2. amps-preamps
  3. 159420-7415

Left channel of Pass X250.5 runs warmer than right

I’ve noticed over the years that the left channel of my Pass X250.5 runs warmer than the right channel. Both channels warm up at the same time but the left channel gets warmer than the right. I’ve noticed this with almost every amp I’ve ever owned in that one channel gets warmer than the other. I was once told that it was because amps are biased in order to have the least amount of distortion in both channels. Does this indicate mismatched capacitors per channel sides or is the fact that one channel runs warmer a natural state of stereo amps. I’ve noticed this discrepancy in channel heat in every amp I’ve ever owned so I assume it’s just the nature of the beast. Both channels warm up at the same time except the left channel will run a noticeable amount warmer. It’s probably perfectly normal but I thought I would ask.
128x128mitchb
4 responses Add your response
teo_audio
2,197 posts
 
flip the left and right input signals to the power amp, and then also flip the speaker cables. thus the amplifier will be amplifying the opposite channels, while your system is still working correctly, from the listening seat.

See if the temperature, as a change, follows the change in which amp channel is amplifying which preamp channel.

If the temp issue flips to the other amp channel, then you've got something going on with the preamp.

It could also be a fault of some sort , or difference in the speakers. One having a slightly different impedance than the other, for some reason.

The wiring flip will tell you, if there is a channel difference-change in the heating...  that it might be the preamp, and it might be the speaker.


mitchb's avatar
mitchb OP
336 posts
 
The left side is a few degrees warmer. How many exactly I don’t know but it’s noticeable if I hold onto the heat sinks for a minute. Every amp I’ve ever owned had this type of difference in heat per left and right sides.
erik_squires
16,245 posts
 
Caps probably have little to do with it, but I encourage you to get a temp sensor to validate your observations.

Bias is set generally to get the best balance of low idle power and lowest distortion. Class A is, as I recall, the opposite, and attempts to maintain high idle power. The differences you are feeling, if real, are due to the transistors, not caps. 

Best,

E


mitchb's avatar
mitchb OP
336 posts
 
I should mention that it’s not a night and day difference. The left channel is just warmer enough that it is noticeable. Both sides run warm pretty close.
Log in to respond
More to discover
80x80
Aurorasound VIDA Mk.II
80x80
Naim Audio NAC-N172 XS
80x80
Audio Note AN-S8