jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 22, 2020 15:16:47 GMT -5
Hello all. XPA-2 Gen 2 is getting what I would say is uncomfortably hot on the left side only. Right side stays pretty cool. It is getting plenty of ventilation on all sides. I swapped the speaker cables around and the left side still gets hot. Amp sounds perfectly fine and has not gone into protect. It takes it about an hour for it to plateau at whatever temp it goes to (have not measured it yet). I bought this from a guy locally who has stated the amp has always done this since he bought it, but he put a fan on it to keep it cool. Not really familiar with this new stuff (used older amps up until recently), but I imagine it can't be all that much different than some older amps. I did contact Emotiva, and the guy stated the bias adjustment pot might need to be adjusted or might even be bad entirely. He told me where they are, but wouldn't give me the value I need to set it to. I am fairly good at fixing amps, but this is a bit new territory for me. Anyone know by chance how much I need to adjust it? I do not know where to put my DMM either as I can not seem to figure out how to get that amp module out far enough.
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Post by garbulky on Jun 22, 2020 15:28:32 GMT -5
The XPA-2 gen 2 runs somewhat hot. It does 5 watts class A before switching over to class B. So it's not abnormal for it to get warm, even a bit hot. However, it shouldn't be superhot but it should definitely be noticeably warmer than you'd expect an amp to be. I guess what I'm saying it's hard to say just how hot it feels because this is subjective. If the adjustment thing is an actual knob (surprising?) then perhaps you can check the hot side with the knob for the other cooler side to see if they are the same. If the knob is completely different, then that may be a clue?
You can also check your power consumption from the amp. If it is consuming huge amounts of power that may be an indication. Having said that class A power does consume a lot of power so it wouldn't be unexpected for the amp to be idling reasonably high. But not like at 400 watts of consumption.
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 22, 2020 17:00:33 GMT -5
The XPA-2 gen 2 runs somewhat hot. It does 5 watts class A before switching over to class B. So it's not abnormal for it to get warm, even a bit hot. However, it shouldn't be superhot but it should definitely be noticeably warmer than you'd expect an amp to be. I guess what I'm saying it's hard to say just how hot it feels because this is subjective. If the adjustment thing is an actual knob (surprising?) then perhaps you can check the hot side with the knob for the other cooler side to see if they are the same. If the knob is completely different, then that may be a clue? You can also check your power consumption from the amp. If it is consuming huge amounts of power that may be an indication. Having said that class A power does consume a lot of power so it wouldn't be unexpected for the amp to be idling reasonably high. But not like at 400 watts of consumption. The knobs inside are trim pots. I found them, just not sure how much I need to adjust them, or even which direction I need to turn them. I understand the amp is supposed to get somewhat warm, but the thing that confuses me is why would the right side be cool to the touch while the left is considerably warmer. |
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Post by garbulky on Jun 22, 2020 17:41:43 GMT -5
The XPA-2 gen 2 runs somewhat hot. It does 5 watts class A before switching over to class B. So it's not abnormal for it to get warm, even a bit hot. However, it shouldn't be superhot but it should definitely be noticeably warmer than you'd expect an amp to be. I guess what I'm saying it's hard to say just how hot it feels because this is subjective. If the adjustment thing is an actual knob (surprising?) then perhaps you can check the hot side with the knob for the other cooler side to see if they are the same. If the knob is completely different, then that may be a clue? You can also check your power consumption from the amp. If it is consuming huge amounts of power that may be an indication. Having said that class A power does consume a lot of power so it wouldn't be unexpected for the amp to be idling reasonably high. But not like at 400 watts of consumption. The knobs inside are trim pots. I found them, just not sure how much I need to adjust them, or even which direction I need to turn them. I understand the amp is supposed to get somewhat warm, but the thing that confuses me is why would the right side be cool to the touch while the left is considerably warmer. Well it shouldn't be too different because the amp is pretty symmetrical.  However near the front is hotter than the back - because of the power supply I guess? So I guess I want to ask whether you are touching on the same place left and right or whether you touch left near the front and then right near the back. If the trim has a notch to indicate where it is, maybe you can tell if they are set evenly? |
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 22, 2020 18:07:38 GMT -5
The knobs inside are trim pots. I found them, just not sure how much I need to adjust them, or even which direction I need to turn them. I understand the amp is supposed to get somewhat warm, but the thing that confuses me is why would the right side be cool to the touch while the left is considerably warmer. Well it shouldn't be too different because the amp is pretty symmetrical. However near the front is hotter than the back - because of the power supply I guess? So I guess I want to ask whether you are touching on the same place left and right or whether you touch left near the front and then right near the back. If the trim has a notch to indicate where it is, maybe you can tell if they are set evenly? I took another look in it and I see the trim pots have a thin layer of some sort of glue to prevent them from being accidentally moved. They appear to be set the same on both amps. When it is hot it is hot across the whole left side. |
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Post by leonski on Jun 22, 2020 18:24:38 GMT -5
The XPA-2 gen 2 runs somewhat hot. It does 5 watts class A before switching over to class B. So it's not abnormal for it to get warm, even a bit hot. However, it shouldn't be superhot but it should definitely be noticeably warmer than you'd expect an amp to be. I guess what I'm saying it's hard to say just how hot it feels because this is subjective. If the adjustment thing is an actual knob (surprising?) then perhaps you can check the hot side with the knob for the other cooler side to see if they are the same. If the knob is completely different, then that may be a clue? You can also check your power consumption from the amp. If it is consuming huge amounts of power that may be an indication. Having said that class A power does consume a lot of power so it wouldn't be unexpected for the amp to be idling reasonably high. But not like at 400 watts of consumption. The knobs inside are trim pots. I found them, just not sure how much I need to adjust them, or even which direction I need to turn them. I understand the amp is supposed to get somewhat warm, but the thing that confuses me is why would the right side be cool to the touch while the left is considerably warmer. Trim pots are probably BIAS. You need to determine WHERE to measure this and what the correct value actually SHOULD be. Maybe EMO service can help? Now? Are you confident making such adjustments? And also? You are talking about 2 things here. TEMPERATURE and HEAT. A lot of heat in a small space will rsult in a higher temp. But an amp should not get too hot so needs plenty of heat sink. What might be happening is too high a bias results in too much 'dissipation' and the heat sinks can't quite keep up..... Now you know what a full 'class-A' amp will weigh 1lb per watt or more. |
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Post by novisnick on Jun 22, 2020 18:29:27 GMT -5
Sounds like one of the blades has a problem, is it under warranty?
Have you given Emotiva a call about your concerns? I would. Good luck, please let us know what they say.
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 22, 2020 18:37:54 GMT -5
The knobs inside are trim pots. I found them, just not sure how much I need to adjust them, or even which direction I need to turn them. I understand the amp is supposed to get somewhat warm, but the thing that confuses me is why would the right side be cool to the touch while the left is considerably warmer. Trim pots are probably BIAS. You need to determine WHERE to measure this and what the correct value actually SHOULD be. Maybe EMO service can help? Now? Are you confident making such adjustments? And also? You are talking about 2 things here. TEMPERATURE and HEAT. A lot of heat in a small space will rsult in a higher temp. But an amp should not get too hot so needs plenty of heat sink. What might be happening is too high a bias results in too much 'dissipation' and the heat sinks can't quite keep up..... Now you know what a full 'class-A' amp will weigh 1lb per watt or more. Thats what the tech told me when I emailed him. He said it is likely not biased correctly resulting in it getting too hot. He told me where the trim pots are. He stated one will be DC offset and one will be Bias. He seemed to avoid answering what the values actually should be. |
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 22, 2020 18:39:45 GMT -5
Sounds like one of the blades has a problem, is it under warranty? Have you given Emotiva a call about your concerns? I would. Good luck, please let us know what they say. It is well out of warranty. I am trying to avoid shipping this big thing if I can fix it myself. I emailed Emotiva. Details are just above this post. |
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Post by novisnick on Jun 22, 2020 19:09:39 GMT -5
Sounds like one of the blades has a problem, is it under warranty? Have you given Emotiva a call about your concerns? I would. Good luck, please let us know what they say. It is well out of warranty. I am trying to avoid shipping this big thing if I can fix it myself. I emailed Emotiva. Details are just above this post. Ah! Good luck, I hope you can get it adjusted correctly. 🙏🤞🙏🎶🎶🎶🎶 |
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Post by leonski on Jun 22, 2020 19:55:27 GMT -5
If it is correct about Non-Disclosure of values OR Schematic, let alone the correct procedure, that alone would disqualify EMO from my consideration.
It si also possible that a COMPARISON with the good channel might still yield a result. A competent tech may be able to discern the test points used.
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Post by willcycle on Jun 23, 2020 4:59:18 GMT -5
Measure voltage across one of the power transistor's emitter resistor on the cool channel and adjust the bias on the hot one to the same value. Make sure the amp is warmed up for an hour and turn the pot slowly. Be sure to recheck DC offset afterwards.
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 23, 2020 8:24:28 GMT -5
Measure voltage across one of the power transistor's emitter resistor on the cool channel and adjust the bias on the hot one to the same value. Make sure the amp is warmed up for an hour and turn the pot slowly. Be sure to recheck DC offset afterwards. I assume with these I can put one lead on the emitter and one on the chassis to get the value correct? |
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 23, 2020 8:27:52 GMT -5
If it is correct about Non-Disclosure of values OR Schematic, let alone the correct procedure, that alone would disqualify EMO from my consideration. It si also possible that a COMPARISON with the good channel might still yield a result. A competent tech may be able to discern the test points used. I emailed him again. Sounds like he misunderstood what I was asking first. He actually sent me part of the schematic for that amp. It says 40mA next to each resistor. |
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jhud
Seeker Of Truth
Posts: 8
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Post by jhud on Jun 23, 2020 11:54:39 GMT -5
Cracked it open and found the bias adjustment. Took measurements on one of the transistor resistor emitters like stated above and I was reading 70mV compared to 20mV on the 'good' side. I tweaked it just a little and got it down to 20. No issues with heat. If anything the right side gets just a hair warmer now. I'm going to leave it alone now, and keep it running for a good while to make sure, but after about half an hour it appears to be fine.
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