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Post by garbulky on Oct 4, 2018 16:36:07 GMT -5
Let me add one other component to class A "success." With class A you are getting the entire waveform with no simplification/doubling as you do with A/B. As a result, you will get whatever "B" part of the waveform is being transmitted by your source. This is critical. If you have not maintained the entire waveform during ripping, storage, conversion, or DAC processes, then class A will reproduce whatever is there but the overall improvement will not be great. SO, I find it necessary to keep all rips as wave files, undisturbed, and use room correction as convolution files, also operating as wave file adjustments (REW and JRiver do this well together and at a high-res level). This is another reason why class A can be so powerful -- if the original wave file as captured in the recording process is duplicated in its entirety in your room, you will notice the improvement to class A and it will have the effects noted above. MP3, APE, and other file formats sufficiently alter the waveform so there is little reason to bother with class A. Craig, i notice you have both XPA-1 and xpa 1L's, do notice a great difference between the two in sound wise? I do actually. With towers the XPA-1 gen 2 has greater bass extension. Though the XPA-1 L's sound nice they are limited in natural sounding dynamics and extension compared to the XPA-1 gen 2 - and I mean this at even lower volume levels. We even tried it with QUAD XPA-1 L's with the same result. There was basically a slightly compressed sound when using tower speakers. And it also cleraly wasn't due to lack of power because the XPA-1 L's could go very loud. This was a surprise to me because I thought the XPA-1 L would be a mini XPA-1. But it wasn't. It still sounded great. But it didn't have the sonic style of the XPA-1 gen 2. The closest thing to an XPA-1 gen 2 imo is the XPA-2 gen 2 which is very similar in its signature sound. |
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Post by teaman on Oct 4, 2018 16:44:05 GMT -5
Personally I own a pair of the XPA-1 Gen 1's but I also owned a XPA-1 Gen 2 and side by side I preferred the Gen 1 in every test. Class A switch on to me did nothing but heat up the amp. The sound, if it changed at all was so minuscule that it was barely noticeable. I sold the Gen 2 a while back and as far as I know he was using it to power a subwoofer.
I agree with the OP in this one, the switching power supply is a new alternative to most and for those of us that grew up on big torroidal transformers that seem to run forever, a change regardless if it is subtle or not is an iffy proposition. My XPA-1 Gen 1 are my favorite amps I have owned and even though the sonic signature is very similar to the XPA-2 that punch waiting to be unleashed is a worthwhile upgrade. I have a buddy who just received a pair of Gen 1 XPA-1 this week and he is instantly in love with them.
I know Emotiva supposedly refined the Gen 2 amps but to me side by side comparisons on any Gen 1 to Gen 2 I always select the Gen 1 for my ears.
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Post by Boomzilla on Oct 4, 2018 18:27:38 GMT -5
ROTFLMAO... Were I a betting man, I'd bet that very, very few could EVER tell the difference between a "conventional" power supply and a switching one in a mythical "double-blind ABX listening test." Those new-fangled cars are OK, but nothing will ever replace a good horse! Don't fall into the trap of being a curmudgeon.
When Emotiva introduced the Generation 3 amplifiers, they didn't ONLY change the power supply - they also made their actual amplification circuitry a plug-in card that operates over a bus. Don't underestimate the potential of that alone, because I'm going to hypothesize that the "blade architecture" may have a greater effect on the amplifiers' sound than the power supply. Now all the amplification circuitry is on a MUCH more compact circuit board, and due to the inverse-square law, electromagnetic interference potentials are significantly higher. This CAN be compensated for with shielding and good board layout, and I'm pretty sure that the Emotiva engineers know their business. But one has to wonder...
Having owned lots of Emotiva amps, I (personally) think that the jury's still out on the new power supplies. But I also think that switching power supply technology is here to stay. By the next generation of Emotiva power amps, I'd think that the (already minuscule) audio effects of the different power supplies will mostly vanish.
And, as always, I could be wrong...
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dan397
Seeker Of Truth
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Post by dan397 on Oct 4, 2018 19:41:15 GMT -5
One potential criticism of the OP? I don't get the feeling of coherent system goals. Maybe it's just me, but the gear choices span quite a range. I'd just be curious to know how much live music the OP listens to. Geez, I can barely set and accomplish life goals and now I have to have audio system goals too? lol. I actually prefer live / acoustic performance recordings most of the time, although sometimes the quality of the recording and mixing on these is so poor that they won't sound good no matter what system you have. My audio goals, such as they are, are to have a quality surround sound movie system in our upstairs room (smaller space) and a 2 channel system downstairs that can handle basic TV and movie duties (we do have a TV there too) but is otherwise optimized for 2 channel music and filling all the open first floor space. Yes I could have bought cheaper speakers and spent more money elsewhere, but those Revels should last 30 years and I can splurge again on other components in the future. |
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Post by Gary Cook on Oct 4, 2018 20:32:06 GMT -5
One potential criticism of the OP? I don't get the feeling of coherent system goals. Maybe it's just me, but the gear choices span quite a range. I'd just be curious to know how much live music the OP listens to. Geez, I can barely set and accomplish life goals and now I have to have audio system goals too? lol. I actually prefer live / acoustic performance recordings most of the time, although sometimes the quality of the recording and mixing on these is so poor that they won't sound good no matter what system you have. My audio goals, such as they are, are to have a quality surround sound movie system in our upstairs room (smaller space) and a 2 channel system downstairs that can handle basic TV and movie duties (we do have a TV there too) but is otherwise optimized for 2 channel music and filling all the open first floor space. Yes I could have bought cheaper speakers and spent more money elsewhere, but those Revels should last 30 years and I can splurge again on other components in the future. I think leonski was referring to actual live performances themselves, not replaying recorded live performances. It's a common theme on here (you'll get used to it  ) where we talk about the comparison between what we hear live and what we hear when we play back the same performance on our gear at home. Room acoustics not withstanding it's an interesting way to compare how much "colouration" our systems are adding to what we heard live. For example, I have a few recordings where I was actually at the concert that was recorded (Idina Menzel, Billy Joel, Elton John, Eagles, John Fogerty etc) and if I'm listening to those recordings on my system I'd like them to sound like the live performance sounded. Obviously subtle differences are hard to pick, but some differences just smack you right in the face. That's my preference, whereas others prefer to listen to a sound that they like, which may or may not be the same as the live performance was. No right or wrong, just different preferences. Cheers Gary |
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Post by leonski on Oct 4, 2018 22:39:30 GMT -5
There is feedback in all modern ss amplifiers and feedback can insure linearity but wouldn't it be safe to say the more linear the initial amplification device, is the less feedback required to correct the non linearity, and therefore the more desirable outcome? Other effects of feedback include increasing the damping factor (DF) and lowering distortion. 2 main types of feedback, too. Global is from output BACK to the input of the amp. Other feedback is by stage where the output of the stage feeds back to the input of the same stage. This is a 3rd rail topic and everyone who feels they are right, wlll get excited if opinions diverge from what they feel is right. Feedback would appear to be a 2-edged sword with an excess or wrongly applied being detrimental to the sound. If anyone makes an amp, SS or Tube WithOut feedback that would be Nelson Pass. Check his 'First Watt' pages and the various amps he makes and others he still supports. Big DIY community devoted to this subject |
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dan397
Seeker Of Truth
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Post by dan397 on Oct 4, 2018 23:22:43 GMT -5
There is feedback in all modern ss amplifiers and feedback can insure linearity but wouldn't it be safe to say the more linear the initial amplification device, is the less feedback required to correct the non linearity, and therefore the more desirable outcome? If anyone makes an amp, SS or Tube WithOut feedback that would be Nelson Pass. Interesting you should mention this. Here is a bit of the marketing literature for that BAT VK-200 that I mentioned above. As I mentioned, both THD and inter-modulation distortion are very high in this amp despite many subjective listeners' glowing reviews. Again I'm definitely not an expert in the field, but it seems like the designer tried to reinvent the wheel and came up with something with both positive and very negative attributes. |
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Post by garbulky on Oct 5, 2018 0:29:58 GMT -5
If anyone makes an amp, SS or Tube WithOut feedback that would be Nelson Pass. Interesting you should mention this. Here is a bit of the marketing literature for that BAT VK-200 that I mentioned above. As I mentioned, both THD and inter-modulation distortion are very high in this amp despite many subjective listeners' glowing reviews. Again I'm definitely not an expert in the field, but it seems like the designer tried to reinvent the wheel and came up with something with both positive and very negative attributes. Audio Gd's Master amp is also non feedback www.audio-gd.com/Master/Master-2H/Master-2HEN.htm ![]() |
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Post by leonski on Oct 5, 2018 2:01:33 GMT -5
Geez, I can barely set and accomplish life goals and now I have to have audio system goals too? lol. I actually prefer live / acoustic performance recordings most of the time, although sometimes the quality of the recording and mixing on these is so poor that they won't sound good no matter what system you have. My audio goals, such as they are, are to have a quality surround sound movie system in our upstairs room (smaller space) and a 2 channel system downstairs that can handle basic TV and movie duties (we do have a TV there too) but is otherwise optimized for 2 channel music and filling all the open first floor space. Yes I could have bought cheaper speakers and spent more money elsewhere, but those Revels should last 30 years and I can splurge again on other components in the future. I think leonski was referring to actual live performances themselves, not replaying recorded live performances. It's a common theme on here (you'll get used to it ) where we talk about the comparison between what we hear live and what we hear when we play back the same performance on our gear at home. Room acoustics not withstanding it's an interesting way to compare how much "colouration" our systems are adding to what we heard live. For example, I have a few recordings where I was actually at the concert that was recorded (Idina Menzel, Billy Joel, Elton John, Eagles, John Fogerty etc) and if I'm listening to those recordings on my system I'd like them to sound like the live performance sounded. Obviously subtle differences are hard to pick, but some differences just smack you right in the face. That's my preference, whereas others prefer to listen to a sound that they like, which may or may not be the same as the live performance was. No right or wrong, just different preferences. Cheers Gary Yep. LIVE MUSIC as the ultimate reference. Movies? Not so much, since most of the sound effects are 'made up' and NoBody has the vaguest idea what they are supposed to sound like. One example, if I may? Going to a live symphony. We have one in the adjacent town. They spent a bundle on a 'performing arts center' and have shows, plays and the local Symphony. One of the Violinists is a Doctor over at a local hospital and will serenade people at lunch! Good practice and you get to really hear a properly played violin up close. But the point? A symphony doesn't have much in the line of 'imaginge' or some other AudioPhile Buzz Words. Good dynamics, though and 'presence' as long as everyone in the audience is both attentive and quiet. But some of the stuff you can get with a good recording / system is simply absent at a live performance. Except the sound is marvelous. and LIVE. |
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Post by Boomzilla on Oct 5, 2018 4:17:32 GMT -5
One of the reasons that I find garbulky so credible is that both he and his wife are most excellent musicians. Gar records their own performances (often with friends) and since he was there at the original performance, should have a better idea of how accurately his recordings mimic the live one. I'm also blessed by having a major university and a local symphonic orchestra in my town. I've been to numerous live performances over the decades in the university's music hall and the symphony's "Centroplex" auditorium. In addition, there is a LOCAL recording company (Centaur Records) that occasionally does recordings in both of these venues. Therefore, I get to buy performances (that I was sometimes present for) in venues whose acoustics I'm familiar with. This isn't as good as Garbulky being able to hear his own wife's voice on his own recording, but it's better than using a commercial CD where I've never heard the original recording venue. But ultimately, I'd still contend that the ears are easily able to tell the difference between a live performance and the recording of one. And that difference is NOT the fault to the XPA-2, Gen. 3. |
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Post by AudioHTIT on Oct 5, 2018 6:06:32 GMT -5
I don't think there is actually a class AB in a sine wave. You are either in a or b right? The AB allows you to switch between the two depending on current demands. Depending upon the amplitude of the wave, and the bias of the amplifier, the entire sine wave could be in Class A; or only in Class A while in the crossover region, after which it would be in Class B. Whether it’s a sine wave or a more complex waveform, it would be the same. So yes, at any given moment it’s either in A or B (which may be your point), but most are comfortable calling it AB; though in higher bias amps like the XPA-1 some might say A/AB, indicating that it could spend a lot of its time in pure class A. |
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Post by garbulky on Oct 5, 2018 11:31:33 GMT -5
I don't think there is actually a class AB in a sine wave. You are either in a or b right? The AB allows you to switch between the two depending on current demands. Depending upon the amplitude of the wave, and the bias of the amplifier, the entire sine wave could be in Class A; or only in Class A while in the crossover region, after which it would be in Class B. Whether it’s a sine wave or a more complex waveform, it would be the same. So yes, at any given moment it’s either in A or B (which may be your point), but most are comfortable calling it AB; though in higher bias amps like the XPA-1 some might say A/AB, indicating that it could spend a lot of its time in pure class A. I did not know it can switch between a and b while in the middle of a waveform. Good info to know. Thanks. I wonder how they accomplish that quick switch at such a fast speed (within a waveform). |
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Post by tchaik on Oct 5, 2018 13:42:55 GMT -5
One of the reasons that I find garbulky so credible is that both he and his wife are most excellent musicians. Gar records their own performances (often with friends) and since he was there at the original performance, should have a better idea of how accurately his recordings mimic the live one. I'm also blessed by having a major university and a local symphonic orchestra in my town. I've been to numerous live performances over the decades in the university's music hall and the symphony's "Centroplex" auditorium. In addition, there is a LOCAL recording company (Centaur Records) that occasionally does recordings in both of these venues. Therefore, I get to buy performances (that I was sometimes present for) in venues whose acoustics I'm familiar with. This isn't as good as Garbulky being able to hear his own wife's voice on his own recording, but it's better than using a commercial CD where I've never heard the original recording venue. But ultimately, I'd still contend that the ears are easily able to tell the difference between a live performance and the recording of one. And that difference is NOT the fault to the XPA-2, Gen. 3. at one of the axpona events in Chicago I attended, I was going from room to room sampling the best of what high end audio has to offer. at one point I heard what to me sounded like the best cello sound I had ever heard coming from the doorway of one of the smaller rooms. I rushed down to see what equipment and recording was playing... and sho nuff, it was an actual cellist. no matter how heard we try, nothing compares with the live performance. as a performing classical pianist, (check out youtube and type in evans, stravinsky rite of spring and you can watch/listen to a recent performance I and dr. denenburg did) I am always disappointed with the sound of piano through any sound system partly because I normally hear the instrument from inches away. I'm not totally sure what my point was, but I agree that being a professional musician does give one a unique perspective as to the strengths and weaknesses of recorded sound. although the experience of high end audio can be thoroughly engaging, enjoyable and expressive beyond measure, it still falls short of live performances. on the other hand, I often prefer the recorded version of something over it's live counterpart especially in the areas of pop and rock music. as for the XPA-2 gen 3, it is a very neutral yet dynamic and robust amplifier to my ears. tchaik.......... |
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Post by AudioHTIT on Oct 5, 2018 14:27:16 GMT -5
Depending upon the amplitude of the wave, and the bias of the amplifier, the entire sine wave could be in Class A; or only in Class A while in the crossover region, after which it would be in Class B. Whether it’s a sine wave or a more complex waveform, it would be the same. So yes, at any given moment it’s either in A or B (which may be your point), but most are comfortable calling it AB; though in higher bias amps like the XPA-1 some might say A/AB, indicating that it could spend a lot of its time in pure class A. I did not know it can switch between a and b while in the middle of a waveform. Good info to know. Thanks. I wonder how they accomplish that quick switch at such a fast speed (within a waveform). Which is the essence of the pure Class A advantage, both output devices stay on all the time so there is no switching. In pure Class B the switch occurs at the transition from positive to negative and visa versa, and is complete, that is only one device at a time is on (but it’s never used for audio). AB blends the two by the amount of the bias, which smooths the transition. As for the speed of switching I’d just say that audio frequencies are probably trivial for such things. |
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Post by garbulky on Oct 5, 2018 14:38:23 GMT -5
I did not know it can switch between a and b while in the middle of a waveform. Good info to know. Thanks. I wonder how they accomplish that quick switch at such a fast speed (within a waveform). Which is the essence of the pure Class A advantage, both output devices stay on all the time so there is no switching. In pure Class B the switch occurs at the transition from positive to negative and visa versa, and is complete, that is only one device at a time is on (but it’s never used for audio). AB blends the two by the amount of the bias, which smooths the transition. As for the speed of switching I’d just say that audio frequencies are probably trivial for such things. Interestingly schiit has developed a design called continuity which is supposed to blend further class a with ab |
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Post by Boomzilla on Oct 5, 2018 14:43:18 GMT -5
at one of the axpona events in Chicago I attended, I was going from room to room sampling the best of what high end audio has to offer. at one point I heard what to me sounded like the best cello sound I had ever heard coming from the doorway of one of the smaller rooms. I rushed down to see what equipment and recording was playing... and sho nuff, it was an actual cellist... And isn't it AMAZING how your brain knows, absolutely, and within milliseconds? Your "expectation bias," since this was an audio show, was to hear a reproduction system. But even there, your hind-brain KNEW (before your consciousness did) that the cello was LIVE. Those who say we know everything that there is to know about audio conveniently leave out the "real recognition-factor" that we all have. And until we get a performance-to-living-room chain that can fool that old hind-brain into believing it's real, well, we'll all continue to listen to "just recordings." Boomzilla |
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Post by leonski on Oct 5, 2018 15:34:15 GMT -5
Depending upon the amplitude of the wave, and the bias of the amplifier, the entire sine wave could be in Class A; or only in Class A while in the crossover region, after which it would be in Class B. Whether it’s a sine wave or a more complex waveform, it would be the same. So yes, at any given moment it’s either in A or B (which may be your point), but most are comfortable calling it AB; though in higher bias amps like the XPA-1 some might say A/AB, indicating that it could spend a lot of its time in pure class A. I did not know it can switch between a and b while in the middle of a waveform. Good info to know. Thanks. I wonder how they accomplish that quick switch at such a fast speed (within a waveform). The A-A/B thing is NOT a 'brick wall'. There is NO 'Switching' like on a light or appliance. It is a condition of transistor 'bias' or maybe 'preload'. If the bias voltage or current (depending on circuit configuration) is constant, as the signal level rises, the bias level will appear to decrease. I would therefore TEND to disagree with AudioHTIT. That's why, also IMO, the correct designation for many 'A' amps would be to call them 'High Bias'. Parasound Halo amps are such designs. The Pass XA series also qualifies. In particular, for an amp I have data for, the XA30.5 is roughly 30 x 2 8ohm watts and fully class 'A'. But, that same amp has nearly 6db headroom (120watts X 2) which would be considered A/B. The Meter on the front of Pass 'A' amps does not indicate power but rather bias level and under normal circumstances will not move from center. But, when you tap into the amp? The meter will deflect. Pass indicates in the linked article that 'A' has the most bias and 'B' has NONE. the A/B amp has some bias ..... www.passlabs.com/press/leaving-class |
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Post by novisnick on Oct 5, 2018 15:40:56 GMT -5
at one of the axpona events in Chicago I attended, I was going from room to room sampling the best of what high end audio has to offer. at one point I heard what to me sounded like the best cello sound I had ever heard coming from the doorway of one of the smaller rooms. I rushed down to see what equipment and recording was playing... and sho nuff, it was an actual cellist... And isn't it AMAZING how your brain knows, absolutely, and within milliseconds? Your "expectation bias," since this was an audio show, was to hear a reproduction system. But even there, your hind-brain KNEW (before your consciousness did) that the cello was LIVE. Those who say we know everything that there is to know about audio conveniently leave out the "real recognition-factor" that we all have. And until we get a performance-to-living-room chain that can fool that old hind-brain into believing it's real, well, we'll all continue to listen to "just recordings." Boomzilla Basically, your brain is smarter then you! It’s just not letting on about it! 😲🤔 |
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Post by mgbpuff on Oct 5, 2018 15:51:18 GMT -5
I did not know it can switch between a and b while in the middle of a waveform. Good info to know. Thanks. I wonder how they accomplish that quick switch at such a fast speed (within a waveform). The A-A/B thing is NOT a 'brick wall'. There is NO 'Switching' like on a light or appliance. It is a condition of transistor 'bias' or maybe 'preload'. If the bias voltage or current (depending on circuit configuration) is constant, as the signal level rises, the bias level will appear to decrease. I would therefore TEND to disagree with AudioHTIT. That's why, also IMO, the correct designation for many 'A' amps would be to call them 'High Bias'. Parasound Halo amps are such designs. The Pass XA series also qualifies. In particular, for an amp I have data for, the XA30.5 is roughly 30 x 2 8ohm watts and fully class 'A'. But, that same amp has nearly 6db headroom (120watts X 2) which would be considered A/B. The Meter on the front of Pass 'A' amps does not indicate power but rather bias level and under normal circumstances will not move from center. But, when you tap into the amp? The meter will deflect. Pass indicates in the linked article that 'A' has the most bias and 'B' has NONE. the A/B amp has some bias ..... www.passlabs.com/press/leaving-classI agree with Leonski pretty much. To me Class A means the output device is always conducting. The amount of bias determines the amount of power the amp can put out whilst still in Class A. There is no switching. If the bias is not enough to prevent the output device from turning off, the complementary output devices begin to conduct, constituting Class B operation A moving bias is interesting, does anyone know of such a design? |
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Post by Casey Leedom on Oct 5, 2018 16:31:41 GMT -5
I think that the Krell Amplifiers have a variable bias technology which they refer to as "iBias" ...
Casey
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) where we talk about the comparison between what we hear live and what we hear when we play back the same performance on our gear at home. Room acoustics not withstanding it's an interesting way to compare how much "colouration" our systems are adding to what we heard live. For example, I have a few recordings where I was actually at the concert that was recorded (Idina Menzel, Billy Joel, Elton John, Eagles, John Fogerty etc) and if I'm listening to those recordings on my system I'd like them to sound like the live performance sounded. Obviously subtle differences are hard to pick, but some differences just smack you right in the face.
