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Post by Dark Ranger on Mar 16, 2013 13:44:47 GMT -5
Dumb question - but has all of the testing been done with the amp idle (no input)? If there IS a signal, does it still click at the same time/temp? I have performed the testing during idle and with an input signal. The click/power down occurs whether the amp is sitting idle or receiving an input signal. The time it takes to click/power down seems to be dependent on thermal parameters. With the chassis cover removed and booting up the amp in a cold state (Class A mode), I can go nearly 20 minutes before hearing the click and seeing the power drop. However, if the amp is booted up in a warm state, I can go only 4-9 minutes (depending if top cover is on or off) before hearing the click and seeing the power drop. On a related note, I find it surprising that the top chassis cover is not fully vented like other Emotiva amps. It has three row of vents on the top. Based on my testing and locating that center hotspot, I really believe it would have been wise to include full top venting, or at least full venting on the right side. There may very well be a reason for omitting this, but my temperature readings have me scratching my head. I could easily see some powersave mode..... There is no reason for it to sit there in Class A with no signal indefinitely. Indeed, I had the same thought regarding an automatic power save. That would be handy: throttle down after a period of no input signal. However, this goes against what I know about Class A operation. In addition, I tested the "power save" theory several times. My results disproved the theory. Unless Emotiva posts here over the weekend requesting additional testing, I'm pretty much done measuring and testing this "issue" for now. I would not be surprised if Lonnie/Keith/Dan are doing some testing of their own over the weekend to verify my results, and it's certainly worth checking in to. My plan is to call Emotiva on Monday or Tuesday and try to talk with Lonnie or Keith about what I'm experiencing. While it may seem like I'm making a big deal out of this "issue," my initial goal was to share information on the power consumption and typical operating temperatures for anyone interested. What started out as a simple test turned into something much greater than I ever anticipated. Some of you may feel that I've spent too much time with technical stats instead of evaluating the sound quality and overall sonic presentation of the amplifier. Well, that was never my intent. From my perspective, the testing started to cast doubts on if I was really hearing Class A after experiencing the click and electrical current drop. I cannot properly evaluate the amplifier if something is not quite right. Anyway, I intend to spend the rest of the weekend enjoying the new amp. Other than this curious event, there is nothing wrong with the amplifier that I've noticed so far. It sounds amazing. I've wanted a mono-block for my center channel for a while. The XPA-100 would be great, but I wanted a fully-balanced amplifier with 29dB gain to mate with the eventual XMC-1. The 1L does that for me with plenty of power to spare. My other "review" thread is not finished, and I will eventually update it with more info regarding the sonic performance. However, I need a break from evaluation. I've still got to disassemble my rack to install the new shelf, and there are more movies/music on the agenda.
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Post by Dark Ranger on Mar 16, 2013 13:48:42 GMT -5
ocezam - I know you said you would not have time to listen to them until at least Wednesday, but how about unboxing 1 and plugging it in...see if you here the "click" at the ~5 minutes...? Mark Ocezam, Since you will have a "cold" amp, it will likely take more than 5 minutes. The ~5 minute reading is for a "warm" amp (one that's been ON until "click" threshold, then powered OFF for 5 minutes, then powered ON again). Expect closer to 10-15 for a cool/cold amp and with the chassis cover on. I also recommend plugging in the amp to a power meter. If your experience mirrors mine, you'll be pulling around ~2.5 amps for the 1L while in Class A mode. After the click, it'll drop to ~1 amp. This is a visual confirmation of the event.
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Deleted
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Post by Deleted on Mar 16, 2013 14:17:57 GMT -5
One thing I have noticed on this thread is that when the amp is switched from Class A mode to Class A/B mode no mention is made of a sound quality change.
I'm just sayin'....
-RW-
PS: I'm sure BD and Lonnie will set things right, they almost always have in the past...
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Post by Dark Ranger on Mar 16, 2013 14:24:02 GMT -5
Well, only a handful of folks have received their 1Ls so far. I suspect we'll be hearing more about audible differences as more time passes. I did make a quick post about this yesterday, and so far it remains the same. I'm withholding my final answer on this until I can talk more with Emotiva support. No worries here.
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Wojtek
Seeker Of Truth
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Post by Wojtek on Mar 16, 2013 14:31:39 GMT -5
Hello This is my first post in forum for Emotiva-maniacs I come from Poland, so at beggining sorry for my English language I wonder on one thing about XPA-1L. Can it happen that left amplifier quickly switches to class AB while the right will remain in Class A? What then? Right channel sound will play with monoblock class A, and the left channel class A/B monoblock. If the sound quality class A differs from the class AB will sound like music in stereo on both channels? Regards Wojtek
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Post by milt99 on Mar 16, 2013 14:34:18 GMT -5
DR you are not making a "Big Deal" out of the switch over. You are providing valuable facts and data and ruining my weekend
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Post by Jim on Mar 16, 2013 14:44:03 GMT -5
Thanks for the information DR, you've appeased my curiosity and answered my dumb questions. Sounds like you've thought of everything! Hope you get to enjoy some listening time this weekend
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Post by davidas6350 on Mar 16, 2013 14:56:51 GMT -5
I wonder on one thing about XPA-1L. Can it happen that left amplifier quickly switches to class AB while the right will remain in Class A? What then? Right channel sound will play with monoblock class A, and the left channel class A/B monoblock. That's a good point. I have the XPA-1 which supposed to have the first 10w in Class A, but I haven't really noticed any sound quality change when switching from A to A/B and there are no indication that it switched. So, I probably won't be able to tell if the left channel amp doesn't switch at the same time as the right channel amp. Now I'm curious, will I noticed a drop or change in current draw on the XPA-1 when it switched from Class A to A/B?
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Post by Jessica on Mar 16, 2013 15:37:22 GMT -5
Well, only a handful of folks have received their 1Ls so far. I suspect we'll be hearing more about audible differences as more time passes. I did make a quick post about this yesterday, and so far it remains the same. I'm withholding my final answer on this until I can talk more with Emotiva support. No worries here. I just spoke with Dan, he is very curious as to why this happening. He'll be on the forum soon with a response. Stay tuned!
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Post by milt99 on Mar 16, 2013 15:41:50 GMT -5
Thank you!
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Post by Dark Ranger on Mar 16, 2013 16:21:07 GMT -5
Thank you, Jessica!
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Post by ocezam on Mar 16, 2013 17:02:25 GMT -5
On a related note, I find it surprising that the top chassis cover is not fully vented like other Emotiva amps. It has three row of vents on the top. Based on my testing and locating that center hotspot, I really believe it would have been wise to include full top venting. Yeah, I think that was a mistake. While it may seem like I'm making a big deal out of this "issue," my initial goal was to share information on the power consumption and typical operating temperatures for anyone interested. What started out as a simple test turned into something much greater than I ever anticipated. Some of you may feel that I've spent too much time with technical stats instead of evaluating the sound quality and overall sonic presentation of the amplifier. Well, that was never my intent. From my perspective, the testing started to cast doubts on if I was really hearing Class A after experiencing the click and electrical current drop. I cannot properly evaluate the amplifier if something is not quite right. I don't think you are making a "big deal" of it at all. There is no doubt in my mind your amp is malfunctioning. This is supposed to be an amp that can provide 35 watts of pure class A power before "seamlessly" transitioning to class AB. I believe your amp is experiencing a "thermal event" that is forcing class AB operation way too early. Essentially you have a very good AB amp. That's fine, except it isn't what the amp was sold as. It might not make a difference to some, but it would for me. Thank you for your hard work! I've finished my subwoofer and only need to install it into the system and run Audyssey and enjoy it some tomorrow. I promise before I even start to play with the sub, I will unpack both of my XPA-1L's and plug them in and see what happens. I've got a Monster Power center that I believe will show amps used and will try to use that as a power source. I will not have time to put it into my system and play music. But I should be able to determine if my two are acting like Dark Ranger's. Right now I fell like a tired old man, that sub is HEAVY! Peace, out.
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Post by ocezam on Mar 16, 2013 17:09:17 GMT -5
On a related note, I find it surprising that the top chassis cover is not fully vented like other Emotiva amps. It has three row of vents on the top. Based on my testing and locating that center hotspot, I really believe it would have been wise to include full top venting, or at least full venting on the right side. There may very well be a reason for omitting this, but my temperature readings have me scratching my head. I wonder if the XPA-100 cover would fit? Assuming this apparent problem is worked out, I'd like to put XPA-100 covers on mine if that were possible. They should be the same size, wonder if the bolt pattern is the same and if they are available?
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Post by milt99 on Mar 16, 2013 17:36:04 GMT -5
There is no doubt in my mind your amp is malfunctioning. This is supposed to be an amp that can provide 35 watts of pure class A power before "seamlessly" transitioning to class AB. I believe your amp is experiencing a "thermal event" that is forcing class AB operation way too early. I'm speculating that the sensor(s) are malfunctioning or mis-calibrated and there is no event thermal or otherwise.
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Post by ocezam on Mar 16, 2013 18:14:07 GMT -5
I'm speculating that the sensor(s) are malfunctioning or mis-calibrated and there is no event thermal or otherwise. Yeah, OK. Except I would consider a malfunctioning thermal sensor an event. In fact, I would call that a "thermal event". My first 1080P TV, a 57 inch Mitsu DLP had a faulty thermal sensor. Pretty much the entire Mitsu DLP line was plagued with bad sensors that year. Mitsu fixed the prob on the assy. line but dragged their feet about fixing the TV's in the field saying there was no prob. After a year passed, after the warranties expired, they miraculously came up with a different sensor that fixed the problem. Of course at that point they got to sell the sensor, not give it away. ...
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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"
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Post by geebo on Mar 16, 2013 18:22:48 GMT -5
I'm speculating that the sensor(s) are malfunctioning or mis-calibrated and there is no event thermal or otherwise. Yeah, OK. Except I would consider a malfunctioning thermal sensor an event. In fact, I would call that a "thermal event". My first 1080P TV, a 57 inch Mitsu DLP had a faulty thermal sensor. Pretty much the entire Mitsu DLP line was plagued with bad sensors that year. Mitsu fixed the prob on the assy. line but dragged their feet about fixing the TV's in the field saying there was no prob. After a year passed, after the warranties expired, they miraculously came up with a different sensor that fixed the problem. Of course at that point they got to sell the sensor, not give it away. ... A faulty or miscalibrated thermal sensor does not make it a thermal event. It's a false indication of one.
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KeithL
Administrator
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Post by KeithL on Mar 16, 2013 18:35:06 GMT -5
As you might guess, we're looking into this I can confirm a few things for you, though..... 1) You may or may not be able to tell the difference in sound between Class A and Class A/B. I'm afraid we screwed up and made the XPA-1L sound so good in Class A/B that sometimes it's hard to tell. Whether you can hear a difference will depend on your other equipment, your source material, and your hearing. All we can say for sure is that everybody who does hear a difference prefers Class A. Luckily the XPA-1L sounds so good, and is such a bargain, you'll want to keep it even if you don't notice the difference in your particular setup (as a few people have already commented). And sometimes, after you listen for a while, you start to notice more things...... 2) There is no visible indicator on the XPA-1L (like a light) that tells you which mode it is operating in (other than the switch). This is something we certainly will consider for any future models that have this feature. The power draw at idle will indeed be much higher in Class A than in Class A/B. 3) The XPA-1L does not have any sort of "timed power saver" that switches back into Class A/B mode after a certain amount of time with no signal. 4) The XPA-1L does have a thermal sensor that will transition it back into Class A/B mode if it gets too warm. (Of course, it also has a thermal safety sensor, but we figured you'd rather have it move back into Class A/B instead of Off if it starts to get too warm.) (In any case, the XPA-1L will never get excessively or dangerously hot. There are actually CE safety regulations about things like that and, unlike garage-based operations, we have to make sure our amps won't get hot enough to burn you or we would get in trouble. ) 5) In answer to this post: When you are in Class A mode, there is indeed no particular indication when you are transitioning from Class A to Class A/B mode. [We could have put an LED there, and labelled it "turn me down", but that would just have looked silly.] The whole idea of transitioning into Class A/B mode is that you can continue to listen uninterrupted if the occasional peak needs some Class A/B power to avoid getting squished. Ranger haven't you heard...?, class A amps take 10 times longer to break in then the class A/B amps do........lol gotcha....enjoy the music my friend. Chad Ah yes, I completely forgot about that. Are you still measuring power draw? Assuming that "click" (and associated idle power drop) occur because the internal sensors are forcing A/B mode, are you certain you're actually listening in class A at all times? If you play so loud in class A that you exceed 35W peaks, is there any indication from the amp of this? I suppose in that case, the bias would not change, so it'd be much like a normal A/B amp leaving the class A portion (which happens constantly for most A/B amps where the bias is much lower). I've finished measuring power for tonight. Going to bed, actually. I have a few more tests to run tomorrow. Regarding your question, yes, I am absolutely certain the amp was in Class A. Listening to just the center speaker, I was measuring 75-85 dBC at my listening position (approximately 5 feet back). The speaker sensitivity is approximately 90 dB (anechoic). There is no indication from the amp regarding the current operating mode except the front panel switch. I first noticed something was different because my Furman ammeter suddenly dropped. I had also heard a click just a second before the power draw went way down. I've kept the amp in Class A mode for most of my listening session and the power draw has not increased again, it's still running like it's in A/B mode. If I turn it off for 5 - 10 minutes, and then turn it on again in Class A mode, it will start eating ~2.5 amps again for 4-6 minutes, and then it will click, and the power draw meter will show it back to to ~1 amp. Strange. I must be misunderstanding something. For a moment I thought it had an intelligent switch so that it conserves power while idling. Perhaps after ~5 minutes of idling with no input, it would switch to Class A/B mode. That would be kind of clever. I tested the theory by playing content. - Turn off amp for 10 minutes - Turn on amp in Class A mode - Start playing music - Amp clicks about 4-6 minutes in and power draw goes way down again So that theory seems to be out. I guess my biggest question at this point is, do I just misunderstand how the 1L works in Class A mode or is the amp really throttling down due to temperature or some other condition? I can't believe that after ~5 minutes of idling with no input signal, it would throttle down due to heat (yes, I understand that the output devices are always on). This raises the question, how much Class A am I really getting if it's not chewing up power like a traditional Class A amp? EDIT: By the way, when the amp is turned on for the first 4-6 minutes, I can toggle between Class A and A/B modes and watch the Furman meter/Kill-A-Watt change accordingly. From A to A/B, the amperage draw decreases significantly, as expected. When I switch back to Class A, amperage increases significantly, as expected. However, once the internal click occurs, switching between Class A and A/B doesn't blip the Furman ammeter or Kill-A-Watt. There is no change, the amperage draw remains nearly constant regardless of what mode is selected. EDIT #2: In case anyone wonders, the amp does NOT click after ~5 minutes when in A/B mode. I tested this, twice. It only clicks in Class A mode. Perhaps this is an anomaly with my amp alone. I would appreciate if someone could test this to verify my results. You'll need a Kill-A-Watt (or other method of measuring current) and a Stopwatch. Turn on the amp in Class A mode, start the Stopwatch, and note the current amperage draw. You can do this test during idle state or while playing music, but it will be easier to hear the click without an input signal. Note the time when/if you hear an internal click (rear part of the amp, on the right side). My testing was with a warm amp, so 4-6 minutes was all it took. If you're starting from a cold or cool amp, it may take 10 - 15 minutes for the click to occur. I just tested it again from a "cool" state and it took 11 minutes, but it clicked. After you hear the click, look at the current draw meter. It should drop significantly. OK, I'm going to bed now. Really.
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Post by audiophill on Mar 16, 2013 18:42:27 GMT -5
As far as venting i wouldn't have a fan blow on or into a amp, it actually helps heat the board. I am using the antec fans which sit on top of the amp which also has a pretty blue light in the middle of it as well. The unit has two fans with two speeds pulling the hot air out of the amp and blows it out the back of the fan unit. Now as far as the clicking i too can confirm after a cold start i also heard the loud click after about 15 minutes. I had no fans on during the test nor any signal or speaker wires hooked up to it during the test, i just wanted to see if i could repeat what dark ranger was experiencing. I have a pair of these xpa-1L's but only tested one so far. I hope this isn't a problem with these amps, i will be fully connecting these amps tomorrow and will listen more for the click and report back if i hear anything else and will report on how they sound also. I tested again after having the amp cool for about 5 minutes, turned the amp back on then waited about 5 minutes and once again the click was there, oh boy now i'm a little concerned! Hope we get a answer as to why this is happening soon as i too have confirmed this issue!
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Post by hobbs on Mar 16, 2013 18:53:50 GMT -5
A comparison between XPA-1-L vs XPA-100 could in theory reveal sonic differences (if any) between Class A and Class A/B below 35 watts, as they are somewhat closely matched in specs. Just a thought... from a non-audiophile. Cheers
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Post by Dan Laufman on Mar 16, 2013 19:06:52 GMT -5
Hi Guy's, Well, I have no idea at the moment what is going on.
There is no relay that "clicks" to change the output bias mode from Class A to Class AB. So, I'm not quite sure what you are hearing, unless it happens to be thermal expansion.
The Class A bias current is designed to throttle back when the heat sink temperate exceeds a safe level, but it should not just "drop" It will try to maintain thermal equilibrium in Class A mode, and not revert "hard" to Class AB.
We'll get it back on the bench on Monday and let you know what we find. Very strange stuff indeed....
In the meantime, try to enjoy your amps. They sound pretty amazing. Cheers, Big Dan
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