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External amp question


wuzzzer

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Within the next month or so I hope to buy an external amp as a home theater upgrade. I'm seriously considering the Emotiva UPA-2 amp.

The UPA-2 is rated at 125 watts x 2 @ 8 ohms and 185 watts x 2 @ 4 ohms. I once read that to make a noticeable difference an external amp should be rated for twice as many watts as your current amplification. My Marantz is rated at 110 watts per channel @ 8 ohms. I know there are many compromises made with amplifiers within receivers and that generally an external amp is always an upgrade over using a receiver's amplification. It seems that the XPA series is much more popular than the UPA series. Do you think the UPA would be a upgrade worth the money? The amp is on sale for $249 plus $25 shipping through December 31st.

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I've wondered myself how much of an improvement 125 watts with a dedicated amp would be over a 140 watts in a receiver. I wouldn't think there would be much of a difference (but I could be totally wrong). I'm going for the XPA-3 when I get a chance.

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I tried a 140 watt 2 channel B&K amp with RF-7s in place of a 140 watt Ultra2 receiver. There was a small, but noticeable improvement. An upgrade to a 200 wpc Sunfire amp was much more noticeable.

The speakers that you have are an easier load than RF-7s by most accounts, but they do have excellent bass. No matter how you slice it, bass takes more power.

In your place, I'd skip the 2 channel 125 watt amp and move up to the 3 channel 200 watt amp. The fronts would be a better match and the power increase would be more likely to get improved results.

I would also wait for someone that has Fortes and has experimented to give their view. Much depends on the actual impedance curve of the Fortes and how the speaker actually interacts with a bigger amp.

Bill

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hey wuzzzer - i have a 120wx5 rotel and my best speaker is a rc7 rated at 200w I think and to me it sounds unbelievable.. my pre, a yammie AVR, is 95wx7, i have not heard my rc7 connected dirrectly to yammie but i recon there will be a big drop in sound quality.

but again, i dont listen to HIGH volumne - mainly -35db to -20db

my post might not help you.. but i wanted to say it anyway.. :-)

good luck in your decission

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i'd experiment for that reasonable price.

i think double the power gives you 3db increase in volume, it takes 10 times the power to double the volume.

that said, is volume what you want to purchase? there is more to consider, more to gain.

The above information is incorrect! 3 db is twice the sound pressure, or twice the volume. It takes twice as many speakers or twice as many watts to go up 3 db! Because our ears are inefficent, it takes an increase of 10 db for us to perceive the increase in volume as twice as loud.

Roger

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Thanks all! I like the value of the XPA-3 but I don't have a center speaker and with my current HDTV and stand I don't really have the appropriate room for one. The XPA-2 of course would be awesome but I don't want to spend that much on an amp and don't think I need 250 watts x 2.

The UPA-2 at $249 is what I really would like to do. Run my surrounds off my receiver and the Forte IIs off the Emotiva.

Actually what I'd really, really like to do is get the UMC-1 pre-amp and the UPA-5 amp. $1198 plus $50 shipping. I could get $400 for my Marantz = $798. Hmm, anything I have laying around I could sell for some quick cash? [:)]

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HUH?

Exactly as I stated, no HUH about it. db is NOT a linear measurenment. An increase in 3 db is twice the sound pressure aka twice the volume. To get an increase of 3 db takes twice as much power. If a K-Horn takes 1 watt to produce 104 db it will produce 107 db at two watts, or two K-horns will produce 107 db if they both have 1 watt each fed into them. So double the power,increases the sound pressure by 3 db. The human ear is an inefficient mechinism, and it takes an increase of 10 db for us to perceive a sound as being twice as loud. This is not new information or rocket sience, that is just the way it is.

Roger

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It is actually a good thing that our auditory systems are 'inefficient' or rather logarithmic as pointed out above. If they were not, we could not handle the wide dynamic range of acoustical sources present in nature. We would either not hear the quiet rustle of wind blowing in trees (or a predator sneaking up on us) or be deafened by noises such as thunder or even normal speech.


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i'd experiment for that reasonable price.

i think double the power gives you 3db increase in volume, it takes 10 times the power to double the volume.

that said, is volume what you want to purchase? there is more to consider, more to gain.

The above information is incorrect! 3 db is twice the sound pressure, or twice the volume. It takes twice as many speakers or twice as many watts to go up 3 db! Because our ears are inefficent, it takes an increase of 10 db for us to perceive the increase in volume as twice as loud.

Roger

Nope, not incorrect:

"A simple chart will help to understand the relationship
of the terms we have introduced:

dB Change Voltage Power Loudness
3 1.4X 2X 1.23X
6 2.0 4.0 1.52
10 3.16 10 2
20 10 100 4
40 100 10,000 16

Looking at the chart, and starting at the left, we can
see than an increase of 3dB results in a voltage
increase 1.4 times the original, a doubling of power, and
yields only a subjective increase in loudness only 1.23
times the original. To get a doubling of loudness, it is
important to note that an increase of 10dB is necessary.
And to reproduce that volume through our loudspeakers, note
that we require ten times more power from the amplifier!"

Full article here http://www.gcaudio.com/resources/howtos/voltageloudness.html

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I noticed a nice difference when I added an outboard amp to power my mains. I have since gone through several amps and am on my third obd stereo amp, a Fort'e 3. I do not feel the need to get a 3 ch amp for better "matching" as my AVR powers the other 5 speakers and there is much less load on the amp, esp with the low content of the #6 and #7 speakers, there is plenty of power in the AVR to take care of the job now.

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wuzz .. i picked up a used carver m1.0-t on a whim to drive my mains and couldn't be happier. it's conservatively rated at 200wpc, but in actuality drives closer to 300wpc. They're older, so reliability is a potential issue, but it plays quite nicely with my marantz (and I'm on the waiting list to have it mk II'd next summer).

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Hi Wuzzer.

When I added Forte IIs to the rear of my 5.1 I talked myself into needing more power than my Yamaha 663 could put out. Yamaha claims 95 x 7 but I've read its about half of that in reality with all channels driven. I realize in a surround sound set up the rears don't use much juice but I was thinking more about listening to music. So I pulled the trigger on a Emotiva XPA-5 (200x5).

To get to the point I think adding an amp helped my sound quality but I don't think the amp made as huge a change as I had hoped. I think if one is using a subwoofer or subwoofers with the crossover set at 80Hz than that is taking a big load off the receiver. I've tried to A/B between my receiver w/amp and just the receiver but honestly by the time you switch all the speaker wires around I'm sure it isn't realistic to think I can remember the difference.

That being said I've never taken the amp back out of the mix. I find comfort that it is there, stops me from wondering "what if I had an amp". I do think it helped the sound quality of my system and I'm not trying to say don't get one, just that it may not be the huge change in SQ I've read others claiming on different threads on here and other forums.

The funny thing is with that weak endorsement of getting an external amp and wondering if it was worth it I'm also thinking of getting a UMC-1 when it is released even though I'm very happy with the job my 663 is doing as a pre/pro. Its an addiction so no matter what anyone said I would have bought a 200w amp at some point!

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