harri009
Emo VIPs 
ReferenceAnalog.com
Posts: 1,425
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Post by harri009 on Jul 13, 2013 22:49:59 GMT -5
Keith I would say you guys need to get your facts straight amongs the employees. I emailed with one of the emotiva employees and he said the XPR-1's go straight into A/B with less than 1 watts in class A. I can provide the email. So you can't just say anything you guys want to sell the amp. It's either less than 1 or apparently up to 30. My understanding of what Keith posted is that 1 watt and/or 30 watts is/are correct answers. In some conditions it could be 1 watt, in other less stressful conditions it could be more. In Keith's previous post I thought he covered it well, if we want "guaranteed" Class A performance from an Emotiva amp then there is only one answer (currently) and that's XPA-1L. Which is exactly the point of the XPA-1L, it's unique and if we truly want Class A then the answer to me is very simple, buy XPA-1L's. Cheers Gary Well obviously they can put a number on it because they do on the XPA1L. My problem is not with Keith's answer of it depends on the heat of the room etc. My problem is that people ask and are being told VERY DIFFERENT ANSWERS. Here is the direct copy from the email I was sent. "Hello Jeff, the XPR-1 is pure Class A/B output from watt 1. There is no Class A power." That's very different than a staff member telling Audiophil that his XPR runs up to 30 watts class A. |
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Post by garbulky on Jul 14, 2013 0:23:24 GMT -5
Keith I would say you guys need to get your facts straight amongs the employees. I emailed with one of the emotiva employees and he said the XPR-1's go straight into A/B with less than 1 watts in class A. I can provide the email. So you can't just say anything you guys want to sell the amp. It's either less than 1 or apparently up to 30. My understanding of what Keith posted is that 1 watt and/or 30 watts is/are correct answers. In some conditions it could be 1 watt, in other less stressful conditions it could be more. In Keith's previous post I thought he covered it well, if we want "guaranteed" Class A performance from an Emotiva amp then there is only one answer (currently) and that's XPA-1L. Which is exactly the point of the XPA-1L, it's unique and if we truly want Class A then the answer to me is very simple, buy XPA-1L's. Cheers Gary I don't think it can't be that wide a range. All the x-series do about a fraction of a watt to a watt or two in class A. Except for XPA-1 (10 watts), and the XPA-1 L (30 watts). So, I think there was a mix-up. If the XPR-1's really could get upto 30 watts in class A "sometimes" I think Emo may have dropped a hint of that even if just on the forum. That's a selling point. |
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Post by AudioHTIT on Jul 14, 2013 10:55:09 GMT -5
I agree, 1 watt to 30 watts is too great a difference to be attributed to heat, impedance, and other operating conditions. It's not specified so no one should be expecting anything significant (unless the 'hearsay' is confirmed by a more official statement).
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Post by Gary Cook on Jul 14, 2013 21:18:25 GMT -5
Well obviously they can put a number on it because they do on the XPA1L. But the XPA-1L is unique in that it has a switch to keep it in Class A, other Emotiva amps do not. Cheers Gary |
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Post by ocezam on Jul 17, 2013 17:29:24 GMT -5
Keith I would say you guys need to get your facts straight amongs the employees. I emailed with one of the emotiva employees and he said the XPR-1's go straight into A/B with less than 1 watts in class A. I can provide the email. So you can't just say anything you guys want to sell the amp. It's either less than 1 or apparently up to 30. Agreed. I've read the same thing here from other Emotiva employees. The bias level claims are all over the board. Especially those apparently made at the Emotiva "On the Road" shows. Emotiva employees make claims that are regurgitated here and they contradict other statements relating to the same topic. Other manufacturers that tout certain levels of Class A power in their amps, state those claims in their rated specs on their specific amps. The XPA-1L is the only Emotiva amp to do so, yet there are Infinite claims of certain levels of class A power with other emotiva amps. My understanding of what Keith posted is that 1 watt and/or 30 watts is/are correct answers. Cheers Gary No. You can calculate at what power level the amp will leave Class A based on bias. Sound pressure may change depending on room, speaker efficiency, et al, (as per Keith) but the power level (watts) won't really change. That's why Emotiva can claim 35 watts with the XPA-1L. Also, the written claims of Pass Labs' amps, go to their website. They have a "leaves class A" spec. As it should be. The claims of high class A bias in other Emotiva amps are all over the board. These unsubstantiated claims are detrimental to the brand and should be clarified and stopped. Immediately. This inaccurate information makes for good forum fodder but is the kind of internet misinformation that kills brand credibility. Believe me, I'm am Emotiva "fanboy" but this kind of misinformation make me ill, and it makes it hard to support Emotiva in a hostile forum. It's kind of funny, before the announcement of the XPA-1L, there was very little, if any, mention of the class A bias of an amp on this forum. Now there are all these unsubstantiated claims of class A bias in emotiva amps other than the 1L, and of rumored emotiva amps. In Keith's previous post I thought he covered it well, if we want "guaranteed" Class A performance from an Emotiva amp then there is only one answer (currently) and that's XPA-1L. Gary No, I'm sorry. There is nothing magic about the 1L. The same physical and mathematical laws that enable Emotiva to cite a Class A spec for the 1L also apply to every other amp. Emotiva or otherwise. I really wish they'd put this stupid topic to rest. ... |
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Post by ocezam on Jul 17, 2013 17:32:05 GMT -5
Well obviously they can put a number on it because they do on the XPA1L. My problem is not with Keith's answer of it depends on the heat of the room etc. My problem is that people ask and are being told VERY DIFFERENT ANSWERS. Here is the direct copy from the email I was sent. "Hello Jeff, the XPR-1 is pure Class A/B output from watt 1. There is no Class A power." That's very different than a staff member telling Audiophil that his XPR runs up to 30 watts class A. Exactly. There are good reasons for a HIGH bias class A amp and good reasons for a Lower bias class A/B amp. Be specific which it is, and let the consumer decide what fits his needs best. ... |
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Post by ocezam on Jul 17, 2013 17:33:33 GMT -5
Well obviously they can put a number on it because they do on the XPA1L. But the XPA-1L is unique in that it has a switch to keep it in Class A, other Emotiva amps do not. Cheers Gary Really? Please... .... |
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Post by Gary Cook on Jul 17, 2013 22:17:29 GMT -5
But the XPA-1L is unique in that it has a switch to keep it in Class A, other Emotiva amps do not. Really? Please....... OK, I'm confused, which other Emotiva amp has "a switch to keep it in Class A"? Cheers Gary |
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Post by GreenKiwi on Jul 17, 2013 22:28:04 GMT -5
The XPA-1L has a switch that will allow it to either try to stay in class A operation for as long as possible, i.e. up to 30W, temp permitting etc... or switch over at 1W.
No other amps have this (that I know of)
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Post by ocezam on Jul 18, 2013 7:44:30 GMT -5
OK, I'm confused, which other Emotiva amp has "a switch to keep it in Class A"? Cheers Gary What does that switch have to do with the Class A bias level of any of the other amps? That switch isn't the reason they can give a class A spec for the 1L and not the other amps. .... |
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Post by Gary Cook on Jul 19, 2013 2:51:49 GMT -5
OK, I'm confused, which other Emotiva amp has "a switch to keep it in Class A"? What does that switch have to do with the Class A bias level of any of the other amps? That switch isn't the reason they can give a class A spec for the 1L and not the other amps. Perhaps my view is different, the only reason an XPA-1L moves from Class A to Class AB is temperature, when the switch is in the Class A position. Other Emotiva amplifiers don't have a switch to hold them in Class A, nor do they have the temperature sensing logic that accompanies it. Hence they move from Class A to Class AB as a result of other factors, variable factors. Which to me means an XPA-1L is unique in having a switch that, when in the Class A position, rules out those other factors. Hence an XPA-1L is definitive in its Class A retention, only temperature can change it, while other Emotiva amplifiers are not so endowed, and as such not definitive. Cheers Gary |
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Post by ocezam on Jul 19, 2013 7:12:41 GMT -5
What does that switch have to do with the Class A bias level of any of the other amps? That switch isn't the reason they can give a class A spec for the 1L and not the other amps. Perhaps my view is different, the only reason an XPA-1L moves from Class A to Class AB is temperature, when the switch is in the Class A position. Other Emotiva amplifiers don't have a switch to hold them in Class A, nor do they have the temperature sensing logic that accompanies it. Hence they move from Class A to Class AB as a result of other factors, variable factors. Which to me means an XPA-1L is unique in having a switch that, when in the Class A position, rules out those other factors. Hence an XPA-1L is definitive in its Class A retention, only temperature can change it, while other Emotiva amplifiers are not so endowed, and as such not definitive. Cheers Gary No. The 1L isn't "forced" into class A operation. All A/B amps stay in class A operation based on the amount of bias built into the amp. All the switch does is lower the amount of bias when it's put in the A/B position. Simple. The class A variability based on heat is also a moot point, having nothing to do with the conversation. The conversation isn't about the switch on the 1L. The conversation is about Emotiva letting lots of rumors persist about the Class A level of their other amps. The levels of class A in amps isn't a mystery to the manufacturer. The same physical laws that enable emotiva to claim 35 watts class A on the 1L, enable them to give a figure of class A on any other amp, should they desire. My point, and the point of a few others, is they should publish those specs. I believe the class A operation of their other amps is at or near zero watts. No problem with that. Many good reasons to have a very low class A bias. Heat and efficiency top that list. I'm simply a little tired of seeing all these wild, unsubstantiated claims of class a operation in other amps. ... |
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Post by pedrocols on Jul 19, 2013 9:38:06 GMT -5
Are you guys still talking about this? What about you buy one and test it at home. You have 30 days to return it so that should give you plenty of time. Don't forget to report back once you have some numbers...
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Post by Gary Cook on Jul 19, 2013 14:51:02 GMT -5
Are you guys still talking about this? What about you buy one and test it at home. You have 30 days to return it so that should give you plenty of time. Don't forget to report back once you have some numbers... The 30 day trial is fantastic for locals, but for us guys downunder the cost of freight (both ways) would be almost as much as the cost of one XPA-1L. So we rely on the reviews of the guys not so limited by distance. Not that it's all that important in this case, I have been listening to Class A amps for a long time, so I know what to expect from the XPA-1L's. Cheers Gary |
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Post by pedrocols on Jul 19, 2013 18:35:02 GMT -5
Are you guys still talking about this? What about you buy one and test it at home. You have 30 days to return it so that should give you plenty of time. Don't forget to report back once you have some numbers... The 30 day trial is fantastic for locals, but for us guys downunder the cost of freight (both ways) would be almost as much as the cost of one XPA-1L. So we rely on the reviews of the guys not so limited by distance. Not that it's all that important in this case, I have been listening to Class A amps for a long time, so I know what to expect from the XPA-1L's. Cheers Gary For what I have gathered so far my speakers won't benefit much from these amps running class A. But I still wamt to get them for their size and A/B power. Although I am happy with my UPA-1s but upgraditis is just creeping on me  |
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Post by Leonski on Sept 22, 2013 23:32:19 GMT -5
I'm thinking of a PAIR of the 'a' amps per speaker. My Magnepans are set up for biamping and plenty of class 'a' power in a fully balanced design is enticing. I have a question, though.....What is the approximate power at 4 ohms while staying in class 'a'? Thirty watts is only about 16 volts. 16 volts at 4 ohms is about 60 watts. Shouldn't these amps be capable of that output?
I'd also be careful with excess forced air cooling. You COULD, if the bias is partly controlled by some temp sensitive device, cause shifts in bias and not for the better. I suspect the amp is DESIGNED to run at a certain temp.
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Post by garbulky on Sept 23, 2013 0:00:35 GMT -5
I'm thinking of a PAIR of the 'a' amps per speaker. My Magnepans are set up for biamping and plenty of class 'a' power in a fully balanced design is enticing. I have a question, though.....What is the approximate power at 4 ohms while staying in class 'a'? Thirty watts is only about 16 volts. 16 volts at 4 ohms is about 60 watts. Shouldn't these amps be capable of that output? I'd also be careful with excess forced air cooling. You COULD, if the bias is partly controlled by some temp sensitive device, cause shifts in bias and not for the better. I suspect the amp is DESIGNED to run at a certain temp. The 1 L's will do 30 watts period 4 ohms or 8 ohms. Sounds wierd I know but that's straight from the chief designer's... |
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Post by leonski on Sept 27, 2013 0:17:45 GMT -5
One way to get an IDEA how much 'A' power your amp produces / uses may be to simply MEASURE the amp at idle / standby....with NO signal and after sitting 1 hour 'warming' up. Dark published some data of over 2 amps for his XPA-1L. That is PER amp. That is ALL heat and the current may actually RISE if you use forced air cooling....sucking up THRU the amp is probably best, not trying to force air down into the amp. If you follow the recommendation I just read here...to leave 'em in A/B and switch to A when you begin listening, I'd suspect you'll need maybe 30 minutes for the amp to reach its 'best' sound.
If / When I get 4 of 'em for my Maggies, I'll take extensive measurements in A/B and A and with and without cooling. One owner of Pass XA amps posted that when he removed the top cover to aid cooling, the amp sounded better. Nelson Pass replied that the amp UPPED the bias current to try to maintain temp....which caused the sound to 'improve'....
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Post by Dark Ranger on Sept 27, 2013 1:46:39 GMT -5
If / When I get 4 of 'em for my Maggies, I'll take extensive measurements in A/B and A and with and without cooling. One owner of Pass XA amps posted that when he removed the top cover to aid cooling, the amp sounded better. Nelson Pass replied that the amp UPPED the bias current to try to maintain temp....which caused the sound to 'improve'.... Hi Leonski, It seems that you are as obsessive detailed as I am when it comes to this stuff.  There's nothing like running your own tests, but if you're interested, I have some data recorded from earlier this year: Note: the forced-air cooling I use today (and originally measured with) is configured to pull out the warm air, thereby removing the waste heat. It does not force-feed cool air into the amplifier. In this case, I believe it's better to remove the heat than try to blow cool air into it. The vents are not blocked at all, so no vacuum is created by using exhaust only. For those wondering why I go through the effort, I think chuckienut summed it up best: There are two things in life that real macho men want to know how hot they get, amplifiers and women. |
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Post by leonski on Sept 28, 2013 11:33:02 GMT -5
Good data, Dark.
You should have also had your Kill-a-Watt hooked up so you could see if, as the amp warms, the current draw changes AND if the power factor changes....usually for the better, as the amp warms.
I would suspect that if you force cool the amp....in 'A' mode, by maybe sucking air UP out of the amp, that bias current and therefore the Kill-a-Watt reading would change. A thermister, which is a resistor which changes value as a function of tempreture could be used to control bias current. so when the amp is 'cooled' bias current goes UP.
These kinds of measures can be tricky in a home environment and you may want to repeat 'em at least 3x to confirm repeatability. There goes the weekend!
As kind of an aside, to reduce the number of variables, you might consider a variac to maintain line voltage at 120vac or whatever is convenient.
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