakers you should do so (within reason of course). Especially if you like to play your music loud.


Dsmith
 

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Wattsup!!


Not all 100watts per channel amps are built alike. So look for the following basic info.


1. 100 watts RMS all channel driven into 8 ohms. This would double the watts into 4 ohms


2. If not then output into 4 ohms should be = or greater than 1.5x of 8 ohm rating. All channels driven


3. If output is quoted for 6 ohms instead of 4 ohms then at least it should be proportional i.e. 133 watts.


4. The distortions ratings should not increase significantly from 8 ohms at les than 8 ohms.
 

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Discussion Starter · #12 ·
Here are specs of the 100 watt amp:


Power Output (FTC): 7 x 100 watts @ 8 ohms, 20 - 20kHz, 0.05% THD, All Channels Driven


7 x 165 watts @ 4 ohms, 20 - 20kHz, 0.05% THD, All Channels Driven


Signal to Noise: 119dB "A" weighted


Frequency Response: 20Hz. -20kHz. +/- 0.1 dB at rated output


Total Harmonic Distortion:

Damping Factor: > 400 from 10 Hz to 400 Hz


Crosstalk: > -90 dB from 20 Hz to 20Khz


Gain: Voltage gain of 28.


Slew Rate: 50v/Microsecond


Input Impedance: Nominal 50k ohms


Input Sensitivity: 1.00 Volts for Full Rated Output


Remote Trigger Voltage: 3 - 32 Volts DC at 5 milliamperes or greater


Dimensions: (HxWxD): 5" with feet x 17.2" x 16.2"


Weight: 51 lbs


Power Requirements: 115VAC, +/- 3%, 50Hz - 60 Hz. 1200 watts, maximum
 

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Discussion Starter · #13 ·
The specs on the 200 watt Amp is as follows.


Power output: 200 watts RMS x 7 (all channels driven simultaneously into 8 ohms from 20 Hz to 20 kHz with less than 0.05% total harmonic distortion). 300 watts RMS x 7 @ 4 ohms


S/N: 119 dB


Power Bandwidth: 5 Hz - over 100 kHz (+0/-3 dB)


Damping factor: 850 (10 Hz - 400 Hz)


Input sensitivity/Impedance: 1.43 volts for full output/28 k ohms


Crosstalk: Greater than -90 dB from 20 Hz to 20 KHz


Gain: Voltage gain of 28 dB


Slew rate: 50 Volts/microsecond


Remote Trigger voltage: 3 - 32 volts DC


Power requirements: 115 V 50-60 Hz


Power consumption: 1,800 watts (maximum)


Dimensions (W x H x D): 17.2 x 7.75 with feet x 18 (inches)


Weight: 90 (lbs)
 

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KurtOneill


From everything I gathered from your info if budget is not an issue in purchasing the larger amp go for it!!

You have a very large room so if you want to really crank it up you can do so! Whatever you decide enjoy!
 

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100 to 200 Watts is only 3 dB.


Both units look to do fine with high current (the watts go up more than 50% when impedance is dropped form 8 to 4 Ohm).


Numbers suggest both these units are solid. There is nothing here to suggest one is better/worse than the other, except for how much power they will give you.


I long ago decideed I'd rather have a good solid 50 WPC much more than a rough 200 WPC.


You should be happy with either one - unless there is something else that just doesn't work for your setup.
 

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All things equal, more power rules!


Dsmith
 

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Another consideration is your circuit rating of the outlet you will use to power these amps. 7x 200W out means more than 1400W drawn, due the amps inefficiencies. I wouldn't put a 7x200W amp on a circuit with only 14 ga wire providing the power. But if you have a 20A dedicated circuit, you are in good shape either way. If you have the freedom of deciding, I'd put in 10 ga wire with a 20A breaker (can't go higher than 20A breaker for general use receptacle).
 

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Well I am an Amplifier newb and have had a small AV Receiver that took care of my HT sound for my family room and have enjoyed it. JVC 8010


Anyhoo.. I'm gonna be adding onto my house and finally have the ability to make some sound purchases for my HT room. I guess my simple question to you guys is why do I need an amp for say a Yamaha 2400 or a Denon 4802R receiver both of which say they put out 125/channel. Does it add the watts/channel from the amp and receiver to the speakers making you buy better speakers? Is the amp gonna make everything that much better? System would be used for movies mainly.


What are the reasons for adding an amp to a system like this? Speakers are still up in the air as well in what I'm getting. Was trying to get under the $5000 range for sound if possible. speakers receiver amp


Room 15x23x8'ceiling


Not trying to steal the thread


Thx for any input ahead of time
 

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Someone with a physics background can give more detail, but more watts really isn't for louder music. You need to almost exponentially increase wattage to get more sound level once you get to a reasonably loud level. That said, the one thing you will definitely notice (assuming the 2 amps are of similar quality) is the quality, texture and dynamic range produced by a more powerful amplifier. A reasonable parallel is a car with two engine options. Both engines can get the car going 60 mph, but the one with more hp. will accelerate more quickly, cruise at lower RPM, frequently last longer and sometimes even get better fuel efficiency than a smaller engine which has to work harder to produce the same power.


I recently swapped amps on my B&W 802's and nearly doubled the power. While my old amp(s) were of high quality (Adcom & Yamaha), the new one (Cinenova) produced noticably better sound at similar volume levels with the quality advantage growing as the volume and demands on the amplifier increased.


A 100 W amplifier will definitely work, but IF you can afford it without too much sacrafice, go for more watts (only a significant difference in watts will make an impact assuming amps of the same quality - ie. don't bother upgrading to 125 or 150W).


Just my opinion.
 
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