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Post by orthikon on Apr 17, 2014 2:25:43 GMT -5
I tried searching but could not find a definite answer.
I read somewhere that it was 17.5 and another 35 so some clarification would be nice.
I was thinking of getting this or the XPA-1 gen2 to power my Magnepan 3.6s
TIA
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Post by Gary Cook on Apr 17, 2014 2:48:25 GMT -5
35
Cheers
Gary
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Post by garbulky on Apr 17, 2014 3:57:09 GMT -5
It's 35 watts no matter 8 or 4.
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Post by routlaw on Apr 17, 2014 10:04:44 GMT -5
Hate to be a contrarian but you're both wrong, here's direct quote from the product page:
It’s a whole new generation of Emotiva’s most popular monoblock power amp. Now, you get the immense, relaxed power of the previous XPA-1, together with switchable 60W Class A mode for even more amazing musicality. And, if that wasn’t enough, we upped the power output to 600W into 8 ohms in Class AB mode.
It doesn't seem logical to me that the Class A rating would half, by dropping down to a 4 ohm load, but I'm not an EE either.
Hope this helps.
rob
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Post by pedrocols on Apr 17, 2014 10:53:54 GMT -5
Hate to be a contrarian but you're both wrong, here's direct quote from the product page: It’s a whole new generation of Emotiva’s most popular monoblock power amp. Now, you get the immense, relaxed power of the previous XPA-1, together with switchable 60W Class A mode for even more amazing musicality. And, if that wasn’t enough, we upped the power output to 600W into 8 ohms in Class AB mode. It doesn't seem logical to me that the Class A rating would half, by dropping down to a 4 ohm load, but I'm not an EE either. Hope this helps. rob I think you the one who is wrong. They are talking about the XPA-1L and you are talking about the XPA-1. |
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Post by routlaw on Apr 17, 2014 11:26:56 GMT -5
Hate to be a contrarian but you're both wrong, here's direct quote from the product page: It’s a whole new generation of Emotiva’s most popular monoblock power amp. Now, you get the immense, relaxed power of the previous XPA-1, together with switchable 60W Class A mode for even more amazing musicality. And, if that wasn’t enough, we upped the power output to 600W into 8 ohms in Class AB mode. It doesn't seem logical to me that the Class A rating would half, by dropping down to a 4 ohm load, but I'm not an EE either. Hope this helps. rob I think you the one who is wrong. They are talking about the XPA-1L and you are talking about the XPA-1. Nope the original OP definitely was asking about the XPA-1 Gen 2, not the XPA-1L thanks |
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Post by routlaw on Apr 17, 2014 11:29:10 GMT -5
Excuse me, within his text he was talking about the XPA-1 Gen 2, but I do now see his title for the thread is discussing the 1L. I was referring to the XPA-1, Gen 2
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Post by pedrocols on Apr 17, 2014 11:34:51 GMT -5
Excuse me, within his text he was talking about the XPA-1 Gen 2, but I do now see his title for the thread is discussing the 1L. I was referring to the XPA-1, Gen 2 He stated he is "thinking of getting the XPA-1 gen2." So you still wrong. |
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Post by pedrocols on Apr 17, 2014 11:36:36 GMT -5
I ran my mg12 with two UPA-1 amps for a while and it was a good sounding system.
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Post by orthikon on Apr 21, 2014 11:03:19 GMT -5
Is 3db of Class A headroom worth the extra $1000 though???
I currently am using XPA-1 gen1s
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Post by AudioHTIT on Apr 22, 2014 11:49:23 GMT -5
Is 3db of Class A headroom worth the extra $1000 though??? I currently am using XPA-1 gen1s If, as reported elsewhere, the XPA-1 G1 has 10 Watts of Class A and the G2 has 60, then there would be closer to 8 dB of Class A headroom. I imagine your G1's do a good job so hard to say if it's worth it to you. |
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Post by Gary Cook on Apr 22, 2014 16:41:23 GMT -5
This thread is in the XPA-1L section. So I'm sorry but I'm totally confused, are we talking about a possible upgrade from a pair of XPA-1 Gen 1's to a pair of XPA-1 Gen 2's or to a pair of XPA-1L's Gen 1 (currently at the run out special price) or to a pair of XPA-1L Gen 2's (which haven't been released yet)?
In Class A terms;
XPA-1 Gen 1 = 10 watts
XPA-1 Gen 2 = 60 watts
XPA-1L Gen 1 = 35 watts
XPA-1L Gen 2 = ?? watts
Personally if I had a pair of XPA-1 Gen 1's I'd probably stick with them as the upgrades are not earth shattering. I might go to the XPA-1 Gen 2's if I had a ready buyer for the XPA-1 Gen 1's and the net cost (to me) was less than, say, $500. Then the extra 50 watts of Class A plus the other Gen 2 upgrades might represent value for money.
Cheers
Gary
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Post by orthikon on Apr 22, 2014 17:30:30 GMT -5
Is 3db of Class A headroom worth the extra $1000 though??? I currently am using XPA-1 gen1s If, as reported elsewhere, the XPA-1 G1 has 10 Watts of Class A and the G2 has 60, then there would be closer to 8 dB of Class A headroom. I imagine your G1's do a good job so hard to say if it's worth it to you. This thread is in the XPA-1L section. So I'm sorry but I'm totally confused, are we talking about a possible upgrade from a pair of XPA-1 Gen 1's to a pair of XPA-1 Gen 2's or to a pair of XPA-1L's Gen 1 (currently at the run out special price) or to a pair of XPA-1L Gen 2's (which haven't been released yet)? Sorry for the confusion, I was comparing XPA-1L upgrade to the XPA-1 gen 2 upgrade (coming from XPA-1 gen 1). Which is about $1000 difference at current prices 25 more class A watts so ~3db more headroom. I guess I can do the hard thing and be patient (very very hard) and wait until used XPA-1 gen2 come out to the market and see what the class A fuss is all about. Thanks. |
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Post by dima333a on May 12, 2014 21:32:38 GMT -5
Hmmm I have mentioned it before.... Normally class A refers to the bias of output devices. While amp can give higher power with 4 Ohm load, 8 ohm load requires less current for a given output power. So, if biasing does not change, you get twice as much of Class A operation with 8 Ohm load (comparatively to 4 Ohm). That is why the official specs are written in a specific way:
Power output (all channels driven):
250 watts @ 8 ohm (0.1% THD)
500 watts @ 4 ohm (0.1% THD)
35 watts @ 8 ohm; Class A operation
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?? watts @ 4 ohm; Class A operation
Not just an assurance, but actual technical explanation from Emotiva regarding 4 Ohm /Class A output would be certainly very interesting.
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Post by Gary Cook on May 12, 2014 21:48:15 GMT -5
Hmmm I have mentioned it before.... Normally class A refers to the bias of output devices. While amp can give higher power with 4 Ohm load, 8 ohm load requires less current for a given output power. So, if biasing does not change, you get twice as much of Class A operation with 8 Ohm load (comparatively to 4 Ohm). That is why the official specs are written in a specific way: Power output (all channels driven): 250 watts @ 8 ohm (0.1% THD) 500 watts @ 4 ohm (0.1% THD) 35 watts @ 8 ohm; Class A operation ---------------------------------------- ?? watts @ 4 ohm; Class A operation Not just an assurance, but actual technical explanation from Emotiva regarding 4 Ohm /Class A output would be certainly very interesting. I have read several posts by Emotiva technical staff stating that that the XPA-1L is 35 watts for both 4 ohms and 8 ohms. If that is in fact the case, and I have no reason to doubt it, then the Class A biasing must be impedance sensitive. Cheers Gary |
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Post by GreenKiwi on May 13, 2014 11:27:00 GMT -5
My guess is that the class A power output does not increase much when driving 4 ohm speakers because my understanding is that the class A mode is basically thermally limited, and the system probably has about as much heat generated with 60w at 4 ohms as 60w at 8 ohms.
Also, your best bet to get the official answer is to pick up the phone.
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Post by dima333a on May 17, 2014 19:36:40 GMT -5
My guess is that the class A power output does not increase much when driving 4 ohm speakers because my understanding is that the class A mode is basically thermally limited, and the system probably has about as much heat generated with 60w at 4 ohms as 60w at 8 ohms. In order to have the same power output in class A for 8 ohms and for 4 Ohms, the bias current through output devices must double for 4 Ohms reltively to 8 Ohms. That is a big deal  |
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Post by garbulky on May 17, 2014 19:55:57 GMT -5
My guess is that the class A power output does not increase much when driving 4 ohm speakers because my understanding is that the class A mode is basically thermally limited, and the system probably has about as much heat generated with 60w at 4 ohms as 60w at 8 ohms. In order to have the same power output in class A for 8 ohms and for 4 Ohms, the bias current through output devices must double for 4 Ohms reltively to 8 Ohms. That is a big deal The quoted specs by Lonnie is 35 watts for both 4 and 8 ohms. How they do it is nobody's idea. But it is not jumping to 70 watts in 4 ohms if that was your question. There are at least two things that cause the switch to class AB. First is the standard 35 watts bias. The other is a thermal bias that switches it to class AB mode when the heat gets past a certain amount. There may be a third control too. |
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Post by eliwankenobi on Jun 1, 2014 23:32:56 GMT -5
Hello All! Long time no post here!
Regarding watts, Watts is Watts... A speaker that drops to 4ohms will consume more current than at 8ohm. More current consumed are more watts consumed and assuming voltage stays the same (which I believe it is depending on the volume selected), it will go into AB mode faster than at 8 ohm. And faster still if it dips lower but I'm not sure if this amp is stable down to 2-ohm, but I'm sure its fine if it goes to 3.X ohms too. So a very efficient speaker, even if it dips to 4ohm or lower might not consume enough current to change the mode to AB and stay all the way in classA. I've always wondered is some thing like the Legacy Audio speakers which are all around 92-94db efficient would be able to keep the amp in classA operation.
I hope this helps the thread starter.
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KeithL
Administrator 
Posts: 10,261
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Post by KeithL on Jun 2, 2014 9:41:03 GMT -5
And you've asked the magic question  (well, as far as there is one). Incidentally, the XPA-1 Gen1 stays in Class A mode for about 10 watts - and that will vary considerably depending on how warmed up it is. The operating class/power of a high-bias amplifier basically depends on the amount of bias current it uses. In Class A operation, the most current swing you can get is between none and twice the resting (idle) bias current at the output. If the signal goes above that, and your amplifier doesn't clip, then the current for each output device "side" will go above that in one direction, but will "cut off" in the other direction - which is the definition of Class A/B operation. It is industry standard to rate this at 8 ohms - which is what we do. Since this is based on CURRENT, and you actually need more current to get the same power into 4 ohms as into 8 ohms, a given bias level will actually get you slightly LOWER power in Class A mode for a given setting of bias current into 4 ohms than into 8 ohms. HOWEVER, real speakers vary wildly in terms of what their real impedance is at a given frequency. Also, for most people - and most music - your average listening level is going to be 1/10 or even 1/20 of the amp's full power when playing loudly, and much less even that that when playing quietly. In other words, most of the time you're actually going to be listening at a few watts, with only the loud peaks going above that. Add to that the fact that most of our amps (especially the XPA-1L) sound so good in Class A/B mode that it's extremely unlikely that you could hear the difference in how those peaks sound in either mode anyway, and it becomes very unlikely that you could tell the difference between whether it "switches modes" at 5 watts, or 17 watts, or 60 watts, or whatever. (It is a historical fact that, IN THE PAST, many Class A amplifiers sounded better than their Class A/B counterparts... but I don't honestly think it's much of a factor any more. While it's true that Class A operation produces different distortion products, and most people agree that, IF THEY WERE AUDIBLE, the distortion products produced by Class A operation are "more benign", the amount of distortion produced by a good amp of either class is so low that it really isn't especially audible anyway. ) The XPA-1L also complicated matters somewhat because it sounds ridiculously good in either mode  The XPA-1 Gen1 (which is what you have) transitions from Class A operation to Class A/B operation somewhere between a few watts and about 10 watts (it will depend on how warmed up it is). The XPA-1 Gen2 has several circuit refinements; and the option of running in Class A for the first 60 watts is just one of them. Personally, I wouldn't be willing to bet serious money that I could tell the difference between Class A and Class A/B operation for either amp. Both sound very good in either mode. In absolute terms, the XPA-1 Gen2 sounds a tiny bit better than the XPA-1 Gen1 (although, as I said, I'm not sure I could tell the difference with the Class A switch on or off). Therefore, given the choice, I'd rather have the Gen2 than the Gen1, but I don't think I'd even consider paying $1000 to go from one to the other (but don't let me discourage you  . Is 3db of Class A headroom worth the extra $1000 though??? I currently am using XPA-1 gen1s |
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(well, as far as there is one).
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