geebo
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"Too bad that all the people who know how to run the country are driving taxicabs and cutting hair"
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Post by geebo on Aug 6, 2014 8:35:42 GMT -5
Here's a question about this amp. When switched to Class A mode, it acts as a 35 watt amp, and switches to AB mode when that wattage is exceeded. The issue is that I have not heard anyone claim that they can hear a difference in sq between the Class A and the class AB mode of operation. In a way, that is understandable, since a drop in sound quality with the switch from Class A to Class AB, would make the amp seem like a bad performer... However here's my question: given that there appears to be no discernible difference in sq between Class A and Class AB operation (and assuming that this claim is fully valid), what is the advantage of ever starting the amp in Class A mode at all? Why not keep it functioning in Class AB mode all the time, in order to avoid the rather expensive power consumption associated with Class A operation, as well as the overheating problems that are come with it. Is there something I am overlooking? All thoughtful inputs are welcome and appreciated. For me, the jury is still out on a Class A Class A/B difference. I leave my XPA-1Ls switched to A/B most of the time. If and when I am in the mood to listen to some good high quality two channel music and the surroundings at the time permit such (ie late at night in a darkened quiet room), then I will switch to class A and just enjoy the music to no end and not worry about A A/B modes.
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novisnick
EmoPhile
CEO Secret Monoblock Society
Posts: 27,230
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Post by novisnick on Aug 6, 2014 8:49:51 GMT -5
Here's a question about this amp. When switched to Class A mode, it acts as a 35 watt amp, and switches to AB mode when that wattage is exceeded. The issue is that I have not heard anyone claim that they can hear a difference in sq between the Class A and the class AB mode of operation. In a way, that is understandable, since a drop in sound quality with the switch from Class A to Class AB, would make the amp seem like a bad performer... However here's my question: given that there appears to be no discernible difference in sq between Class A and Class AB operation (and assuming that this claim is fully valid), what is the advantage of ever starting the amp in Class A mode at all? Why not keep it functioning in Class AB mode all the time, in order to avoid the rather expensive power consumption associated with Class A operation, as well as the overheating problems that are come with it. Is there something I am overlooking? All thoughtful inputs are welcome and appreciated. For me, the jury is still out on a Class A Class A/B difference. I leave my XPA-1Ls switched to A/B most of the time. If and when I am in the mood to listen to some good high quality two channel music and the surroundings at the time permit such (ie late at night in a darkened quiet room), then I will switch to class A and just enjoy the music to no end and not worry about A A/B modes. I've spent some time with a set of -1Ls so I do have some basis of which I speak. Try this analogy; you buy a new car that has new brakes on it, as you drive and over time the brakes deteriorate and get less effective. You never notice till there about gone, how is this,,,,.you become accustomed to the Effect of the brake wear, same as the transition from class A to A/B slow and easy transition, not an abrupt change. this am starts off so sweet that by the time you get to 40 watts your ear can not detect any difference in SQ. ie: it's all good!!!
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Post by monkumonku on Aug 6, 2014 9:03:30 GMT -5
For me, the jury is still out on a Class A Class A/B difference. I leave my XPA-1Ls switched to A/B most of the time. If and when I am in the mood to listen to some good high quality two channel music and the surroundings at the time permit such (ie late at night in a darkened quiet room), then I will switch to class A and just enjoy the music to no end and not worry about A A/B modes. I've spent some time with a set of -1Ls so I do have some basis of which I speak. Try this analogy; you buy a new car that has new brakes on it, as you drive and over time the brakes deteriorate and get less effective. You never notice till there about gone, how is this,,,,.you become accustomed to the Effect of the brake wear, same as the transition from class A to A/B slow and easy transition, not an abrupt change. this am starts off so sweet that by the time you get to 40 watts your ear can not detect any difference in SQ. ie: it's all good!!! But then if in substance the effect is you hear no difference, then what is the point of having class A in the first place? I understand your analogy about the brakes, but in that case, you are talking about a long period of time and also the need to avoid having a dangerous situation with your car. In the case of an amp, if the transition is so subtle that you don't notice it at all, then why even need to have class A? I would think the test would be to do an A/B with A versus A/B (pun intended) and see if you could detect any audible difference.
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geebo
Emo VIPs
"Too bad that all the people who know how to run the country are driving taxicabs and cutting hair"
Posts: 24,204
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Post by geebo on Aug 6, 2014 9:09:11 GMT -5
I've spent some time with a set of -1Ls so I do have some basis of which I speak. Try this analogy; you buy a new car that has new brakes on it, as you drive and over time the brakes deteriorate and get less effective. You never notice till there about gone, how is this,,,,.you become accustomed to the Effect of the brake wear, same as the transition from class A to A/B slow and easy transition, not an abrupt change. this am starts off so sweet that by the time you get to 40 watts your ear can not detect any difference in SQ. ie: it's all good!!! But then if in substance the effect is you hear no difference, then what is the point of having class A in the first place? I understand your analogy about the brakes, but in that case, you are talking about a long period of time and also the need to avoid having a dangerous situation with your car. In the case of an amp, if the transition is so subtle that you don't notice it at all, then why even need to have class A? I would think the test would be to do an A/B with A versus A/B (pun intended) and see if you could detect any audible difference. An A/A/BAB test?
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Post by monkumonku on Aug 6, 2014 9:11:22 GMT -5
But then if in substance the effect is you hear no difference, then what is the point of having class A in the first place? I understand your analogy about the brakes, but in that case, you are talking about a long period of time and also the need to avoid having a dangerous situation with your car. In the case of an amp, if the transition is so subtle that you don't notice it at all, then why even need to have class A? I would think the test would be to do an A/B with A versus A/B (pun intended) and see if you could detect any audible difference. An A/A/BAB test? Or A/B B/A test...
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geebo
Emo VIPs
"Too bad that all the people who know how to run the country are driving taxicabs and cutting hair"
Posts: 24,204
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Post by geebo on Aug 6, 2014 9:12:02 GMT -5
An A/A/BAB test? Okay, I'll try that tonight.
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novisnick
EmoPhile
CEO Secret Monoblock Society
Posts: 27,230
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Post by novisnick on Aug 6, 2014 9:15:19 GMT -5
I've spent some time with a set of -1Ls so I do have some basis of which I speak. Try this analogy; you buy a new car that has new brakes on it, as you drive and over time the brakes deteriorate and get less effective. You never notice till there about gone, how is this,,,,.you become accustomed to the Effect of the brake wear, same as the transition from class A to A/B slow and easy transition, not an abrupt change. this am starts off so sweet that by the time you get to 40 watts your ear can not detect any difference in SQ. ie: it's all good!!! But then if in substance the effect is you hear no difference, then what is the point of having class A in the first place? I understand your analogy about the brakes, but in that case, you are talking about a long period of time and also the need to avoid having a dangerous situation with your car. In the case of an amp, if the transition is so subtle that you don't notice it at all, then why even need to have class A? I would think the test would be to do an A/B with A versus A/B (pun intended) and see if you could detect any audible difference. I deal with food, when the first bight,,,,the one that spoils you, tastes so good it becomes hard if not impossible to tell that the third and fourth night is not just as good. If the first bite tastes like sh*** then there's no helping you. the Class A of these amps is not cold and sterile they are warm and friendly to the ear.
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hemster
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Particle Manufacturer
...still listening... still watching
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Post by hemster on Aug 6, 2014 9:27:01 GMT -5
Okay, I'll try that tonight. Can you hear the drums Fernando?
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Post by jmilton on Aug 6, 2014 10:22:11 GMT -5
Okay, I'll try that tonight. Can you hear the drums Fernando? Great. Now I can't get Dancing Queen outta my head...
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Post by Dark Ranger on Aug 6, 2014 10:43:44 GMT -5
I'm intrigued, what kind of music do you listen for the differences in? For example, I just scored a copy of the BBC Big Band CD which I reckon might make for a good Class A versus Class AB comparison. Alto sax, right hand piano, cymbals, flute, trumpet, clarinet etc. Hi Gary, I listen to a variety of music: classical, electronic, jazz, rock, symphonic metal, choral, folk, and new age. Not rap though. Some of my favorite artists include Jesse Cook, Melody Gardot, David Helpling, Jon Jenkins, Howard Shore, Patrick O'Hearn, Within Temptation, and Sarah Mclachlan. Just for clarity, I'm saying that I cannot hear a noticeable difference rather than there is no difference. It might be my ears or how I process sound physiologically. It's also possible that the differences between A and A/B (for the XPA-1L) might only show up in measurements. Some have said they can hear a difference toggling between the two bias levels. Others have said they cannot hear a difference. Nevertheless, I can say that A/B mode (or more correctly, low-bias) does not leave me wanting for anything.
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Post by Gary Cook on Aug 6, 2014 16:15:17 GMT -5
I'm intrigued, what kind of music do you listen for the differences in? For example, I just scored a copy of the BBC Big Band CD which I reckon might make for a good Class A versus Class AB comparison. Alto sax, right hand piano, cymbals, flute, trumpet, clarinet etc. Hi Gary, I listen to a variety of music: classical, electronic, jazz, rock, symphonic metal, choral, folk, and new age. Not rap though. Some of my favorite artists include Jesse Cook, Melody Gardot, David Helpling, Jon Jenkins, Howard Shore, Patrick O'Hearn, Within Temptation, and Sarah Mclachlan. Just for clarity, I'm saying that I cannot hear a noticeable difference rather than there is no difference. It might be my ears or how I process sound physiologically. It's also possible that the differences between A and A/B (for the XPA-1L) might only show up in measurements. Some have said they can hear a difference toggling between the two bias levels. Others have said they cannot hear a difference. Nevertheless, I can say that A/B mode (or more correctly, low-bias) does not leave me wanting for anything. A long time ago, while my parents were away on their annual winter escape to the Sunshine Coast, we had a bit of a party, as you do. Back then I had a Class A amp running the mids and highs and a Class AB amp running the lows plus a separate sub woofer (a pretty unusual thing back then). As an experiment I mono'd the output of the TT and ran one channel with the Class A amp and the other channel with the Class AB amp. None of us, some musicians and another HIFI nut, could tell a difference with our usual selection of music, rock, metal, etc. In desperation I put on one on my parents' Sinatra LP's, bingo at relatively low volumes, to a man we could pick it, even blind. I swapped the amps/channels many times, tried a few tricks, like both channels via the same amp etc. Back to the high volume rock (what we would call "classic rock" these days) and no one could pick it consistently, a Strat sounded the same in Class A or AB. Looking back on it, that was pretty much the end of my days with Class A amplifiers, if I couldn't hear a difference when listening to my music at my volumes then why bother? Having developed a much broader appreciation of music over the intervening decades I have a feeling Class A capable amp/s are going to find their way back into my setup. Maybe the Class AB amps are so good theses days that there's no noticeable difference to my older ears. Regardless, it'll be fun trying and with an XPA-1L or an XPA-1 there's no loss, I can always run it in Class AB all of the time. Cheers Gary
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Post by Dark Ranger on Aug 6, 2014 17:38:55 GMT -5
Regardless, it'll be fun trying and with an XPA-1L or an XPA-1 there's no loss, I can always run it in Class AB all of the time. I agree that you should try it yourself, in your own system with your own ears. Who knows, maybe you'll experience an audible difference. And like you said, no harm done if you can't tell a difference. Just run in A/B mode to save electricity and reduce heat. That's what I do--run in A/B mode 99.9% of the time and saving that 0.01% for the occasional cold day in Florida. You know, like 40° F.
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