One XPA-1 Gen 2 hotter then the other

[odedia]

Hi,
I just got a pair of XPA-1 Gen 2's (used).

They sound wonderful.

I'm a bit worried because I notice the one of them is considerably and consistently hotter then the other, in both Class A and Class A/B Mode (less hot in A/B).

Any ideas what would be the reason for this? Anything I can do or test to prevent it? They both sound the same so I don't think there's any specific defect with it that I notice.

[odedia]

Come to think of it - I think it was the same issue with my old XPA-1L monoblocks. This is odd. Could this just be a coincidence?

[garbulky]

Well I guess it's about how much hotter it is or if one is substantially cool. If the differences are really major, then it may be an issue with bias. Pay attention to their location. If one is sitting on top of the other or if one of them is sitting in a significantly enclosed space, that itself may account for the issue. Otherwise it may be normal variance. My XPA-1 gen 2's get equally hot to my base estimation. On class A mode they are both uncomfortably hot to touch though it is possible for a short while. On class AB mode they aren't very hot but are still a little warm.

[LCSeminole]

I'd be curious to know if it is an issue with bias, as I thought Emotiva could do something to change it, but not sure. You may want to give Tech Support a call and see if there is a way to get them to run cooler, come back and update us if you do.

[ttocs]

Feb 3, 2021 17:32:52 GMT -5 odedia said:

Come to think of it - I think it was the same issue with my old XPA-1L monoblocks. This is odd. Could this just be a coincidence?

Swap the speaker cables to see if the heat follows the cable or stays with the amp.

[odedia]

Thank you all, can you please elaborate on the bias part? I’m guessing it’s not a setting I can configure.

I will give the speaker swap a try, interesting idea.

[garbulky]

Feb 4, 2021 0:57:31 GMT -5 odedia said:

Thank you all, can you please elaborate on the bias part? I’m guessing it’s not a setting I can configure.

I will give the speaker swap a try, interesting idea.

I believe Emotiva can adjust it. At one point there was an XPA-1 amp was it a 1L or a 2 gen 2 I forget which but it's bias was way off. It was just set incorrectly.
In case you don't knwo the bias is what makes it run hot. So in class A mode there is much more class A bias which makes it output large amounts of heat even when it's doing nothing. Interestingly in class A mode the closer it gets to its class A output limit, the less hot it will run. With less bias there is less class A power and therefore less heat.
But... I think it's more likely other factors are to cause for the uneven heating - namely poor ventillation or having one amp sit on top of the other or perhaps some sort of weird faulty cabling.

[odedia]

The amps are in the "open air" and are side by side, spaced, so ventilation is not the issue.

I switched the cables and the same amp is still running hot.

Would I need to service the amp with Emotiva to adjust the bias? that would be impossible to ship overseas...

Thanks.

[ttocs]

Feb 4, 2021 4:01:17 GMT -5 odedia said:

The amps are in the "open air" and are side by side, spaced, so ventilation is not the issue.

I switched the cables and the same amp is still running hot.

Would I need to service the amp with Emotiva to adjust the bias? that would be impossible to ship overseas...

Thanks.

Too bad, I was hoping for an easy fix.

To rule out something in a  speaker, switch which amp drives which speaker. Since the amps are next to each other, it should be simple to just switch the speaker cable connections at the amp outputs, so the Right amp drives the Left speaker.

To rule out something in the processor, switch the output cables at the processor running to the amps, so Left and Right channels are reversed.

And lastly, the only other thing I can think of is power, which involves two tests if each amp is on a dedicated electric outlet.
1. Switch power cables and see if the heat follows the power cable.
2. Switch which amp is plugged into which outlet and see if the heat follows the outlet.
Wires connected to electric outlets "can" become loose over time and need to be tightened. Poor power delivery can cause a number of issues along the way.

[odedia]

Thank you so much for the tips my friend.

I did all those things and the left amp still remained hotter.

On the other hand, after playing music for a few hours now (in class A mode), it appears that eventually both amps reach the same hot temperature, so I HOPE this is good news?

I had XPA-1Ls before, and those ran hot as well, but wow the XPA-1 can get REALLY hot. Is there a max temperature we can say still makes sense for these in Class A if I want to check the temperature?

[audiobill]

Too much heat will kill capacitors, be careful.

[garbulky]

Feb 4, 2021 17:03:31 GMT -5 odedia said:

Thank you so much for the tips my friend.

I did all those things and the left amp still remained hotter.

On the other hand, after playing music for a few hours now (in class A mode), it appears that eventually both amps reach the same hot temperature, so I HOPE this is good news?

I had XPA-1Ls before, and those ran hot as well, but wow the XPA-1 can get REALLY hot. Is there a max temperature we can say still makes sense for these in Class A if I want to check the temperature?

You need to contact Emotiva. Talk to Keith or Lonnie.

[routlaw]

I wouldn't worry about it too much. I Used to own a pair of them myself and one was hotter than the other, after about six years of use it never became a problem and quit being concerned about it. BTW after contacting customer service Lonnie got back to me on this and also said no worries, probably a slight difference in bias settings. That said, in Class A mode these amps really do get hot and for the most part quit playing them in that mode.

[cawgijoe]

Heat kills.

Class A amps do get hot. I personally would run them in AB mode. Let us know how hot they get.

I would also contact Emotiva and ask to speak to Lonnie or Keith to get their opinions. Better safe than sorry.

[KeithL]

In Class-A mode the bias is turned up really high...

Which is why anything that operates in Class A gets really hot...

(And your two amps are probably running at about the same bias level.)

In Class-A/B mode the bias is much lower...

But it is controlled automatically...

Due to some minor difference in their circuitry, or how they're adjusted, that level may be a bit different on your two amps.

It really means that the one that runs hotter is "running a little bit closer to Class A mode".

(Think of it like two cars of the same make and model idling at slightly different speeds...)

However, unless that one gets really hot, it's not a problem.

Feb 4, 2021 17:03:31 GMT -5 odedia said:

Thank you so much for the tips my friend.

I did all those things and the left amp still remained hotter.

On the other hand, after playing music for a few hours now (in class A mode), it appears that eventually both amps reach the same hot temperature, so I HOPE this is good news?

I had XPA-1Ls before, and those ran hot as well, but wow the XPA-1 can get REALLY hot. Is there a max temperature we can say still makes sense for these in Class A if I want to check the temperature?

[odedia]

Thanks Keith.

I’ll try to measure the temperature soon and report back.

Is there some measurable metric of what it means that get “real hot”?

[garbulky]

Feb 4, 2021 18:18:43 GMT -5 odedia said:

Thanks Keith.

I’ll try to measure the temperature soon and report back.

Is there some measurable metric of what it means that get “real hot”?

It also matters WHERE you are measuring the temperature. Heatsink. Power supply. Amp blade. Outside case.

[leonski]

Feb 3, 2021 16:45:14 GMT -5 odedia said:

Hi,
I just got a pair of XPA-1 Gen 2's (used).

They sound wonderful.

I'm a bit worried because I notice the one of them is considerably and consistently hotter then the other, in both Class A and Class A/B Mode (less hot in A/B).

Any ideas what would be the reason for this? Anything I can do or test to prevent it? They both sound the same so I don't think there's any specific defect with it that I notice.

Amp, if the ventilation is the SAME for both and not stacked?

Problem is BIAS adjustment.     You'll need a tech for that unless you are very handy.

High bias, like class 'A' runs will heat an amp up.    Low bias, not so much.    That's why thos e amps have an A/A-B switch.   It basically controlls BiAS to the output devices.   

[jdmusante]

These amps in A/B mode will heat my living room. They run hot, period. I have often thought of the Gen 3s for how cool they run but the Gen 2s sound wonderful.

[leonski]

Keep in mind that HEAT and TEMPERATURE are different, though related.

If you have an amp with an incredible 50lb of heat sink and it runs at 100f? You could probably drive yourself OUT of the house.

But with a small heatsink of lets say.....3lb? You could run at a much higher temp and still not produce as much heat.

I was raised with the rule of thumb which is 'Can you place your hand on it?' If So? 'for how long?'

I was at an audio show where the PASS XS amp was shown. When I got to that room? Amps were OFF and the room (it WAS summer) was Stiffling Hot. Much hotter than outside which was cookin' hot.
Amps were right at the edge of too hot to touch.
And not to forget? The XS 300 weighs nearly 300lb per channel. Each channel is a driver section of 168lb and the PS goes a mere 130lb. Times 2 for a stereo pair of only 596lb. When THAT much metal gets hot, it'll stay
that way for a while. I couldn't afford the Air Conditioning bill but would welcome the heat output in winter. They'll put a Dent in the electric bill, too. They IDLE at 1000 watts.

HOME Theatere and Hi Fi in the review of the XPA1 G2 claims 90 watts at idle.    This can be confirmed with a Kill-A-Watt meter, available for maybe 25$ on Amazon.     And is accurate enough for this purpose.

Higher or lower by a LOT confirms bias issue.    Or a high side / low side.     Amp is 'differential' and based on the image I looked up, has 2 sets of output devices.   Look at all that nice Heat Sinking!