Linear power supply runs hot AF!

[sdmarquart]

Hi. I’m loving my optical Rendu. I bought this LPS from Small Green Computer to power it. 
 

https://www.smallgreencomputer.com/collections/linear-power-supplies/products/sgc-7v-linear-power-supply-50w-opticalrendu?variant=29452410519586
 

 

Man, I don’t know much about LPS except it does sound much better using it. Lower sound floor and everything. Just makes the Rendu sound superb compared to another power supply I was using. 
 

My only concern is this LPS I bought is super hot! I can barely touch it. The Rendu runs warm which is fine, but should the LPS be frying my hand when I touch it!?

 

i know these things run hot so hopefully this is normal. It does get plenty ventilation.

 

Any info and calming words is appreciated!

 

Thanks,

Spence

[sdmarquart]

I guess I need a better education of LPS in layman’s terms. I google and it says it converts AC to DC and how they run warm and need heat sinks. Also very inefficient but are used for audio products as they are very low noise.

 

That’s great but what does it mean. Why is the damn thing so hot? And it’s sold in tandem with the optical Rendu but nowhere in the literature does it state you can fry an egg on the LPS. Plus, it’s not cheap. The only response I’ve got is “it’s normal”. 
 

I need more. I’m too OCD to be okay with this thing nearly showing red it’s so hot. 
 

I’ve also done enough research to find LPS do make a “sound” difference. I know that’s an audiophile thing but I just want good sound. And a good explanation on what it does. I tried to explain this power supply to a friend yesterday and he looked at me like, “what?” I’d like to be able to explain a little better. It seems with the heavy cost it would be laid out in clear writing what the LPS is made of and what exactly it does and why it gets so hot. 

[elan120]

2 hours ago, sdmarquart said:

I guess I need a better education of LPS in layman’s terms. I google and it says it converts AC to DC and how they run warm and need heat sinks. Also very inefficient but are used for audio products as they are very low noise.

 

That’s great but what does it mean. Why is the damn thing so hot?

One of the key is efficiency, and it is calculated as:

 

                        Output power

Efficiency =  ------------------------

                         Input power

 

Using an example, if the power supply has 50% efficiency and the requested load power is 100W, then the total input power required to provide this 100W of output would be 200W.  The other 50% of input power (100W) is wasted, and most of this wasted power will become heat that has to be dissipated.

 

Better linear power supply will have better efficiency, design, parts, and workmanship so they will run at lower temperature.  Meanwhile, power supply will run hotter when pushing closer to the upper limit of their output.

 

In general, there are many possible factors that could drive a power supply to run hot, and when the power supply gets too hot, it could affect their overall service life.

 

Hope this helps a bit...

 

[sdmarquart]

Thanks! Yes, this helps a bit. I do worry about the overall service life of the LPS since it does run very hot but I do understand why it’s gets so hot too.

 

Appreciate the info!

[sandyk]

5 hours ago, sdmarquart said:

Hi. I’m loving my optical Rendu. I bought this LPS from Small Green Computer to power it. 
 

https://www.smallgreencomputer.com/collections/linear-power-supplies/products/sgc-7v-linear-power-supply-50w-opticalrendu?variant=29452410519586
 

 

Man, I don’t know much about LPS except it does sound much better using it. Lower sound floor and everything. Just makes the Rendu sound superb compared to another power supply I was using. 
 

My only concern is this LPS I bought is super hot! I can barely touch it. The Rendu runs warm which is fine, but should the LPS be frying my hand when I touch it!?

 

i know these things run hot so hopefully this is normal. It does get plenty ventilation.

 

Any info and calming words is appreciated!

 

Thanks,

Spence

 

What is the rated current for the Optical Rendu ?

 

 A PSU with a 50VA transformer using a typical Bridge rectifier and Capacitor Input gives only 62% of it's rated current.

This means that it's DC current out will be around 31W, and means that at 7V output it's maximum current will be about 4.4Amps continuous.

A Linear PSU should never run as hot as you are finding for long term reliability.

 Ideally ,  you need a higher rated PSU, or you will need to find a way to reduce it's heat,  perhaps by bolting an additional heatsink to it's metal case .

Quote

Specifications

• Input voltage: 110V AC (220v available on request)
• Output voltage: 7VDC
• Toroidal transformer: 50VA
• Size: 100*50*200mm (W*H*D)
• Voltage display LED color: Blue

It would have been much more helpful for the manufacturer to have stated it's maximum output current at 7V Output.

 

IDC=0.62 x Sec. I A.C.

[vinylvalet]

You're correct, these supplies run extremely, dangerously hot especially with the opticalRendu. I get the same answer from SMG, it's normal, it's okay. I can't touch mine for more than two seconds. This kind of heat will absolutely cause a rapid deterioration of internal components, especially the electrolytic capacitors.

 

Their 15W supplies also can run extremely hot. Burning to the touch when used with a Chord Qutest.

[sdmarquart]

Gotcha. I’m using the recommended power supply from Small Green Computer. It does run very hot but the optical Rendu does sound amazing. Are u insinuating it’s doing more harm than good? Is there a reasonably priced alternative LPS?

 

Thanks!

[sdmarquart]

The optical Rendu does not run hot so I’m cool with it.

[charlesphoto]

I just added some AC Infinity USB fans to the setup, both in the living room and the server closet in the office basement. Inexpensive, efficient, and run super quiet (low setting is enough). Now all of my Sonore, Uptone, and SGC devices are actually cool to the touch (scarily hot before, esp during our short heat wave). The living room ones I use the SMPS adapter (and plugged into the TV circuit, not the hifi one) and the server closet I power from a USB port on the Roon NUC. 

[barrows]

Sonore Power Supply, 7 VDC version is specifically designed to get the best performance out of the opticalRendu and it will run warm, not hot.  Yes, it is more expensive, but one gets what one pays for in this case: a hand made in the USA, high performance ultra low noise and impedance linear power supply.

 

[R1200CL]

On 8/25/2020 at 5:20 PM, sdmarquart said:

Is there a reasonably priced alternative LPS?

https://www.paulhynesdesign.com/sr4t

Will not get hot. 
 

I don’t think you can get good quality at lower price. 
Uptone JS-2 is another very good alternative. 

[Jerry S]

On 11/28/2020 at 3:44 PM, R1200CL said:

https://www.paulhynesdesign.com/sr4t

Will not get hot. 
 

I don’t think you can get good quality at lower price. 
Uptone JS-2 is another very good alternative. 

Old thread I'm bumping.  I have the Uptone LPS 1.2 and it runs quite warm too. Uptone says no problem, 3 yr warranty.  Don't worry about it.  

 

For $15 you can buy a temperature gun on ebay and measure the temp.  Mine runs about 125F which is well within design, even though it is hard to keep your hand on it. 

 

Jerry