Conversion of a Chord DAVE to DC power using two Uptone Audio JS-2s

[asdf1000]

15 hours ago, ecwl said:

but having read @JohnSwenson’s comments about ground loop leakage current noise being a major component of noise affecting performance and that solution is proper grounding and not using SMPS and using linear power supplies instead

 

Maybe I misunderstood here but I don't think @JohnSwenson ever generalised that the solution for proper system grounding necessarily means using linear PSUs instead of SMPSs.

 

In fact I'm pretty sure I've read both John S and Rob Watts mention there are SMPSs better than linear PSUs and vice versa..

 

The solution for proper system grounding isn't always straight forward because it will vary between each unique total system.

 

[asdf1000]

9 minutes ago, ecwl said:

it’s so much easier to say let me switch the SMPS to LPS so that I don’t have to worry about the high impedance leakage current noise

 

But this is the point I was making... John has never said that all LPS's measure better regarding this noise, than all SMPS's.

 

He can only comment on the ones he has measured - he hasn't measured every LPS and SMPS on the planet...  Same for Rob...

 

My point was they both will tell you there are some good SMPSs that measure better than some badly designed LPSs... and there are some good LPSs that measure better than badly designed SMPSs...

 

[asdf1000]

Btw: I don't write all this just to argue.

 

I just think people in the past have taken some of what each has said and tried to make a generalisation. 

 

To write it a different way: has Rob Watts measured an LPS-1.2 or JS-2 ? Has John S measured Chord DAVE's power supply? I haven't read anything anywhere that says yes to either question.

 

I'm happy to be proven wrong though. Maybe John S will chime in.

 

[asdf1000]

10 hours ago, JohnSwenson said:

Correct, I have never measured a Chord power supply.

 

There are two main aspects of power supply that I find important for digital audio:

1) leakage current

2) output impedance over frequency

 

#1: I have written MANY posts on this, in a nutshell there are two types of leakage current, high impedance, which only comes from SMPS and low impedance leakage which is found in both SMPS and LPS. Every SMPS I have ever tested has significant amounts of high impedance leakage. Fortunately grounding the output of the SMPS gets rid of almost all of this. Once you do the grounding SMPS and LPS are on a similar footing. Good SMPS have leas leakage then poor LPS and good LPS have less leakage than poor SMPS. So far with what I have tested the best LPSs have lower leakage than the best SMPS.

 

#2 output impedance is very important to digital. This is NOT a single number, it is a graph of output impedance VS frequency. MOST PS of either type have fairly high impedance at both low and high frequencies. Most SMPS to not have separate regulators AFTER the switching converter, and thus rely on how good the regulation is of the whole converter. Usually this is quite poor. To improve this you can make the switching converter system as a whole have a much higher bandwidth, which CAN be done but costs a lot of money, OR use a linear regulator after the Switching converter. Both approaches can radically improve the output impedance at the extremes, but increase cost and space.

 

Note that no test equipment manufacturer actually makes a power supply tester that measure output impedance VS frequency. If you want to measure this you have to design and build your own. Doing a good job of this is NOT easy or cheap. Thus VERY few power supplies have actually been tested for this. I have built several over the years and have tested some of both SMPS and LPS and the results are all over the map.

 

John S.

 

Thanks John S! Yes I have read nearly all your posts on the topic.

 

I think a lot of people have generalised a lot of what you've said (that's not your fault or problem) but as you noted:

 

10 hours ago, JohnSwenson said:

Correct, I have never measured a Chord power supply.

 

10 hours ago, JohnSwenson said:

Good SMPS have leas leakage then poor LPS and good LPS have less leakage than poor SMPS.

 

10 hours ago, JohnSwenson said:

I have built several over the years and have tested some of both SMPS and LPS and the results are all over the map.

 

Having said that, I know the LPS-1.2 and and JS-2 are stellar.

 

[asdf1000]

12 hours ago, ecwl said:

As i said in my first response in this thread, Rob Watts has this funny idea that if your USB streamer needs galvanic isolation, that’s your streamer’s problem, not the Blu2/DAVE problem. Now that’s an exaggeration because DAVE USB input does have galvanic isolation.

 

Let's not forget the time Rob said the Audioquest Jitterbug made a difference to DAVE's USB input !! 😃

 

For any technical disagreements please direct them to Rob, not me !

 

 

[asdf1000]

23 minutes ago, Nenon said:

It's proudly sitting side by side next to my reference DAC

 

What is your reference DAC ?

[asdf1000]

27 minutes ago, skatbelt said:

I have an idea! Why not send the SMPS that you @DAVE JS2 have taken out of DAVE and is now unemployed to @JohnSwenson with the intention to test it on the important properties of a power supply he mentioned above. I think a very large group (DAVE owners but also others) is interested in the outcome and maybe it also says something in general about the state of purposely built SMPSs in high end audio products. I am sure John will take on this challenge!

 

To make it worth his while, send him the entire DAVE DAC ... He can't listen to a state of the art DAC with just it's PSU ! LOL

 

It would be cruel to just ask him to measure and deny him a chance to listen 😢 

[asdf1000]

19 minutes ago, DAVE JS2 said:

I have just got round to earthing all the unused inputs on my DAVE (couple of BNC's, XLR and USB) and Blu Mk II and was pleased with the improvement / effort ratio - further reduces the RF noise, a 'calmer' listen. Should have done it long ago. You guys have probably done it already, but I mention it 'just in case'.

I'm not question the improvement you hear but this is generally not recommended practise (earthing all inputs).

 

I don't think this would be recommended by John S or Rob Watts.

[asdf1000]

13 minutes ago, DAVE JS2 said:

Interesting thanks - do you know what the issue might be? It seemed like a logical thing to do to me.

 

System grounding is a really complex topic.

 

@JohnSwenson has written a lot about it on various threads.

 

This is a good place to start

 

https://www.ranecommercial.com/kb_article.php?article=2107

 

[asdf1000]

1 minute ago, DAVE JS2 said:

@asdf1000 Thank you very much, I will read that.

 

For clarity; I earthed the grounds, not the signal lines (apologies for my sloppy language).

 

All good. I don't know if that's any better though 😀

 

The main thing is it didn't get worse for you, which is the biggest danger with improper system grounding - when you start to hear audible buzz/hum.

 

And I guess it is possible that (by luck) you actually have objectively improved things too. 

 

It's such a complicated thing that the only way to get good advice on system grounding is to sketch up a full system diagram LOL. Showing how everything is connection.

 

That's a lot of work but it's really the only way an expert here (not me) could give good advice.

 

Other than that, reading the Rane article is a great place to start.

[asdf1000]

14 minutes ago, DAVE JS2 said:

@asdf1000 I'm coming at it from trying to tame the RF sensitivity of the DAVE and Blu Mk II - I definitely feel like I'm on the front foot of the battle at the moment. I'll take my lucky shot!

I feel it did help me, but I will be sure to be mindful in future

 

If you have a chance to ask Rob Watts over on Head-Fi forum, it'd be interesting to read his opinion on it !

 

I might have it completely wrong.

 

If you do end up doing that (if you can be bothered) then please share what the Guru says here !