Power supplies and cables - observations, considerations & commentary

[lmitche]

Hi Barrows, my understanding is that the Supercaps in the Uptone LPS -1 are essentially batteries with lower capacity. They are disconnected from the charger during use (discharge). What is the benefit of charging batteries with batteries?

[lmitche]

Because the charge cycle of the Super capacitors is short, the charger (actually just another power supply) needs to be connected and powered up at all times. So the charger becomes the problem, typically most will use a wall wart SMPS based charger for this, and hence one will have all the problems associated with placing an affordable (read cheap as *hit) SMPS in close proximity to the audio system: it will broadcast a fair amount of interference into the air, and spray a bunch of nasty harmonics back on to the AC line to be shared with one's precious music signal via DAC and amp power supplies. By powering the LPS-1 with batteries, one eliminates any possibility of the supply causing problems with the rest of the audio system and the AC line. Or, one could build a nice linear based charger, either way, a good linear power supply, or a big LiFePO4 battery pack with regulator and charger, there is going to be some additional expense.

Thanks Barrows, so a good LPS that minimizes the backwash into the AC side should do the trick? And the output of the LPS1 will be the same regardless?

 

Did I get it right?

[lmitche]

Yes, stopping the backwash is one of the benefits claimed for the ac-7a.

[lmitche]

Hand up here! I have isolation transformers on all my equipment except my amp which already has a floating ground switch. The transformers cost around $100 each and make a world of difference in sound quality. Combined with ethernet isolation transformers, most devices are isolated on the digital as well as the AC side.

 

I am waiting for the next generation of PSU and USB isolation devices to complete the job.

[lmitche]

First thanks so much for your concern about my safety. You should know that prior to purchasing the isolation transformers I did a lot a research.

 

Here is one article suggesting the use of isolation transformers with SMPSes.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.signaltransformer.com/sites/all/pdf/IsolationTransformers%2520Increase%2520Safety%2520of%2520Electronic%2520Systems.pdf&ved=0ahUKEwj3u_7diO_OAhVCtRoKHSOKBZ4QFggzMAM&usg=AFQjCNH-wQhQ7tRIa4QZQYvyfquINqWREg

 

But you can't always believe what you read on the internet, so I had a trip to one of the largest manufacturers of toroids and isolation transformers in the states to ask about safety. They manufacture the toroids used in many of the high end audio components made in the states. They also crank out isolation transformers all day long from very small, less than an inch in diameter, to huge four foot diameter isolation transformers used by power companies.

 

Much of their business is in hospitals where their transformers are used with computers in operating rooms and patient monitoring systems. These isolation transformers are mandated by US regulation. My bet is that most of those computers use a SMPS to power the computer.

 

They also manufacture isolation transformers used on boat docks to avoid tragedies where kids swimming around a dock inadvertently hit water conducting current to ground. These tragedies seem to happen annually in the US.

 

So after a two hour discussion with the owner of the company about safety I feel confident that the use of isolation transformers on my audio system is safe.

 

Lastly, I don't run my equipment with exposed PCBs as is commonly done on workbenchs used by engineers and repair technicians. I am sure that Tektronix knows what they are talking about in this environment.

 

Thanks again for your concern for my safety.

[lmitche]

7 minutes ago, Ralf11 said:

Anybody know of a good USB cable based on the John Swenson way of doing shielding?

Take a look 11 posts up.

[lmitche]

http://www.ghentaudio.com/part/u01(jssg).html

 

The JS in JSSG are Mr. Swenson initials.