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Post by nickwin on Apr 1, 2018 9:00:51 GMT -5
Happy Easter y'all!  |
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Post by nickwin on Apr 1, 2018 9:14:51 GMT -5
UPDATE: I cleaned my ears and now all my amps sound the same. Sorry for the confusion.  |
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Post by leonski on Apr 1, 2018 11:07:28 GMT -5
At this point in the development of amplifiers, differences are becoming less and less perceptible. Distortion of .01 or .009? Kooky.
And many other measurments too boot. Frequency extremes are one thing, though, and an amp bandwidth limited to say 25khz will probably have phase shift in the audible area.
During the Stereophile test of the original hand-modified amp, they were UNABLE to tell the difference between the Carver amp and the 'target' amp. And ugliness ensued. And this
was from a bunch of REAL pro listeners who had organized the test. I'll stipulate that with a different speaker, they test may have had a different result.
The real huge differences, however, I'll maintain, are in the ability to drive REACTIVE loads. They look to the partnering amp as largely capacitive or inductive, NOT purely resistive.
Even some pretty expensive stuff falls flat when asked to drive loads which are highly one-or-the-other.
My mantra has always been that everything that can be measured doesn't matter and everything that matters can't (maybe isn't, yet) measured.
Worst case Example? Maybe the Apogee Scintilla which dropped to ONE ohm in spots and was a Notorious amp-killer. Some Electrostats also are difficult to drive with HUGE phase shifts at what amount
to low-power-required frequencies. Most persons HT speakers? Not so much.
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Post by leonski on Apr 1, 2018 22:20:26 GMT -5
I'm sorry, I'm not into the minutia of measurement. Going over pages of AP data puts me to sleep. A few measurments which I look for, are generally NOT provided in anything but a stereophile test. Like 10khz square wave. Sure, differences in measured performance exist. But MEANINGFUL? Mostly not. Minute differences in the stuff EMO users obsess over, like crosstalk (mostly exceeds source) and seperation? SNR is nearly meaningless except if some flaw exists for some assignable reason. For me? Just for power? Within 2 or 3 db is probably close enough. No mention is usually made of dynamic range which makes more of a difference. I don't know how much difference, all other things being equal, you hear in 2 amps, one of which is 100watts with ZERO headroom and an amp of 25wetts with maybe 6db headroom. I generally draw the like 1%, accepted by many. The Peachtree, as linked, has a HUGE ultrasonic noise product at the outputs. 1 volt? That's a LOT and should have audible consequences. www.stereophile.com/content/peachtree-audio-nova300-integrated-amplifier-measurementsName me 2 amps on which I can examine data which you consider 'completely different' .......I'm curious just what you mean. |
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KeithL
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Post by KeithL on Apr 2, 2018 1:35:43 GMT -5
I absolutely agree... but I will add one thing. While there are certainly a few speakers that offer a really weird load, like those Apogees, MOST speakers offer a more or less benign load. In fact, there are sort of "unofficial standards" for speaker design.... for example, a "well behaved" 4 Ohm speaker really SHOULDN'T drop to below 1 Ohm. The bottom line is that, unless you have really unusual speakers, you shouldn't have to worry about your amp being able to drive really unusual loads. (It would be sort of like if a car magazine were to test pickup trucks to see if they could tow a 20,000 pound load up a 10 degree incline....... It's a very unusual requirement, and not at all the thing that most people would bother to test for, or worry whether their truck could handle or not.) In other words, unless you own those Apogee Scintillas, or one of the few "problem" models of electrostatics, it really isn't worth thinking about. And, if you DO own Apogee Scintillas, it would probably be a good idea to Google, and find out what particular amps other Scintilla owners have had good luck with. (But, if you own normal speakers, then there's no reason you would want to pay a huge premium for an amp that can drive UN-NORMAL ones well.) At this point in the development of amplifiers, differences are becoming less and less perceptible. Distortion of .01 or .009? Kooky. And many other measurments too boot. Frequency extremes are one thing, though, and an amp bandwidth limited to say 25khz will probably have phase shift in the audible area. During the Stereophile test of the original hand-modified amp, they were UNABLE to tell the difference between the Carver amp and the 'target' amp. And ugliness ensued. And this was from a bunch of REAL pro listeners who had organized the test. I'll stipulate that with a different speaker, they test may have had a different result. The real huge differences, however, I'll maintain, are in the ability to drive REACTIVE loads. They look to the partnering amp as largely capacitive or inductive, NOT purely resistive. Even some pretty expensive stuff falls flat when asked to drive loads which are highly one-or-the-other. My mantra has always been that everything that can be measured doesn't matter and everything that matters can't (maybe isn't, yet) measured. Worst case Example? Maybe the Apogee Scintilla which dropped to ONE ohm in spots and was a Notorious amp-killer. Some Electrostats also are difficult to drive with HUGE phase shifts at what amount to low-power-required frequencies. Most persons HT speakers? Not so much. |
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Post by nickwin on Apr 2, 2018 12:00:06 GMT -5
At this point in the development of amplifiers, differences are becoming less and less perceptible. Distortion of .01 or .009? Kooky. And many other measurments too boot. Frequency extremes are one thing, though, and an amp bandwidth limited to say 25khz will probably have phase shift in the audible area. During the Stereophile test of the original hand-modified amp, they were UNABLE to tell the difference between the Carver amp and the 'target' amp. And ugliness ensued. And this was from a bunch of REAL pro listeners who had organized the test. I'll stipulate that with a different speaker, they test may have had a different result. The real huge differences, however, I'll maintain, are in the ability to drive REACTIVE loads. They look to the partnering amp as largely capacitive or inductive, NOT purely resistive. Even some pretty expensive stuff falls flat when asked to drive loads which are highly one-or-the-other. My mantra has always been that everything that can be measured doesn't matter and everything that matters can't (maybe isn't, yet) measured. Worst case Example? Maybe the Apogee Scintilla which dropped to ONE ohm in spots and was a Notorious amp-killer. Some Electrostats also are difficult to drive with HUGE phase shifts at what amount to low-power-required frequencies. Most persons HT speakers? Not so much. I appreciate the genuine explanation! Don't get me wrong, I know its a legitimate argument because I see a lot of reputable engineers making this case. I just can't ignore what my ears tell me which is that there are more that subtle sonic differences between most amps. The way I rationalize it is maybe many small but measurable differences combine makes for a bigger difference in the final sound. While I agree that the difference between .01 and .009 percent distortion would be inaudible in isolation, what about .001 and .01 with different harmonic spectrum, different noise level, square wave and impulse response behavior, MOSFETS vs JFETS etc... I don't think its out of the question that this all together could make a significant difference. I also think its possible that all of those metrics mean very little and that there is some other metric(s) that we can't or don't measure. I certainly don't disagree with your mantra: "My mantra has always been that everything that can be measured doesn't matter and everything that matters can't (maybe isn't, yet) measured. " For me there are a couple aspects that generally sound quite different from amp to amp, whether it be a headphone or speaker amp. The first thing I notice right away and simply can't ignore is the perceived tonality, particularly the degree of fullness in the mids and bass. While I don't think these amps would measure substantially different in freq response, the percieved difference, to me, is huge. Going from one extreme, something like a Parasound HCA series amp or McCormack DNA 125/225/HT5 to something on the other end, basically any Emotiva, but certainly the XPA1L and SA250, literally sounds like I swapped speakers with the latter sounder much bigger and "fuller". One side effect of this is the degree to which male or female vocals stand out in the mix. For example, with the Parasound or McCormack female vocals really stand out of the, whereas on "fuller" amp female vocals are a bit more buried in the mix and male vocals take the lead (or at least equal). Between my to favorite amps of the bunch, the HT5 and the SA250, the SA250 sounded much fuller and seemed to have more mid bass. To me the HT5 sounded perfectly neutral and the SA250 a bit bloated but that might just be what Im used to. I wouldn't even guess which was actually more accurate. Never the less I heard a substantial difference. The next most obvious thing I notice is the degree of "forwardness". Is it a smooth and mellow sound that begs you to keep turning up the volume in order to make it more engaging, or does it sound lively and clear even at modest volumes but you find yourself getting ear fatigue, cringing or turning down the volume during dynamic passages? I found the Parasound HCA VERY forward. Music played through this amp is intense no matter what the volume. Not necessarily a bad thing, but, listening to relatively edgy recordings at reference SPLs was downright grating to the point of really not being enjoyable. At the same SPL the Emotivas, particularly the UPAs, where very laid back and relatively smooth/soft sounding. Words like dark, syrupy and smooth come to mind when swapping form the Parasound to the UPA. At the same volume that the HCA sounded fatiguing, the UPA sounds completely pleasant. The flip side is, relatively speaking, the UPA sounded lifeless at lower volumes and no matter how loud you turned it up it really never had the same liveliness and crisp clarity as the HCA. One way I tested this, which lead to some interesting results, is play a familiar track and turn up the volume by ear where it sound good, your normal listening level, with both amps, and then play some pink noise on both and record the actual SPL. I found that I was always turning the UPA up 1-3db more than the UPA in order to make it sound equally engaging. This is where the HT5 AND SA250 really shined IMO, and also where I thought the SA250 really separated itself form the rest of the Emotiva amps. I find that Emotiva does have a house sound, most of there amps sound more similar that not, and I would describe that house sound as being full, laid-back and smooth, maybe even boarding on dark in some cases. On the other hand the HT5 and SA250 are both right down the middle with just the right amount of edge and forwardness. Neither sounded lifeless at low volumes or seemed to get fatiguing now matter how long and loud I listened. At a normal listening level they where simultaneously lively and engaging and smooth/pleasant souding. To me this is the key attribute for music enjoyment and both of these amps nailed it. These a-b comparisons where done with, among other speakers, Paradigm studio 20s, 8ohm nominal 88db/watt monitors in a near field arrangement. Avg wattage draw was probably well under 1 watt with peaks of 2-3 watts. This load shouldn't have been stressing any of these amps. I chose a near field setting in order to reduce the effect of room acoustics which can very easily obscure these differences. I also found that these differences only really came to light when a-bing. Simply listening to one amp, I never really got to know its true character relative to to other amps. It was only when compared side by side that the sonic differences became apparent. I also think it’s worth noting that hearing can be trained just like any other sense. The more you “ practice” by actively listening, the easier it will be to hear subtle differences. Harmon has a really cool free app called “how to listen” that’s worth checking out of this is of interest to you. |
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Post by leonski on Apr 2, 2018 13:47:45 GMT -5
Keith and NickWin:
Differenes in Nick's amps MIGHT be accounted for in the speaker. It is very difficult to listen to JUST an amp!
And for Keith? Sure, Low impedance can damage an amp. Those Scintilla's? Notorious.
But at the same time we are back to PHASE which ALL speakers exhibit to one degree or another as well as the normal up/down of Impedance. It's the COMBINATION which creates the speaker load.
And yes, given that most HT receivers have just OK amp sections, the speakerss intended to partner are also generally a benign load. You know you've got trouble in the amp when its got a a '6 ohm switch'.
Some Thiel and B&W models were / are sort of noted for being difficult to drive. While one poster here recently asked about low sensitivity speakers and tubes. Nobody thought to mention Harbeth, which
are considered very good with tube amplification and yet are fairly below average in sensitivity. Like the LS3/5 'copies' which have been around for years. Wasn't the original a 16ohm speaker?
I'll check out the Harman app. Might be interesting
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Post by Gary Cook on Apr 2, 2018 15:54:27 GMT -5
My XPA-1L’s don’t run at any higher temperature in Class AB than my XPA-5 Gen 1, that’s measured at the heat sinks. I have also had an XPA-2 and an XPA-3 and they have all run around the same temperature. Of course the XPA-1L’s run hotter in Class A but that’s to be expected. Really? This is very different than my experience. What kind of temps are you seeing? My XPA5 literally stays cold unless I drive it hard for ~20 min and then it barely warms to the touch. This is driving 80db/watt speakers. The XPA1Ls I had were idling well over 100 and went up from there fast when driven hard. It depends on the measuring equality, for example running the side, rear and centre channels will result in less usage and therefore less temperature than the FL and FR. I do all of my comparisons with one amp (or one channel of the amp) ruining the FL and then one amp (or one channel) running the FL. I then play music in mono stereo so that both channels are getting the same signal. I then either listen if I'm doing an amp sound comparison and/or carry out another measurement, in this case temperature with a pyrometer probe to the heatsinks. It's then easy to do a one song, 10 minute, 1 hour or all day comparison. My speakers are 8 ohm, not hard to drive and have an efficiency at 91 db. Which BTW is not an accident, I firstly choose speakers on their sound (dah) but I then pay attention to their electronic characteristics. If I have 2 equally sounding speakers then I'll chose the not so tricky to drive, efficient ones. Why make life difficult if they sound the same to me. If doing an amp sound comparison the above method (parallel) picks up all sorts of sound differences, even very subtle ones that the one after the other listening (serial) often doesn't. Simply because in serial listening we are relying on memory, which is not the most reliable. The same applies to other testing, such as temperature, on the same day, same time, no ambient temperature differences, same music etc. Looking at the heat sink size, the number of drivers and the power output there is every reason there that XPA-1L should run slightly cooler at the same db output. This is I believe is engineered compensation for the high bias Class A capability ie; the amp designer knew what he was doing. Cheers Gary |
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Post by leonski on Apr 2, 2018 20:14:40 GMT -5
IMO, the real measure would be current draw VS amp weight. 60 or 80lb of Class 'A' amp should run pretty warm just sitting there. 'A' amps pass the SAME load current even with 'no demand' on the amp with efficiency probably in the 25% ro 30% area at rated power.
I'd measure current draw of a 1L at idle. It should be about 3x to 4x the maximum 'A' power rating.
In A/B? Quite a bit cooler, as Gary notes. The Whole Thing depends on just 2 things. BIAS and HEAT SINK weight. Bias and therefore current draw is MUCH less in an A/B amp which accounts for it running much cooler.
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Post by nickwin on Apr 4, 2018 8:38:38 GMT -5
Really? This is very different than my experience. What kind of temps are you seeing? My XPA5 literally stays cold unless I drive it hard for ~20 min and then it barely warms to the touch. This is driving 80db/watt speakers. The XPA1Ls I had were idling well over 100 and went up from there fast when driven hard. , for example running the side, rear and centre channels will result in less usage and therefore less temperature than the FL and FR. I do all of my comparisons with one amp (or one channel of the amp) ruining the FL and then one amp (or one channel) running the FL. I then play music in mono stereo so that both channels are getting the same signal. I then either listen if I'm doing an amp sound comparison and/or carry out another measurement, in this case temperature with a pyrometer probe to the heatsinks. It's then easy to do a one song, 10 minute, 1 hour or all day comparison. My speakers are 8 ohm, not hard to drive and have an efficiency at 91 db. Which BTW is not an accident, I firstly choose speakers on their sound (dah) but I then pay attention to their electronic characteristics. If I have 2 equally sounding speakers then I'll chose the not so tricky to drive, efficient ones. Why make life difficult if they sound the same to me. If doing an amp sound comparison the above method (parallel) picks up all sorts of sound differences, even very subtle ones that the one after the other listening (serial) often doesn't. Simply because in serial listening we are relying on memory, which is not the most reliable. The same applies to other testing, such as temperature, on the same day, same time, no ambient temperature differences, same music etc. Looking at the heat sink size, the number of drivers and the power output there is every reason there that XPA-1L should run slightly cooler at the same db output. This is I believe is engineered compensation for the high bias Class A capability ie; the amp designer knew what he was doing. Cheers Gary Good point, it sound like you where more thorough than I was. I just go by touch generally but when I noticed the xpa1ls seems abnormally hot I pulled out my IR thermometer to confirm. Maybe there is some variation in biasing from unit to unit? Mine seemed to run much warmer than yours. Glad to hear yours are working out for you though! It sounds like your very happy with you xpa1l’s and that’s all each of us can hope for. |
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Post by nickwin on Apr 4, 2018 8:41:26 GMT -5
IMO, the real measure would be current draw VS amp weight. 60 or 80lb of Class 'A' amp should run pretty warm just sitting there. 'A' amps pass the SAME load current even with 'no demand' on the amp with efficiency probably in the 25% ro 30% area at rated power. I'd measure current draw of a 1L at idle. It should be about 3x to 4x the maximum 'A' power rating. In A/B? Quite a bit cooler, as Gary notes. The Whole Thing depends on just 2 things. BIAS and HEAT SINK weight. Bias and therefore current draw is MUCH less in an A/B amp which accounts for it running much cooler. All true, but I was running my XPA1Ls in class AB. |
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Post by Gary Cook on Apr 4, 2018 18:06:07 GMT -5
Good point, it sound like you where more thorough than I was. I just go by touch generally but when I noticed the xpa1ls seems abnormally hot I pulled out my IR thermometer to confirm. Maybe there is some variation in biasing from unit to unit? Mine seemed to run much warmer than yours. Glad to hear yours are working out for you though! It sounds like your very happy with you xpa1l’s and that’s all each of us can hope for. A wise old hifi salesman, no longer with us unfortunately, a few decades ago told me about the "mono comparison method" which works for all sorts of equipment. Except sources, it's hard to compare them as there are synchronisation issues that confuse the ears no end. But comparing pre amps, amps and speakers it shows up all sorts of differences. Yep, I'm happy with the XPA-1L's, they sound great to me and have more grunt than I'll ever use. Plus I've taken advantage of the mono block physics (short Emotiva speaker cables) and quad differential circuitry (long Emotiva XLR cables) that makes a noticeable difference, even though my environment wasn't particularly noisy. I don't think I could ever go back to a multi channel amp for stereo music ever again, monoblocks rule Cheers Gary |
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Post by novisnick on Apr 4, 2018 18:11:36 GMT -5
Good point, it sound like you where more thorough than I was. I just go by touch generally but when I noticed the xpa1ls seems abnormally hot I pulled out my IR thermometer to confirm. Maybe there is some variation in biasing from unit to unit? Mine seemed to run much warmer than yours. Glad to hear yours are working out for you though! It sounds like your very happy with you xpa1l’s and that’s all each of us can hope for. A wise old hifi salesman, no longer with us unfortunately, a few decades ago told me about the "mono comparison method" which works for all sorts of equipment. Except sources, it's hard to compare them as there are synchronisation issues that confuse the ears no end. But comparing pre amps, amps and speakers it shows up all sorts of differences. Yep, I'm happy with the XPA-1L's, they sound great to me and have more grunt than I'll ever use. Plus I've taken advantage of the mono block physics (short Emotiva speaker cables) and quad differential circuitry (long Emotiva XLR cables) that makes a noticeable difference, even though my environment wasn't particularly noisy. I don't think I could ever go back to a multi channel amp for stereo music ever again, monoblocks rule Cheers Gary
Ah!,,,,wait, I wasn’t supposed to reveal any of this, was I? 🤭 |
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Post by DavidR on Apr 4, 2018 18:36:52 GMT -5
Here Gentleman is a true cornerstone of The “Secret Monoblocks Society” , with a firm grasp of understanding and a keeper of the faith!
Ah!,,,,wait, I wasn’t supposed to reveal any of this, was I? 🤭 I don't know Mr CEO but there will be a never ending investigation into this matter. |
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Post by novisnick on Apr 4, 2018 18:42:59 GMT -5
Here Gentleman is a true cornerstone of The “Secret Monoblocks Society” , with a firm grasp of understanding and a keeper of the faith!
Ah!,,,,wait, I wasn’t supposed to reveal any of this, was I? 🤭 I don't know Mr CEO but there will be a never ending investigation into this matter. Lets have drinks while they investigate, sure hope this takes awhile! LOL |
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Post by jjkessler on Apr 4, 2018 22:00:09 GMT -5
I have 7 XPA-1L amps (and 3 XPA-1). Looking for an 8th unit in preparation for the XMC-1 Atmos board in a few months. I love all of my mono blocks and have never had any issue with my XPA-1L’s, ever and use them to drive my surrounds that are rated to 400watts at 4ohms. I have them set in the AB mode (switch in the AB position)
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Post by leonski on Apr 4, 2018 23:19:50 GMT -5
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Post by jjkessler on Apr 5, 2018 5:55:35 GMT -5
I already own an Oppo 105D and will keep it for as long as possible
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Post by nickwin on Apr 5, 2018 9:06:01 GMT -5
Wow, I didn’t see that one coming! That’s to bad. |
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Post by nickwin on Apr 5, 2018 9:07:33 GMT -5
I have 7 XPA-1L amps (and 3 XPA-1). Looking for an 8th unit in preparation for the XMC-1 Atmos board in a few months. I love all of my mono blocks and have never had any issue with my XPA-1L’s, ever and use them to drive my surrounds that are rated to 400watts at 4ohms. I have them set in the AB mode (switch in the AB position) I would usually say one person is to small a sample to have any statistical significance but with this amount of amps your getting pretty close! Do they heat your house too? |
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