[andrewinukm]

Yes, it's a switching power supply. I can't seem to find any linear power supply for less than £60 ($70?) and the ones I can will take weeks to come (from China or HK). I'll see how I get on with the one I got and take it from there.

That's the one I'm getting
https://www.amazon.co.uk/gp/product/B0732NNKGF/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1

EDIT: Cr*p. Only just noticed that it's actually 2A at 5v. Will it still be OK?

Oh, you're in UK. You should check out iFi iPower (5V). A really clean switching power. Someone at Computer Audiophile forum did a test between iPower vs Chinese linear power supplies. The iPower's noise level beat all LPS in the test.
audiophilestyle.com/forums/topic/31119-power-supply-8-group-test-lps-and-smps/

I got another powered USB hub with individual power switches. You can switch on and off every single usb input, the lights showing on in which mode is connected UBS device currently, the possibilities being: Off - Charging only - Data or Charging & Data.

If I connect any other dac to the powered hub and switch the corresponding input button on, there is no light on the hub until there is a real signal transmission from the Mac through the usb hub to the dac. When I connect the usb signal out of the D50 to the USB hub, it lights right away, even when the hub is not receiving anything from the Mac. The usb hub is showing clearly that the D50 is drawing power from both the usb signal input and the other usb cable connected to power supply, something other dacs don't do. I have double checked with the SMSL M8a, the M8 and the x-usb II, there is no charging light on the hub when connected, their corresponding inputs start lightning only when the audio digital transmission starts. The D50 on the contrary makes the USB hub lighting right away and all the time. I have also tried to switch off the auto on function, following the logic that there must be some current flowing through the USB input needed for auto powering the dac but even with the auto power switched to off, it was the same.
It is clear that there is no isolation on the USB signal input of the D50, the dac is basically receiving the current at the same time through two separate usb inputs. This might also explain why does the sound using spdif change considerably for better when connected with a single USB cable, the one from the power supply.

I re-did my test again by taping up the 5V & ground contact point on Type A of USB cable and the metal exterior of both ends (type A and type B).

D50 does not require 5V or ground on the USB cable to work, it doesn't care about the handshake ground etc. It just needs Data+ and Data-.
It's just that the USB circuit never really powers down completely (drawing power from the external power supply), so it is always detected by the PC.

All power comes from the power supply.

Unplug the power supply, and I believe your hub's light would go off.

Anyway, I may have heard a small difference with the 5V & ground disconnected, but too minor to confirm if it is worth it. If you're using tape, then do it (no cost involved). If you're gonna buy a special cable to disconnect the 5V+gnd... not worth it. Might as well save the money and upgrade the cable or power supply.

 

[bogi]

D50 does not require 5V or ground on the USB cable to work, it doesn't care about the handshake ground etc.

Then the handshake uses ground connection through mains cables. Or maybe through USB cable shield. Without some sort of ground connection the handshake would not function. It could be verified with +5V battery supply ... but read carefully the post I linked below.

Some people at Computer Audiophile forum reported improved sound when really NO ground connection exists between the USB audio source and DAC, but such a setup can be dangerous for your DAC. See more here: https://audiophilestyle.com/forums/topic/28604-usb-ground-lift/?do=findComment&comment=561294 especielly the paragraph starting with "This means that if you setup ..."

Cuting only the +5V VBUS wire is safe.
If your handshake works with other ground connection than through USB cable it can still have positive effect on sound quality.

 

[HiFiRebel]

Thanks guys @lacknothing @andrewinukm . If PSU makes such a difference, I'm surprise they don't include one in the package. Most people will draw their conclusion on whatever is in the package and not many will trawl through hifi forums to find out that if you buy a £100 PSU for your £200 DAC it "might" improve a bit.

I've looked at iPower, but couldn't force myself to spend a £50 on a PSU. I've decided to see how will I get on with the unit and normal PSU. I can always upgrade it in future if needed be.

 

[carlmart]

I've looked at Farnell's linear PS offerings, and in fact they do not seem to offer wall type linear supplies anymore, which was the norm in the past.

I have an old Farnell catalog and will have a look at what they had then, and maybe they still stock them.

A linear supply would be a very easy DIY project to do, but they do not seem to sell complete kits, with case and all anymore.

 

[lacknothing]

Some people at Computer Audiophile forum reported improved sound when really NO ground connection exists between the USB audio source and DAC, but such a setup can be dangerous for your DAC. See more here: https://audiophilestyle.com/forums/topic/28604-usb-ground-lift/?do=findComment&comment=561294 especielly the paragraph starting with "This means that if you setup ..."

Cuting only the +5V VBUS wire is safe.
If your handshake works with other ground connection than through USB cable it can still have positive effect on sound quality.

spot on!

 

[andrewinukm]

Then the handshake uses ground connection through mains cables. Or maybe through USB cable shield. Without some sort of ground connection the handshake would not function. It could be verified with +5V battery supply ... but read carefully the post I linked below.

Some people at Computer Audiophile forum reported improved sound when really NO ground connection exists between the USB audio source and DAC, but such a setup can be dangerous for your DAC. See more here: https://audiophilestyle.com/forums/topic/28604-usb-ground-lift/?do=findComment&comment=561294 especielly the paragraph starting with "This means that if you setup ..."

Cuting only the +5V VBUS wire is safe.
If your handshake works with other ground connection than through USB cable it can still have positive effect on sound quality.

I see what you mean.
I also taped the metal "box" of the usb plugs that connect to the USB cable shield. So totally no ground connection between DAC to PC.

USB handshake is a USB protocol used by some USB devices, and requires 5V and ground. If we cut off 5V, no handshake can happen. Handshake is only possible with a direct connection, not through shield or mains.

What you're referring to is leakage current and potential between devices. It does seem it is a possible risk to isolate the ground.

I dont cut off 5V+gnd as the ISO Regen needs them to work, it then galvanically isolates 5V & ground.

 

[carlmart]

The usb line is balanced, so you do need the ground wire. If you are powering the unit separately, you can eliminate the +5v wire.

Even if you have galvanic isolation, that happens between the "live wires", the ground is the reference, so it can't be eliminated. That is on three-wire interface.

As you can see on the drawing, you can't eliminate the ground or you will disconnect the link.

 

[HiFiRebel]

And we have a lift off...

Here are my initial thoughts of D50 comparing to my old DAC - FX Audio DAC X6 for what they're worth. Not really a fair comparison, I know, as I paid £60 for X6 and £170 for the other. Also it's straight out of the box, no burn in and only a couple of hours listening.

The sound seems to be much more natural with D50. With X6 the lows were very deep, mids shouty to the point of being irritating after a while (with Argon Mk3 headphones, a bit better with Fidelio X2 headphones), highs were a bit recessed and I kept on wishing there were more high tones (for a while thought it might be the headphones fault), as it seemed the whole sound was pushed to the left of the scale (lots of lows and mids, not much highs).

It seems that with D50, the sound is much more neutral. The lows are still plentiful, but mids calmed down a lot and are quite enjoyable now and also I got my highs now. Not too much as rest of my equipment is quite bass heavy (Emotiva A-100 power amp with jumpers installed so 50W per channel to the cans, cans are modified Fostex T50RP Mk3 called Argon Mk3), but enough to be much more enjoyable experience.

A lot more listening is required. I have went through the filter list a couple of time but couldn't really tell much difference so I settled on 5th, as I thought it was giving me the most neutral sound.

Now, I'm not sure if I'm imaging it but there seems to be a tiny bit of floor noise added to the signal now. If I'm not imaging it, I'm not sure is it because I have used the onboard volume control to lower the signal going to my power amp by 5dB or is it because of the generic cheap power supply I'm using. It's quite low and at the moment not irritating.

Overall I'm happy with it for the time being. I was getting a bit annoyed by the unnatural sound, pushed to the left with X6 on my Argons Mk3 (hence the urge to upgrade), but this is so much better.

D50 is connected via USB cable to my PC. Feeding FLACs with WASAPI from Foobar. After a very quick test I can't hear much difference between USB and optical. With USB I can feed it 32 bit, with optical 32 gives me a bunch of loud white noise, 24 bit on optical works fine though.

I'm on Windows 10 and I've not installed any drivers, it's got recognised as D50 straight away in Foobar and Windows. Should I install drivers?

What I like:
- tells me what I feed it with
- clean and simple design, small footprint
- sound - upgrade from my old DAC

What I don't like
- the joystick idea is a bit pants (I keep switching source instead of volume)
- in AUTO screen mode (so that it goes to sleep) it's stuck at 100% brightness

For the time being, after a quick test, I'm happy and it gets thumbs up from me. Most likely will sell the X6.

 

[andrewinukm]

The usb line is balanced, so you do need the ground wire. If you are powering the unit separately, you can eliminate the +5v wire.

Even if you have galvanic isolation, that happens between the "live wires", the ground is the reference, so it can't be eliminated. That is on three-wire interface.

As you can see on the drawing, you can't eliminate the ground or you will disconnect the link.

You're right.
The D50 will work without USB ground connected, but it poses a risk.

 

[bogi]

USB handshake is a USB protocol used by some USB devices, and requires 5V and ground. If we cut off 5V, no handshake can happen. Handshake is only possible with a direct connection, not through shield or mains.

Handshake protocol signals use DATA and against Ground (probably DATA+ from the two data wires). +5V VBUS wire is used to supply power to the USB receiver connected to DAC USB port. When DAC provides those 5V self to it's USB receiver, then +5V coming from USB cable is not needed and handshake will still function. That's the D50 case.
Because of the handshake signals are transferred through DATA wire and ground, any parallel ground connection between the 2 devices with sufficiently low impedance can substitute the ground wire of the USB cable.

When I experimented without ground with home made USB cable, handshake was running when I had connected monitor cable to my battery powered notebook. So the ground path was PC > monitor cable > LCD monitor > monitor mains cable > wall > DAC mains cable > DAC. When I pulled out the monitor cable, no handshake ocurred with battery powered notebook. Simple: no alternate ground path for handshake => no handshake without ground.

IMO if you own ISO Regen you really don't need these 'tricks'.

 

[Taz777]

I used my 5V 1A linear power supply with my D50 that's part of my computer-based HiFi system today and it has improved the sound. It was previously powered with an iFi iPower supply. I prefer the sound with the LPS. if anyone is interested then the power supply I have is a 5V 1A power supply by LKS Audio. It's a Chinese-made power supply that I bought off eBay and it arrived within two weeks. Highly recommended if you're after an LPS for your Topping D50.

 

[carlmart]

If this is the one, it's too expensive:

https://www.ebay.co.uk/itm/L-K-S-Au...linear-power-supply-Talema-25VA-/311950695797

The one I bought is very high quality and much less expensive:

https://www.ebay.com/itm/323497118424

 

[Taz777]

If this is the one, it's too expensive:

https://www.ebay.co.uk/itm/L-K-S-Au...linear-power-supply-Talema-25VA-/311950695797

The one I bought is very high quality and much less expensive:

https://www.ebay.com/itm/323497118424

Yes, it's the one in your first link although I paid a lot less and it was from a different seller.

 

[carlmart]

A linear power supply is something I could have done myself. But I couldn't have done it for the price and finish of the one I bought.

The regulator inside is really low noise, a version of the Jung super regulator.

But I'm very happy you could hear a difference when you connected yours,

 

[BrotherKathos]

What does everyone think of this unit? Anyone tried it?

Nobsound 25W USB DC5V-24V Adjustable DC Regulated Linear Power Supply

https://www.amazon.com/Nobsound-DC5...ywords=5v+linear+power+supply#customerReviews