What is a linear power supply and what is it used for/advantages?

Sorry for the seemingly silly question - I just do not understand the purpose of such linear supplies nor know whether they can be used with any audio equipment (bearing in mind that most if not all of them already have PSUs built-in).

You can find more information on our web, so please take a look.

Lastly: can someone provide links to the most recommended/common linear supplies so I know what they are/look like?

If a device can take an external power supply then they can make a difference. Using an RPi with a better supply than the £8 stock one is worthwhile for example.

Don’t get too hung up about the type of power supply though. True a lot of the better ones are linear. But switched mode ones can work well too. dCS use a mixture of linear and switched mode in some of their kit for example, and for sure they’re not going to use anything substandard. At a price more relevant to most of us Allo’s Nirvana is switched mode.

Was the question a generic one or do you have a specific device in mind? I’d certainly put power supplies way ahead of power cables or ethernet switches in importance / impact on SQ.

A liner supply has a much lower noise floor then a switch supply. So it sends less noise to the device it’s connected to. It’s an AC to DC supply so you can only use one if your device has a DC input.

I recommend Linear supplies (LPS) for our Rendu (Ethernet to USB) players.

My customers have also heard improvements in sound by using them to replace the switching supplies that came with their DAC.

This is a link to a good one from our web site.

You will notice they are quite a bit bigger then the supplies they replace. This is because they need a large copper transformer to reduce the AC voltage coming in to a voltage that the linear regulator can use.

Bill

Hi, happy Friday

I don’t have comparative measurements but if we take the iFi £50 supply as a benchmark (it’s what I was thinking of for the RPi) then iFi provide some info on their website here. Likewise Allo on their equivalent, the Nirvana, here.

I’ve also listened to the difference the iFi makes to an RPi; in my view it’s well worth the cost.

Interestingly when my son was looking for a new DAC we tried an RPi with Allo Boss HAT against an Audioquest Red. With stock power supply he preferred the Dragonfly. With the iFi power supply the improvement was obvious (to him and me). He ended up buying it (or rather muggins dad did here for his Xmas present). The key point is that he’s a relative newbie in audio, yet he could clearly heard the difference (through a crappy amp and speakers too). If you’re interested his next purchase was IsoAcoustics Pucks for his speakers - again he heard a clear difference with and without them.

I know you’re a measurements guy, I suspect I haven’t convinced you. If so fine. I would encourage people to try better power supplies though. Whether internal or external, power supply circuitry is a big focus for most electronics designers as lower noise equals better sound. And noise is measureable.

Cheers, Phil

The Allo Nirvana is SMPS as well. Although I haven’t heard that.

As I said the technology per se is less important than how it’s implemented. A poor linear supply will sound worse than a good SMPS one. The dCS example came from when I visited them. They said they used whichever was better for the job, linear wasn’t inherently better than switched mode and vice versa.

And yes I heard a difference between stock power supply and the iFi one with an RPi (3 to be precise). The stock one sounded harsher, particularly in the treble. The iFi one was more refined. The point about my son is that it wasn’t just my more experienceed ears that heard it, a newbie did too (and I didn’t lead him).

Two marketing sites, Phil. No measurements there that I can see.

“Interestingly” isn’t the word I’d use there . Anecdotes are not convincing, you’re right.

I agree. Where are the measurements showing these power supplies that you are urging people to try are improvements?

What someone else may or may not have imagined they heard isn’t all that interesting to me, no matter how often it’s repeated. Measurements would be.

You will get efficient and thoughtful service from Tianya.

If you really want to influence people, you have to engage with them where they are, not where you want them to be. Come on, change my thinking about this! Show me some data!

Bill

Like I said, I didn’t think you’d be convinced! Oh have another look at the Allo link by the way - there’s a link in the page to some meaurements.

Anecdotes or experience? I say the latter, you say the former.

“What someone else may or may not have imagined they heard”. No, heard, not imagined. Call it empirical data. And yes I know a sample size of two is not statistically relevant.

Hey, we both know none of the above is going to change your mind. So I’ll wish you a good weekend as I need to get out for a walk before it’s too late. Take care my friend

Phil

I’m going to try to explain this without getting too technical, and without trying to sell you anything.

DC power supplies have a job, and that job is to convert AC power (your wall) to DC power (what electronics usually need).

Both linear and switching power supplies do that task, but they accomplish it in using different methods.

The biggest “technical” difference is that linear power supplies use a large power transformer to do that conversion, and switching power supplies do not (they use more advanced circuitry that only became reasonable in the s). I digress into these technical details only to serve as an anchor to your second question which I address at the end of this post.

The “linear solution” is nice because it’s a very clean (low noise) solution, but it’s expensive, heavy, and very inefficient (input power is converted to heat and not output power).

The “switching solution” results in an inexpensive, lightweight, and very efficient power supply. It also produces less clean (more noise) electricity.

Switching pretty much won over the world in the last 40 years, and it’s why everyone piece of consumer electronics has a little wall wart or tiny PSU inside the unit.

Nowadays, linear power supplies tend to be used where the noise from electricity could impact the device it is powering. For example, if your device had a high sensitivity sensor, the noise from the electricity could interfere with the operation of that sensor by introducing noise into the sensor’s output signal. If the sensor is critical to the operation of the device, using a noisy power supply could render the entire purpose of the device moot.

In audio, the digital-to-analog conversion and amplification are analog processes that could potentially be impacted by electrical noise. The rationale is that linear power supplies are “better” for powering these types of audio processes. There are things you to do to make them less susceptible to noise, but most proponents will just want to avoid the noise in the first place.

In modern times, switching power supply technology has become quite noise-free, while maintaining the many other benefits of a switching power supply (efficiency and size, but not cost). Many audio manufacturers, including high-end brands (like dCS) have been able to achieve noise levels equal or better than even traditional linear power supplies while maintaining efficiency and size. Note that there are still a ton of really noisy switching power supplies out there still, but the story today is not quite as clear as “linear clean” vs “switching dirty”.

It’s also worth noting that many linear power supplies out there, like the ones you can get inexpensively on AliExpress and eBay, are often poor quality. They are preying upon those who demand “linear”.

How much does all this impact your sound? That is highly subjective.

They often look the same, but if you look under the hood, you will see large power transformers that will sometimes look like this:

Thanks, @Phil_Wright - my question was generic in the sense of understanding why people talk about them around here, and what the usual options for purchasing are.

My secondary question was: how can one even use them if virtually ALL devices already have a PSU?

And of course, tks a lot as well, @danny - this information is much appreciated. So I take it that, at least nowadays, there is very little advantage in using a linear PSU.

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