DirectStream Junior runing hot

The temperature on the surface of my DS junior is unusually hot. It measures 125F (52C) on the top, 115F (46C) on the front panel and 130F (55C) on the back panel. In comparison, BHK 250 after 2 hours playing at about 30% gets to about 125-130F (52-55C) on the side heat sinks and much less on the top and the front panels. The BHK preamp is not hot at all - approx. 97F (36C). All measurements are taken with a reasonably accurate infrared thermometer.

My setup is Lenovo notebook running JRiver22 playing thru the bridge of DS Junior -> BHK preamp -> BHK250 -> Magneplaners. All interconnects are balanced (wireworld equinox7 and Nordost red dawn), except for the speakers. The volume on DS Junior is 100; BHK preamp’s volume is 30.

I am not sure whether this a problem at all, but nevertheless, I am a bit nervous. I would appreciate it, if someone confirm if this is normal or not. And if not, what can be done about it.



It does run hot - the built in bridge uses 3/4 of the total power and for good sound the box needs linear (non switching) power supplies. To get quiet analog rails I burn some voltage (power) in multiple levels of regulation.

The power it draws doesn’t depend on the output volume at all, a volume of 100 is fine. I don’t know if there’s something to do that would save power if you weren’t using the bridge, but since you are using it, everything is working normally.

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Thank you Ted for the quick reply.

My concern is not about the power consumption but whether the unit operates properly.

You have answered all my questions. Thank you! I am at peace now.



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If the Ethernet port on the DSJ is not connected to the network is the bridge still consuming 3/4 of the total power?

I don’t know how much the load from the bridge module varies depending on it’s load. More than nothing, less than all. I suspect that having the cable connected matters less than playing vs. not playing and I suspect that transcoding uses a little more power than not, but I don’t know for sure. I don’t really have my system set up for using the Bridge so I can’t easily tell here.


Just to toss in my own wild assed guess, I would speculate that the difference between minimum and maximum power consumption of the Bridge is less than one Watt. I would be seriously surprised if it is more than that.


Only 0.00134102 horsepower?

Yes Elk, only 1/745 horsepower range of power consumption. :slight_smile: I am not sure just how much power in total that the Bridge consumes, but I would guess somewhere around 5 Watts, maybe a bit more.


Sometimes it uses the bigger part of 2A at 5V and since the Jr’s power supplies are linear and have to deal with +/-20% of nominal input voltage and a 10-15% deregulation for low current draw in the power transformers that 10W ends up eating a bunch more. It really was designed to be used with a switching power supply :slight_smile:

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Ted - I value and appreciate that direct reply with detailed information. However - as an electronics novice - it went mostly right over my head. But I did hear - I think - a couple of things a novice can understand…

  1. DSJ’s Bridge II gets hot because it was designed for a switching supply.

  2. DSJ does get hot.

From that I’ve got a couple of questions…

  1. Does the lack of switching power in the DSJ mean deleterious impacts on sound quality?

  2. Given that heat is the number one killer of solid state components, what does said heat imply for the life of the DSJ vs. the life of cooler competitors?

Thank you for your candid replies, and support.

No, I think you misunderstood my point about the bridge. The bridge uses significant current so it runs pretty hot by design in any system. But the point was that that higher current also causes the whole box’s power supplies to run hotter. The Jr uses linear supplies since they (in general) are much less noisy, but the downside of linear supplies is more heat compared to switching supplies.

The Jr runs hot, but that heat is accounted for in the design.

The (statistical) lifetime of a box is set by balancing the lifetimes of all components, there’s no need for any given component to last significantly longer than all of the other components.

The more heat sensitive components are further from the heat producing components. There’s plenty of board surface area to spread out the heat of heat producing components. Also heat producing components are connected solidly to the ground plane (a solid layer of copper in the middle of the PC board) which further spreads out the heat.

Extra care was taken to spec parts that are less heat sensitive than typical components. For example: When picking specific aluminum electrolytic capacitors, the capacitors were chosen that are rated at 2000 or 5000 hours at 105C (or 125C) instead of a more typical 1000 or 2000 at 85C. Since the lifetime of a aluminum electrolytic capacitor goes down by approx. 2 ^ (temperature delta in C / 10) that’s quite a difference. That formula basically says that each 10C lowering in temperature doubles the capacitor life so the caps in the Jr which are only rated for 2000 at 105C should still be expected to live about 8 times longer than typical caps or put another way for a given capacitor life the Jr can run 30C (54F) hotter with the better capacitors than it could with more typical capacitors.

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Awesome! Thanks for the clarification Ted.

So the PS is better than the alternatives, just warmer as a consequence. And the heat was taken into account in the overall design and parts used. Could not have asked for more.

Thank you.

So any guidance of what “adequate ventilation” mentioned in the DSJ manual implies? I know any reply could have a lot of caveats, so allow me to provide my own setup as an example…

I’ve got my audio equipment in/on a TV console. The means there is a large top shelf (totally open air), where components can go. But there is also 6"+ high shelf under that top, what is open in the front, but sides and back are closed (except for small holes in back to run cables). And finally for components that generate low/no heat, there are tradition 8" high, cabinet racks under that with doors in front that close the components in. While not air tight, there’s no circulation in the cabinet to speak of.

In that setup, other than the obvious top, is there anywhere else the DSJ might go?

Thank you.

scolley said

But there is also 6"+ high shelf under that top, what is open in the front, but sides and back are closed (except for small holes in back to run cables).

If the front is completely open that sounds fine - there’s enough room for the rising heat to escape and suck colder air in the bottom… The things that most likely would cause problems are a tightly enclosed space or sitting on a hot component (or visa versa.)

Awesome! Thank you.

The front is completely open, and not a crowded shelf either, so lots of room for air to flow. Thanks. :slight_smile:

I recently moved my DS Jr. while working on the stereo rack. Its heat was enough to deform the (cheap) vibrapod footers I’d put under it. I was assuming adding a little more space under the unit would help dissipate heat. Think I’ll be replacing these with simple wood blocks.

Does the DSJ run hot regardless of whether it is being fed a signal? I am thinking about placing it in a cabinet with an open rear and a front that can be opened. So if it runs warmer when playing, I can open the front to help with cooling. In general, how much room would I need to leave above the unit so that it could breathe? Thanks

I recently purchased a DS Jr., and it definitely runs warm in my cabinet. I installed a small DC fan behind the shelf holding the DS Jr., and placed a Component fan on top of the DS Jr. These cooling measures keep the surrounding area cabinet temperature in the low to mid 80s.

The DS Jr. puts out heat in standby mode.

The DSJ runs hot even at idle and its temperature is not changed when a signal is present. Do allow a bit of room for ventilation.

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Placed my DSJ on the top of the rack, suspended by two pieces of wood, about 2" from the surface. There is nothing around it or above it, e.g. it is well ventilated. Since then everything has been absolutely normal. It runs warm like any electronic device, but certainly not hot. We are talking normal temperatures here - below 100F. When idle the unit is as cold as a former wife heart…

I have an Hifi rack with openings on all 4 sides. Is it okay to place the Stellar Gain Cell Pre/dac on top of the DSJ? I notices the bottom clearance of the DSJ is small and it feel warm to touch.