Pass Labs heatsinks temperature


Hi all

I have Pass Labs xa60.5 monoblocks and they are always warm to the touch at the heatsinks and not as hot as other class A amps I'm familiar with. A friend from the US that has the same model visited my place and told me his amps ran very much hotter than mine. I got concerned and looked at the manual where temperature was estimated at 55 degrees Celsius. I estimate mine at around 40 Degrees. I'm concerned my amps are not biased to pure class A as they should be. I contacted Pass and while they repeated that heat should be around 55 deg. they had no idea if my concerns are valid and they sounded quite mysterious about it. Did anyone has a xa.5 series model ever measured its temperature or has an idea what can I measure without opening the amps (with a technician) that will prove that they are working only in pure class A ?
Thanks in advance
icorem
All this temp measurement stuff has me thinking.
It is important in trying to get comparable data to take the data the same way using the same warm up procedures in the same location.
Sticking a baby thermometer up agains the fins is not the best technique. At work we measured hot chuck temperatures using a temp 'Puck'. A flat sensor connected by cable to a handheld device.
Some FLUKE meters can use a thermocouple, too. You just need the right 'type' so MV ouput matches the appropriate temp readout. A 'Type T' may be just the ticket.
I am not using a baby thermometer, using an infrared. I've checked the temps up and down, front to back and all the different fins and the highest I got was the 119.8F. It's warm but not hot to the touch. I'm going to run them all day today and then check again just out of curiosity(sp?).
John,
Good. Now if others use similar equipment with similar competence, the data could be compared.
As it lies? Well, 3 or 4 others have measured, with unknown means and accuracy, while getting results which confuse me.
No relation to bias condition has been stated, though all are on 'a' amps.

I've read, on the Pass DIY site the bias setting procedure for a Pass designed amp, and it was thorough enough that I have trouble believing an amp could leave the Pass factory and be mis-biased.
Magfan,
Ok, I went ahead and rechecked again as promised, I wanted to be sure my first readings were correct.

I'm using an infrared thermometer and checked from front to rear and all fins in an attempt to find the hottest point on the amplifiers. The hottest point does seem to be near the front panel in between the topmost and second fin. The amps have been kept in stand by for days, I set my cdp on repeat, left the house and let them run for several hours at a moderate volume. I got a maximum temp of 121.4F.

FYI; This is a new pair of amps that are only about two weeks old and I agree; I doubt that Pass would let a set leave the factory without checking and double checking the bias.(As a matter of fact I believe they set the bias, run the amps for 24 or 48 hours and then recheck again.)My needle hovers just to the left of the center line and stays there unless the volume is turned to an unbearable to me level. Though I know this is not much of a scientific way of checking for correct bias setting I hope this helps out anyone with questions on their amps bias setting. To be honest I think that Pass Labs class "A" amps just run cooler than most other class "A" amps.
Good data...and taken after complete warm up.

Most people don't know the difference between heat and tempreture.

An iceberg has more heat than a red hot nail even though the nail is at 500c or whatever.

Pass labs have generous heatsinking and huge transformers. Those 60a monos weigh what......60 or 70lb each? More?
And even though you touch 'em after a good warmup and say 'Not too bad!' all you'd have to do is put em in a smallish room on a cool night and see just how much HEAT they reallly kick out.