question for SLP05 owners:

I had them stacked without issue for several years.

Thanks for the feed back on that, @hk_fan .  Does your power supply get pretty hot like mine does?

You might want to call and ask Cary Audio directly what has been learned since the publishing of the last operating manual version. Ask the warranty-repair decision maker person there these days - and not a general sales person. I've had to deal with other components where the operators manuals needed clarification, updating.

What does #8 really mean below and is "stacking" acceptable or not.   

SLP-05 Cary Owners Manual, Page 2, reads: 

7. HEAT: Position the unit away from heat sources such as radiators, heat registers, stoves, or other units (including amplifiers) that produce heat.

8. VENTILATION: Slots and openings in the cabinet create ventilation to protect the component from overheating. These openings on the top and bottom panels must remain unobstructed. Allow at least 6 inches (16cm) of clearance above the unit and an opening behind the unit for airflow. Do not place the unit on a bed, sofa, rug, built-in bookcase, or rack without adequate ventilation.

https://www.caryaudio.com/wp-content/uploads/2021/01/SLP-05_manual.pdf

Thanks @decooney . I would have to email them, because I don’t think they talk to people on the phone anymore unless they want to buy something. The last time I emailed them about something, they were in no hurry to get back to me, but I guess that is what I should do.

As far as stacking, my preowned SLP05 was manufactured back when they were putting those indentations in the top panel of the power supply for the preamp feet to rest its feet in. But I was sort of under the impression that they were no longer building them that way.

I did, just now, consult the owner’s manual Cary provided with my preowned unit, and, as you pointed out, mine says the identical thing under the heading of "IMPORTANT SAFETY INSTRUCTIONS."

But then on page 15 under "BASIC OPERATION" it says "You may wish to stack the preamplifier on top of the matching power supply."  Then it goes on to say that either/or is okay. You are right--I should email them and express my concerns about stacking a component on something that gets as hot as that power supply gets. Either that or just not do it. I am thinking more & more of doing option 2.

If it were me and you see any type of ventilation holes under each of your units, maybe consider ways of ensuring sufficient air gets in.

Yes, we’ve both seen photos SLP-05/Power supply stacked, and I just checked a few reviewers that had them on display not stacked closer together. Maybe you can gap them some if you must stack. Same as some rack mount computer blade systems in racks within big Colo data center facilities. Moving Air is your friend if you want equipment to last.

If you do decide to stack, maybe you could do something like this for each, some kind of risers underneath each one, then stack, sort of like this. Can’t find a good photo but you get the idea. Stuff inside these units melts ages, cracks, over time from heat, this we know.

I appreciate your input, @decooney . I am starting to think that I don’t like the idea of something that gets warm sitting right on top of something that gets hot. When I say hot, I do not mean hot enough to burn flesh, but hot enough to make the palm of my hand feel a bit uncomfortable, and for someone who is not particularly sensitive that way, I guess that’s getting pretty warm. I need to remember to put a thermometer on top of it once to see what it actually reads. It must be those two big caps, huh? I cannot imagine that the 5AR4 is what makes it get that hot.

Anyway, I can find a way to reconfigure without stacking, but thanks again for taking the time to offer input and post the pics.

No worries @immatthewj I was typing this as I rotated my tube monoblock amps out, inserting and warming up my other Class A 50w solid state amp on/off past few days.  That SS class A gets to about 45-47C on the heat sinks as biased, and ensuring I have nothing above it or near it. Above it sits my Cary SLP-98L preamp, I keep the power supply away and sufficient air above it to breath in a similar manner. I use to stack some other dual mono HT SS amps I had years ago, not any more. Burned out one of them on the top of the stack, learned a lesson.   

As for heat, you might compare with others with SLP-05s and see if anyone has used a Infrared Thermometer Laser Temperature Gun and checked temps at all across different surfaces, tubes, etc.  

Are you running a different set of tubes, rectifiers, in it now then compared to the past and do you suspect more heat after trying different tubes - or anything like that?   

They were made to be stacked . I recently sold mine to a buddy who has them stacked just like I did for years.

The reason Cary Audio changed the plate on top of the power supply to one without “foot indentions”, was to discourage people from stacking for the sole reason that sometimes the transformer radiated noise into the preamp above.  When people would complain about hum being radiated into the preamp from the power supply, and we’re told to move the power supply away, they would question “then why are there indentions on the top plate for it to be stacked?”.  So Cary Audio changed the power supply top plate to one without indentions so people wouldn’t stack them or question anymore.  Thus, no more hum issues. 
Heat typically wasn’t the problem although they do get hot because of the rectifier tube in the power supply.  The power supply umbilical cable was made by Kimber Kable for Cary Audio and is pretty good non-shielded wire. 
Some people change the rectifier tube to a solid state type (for sound change purposes) which also runs cool and can make the preamp sound more detailed with much tighter bass.  It’s something to play with you like.  I use SS rectification in mine using high speed rectifiers. Not HexFRED’s but similar. I had an old “Weber Copper Cap” that I upgraded the rectifiers in that just plugs into the octal socket in the power supply.  You can use one of those made by TubeDepot or whatever.  In my system I love the speed, imaging and detail it presents but every system is different. If you already have an overly bright sounding system you probably won’t like SS rectification on your SLP-05.  

 

@lwin They were made to be stacked . I recently sold mine to a buddy who has them stacked just like I did for years.

@harpo75 The reason Cary Audio changed the plate on top of the power supply to one without “foot indentions”, was to discourage people from stacking ...

And yet another photo of the indentions, and not stacking. If the indentions on the power supply top plate were removed - there is a reason for it as @harpo75 suggested. Worth doing more research on this topic, sometimes designs change for a reason. I bet the warranty decision maker at Cary Audio can share updates on what’s important to make the gear last longer. They see the incoming repairs.

@immatthewj no experience with Cary but when I had Pass Labs XP-22 two chassis preamp I heard a very subtle improvement when I separated the preamp from its power supply chassis. Neither one of the units got hot by the way. Slightly warm. I would keep the Cary preamp unit away from its power supply for reasons to not pollute the preamp unit with EMI that the power supply generates and to give the two units space to get proper ventilation.

Thanks for the input, @everyone.  @decooney , as far as the rectifier tube, it came with a Sovtek installed, I tried a Gold Lion for a short time, then a UK Amperex (which I am told is basically a Mullard that was branded Amperex) and recently when I was moving some stuff around to try out a high pass filter in my chain I put the Gold Lion back in.  It gets quite warm, with all of them.

After posting this thread/question and evaluating everything, I am going to continue to find a way not to stack them--for both the possible EMI and the temperature that makes me a bit uncomfortable about the idea.  

I don't remember it getting hot, but it was at least 15 years ago since I had the SLP-05 so take that with a grain of salt!

I've never been a fan of stacking gear on top of each other, even when the pieces were made with those "foot indentations" for stacking.  When I had to set gear up utilizing stacking due to space constraints, I always put a miniature fan behind the gear to keep air blowing across it.

Did it help cool it?  Who knows.  Did it ease my mind?  Abso-freaking-lutely.