Hot Hot Hot

fauxpas · 21st November 2007, 01:16 AM

What on earth could be causing such high temps?

That thermometer will only go to 50c (120+f). It will always go over 55c. I have a dodgy car thermometer that shows 55+c after prolonged use.

I know the point I am measuring is very close to the tube connector and likely to be the hottest part of the amp, but the amp is all alloy and the whole thing gets hot, to all corners.

The other thing I notice is, it gradually gets hotter and hotter and will take over an hour to get to these temps...

SY · 21st November 2007, 01:26 AM

Quote:

What on earth could be causing such high temps?

Exactly what I told you in the other thread- incompetent thermal engineering.

DigitalJunkie · 21st November 2007, 01:33 AM

I'll bet those nifty tube cages are conducting alot of heat down onto the chassis also.
Are the tube cages really hot? I wonder if they are removable.

fauxpas · 21st November 2007, 01:44 AM

I have been running it with the bottom plate cover off totally and a fan nearby breezing over the desk.

The tube cages also measure 50+ off the scale... The alloy looks good, but because the whole thing is alloy the entire amp shares any heat issues.

What exactly is the source of the heat? I need to know so as to kjnow what of the case I need to mod. Do I just need to widen the holes the tubes stick out of?

I have a portable air conditioner I use when the aussie heat gets too much, but running it while trying to listen to tartini kind of defeats the purpose of going tubes in the first place.

Going to try a cheap USB powered cooler for laptops like this before installing a proper casefan at the rear.

Richard Ellis · 21st November 2007, 01:48 AM

Yes, we are seeing several heat management errors...The cages have got to go, your "submerged" driver tubes need to be raised up....the outputs too!
Perhaps you could raise the two panels the tube compliments are on...perhaps five millimeters would do...you might see inside the case, but it should relieve some heat built up underside.
The cages although perhaps needed in your application really are wrong artistically for the rest of the chassis.....they are a bad cathedrel style tacked onto an otherwise really tasteful chassis.
_______________________________________Rick....... ....

fauxpas · 21st November 2007, 01:56 AM

I have no problems chopping up this puppy. Believe it or not I didn't buy it for looks. I bought it cause it was being shipped within my own country. I should have had more guts and sourced from overseas.

One problem I may have is the way the entire case-pcb is assembled.

The 8 screws holding the pcb in place are on posts that double as the screws holding the alloy squares the tubes emerge from.

One fix I can think of is to disassemble the unit, remove the tube protectors and bore out the holes larger and at the same time install a small fan in the rear panel.

SY · 21st November 2007, 01:56 AM

The tubes are the primary source, and the cages don't help. I wouldn't be surprised if the power transformer ran pretty warm itself. You've also got power resistors underneath in the hotbox. There's no ventilation around the tube sockets to allow convection. The output tubes are mounted on solid PC board, which is then covered by unperforated reflective metal.

The fan will help, but no tube amp runs cool, and this one will run hotter than usual. Taking care of thermal issues will mean a radical mechanical redesign and rebuild, so you might want to consider leaving the fan in place and just living with the hot chassis.

As a guideline (my personal opinion and experience only), I'd find any amp with exposed metal surfaces over 55 degrees unacceptable. Under 50 degrees is perfectly doable in a rational design.

edit:

Quote:

remove the tube protectors and bore out the holes larger and at the same time install a small fan in the rear panel.

That's ambitious and a good idea. A fan underneath would be better, and you could use the bottom plate and the rest of the chassis as a way to force the air past the tubes.

fauxpas · 21st November 2007, 02:11 AM

The output transformers(?) on each side are fine and the power transformer(?) in the centre is a bit hotter but I can hold my palm down on all these comfortably...

Richard Ellis · 21st November 2007, 02:31 AM

The proximity of the driver tubes to the cage is almost zero clearance! Ditto the outputs.
A radical one would be to CAREFULLY swiss cheese your PCB?
Opening up these tube holes and running a fan would seem to be the best option. Note, I have had good luck running said fans at lower voltages to keep the noise floor extremely low.
Had a 12VDC "computer" fan running at 9VDC & the noise difference was considerable.
_____________________________________Rick......... ..

fauxpas · 21st November 2007, 02:40 AM

12vDC fan @ 9v = Can do

Widen holes at base of tubes = Can do

Swiss cheese the pcb = Can do [Need to buy a Dremel]

Something else I was looking at too was getting 6L6GC tubes down the track. I'm not fussed on the pear shaped 6P3P.

21st November 2007, 01:16 AM	#1
fauxpas diyAudio Member Join Date: Nov 2007	Hot Hot Hot What on earth could be causing such high temps? That thermometer will only go to 50c (120+f). It will always go over 55c. I have a dodgy car thermometer that shows 55+c after prolonged use. I know the point I am measuring is very close to the tube connector and likely to be the hottest part of the amp, but the amp is all alloy and the whole thing gets hot, to all corners. The other thing I notice is, it gradually gets hotter and hotter and will take over an hour to get to these temps...

21st November 2007, 01:48 AM	#5
Richard Ellis diyAudio Member Join Date: Sep 2006 Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.	Thermal reconfiguration? Yes, we are seeing several heat management errors...The cages have got to go, your "submerged" driver tubes need to be raised up....the outputs too! Perhaps you could raise the two panels the tube compliments are on...perhaps five millimeters would do...you might see inside the case, but it should relieve some heat built up underside. The cages although perhaps needed in your application really are wrong artistically for the rest of the chassis.....they are a bad cathedrel style tacked onto an otherwise really tasteful chassis. _______________________________________Rick....... ....

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21st November 2007, 01:33 AM	#3
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	I'll bet those nifty tube cages are conducting alot of heat down onto the chassis also. Are the tube cages really hot? I wonder if they are removable.

21st November 2007, 01:44 AM	#4
fauxpas diyAudio Member Join Date: Nov 2007	I have been running it with the bottom plate cover off totally and a fan nearby breezing over the desk. The tube cages also measure 50+ off the scale... The alloy looks good, but because the whole thing is alloy the entire amp shares any heat issues. What exactly is the source of the heat? I need to know so as to kjnow what of the case I need to mod. Do I just need to widen the holes the tubes stick out of? I have a portable air conditioner I use when the aussie heat gets too much, but running it while trying to listen to tartini kind of defeats the purpose of going tubes in the first place. Going to try a cheap USB powered cooler for laptops like this before installing a proper casefan at the rear.

21st November 2007, 01:56 AM	#6
fauxpas diyAudio Member Join Date: Nov 2007	I have no problems chopping up this puppy. Believe it or not I didn't buy it for looks. I bought it cause it was being shipped within my own country. I should have had more guts and sourced from overseas. One problem I may have is the way the entire case-pcb is assembled. The 8 screws holding the pcb in place are on posts that double as the screws holding the alloy squares the tubes emerge from. One fix I can think of is to disassemble the unit, remove the tube protectors and bore out the holes larger and at the same time install a small fan in the rear panel.

21st November 2007, 02:11 AM	#8
fauxpas diyAudio Member Join Date: Nov 2007	The output transformers(?) on each side are fine and the power transformer(?) in the centre is a bit hotter but I can hold my palm down on all these comfortably...

21st November 2007, 02:31 AM	#9
Richard Ellis diyAudio Member Join Date: Sep 2006 Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.	The proximity of the driver tubes to the cage is almost zero clearance! Ditto the outputs. A radical one would be to CAREFULLY swiss cheese your PCB? Opening up these tube holes and running a fan would seem to be the best option. Note, I have had good luck running said fans at lower voltages to keep the noise floor extremely low. Had a 12VDC "computer" fan running at 9VDC & the noise difference was considerable. _____________________________________Rick......... ..

21st November 2007, 02:40 AM	#10
fauxpas diyAudio Member Join Date: Nov 2007	12vDC fan @ 9v = Can do Widen holes at base of tubes = Can do Swiss cheese the pcb = Can do [Need to buy a Dremel] Something else I was looking at too was getting 6L6GC tubes down the track. I'm not fussed on the pear shaped 6P3P.

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