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Post by kjgarrison on Aug 24, 2010 13:03:42 GMT -5
Hello all. I've looked at other threads with this question and haven't found the answer I'm looking for.
Can somebody explain to me why the XPA-5's THD+N is an order of magnitude lower than the UPA-5's?
Would that difference be present at lower listening levels as well?
I realize that the THD+N of the UPA-5 is under 1% (but not by much), and that the difference between the U and the X is not going to be audible. It's just that the amp isn't the only component in the chain, and I'm thinking these little things can add up to something that is audible.
For anybody that might be interested, I'm going to go with a "5" and use 2 for my L and R mains; the other 3 are to tri-amp my center channel. My AVR is Denon 4308ci, so even the UPA-5 will be plenty of power upgrade. We don't listen to anything at even close to reference levels.
TIA for any help
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Post by KrellAV on Aug 24, 2010 13:40:02 GMT -5
I have both amps in two different systems and have not noticed any audible distortion or hiss from the speakers at any volume level. I think for the money you cannot go wrong with either amp. I would recommend using the XPA 5 if you are going to run full range speakers across the front. For monitors, the UPA 5 should be more than enough!
KrellAV
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Post by kjgarrison on Aug 24, 2010 16:29:17 GMT -5
Thanks for the reply.
I am not surprised to hear that you can't hear any difference.
My concern and somewhat special circumstance is that I'm going to be using 3 of the outputs for tri-amping my center channel. The power required, especially for the tweeter will be very, very low in comparison to a "main" speaker.
A big part of my question is about the performance at very low gain settings, particularly the tweeter and somewhat also the mid-range. As I'm sure everybody knows these two speakers are THE important speakers for speech/dialogue in the 5.1 configuration.
It could be that the maximum distortion occurs at high gain settings, and that I have nothing to be concerned about. I just don't know enough about such things. I'm hoping somebody that has measured it, or who knows of a post someplace, and will chime in.
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NorthStar
Seeker Of Truth
"And it stoned me to my soul" - Van Morrison
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Post by NorthStar on Aug 24, 2010 17:37:05 GMT -5
That would be nice if you can enumerate your speakers.
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Post by kjgarrison on Aug 24, 2010 17:43:50 GMT -5
Apologies to all.
The answers I seek are right there in the Audio Precision Test Data which is provided for all these amps.
The answer to the apparently better THD+N of the XPA-5 vs the UPA-5 is that it is only true at the "rated power output" where it spikes up for all amps.
At just a little bit below max (rated power output), the amps are very close to identical with THD+N values closer to 0.01%.
At 1W they are almost identical at just over 0.01%. At 1mW the XPA-5 is about 0.13% THD+N, and the UPA-5 is about 0.04% THD+N.
At 100W the XPA-5 is below 0.01%, but the UPA-5 is creeping up a bit to 0.015%.
Bottom line for my purposes: No significant difference in the range I would be using either of the amps. If you want to go over 100W, then the difference is significant with the XPA-5 putting out ~210W with THD+N of <0.1% and the UPA-5 only getting up to 129W with THD+N of ~1%.
So depending on the speakers, this issue isn't just raw power; it is clean power.
These are beautiful products. My mains can handle up to 300W, so I'm going big. My little center amps will do just fine.
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NorthStar
Seeker Of Truth
"And it stoned me to my soul" - Van Morrison
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Post by NorthStar on Aug 24, 2010 17:56:58 GMT -5
The XPA-5 then for your particular speakers. ...That's why I was asking which brands and models' #s are they. ...The Denon AVR-4308CI receiver is a very nice one too, with excellent power from the lab tests. ...And low THD+N and great S/N ratio also, like pretty much all Denon products.
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Post by kjgarrison on Aug 24, 2010 22:51:26 GMT -5
That would be nice if you can enumerate your speakers. Sure can. Mains are PSB Synchrony Two: 4ohm, 90db sensitivity, 300W Center: Woofers: Seas Prestige ER18RNX, 8ohm, 88.5db sensitivity, 80W (2 in parallel) Midrange: Tang Band 75-1558SE, 8ohm, 90db sensitivity, 25W Tweeter: SB Acoustics SB29RDCN-C000-4 Neo Magnet, Ring Dome, 4ohm, 94db sensitivity, 100W Considering changing the midrange from the Tang Band with it's Fs 260Hz (and current crossovers of 750/2700) to Jordan JX92, 85db sensitivity, 50W, FS 52Hz (with crossovers of ~300/4200) Building one of Rod Elliott's active 3-way mono crossover's. That's three of the Emotiva's 5. I'll obviously use the other two for the Synchrony's and let my AVR run the surrounds. The 12v trigger capability is very nice.
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Erwin.BE
Emo VIPs
It's the room, stupid!
Posts: 2,261
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Post by Erwin.BE on Aug 25, 2010 3:18:48 GMT -5
That would be nice if you can enumerate your speakers. Sure can. Mains are PSB Synchrony Two: 4ohm, 90db sensitivity, 300W Center: Woofers: Seas Prestige ER18RNX, 8ohm, 88.5db sensitivity, 80W (2 in parallel) Midrange: Tang Band 75-1558SE, 8ohm, 90db sensitivity, 25W Tweeter: SB Acoustics SB29RDCN-C000-4 Neo Magnet, Ring Dome, 4ohm, 94db sensitivity, 100W Considering changing the midrange from the Tang Band with it's Fs 260Hz (and current crossovers of 750/2700) to Jordan JX92, 85db sensitivity, 50W, FS 52Hz (with crossovers of ~300/4200) Building one of Rod Elliott's active 3-way mono crossover's. That's three of the Emotiva's 5. I'll obviously use the other two for the Synchrony's and let my AVR run the surrounds. The 12v trigger capability is very nice. So the Center is DIY, yes? I can see that you would need the amp to facilitate your active crossover. Does the Center blend in nicely with the LR? I even get annoyed here because the B&W CM Centre is inferior to the B&W CM7 (LR) from the same series! I think the UPA-5 is more than plenty with 3 sections of it driving the center. Maybe in the distant future when the time comes to replace the AVR (with say, the XMC-2 ;D) you could get two UPA-1 for LR and use the other channels of the UPA-5 for surrounds if you have 5.1
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Post by kjgarrison on Aug 25, 2010 10:59:34 GMT -5
Sure can. Mains are PSB Synchrony Two: 4ohm, 90db sensitivity, 300W Center: Woofers: Seas Prestige ER18RNX, 8ohm, 88.5db sensitivity, 80W (2 in parallel) Midrange: Tang Band 75-1558SE, 8ohm, 90db sensitivity, 25W Tweeter: SB Acoustics SB29RDCN-C000-4 Neo Magnet, Ring Dome, 4ohm, 94db sensitivity, 100W Considering changing the midrange from the Tang Band with it's Fs 260Hz (and current crossovers of 750/2700) to Jordan JX92, 85db sensitivity, 50W, FS 52Hz (with crossovers of ~300/4200) Building one of Rod Elliott's active 3-way mono crossover's. That's three of the Emotiva's 5. I'll obviously use the other two for the Synchrony's and let my AVR run the surrounds. The 12v trigger capability is very nice. So the Center is DIY, yes? I can see that you would need the amp to facilitate your active crossover. Does the Center blend in nicely with the LR? I even get annoyed here because the B&W CM Centre is inferior to the B&W CM7 (LR) from the same series! I think the UPA-5 is more than plenty with 3 sections of it driving the center. Maybe in the distant future when the time comes to replace the AVR (with say, the XMC-2 ;D) you could get two UPA-1 for LR and use the other channels of the UPA-5 for surrounds if you have 5.1 Yes, the center is DIY. Like your experience with the B&W center, the PSP Synchrony Two center did not live up to it's siblings. Main problem was lobing and difficulty with dialogue/speech intelligibility. My wife and I sit at the ends of a couch, and nobody sits in the middle at the primary listening position. The center crossover is 2200Hz so the two woofers are lobing badly. In fairness the center was not meant to be in a box on the front of an "entertainment center". So I tried the DIY route with the hope of getting the crossover at a lower point to avoid the lobing problem, and the dialogue is much better. Music through the new DIY center is another story. Not good. My Denon AVR has Audyssey and that helps a lot by boosting the weak midrange. There are times, however, when I would like to use the center alone through a separate amp without surround sound, and without the Audyssey corrections it just is unpleasant. Comparable to the TV's built in speakers in fact.
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Post by ausman on Aug 28, 2010 5:47:00 GMT -5
bi-amp is your best bet, tri-amp you can do unless you have a 1in 3out secondary processor feeding the amps, you will be some what limited on what you can do using a standard pre-amp or avr for signal max across all center speakers will be hard as what you're trying to do nothing but post processing 1 into 3..
i would be inclined to use the xpa-3 for this center setup with a post processor on the center speaker... using a pre-amp with xlr terminals..
mind you, you would total rms of 900 watts, might be better doing a bi-amp on a xpa-1 since that has 1000watt rating into 4ohms..
even to do quin amp setup (xpa-5) for center channel you still need a secondary processor with 1 in 5 out... though it will only be 1 speaker per amp with a max 300 watts in to 4 ohms.
the max on the upa-5 is 185 watts per channel into 4 ohms..
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