rontj
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Posts: 95 
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Post by rontj on Apr 19, 2016 1:00:44 GMT -5
I have a pair of XPA-1Ls driving my 90 dB sensitive mains, under normal listening conditions, and find that the amps never switch to AB. Out of curiosity, I turned up the volume to a level that I could only handle for one track, thinking it would probably switch to AB... and it didn't.
Before I purchased the XPA-1Ls, I had this thought that I would need to enjoy my Class A music at whisper-quite levels, but not only is that not true, I can listen to them as loud as I want.
Is anyone finding their XPA-1Ls switching to AB during listening?
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Post by Gary Cook on Apr 19, 2016 1:19:49 GMT -5
There's not really any "switching", the transfer of from Class A to Class AB to is simply a bias change. Which is pretty much indistinguishable, there's no clicking of relays, a jump in volume or much in the way of sound quality change. With all the same componentry being used it's pretty subtle and not easily heard. Some ears, some speakers, some rooms and some music reveals it but it sure as hell doesn't smack me in the face.
The best way to listen for the bias change is to flick the switch from A to AB at normal listening levels and listen, try a few different pieces of music, I find the female voice, tenor sax and right hand piano is generally where I can sometimes hear a difference. Not every time and sometimes I convince myself that I'm dreaming, then a particular track, bingo there it is.
Cheers
Gary
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rontj
Minor Hero
Posts: 95
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Post by rontj on Apr 19, 2016 3:01:16 GMT -5
Huh. I had this conversation with an Emo tech before, or just after, purchase of my two XPA-1Ls, and thought for certain I was told the switch physically moved to AB.
I would believe the change to AB would not result in an obvious audible "there it is", but would believe there to be some indication the switch occurred, such as the physical switch moved from A to AB.
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Post by geebo on Apr 19, 2016 6:59:50 GMT -5
Huh. I had this conversation with an Emo tech before, or just after, purchase of my two XPA-1Ls, and thought for certain I was told the switch physically moved to AB. I would believe the change to AB would not result in an obvious audible "there it is", but would believe there to be some indication the switch occurred, such as the physical switch moved from A to AB. The switch does not change position. I've never even heard of that. The fact is that there is no physical indication of Class change with the XPA-1L. It transitions automatically back and forth as needed based on power demand at any given moment. |
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rontj
Minor Hero
Posts: 95
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Post by rontj on Apr 28, 2016 1:15:33 GMT -5
Yes, I called Emo tech, and confirmed this is true. Glad I brought this up, and learned the switch doesn't move. Based on the efficiency of my speakers, and the distance between my head and my mains, Emo calculated that any level below upper 90dBs will be Class A. That's great.
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Post by bluemeanies on Apr 28, 2016 5:42:31 GMT -5
Yes, I called Emo tech, and confirmed this is true. Glad I brought this up, and learned the switch doesn't move. Based on the efficiency of my speakers, and the distance between my head and my mains, Emo calculated that any level below upper 90dBs will be Class A. That's great. Just asking...do your really think you are going to notice a big difference in sound. Perhaps on critical listening with special recordings but on a day to day basis? I let my ears tell the story. Mechanically when I had my XPA's switching from A-AB I could never tell the difference except for the XPA getting hotter in A mode I don't think MY ears have that sonic capability of distinguishing between A/AB listening. That said, going to tubes was a whole different experience...for 2channel there was a definite surge in my overall quantitative listening experience consuming, tonal, sonic and spatial properties of recordings with a damn good soundstage. This is NOT to persuade you or suggest going to tubes. Some people prefer SS, it's a matter of choice. I was just giving you my experience which apparently is different from yours and many others. Good luck with trying to achieve the art of perfection in music...it never ends! |
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Post by foggy1956 on Apr 28, 2016 8:19:58 GMT -5
Yes, I called Emo tech, and confirmed this is true. Glad I brought this up, and learned the switch doesn't move. Based on the efficiency of my speakers, and the distance between my head and my mains, Emo calculated that any level below upper 90dBs will be Class A. That's great. Just asking...do your really think you are going to notice a big difference in sound. Perhaps on critical listening with special recordings but on a day to day basis? I let my ears tell the story. Mechanically when I had my XPA's switching from A-AB I could never tell the difference except for the XPA getting hotter in A mode I don't think MY ears have that sonic capability of distinguishing between A/AB listening. That said, going to tubes was a whole different experience...for 2channel there was a definite surge in my overall quantitative listening experience consuming, tonal, sonic and spatial properties of recordings with a damn good soundstage. This is NOT to persuade you or suggest going to tubes. Some people prefer SS, it's a matter of choice. I was just giving you my experience which apparently is different from yours and many others. Good luck with trying to achieve the art of perfection in music...it never ends! With some serious acid rock banging in the 90db range, can anybody hear a fly fart?☺ |
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Post by audiobill on Apr 28, 2016 8:22:00 GMT -5
"serious acid rock banging in the 90db range" What in the world does this have to do with good sound  |
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Post by garbulky on Apr 28, 2016 9:04:38 GMT -5
"serious acid rock banging in the 90db range" What in the world does this have to do with good sound At that point everything becomes groovy  |
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Post by bluemeanies on Apr 28, 2016 9:53:39 GMT -5
Just asking...do your really think you are going to notice a big difference in sound. Perhaps on critical listening with special recordings but on a day to day basis? I let my ears tell the story. Mechanically when I had my XPA's switching from A-AB I could never tell the difference except for the XPA getting hotter in A mode I don't think MY ears have that sonic capability of distinguishing between A/AB listening. That said, going to tubes was a whole different experience...for 2channel there was a definite surge in my overall quantitative listening experience consuming, tonal, sonic and spatial properties of recordings with a damn good soundstage. This is NOT to persuade you or suggest going to tubes. Some people prefer SS, it's a matter of choice. I was just giving you my experience which apparently is different from yours and many others. Good luck with trying to achieve the art of perfection in music...it never ends! With some serious acid rock banging in the 90db range, can anybody hear a fly fart?☺ Well then...there is no point in being concerned with A/AB setting if what you are listening to is loud...noise. I was misguided. I thought we were discussing a difference in amp settings for the quality of sound. That is part of what music is about. |
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Post by foggy1956 on Apr 28, 2016 13:02:13 GMT -5
With some serious acid rock banging in the 90db range, can anybody hear a fly fart?☺ Well then...there is no point in being concerned with A/AB setting if what you are listening to is loud...noise. I was misguided. I thought we were discussing a difference in amp settings for the quality of sound. That is part of what music is about. My point is, at 90+dB, can anybody hear an a/b switch? |
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Post by audiobill on Apr 28, 2016 13:11:51 GMT -5
No, because your hearing is damaged.....Per OSHA,
"The employer shall administer a continuing, effective hearing conservation program, as described in paragraphs (c) through (o) of this section, whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent. For purposes of the hearing conservation program, employee noise exposures shall be computed in accordance with appendix A and Table G-16a, and without regard to any attenuation provided by the use of personal protective equipment."
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Post by foggy1956 on Apr 28, 2016 13:23:00 GMT -5
No, because your hearing is damaged..... Precisely |
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DYohn
Emo VIPs 
Posts: 18,485
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Post by DYohn on Apr 28, 2016 15:13:52 GMT -5
I prefer my serious acid rock closer to 105db. Just sayin...
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Post by foggy1956 on Apr 28, 2016 15:15:31 GMT -5
I prefer my serious acid rock closer to 105db. Just sayin... Question is then, do you hear the a\b switch with acid rock at 105db? |
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Post by jmasterj on Apr 28, 2016 15:31:18 GMT -5
On my small tube integrated amp I can switch from Class A to Class AB with the press of a button. I can hear an audible difference the Class A setting the music is more refined. In the Class AB setting the amp has double the power available in Class A so there is a definite change in the sound level it seems to be more dynamic and have a little more punch. I can't really tell if there is a temperature change in the amp because it's tubes are always hot, I prefer Class AB to Class A.
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Post by monkumonku on Apr 28, 2016 15:49:44 GMT -5
On my small tube integrated amp I can switch from Class A to Class AB with the press of a button. I can hear an audible difference the Class A setting the music is more refined. In the Class AB setting the amp has double the power available in Class A so there is a definite change in the sound level it seems to be more dynamic and have a little more punch. I can't really tell if there is a temperature change in the amp because it's tubes are always hot, I prefer Class AB to Class A. But if there is a definite change in the volume when switching from Class A to Class AB, isn't that comparing apples to oranges? How can you separate what is due to the actual audio quality/character versus what is due to the change in volume? |
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Post by bluemeanies on Apr 28, 2016 16:15:09 GMT -5
Well then...there is no point in being concerned with A/AB setting if what you are listening to is loud...noise. I was misguided. I thought we were discussing a difference in amp settings for the quality of sound. That is part of what music is about. My point is, at 90+dB, can anybody hear an a/b switch? I knew what your point was...my point is at that sound level it's not music...its noise! IMO. This chart will give you an idea of what you are listening to and how in the not to distant future you will damage your hearing capabilities. www.gcaudio.com/resources/howtos/loudness.html |
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DYohn
Emo VIPs
Posts: 18,485
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Post by DYohn on Apr 28, 2016 16:16:32 GMT -5
Anyone who claims they can "hear" when an amplifier switches from class A to class A/B must have precision calibrated ears.
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Post by audiobill on Apr 28, 2016 16:27:23 GMT -5
I prefer my acid rawk on cheap transistor amps pushing 1kw through JBL or Voice of The Theater speakers, listening distance of less than one meter.
It just sounds right that way!!!!!
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