Lonnie
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Post by Lonnie on Sept 27, 2012 15:15:43 GMT -5
I think there is a misunderstanding of the relationship of the THD and rated power vs. actual THD of hte amp. The actual THD for any of our amplifiers is well below .1% usually in the .0X range. That is within the rated output power the actual and real THD is extremely low. 1% is an industry standard for power measurements and not the THD you hear when you are listening to the amp. Think of it like this. Lets say you have a car engine and the red line of that engine is 7000RPM. Below 7000RPM there is no vibration from the engine. When you hit 7000 RPM the engine starts to vibrate and the higher you go the more vibration you get. An amplifier is much like this in that below its rated output (like red line on a car) the THD is very low. When you hit maximum Rated output (the point at the onset of clipping) the THD will start to raise. The harder you drive the amplifier above this point the THD will continue to go up. It could go as high as 20% or more (if the protection circuits would allow this). Since it is not possible for the human ear to detect 1% THD, that became the industry standard for power measurements as that is considered to be the onset of clipping or maximum unclipped output. Just because the power spec is rated at 1%, that does not mean that is the THD of the amp. Far from it, within the power spec the actual THD is much, much less and why it is listed as seperate spec. Hope this helps. Lonnie But what about all the golden ears in this forum that can hear THD of .00000000000001%? Huh? Please address that. ;D ;D ;D ;D ;D |
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Lonnie
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Post by Lonnie on Sept 27, 2012 15:29:19 GMT -5
To get the .01 or .02% rating the power output is right at 387 watts. When we looked at that the first thing we thought was people would say 387, why not just rate it at 400 or 375 or you name it. It was such a odd number that we went up to 400 which then put us at 1%. We even considered rating it at 350 but as time has shown (XPA-2 for example) if we under rate them to much, it comes back to bite in the @$$ as well. ;D
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Post by garbulky on Sept 27, 2012 15:34:43 GMT -5
Could you state @ what power it was doing it at? THD+N: 0.02% @ 387 watts. Then you could easily include the THD at rated power: 1% rating and it wouldn't be awkward. That would make me and anybody else that doesn't like the 1% perfectly happy.
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Lonnie
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Post by Lonnie on Sept 27, 2012 16:18:10 GMT -5
Could you state @ what power it was doing it at? THD+N: 0.02% @ 387 watts. Then you could easily include the THD at rated power: 1% rating and it wouldn't be awkward. That would make me and anybody else that doesn't like the 1% perfectly happy. We already did. Its all in the AP reports. That is why we publish them.  |
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Post by garbulky on Sept 27, 2012 16:42:51 GMT -5
Lonnie, I appreciate the response and the time you give us. Thanks.
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jamrock
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Post by jamrock on Sept 27, 2012 17:02:31 GMT -5
I'm sort of confused. I see that some of my bosom brothers who believe that the performance specs of a component is necessary, trying very hard to determine exactly what performance they have in these components. But I also noticed that some who claim that the specs of audio cables are not important, it is what your ears hear that are important, they are also insisting in getting the specs. Why the flip flop? If these amps sound good, why insist on the specs? You live and die by your ears, don't you? ;D
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Post by garbulky on Sept 27, 2012 17:19:48 GMT -5
Wires aren't amplifiers jam  I agree that it's what sounds good to the ears is most important. However, I wouldn't discount good measurements. Now a product that doesn't measure well can also sound good but that's another story. |
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jamrock
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Post by jamrock on Sept 27, 2012 17:28:05 GMT -5
Wires aren't amplifiers jam I agree that it's what sounds good to the ears is most important. However, I wouldn't discount good measurements. Now a product that doesn't measure well can also sound good but that's another story. You are one of my bosom brothers. And I know your position on the importance of the specs. The others can't have it both ways. They just can't pick & choose which components specs are important and which are not important. That's arguing for both sides of the issue. I just wanna know why? ;D |
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Post by wrinklemash on Sept 27, 2012 19:31:26 GMT -5
Wires aren't amplifiers jam I agree that it's what sounds good to the ears is most important. However, I wouldn't discount good measurements. Now a product that doesn't measure well can also sound good but that's another story. You are one of my bosom brothers. And I know your position on the importance of the specs. The others can't have it both ways. They just can't pick & choose which components specs are important and which are not important. That's arguing for both sides of the issue. I just wanna know why? ;D Q: Why are some specifications more important than others? Rhetorical A1: Do you listen to your system at power? Rhetorical A2: Can you tell the difference between .1% and .001% THD+N with your ears - the range in which most quality amplifiers including all of Emotiva's, Parasound's, McIntosh, Bryston, Adcom, etc., operate? Rhetorical A3: Can you hear the difference in a pair of audio cables when one is 3' shorter than another?  Real Answer - Based on past experiences with my high efficiency theater system, I do hear a hiss from my speakers at normal listening levels when the noise floor of the amplifier is not low. I don't like the hiss.For giggles an grins a friend and I switched out my three UPA-2s with my just purchased UPA-5 in my theater system two days after I bought it. With no material playing, and the volume raised just above normal, you can hear a hiss coming from the speakers when you are very close to them. The hiss is roughly twice as loud with the UPA-2s than with the UPA-500 with the volume set at the same level. The SNR rating for the UPA-2s is >89dB at 1 watt, the UPA-500 is >96dB at 1 watt. I have also experimented and used other amplifiers in this setup, and regardless of their rated power, the level of hiss correlates to the SNR rating. The THD for those amplifiers are all over the place. The noisier amplifiers as measured by SNR at 1 watt always produce more hiss. Since this is my experience, and what has proven to be true with several different configurations using my system, SNR rating is more important to me than THD. I do not think there are any two ways about it. |
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Post by jamrock on Sept 27, 2012 20:31:27 GMT -5
Let me see if I can tackle your concerns. First off, if the SNR of a power amp is 89dB, it means that the noise is 89dB lower than the signal. This is inaudible by the human ears. If the ThD of an amplifier is 0.1% at any volume at 1m or more, it means that the signal deviates from the original by 0.1%. This is indisernible. While I was typing this post, I turned off the source and turned up the UMC-1 to the max (80dB). I could not hear any hiss from the speakers. And I have a UPA-7 & a UPA-2 both of which are high gain amps (32dB). The hiss you hear from your speakers are not necessarily coming from the power amp. The amp is simply amplifying what it received and revealing the weaknesses of lesser components upstream. But the problem could be with your speakers or even poor connections.
However, the above responses do not answer my question. If those who claim that they can hear audio cables insist that specs are not important, only what you hear. Then why concern themselves with the minutae of the specs of an excellent sounding amp? They can't have it both ways. It is either the ears or the specs. Because the specs often times contradict the ears ;D
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Post by garbulky on Sept 27, 2012 21:51:11 GMT -5
Wrinkledmash. In case of the hiss. My UPA-2 also has a hiss in the same way you described it though it is only noticeable when you get close to the speakers and only if you are listening for it. It may be the amp and the SNR values. However, I think that you are hearing the hiss may be due to the gain factor of the two amps. The UPA-2 has a 32db gain factor and the UPA-500 has a 29db gain. The lesser gain might be amplifying the hiss less. The hiss itself may be coming from another device that is connected to the same power strip or in the same audio chain like your AVR or source. Also it could be poor quality electrical wiring in your house's power circuit. So in this case, it's more likely two culprits: high gain circuitry and another component contributing to the hiss.
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Post by wrinklemash on Sept 27, 2012 22:11:42 GMT -5
Let me see if I can tackle your concerns. First off, if the SNR of a power amp is 89dB, it means that the noise is 89dB lower than the signal. This is inaudible by the human ears. If the ThD of an amplifier is 0.1% at any volume at 1m or more, it means that the signal deviates from the original by 0.1%. This is indisernible. While I was typing this post, I turned off the source and turned up the UMC-1 to the max (80dB). I could not hear any hiss from the speakers. And I have a UPA-7 & a UPA-2 both of which are high gain amps (32dB). The hiss you hear from your speakers are not necessarily coming from the power amp. The amp is simply amplifying what it received and revealing the weaknesses of lesser components upstream. But the problem could be with your speakers or even poor connections. However, the above responses do not answer my question. If those who claim that they can hear audio cables insist that specs are not important, only what you hear. Then why concern themselves with the minutae of the specs of an excellent sounding amp? They can't have it both ways. It is either the ears or the specs. Because the specs often times contradict the ears ;D Jamrock, I appreciate the suggestion. If it is the lesser components upstream, then it may be the UMC-1 itself. We have tried to track down the source of the hiss before. We did test with and without components attached trying to track down the source. No luck, same result. We experimented with interconnects, removed antennas, unplugged items in the room, turned off lights etc. Same result - very mild hiss. I have two UMC-1s so it will be easy to switch them out and check. I have also sent you a PM as the remainder of this post, if I go into detail, is off topic for this thread. |
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Post by jhayman on Sept 27, 2012 22:38:45 GMT -5
You are one of my bosom brothers. And I know your position on the importance of the specs. The others can't have it both ways. They just can't pick & choose which components specs are important and which are not important. That's arguing for both sides of the issue. I just wanna know why? ;D Q: Why are some specifications more important than others? Rhetorical A1: Do you listen to your system at power? Rhetorical A2: Can you tell the difference between .1% and .001% THD+N with your ears - the range in which most quality amplifiers including all of Emotiva's, Parasound's, McIntosh, Bryston, Adcom, etc., operate? Rhetorical A3: Can you hear the difference in a pair of audio cables when one is 3' shorter than another? Real Answer - Based on past experiences with my high efficiency theater system, I do hear a hiss from my speakers at normal listening levels when the noise floor of the amplifier is not low. I don't like the hiss.For giggles an grins a friend and I switched out my three UPA-2s with my just purchased UPA-5 in my theater system two days after I bought it. With no material playing, and the volume raised just above normal, you can hear a hiss coming from the speakers when you are very close to them. The hiss is roughly twice as loud with the UPA-2s than with the UPA-500 with the volume set at the same level. The SNR rating for the UPA-2s is >89dB at 1 watt, the UPA-500 is >96dB at 1 watt. I have also experimented and used other amplifiers in this setup, and regardless of their rated power, the level of hiss correlates to the SNR rating. The THD for those amplifiers are all over the place. The noisier amplifiers as measured by SNR at 1 watt always produce more hiss. Since this is my experience, and what has proven to be true with several different configurations using my system, SNR rating is more important to me than THD. I do not think there are any two ways about it.Hi Winklemash I'm curious as to what you consider normal listening level, and I'm not sure what you mean by low noise floor? Can you Please explain what that is so I can understand better.. Thank You |
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Post by AudioHTIT on Sept 27, 2012 22:44:56 GMT -5
I'm going to side with garbulky on this one for just one reason, consistency. If most Emotiva amps spec at 0.1% (or 0.01 or 0.5 or whatever), then Emo customers have a standard of expectation. Maybe that standard varies between the Reference series, the X series, and the Ultra series (as it should), but we all have made a decision that xx.xx whatever %THD is OK with us. Now along comes an amp that has higher distortion - by maybe an order of magnitude - and the explanation is that the distortion is still inaudible (I believe Lonnie and have a well respected amp that's rated ~ 1% and sounds great). But all of that manufacturers amps rate about 1% (or more) and their customers accept that rating, Emo customers have come to expect a higher standard. I would say the amp should have a lower power rating so that the distortion spec can meet the Emotiva standard.
On a related note (to this thread) I gave my new UPA-700 a bit of a ring out last night with the 2nd Robert Downey Sherlock Holmes (can't remember the name). While this amp is underpowered for my speakers and room (while I wait for the XPA-7:~), it did an admirable job pushing SPLs up in the 100 dB range without strain. During a pause I went up and stood about 1 meter from the left speaker and could not hear any noise.
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Post by wrinklemash on Sept 28, 2012 2:19:56 GMT -5
Hi Winklemash I'm curious as to what you consider normal listening level, and I'm not sure what you mean by low noise floor? Can you Please explain what that is so I can understand better.. Thank You Sure, I'll explain the best I can. Forgive me, I don't know how much you know regarding this stuff and I don't mean to be condescending, but since this is being read by so many others, I will be fairly basic and deliberate in the response as it relates to the thread topic. Normal listening level depends on whether I am listening to music or watching movies. Normal Music listening levels for me is between 82 dB and 87dB. rocking the house listening level for me is over 92 dB. There is actually a funny discussion on this on another Karma inspired board about Audio if you care to look it up. And like those other nerds, I do have a Radio Shack spl meter too. Normal Home Theater listening is a bit different as the sounds of movies tend to be more dynamic than music. I haven't used my trusty Radio Shack SPL meter, but I bet its pretty darn loud - my guess is 87dB on average with peaks during booms approaching 120dB. I have a pair of DIY subs that hit that in room With my living room system using Definitive Technology BP-10s, I only need a little more of 1 watt of power on average to happily listen to music because my speakers produce an SPL of 91 dB at 1 meter with 1 watt. With my high efficiency SPL of 96dB a 1 meter w/ 1 watt, HT system, I need less power to produce the same in pressure level with the same signal. What is salient to the above is that it does not take a lot of power to produce and average level of SPLs of a normal volume with a given signal. However, I believe that it takes a lot of power to make the qualities of that signal sound right, as sound in itself is not an average. Noise Floor: All components in a sound system produce measurable (and sometimes audible) noise. In the case of an amplifier, noise floor basically refers to the amount of noise the component is producing itself as it attempts to amplify the signals it is fed. Now the actual noise of an amplifier is rarely if ever specified. However, the gap between the power of the noise produced by the amplifier relative to power of the output signal at a given strength is common - the Signal to Noise Ratio or SNR. ( I think phrased that correctly. If in doubt, please look it up.) Per the revised specifications, the XPA-100 and 200 have a SNR of >89 dB at 1 watt. That is to say that at worst, there will be an 89dB difference in the sound noise the amplifier is producing and the sound signal the amplifier is amplifying at 1 watt of output. The larger the dB number the better. As the sound signal fed to the amplifier increases and is amplified, so should the spread between the signal and the noise of the amplifier itself. This is usually noted as the SNR "at power." And to me, SNR at power is nice to know, but 99.99999999% of the time, your amplifier is not working at full power. A SNR of >89 dB at 1 watt is a really good number, but it is not state of the art. The Emotiva XPA-1 is spec'd at SNR of 100 dB at 1 watt - you'd be hard pressed to find an amplifier that performs better at any price. Considering its cost and power capabilities, that's pretty much state of the art. When making comparisons using the noise floor terminology, the specified SNR of >100dB at 1 watt of the XPA-1 suggests that at its worst, it produces less noise than the XPA-100 with the SNR of >89dB at 1 watt. Thus the XPA-1 has the lower noise floor because it likely produces less noise and the XPA-100 has a higher noise floor because it likely produces more noise. Again, the actual noise produced by the amplifier is not being given in SNR. The reason why I feel this is all germane to the thread is that some people have special circumstances. I, like the person who started this thread, focused on the rather pedestrian (for Emotiva amps) and erroneous original SNR ratings of the new amplifiers. Turns out, the first specs posted were wrong due to errors produced by the testing system itself. My DIY theater setup appeared to be sensitive to accumulated (perhaps interactive) noise produced by the components. And if you already have a problem with noise, you don't want to add any more than you must to the system. Now, here's the egg on my face part.  Based on comments offered by jamrock and garbulky this evening, I switched the old UMC-1 of the HT system out with the newly acquired UMC-1 from Emofest. And well, now I have to turn the volume up ALL the way to hear any hiss in the HT system now. When I put the old UMC-1 in the living room and turned it up a lot with no signal, the system that had no hiss before, suddenly had some hiss. Soooooo.... I am happy to report that the old UMC-1 appears to be the main source of my noise issues. It also appears that I have some other, very faint noise issue in the HT room that is producing a tiny bit of hiss. My best guess is it is the house electrical system. Using the suggestions offered by garbulky and jamrock, THANKS GUYS!!! ;D ;D ;D, I'll be trying a couple of things to eliminate that hiss altogether but it is greatly improved!!!  |
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Post by jhayman on Sept 28, 2012 5:22:38 GMT -5
Well Thank You very much for the in depth explanation, I now understand sort of, lol
I'm glad you figured out the UMC-1 was the culprit good thing you had another one to swap out..
Thanks
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Post by wrinklemash on Sept 28, 2012 6:31:52 GMT -5
I'm going to side with garbulky on this one for just one reason, consistency. I agree with the above. For the Emotiva team, a boilerplate list of spec's might help avoid some of the issues experienced with these product releases. It might also help the team spot abnormalities in the test results before they are published on the website. It invokes the KISS principle. Maybe that standard varies between the Reference series, the X series, and the Ultra series (as it should) I don't agree with this. It's not apples to apples. I'd run the same battery of tests on each amplifier model, using the same parameters. This allows customers to see the differences between the amplifiers. It might also help them justify the choice of a more expensive amplifier over one in a lower line. You know, sometimes you need a reason to spend that extra bit of money. As far as what distortion level rated power should be listed at, I think being conservative at 0.1% THD is okay. Yes the industry standard is 1% THD, but Emotiva tends to kick the rest of the industry's behinds in terms of the price to power ratio with the conservative 0.1% THD power ratings anyway. Most of the amplifiers are rated this way. Price and power are the two most recognizable numbers to buyers. Just look at the way they are listed on the amplifier menu of the website. The name of the unit is given, the price, and the power rating. Power and price, not the name, is the most common way the amplifiers are categorized by average consumers when making comparisons. Emotiva should not shy away from these cross brand comparisons. Who else puts out an audio product that provides as much value on the two most recognizable parameters? Answer: no one. In addition, Emotiva should stay with the more conservative power rating parameters because if they don't, it takes an element of value away from the loyal enthusiasts that buy and shamelessly promote Emotiva products. I kind of get the feeling that Emotiva enthusiasts like the idea that their amplifiers have a little something extra in the hip pocket. Its kind of a secret, and no matter how much someone who has the dollars to buy other more expensive brands pans Emotiva, the truth is that the Emotiva owner is actually and tangibly better than what they are perceived it to be. In a hobby where a person often correlates "better "with the amount of the money spent, it is nice to have a company whose products do focus on value and performance. My best example of the above is this: I remember reading the "Secrets of HT and Hifi" review of the XPA-1 and its commentary on how conservative the stated output of the XPA-1. It impressed the reviewer, and it certainly impressed me. Here was a company selling a product that was better than advertised. Way cool, honest but paradoxically sneaky too. And like it or not, it is an expectation and part of the cache that has been created with the Emotiva brand, especially with its amplifiers. Seriously, Big Dan and Lonnie if you read this, what would you rather have people complain about? They are going to complain no matter what, and heck, you give them a forum to do it in, with the company name on it. Would you rather have them complain about conservative specification numbers on products that represent a ridiculous value in the market place? Or would you rather maximize the specified power numbers, removing some of that inside ownership pride that is part of the Emotiva brand. I mean, this forum is a pretty stout echo chamber that carries over to other forums. Could you imagine being called sellouts and conformists in one of your major advertising channels - the chaos of which you loosely control? Then having it echo into others that you have no control over. Buzz is real, and it gets magnified. I personally like what Emotiva has done overall. Emotiva would make a fantastic academic case study subject. Having followed this industry for some time, I know it is a fluid landscape as many of the companies that used to flourish, no longer exist, or are unrecognizable - Carver for example. If not unrecognizable, the companies are severely diminished and have lost their luster because their distribution channels have been all but eliminated and the brands that used to represent value no longer do so, i.e., ADCOM & NAD. I have owned a number of products from these companies and others, only to wake up one day and find that the support for them no longer exists, whether or not they went out of business themselves, or the local dealer did. In a very forward thinking way, Emotiva has succeeded by creating unique customer relationships via a mixture of community (forum & Emofest), customer service (warranties and return policy), demand responsiveness (tailoring your products to the enthusiast via forum feedback), smart product innovations (incorporation of TACT in consumer products), with incredible value, and insertion of humanizing elements (podcasts). And, yeah, killer products too. It all makes for a nice business model. Don't discount the comfort level between Emotiva and its customers. That relationship is a significant part of the value equation sold by Emotiva and it is sustainable. To keep it sustainable, that value equation will have to adapt and change over time. But I hope Emotiva is careful not to cheapen that equation in the process and the pressures of growth and expansion. Doing things like being needlessly inconsistent with measurement specifications is in the overall picture of things, insignificant. But in this case being needlessly inconsistent steals time, creates unnecessary work, and robs key individuals within the organization of the freedom to focus on other tasks. But if inconsistencies are recurrent and result in systemic problems or vice-a-verse, that value equation will eventually be cheapened. Don't get me wrong, I am rooting for Emotiva. I want them to continue to succeed. If anything, I own Emotiva products that may need to be serviced someday soon. ~Scott PS: When everybody has more free time, someone should ask me what I really think. |
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Post by garbulky on Sept 28, 2012 8:29:32 GMT -5
That's a good post wrinkledmash (and audiohtit). I'm glad some people feel the way I do.
Lonnie mentioned the true THD+N figures @ what wattage are mentioned in their AP test figures. But that only helps people that go to the effort to look it up like me. But not necessary a regular customer who has some audio knowledge but isn't going to go downloading a pdf file and looking at page 4 while trying to find out where the THD+N at what watt figure is. I guess it may be a business decision not to list the watt figures for THD N on the main page or they simply can't be bothered further because they don't see the point.
I think its a good idea to list it on the main page. Because what it shows at a glance that the amp can produce a hefty level of power without any problems AT ALL at 375 watts for the xpa-100. However, if you wanted to push it, you still have very useable power at 400 watts. This way everybody is on board when they glance at the gallery figures. Also if you note that is 25 watts of range where the THD rises significantly to just near the point of clipping. It shows that the company isn't trying to fudge figures just trying to give us an idea of how darn good their amplifier is.
So in my case as long as the THD N @ what watt figures are listed on the ap test reports (and they are around 0.1% or less) then I'm okay. But there are people that will not be as impressed because they have no idea what they have in the ap reports.
A big +1 on the little something extra in the hip pocket and reviewers stating that these amplifiers were performing above specification. That is such good PR. I had a choice between Harmon Kardon and the UPA-2. What made me choose emotiva was and I didn't know a whole lot about amps then:
1. The THD spec was great and I read that it was done at THD+noise at rated power.
2. Whole lot of details given.
3. All channels driven spec.
4. SNR ratings
5. All the reviewers mentioned that emotiva rates conservatively. This is prestige. It's the "magic" under the hood. <Whisper> Who knows how AMAZING it could be?! ;D
Reasons I would have bought it now that I know what I know:
1. If I had known about the capacitance difference (why that's important)
2. The importance of the 1 watt SNR rating.
3. The dual amp blades. How cool is that for a 300 dollar purchase?
4. The true meaning of THD+noise at rated power. (I mean the darn thing does not audibly distort when driven at full volumes. It's amazing. I never have to worry about that. )
5. Weighty torroidal transformer that has actual guts to it.
6. Just how well it can demolish most AVR's in the market.
7. Really really good audio quality. Very clean detailed sound that keeps up with all the upgrades I've thrown at it. How do you ask that from a 300 dollar purchase? When a DAC that sold originally for 400 dollars has the amp keeping up with it without breaking a sweat?
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Post by jhayman on Sept 28, 2012 9:50:34 GMT -5
On a side note for my own benefit I powered on my gear and then turned the volume up to reference level 0db and put my ear to my PSB's and they were whisper quiet..
I guess that's a good thing as they are Anechoic Chamber 89db, and listening room 91db
1w(2.83v) @ 1m, IEC-Filtered pink noise, C-weighted)
Whatever that means..lol
I'm really just starting to get back into music again
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