DC Power Cables - Effects on SQ

[Ralf11]

I suspect DC power cables might have an effect on SQ.  I don't know and have never measured one, nor have I conducted any blinded listening tests.

 

If you have done either - or just have an informed opinion on the matter, this is your thread.

 

Remember NO AC power cable discussion - there is another thread for that.

 

I further suspect that the most likely type of unit - if such SQ effects occur - would be at a DAC.  Wall wart power supplies are often placed near an AC outlet or plugged directly in, and a DC cable then extends a couple of feet (or a metre) to the DAC itself.

 

The DC cable may often run near noisy devices, and there is no transformer between it and the processing circuits in the DAC.

[Speedskater]

Only with poorly designed products.

A skilled circuit designer anticipates less than perfect DC from an external basic supply. The final DC supply is inside the product.

[Ralf11]

what's in the final DC supply ?  any transformers or other components that might or would remove noise?

 

BTW, in the OP I forgot to mention that Ghent makes inexpensive DC cables for those interested in trying new things

[Speedskater]

47 minutes ago, Ralf11 said:

what's in the final DC supply ?  any transformers or other components that might or would remove noise?

It's the voltage regulator circuit's job. That's what does the real work of both filtering incoming noise and all the noise generated by the product's circuits.

[Ralf11]

but won't a Vreg introduce noise by its operation?

 

(admittedly, I have not wired up one since the early '80s...)

[mansr]

3 hours ago, Ralf11 said:

what's in the final DC supply ?  any transformers or other components that might or would remove noise?

Typically, the raw DC input feeds a buck (or linear if you're so inclined) regulator outputting 5-12 V. From this, low-noise LDO regulators provide the voltages (usually 3.3-5 V) required by various components. The noise seen by the critical circuits is mainly determined by the local regulator, not the external power supply, provided the latter is of reasonable quality.

[sandyk]

4 hours ago, Speedskater said:

Only with poorly designed products.

A skilled circuit designer anticipates less than perfect DC from an external basic supply. The final DC supply is inside the product.

 Nevertheless, many members have reported worthwhile improvements when using the techniques described by E.E. John Swenson in this thread.

 

[mansr]

Just now, sandyk said:

Nevertheless

Another thread sanded.

[sandyk]

Just now, mansr said:

Another thread sanded.

 

The information from John's thread is completely on topic , and many members have reported a great deal of success when using the information that he has supplied.

 Note also that the thread also has 1185 replies, perhaps because you were unable to disrupt it ? 

[Ralf11]

I agree Sandy's post is on topic here, if a bit overly accepting of anecdotal reports.

[kumakuma]

2 minutes ago, Ralf11 said:

I agree Sandy's post is on topic here, if a bit overly accepting of anecdotal reports.

 

And he used the phrase "many members" for extra style points...

[marce]

8 hours ago, mansr said:

Typically, the raw DC input feeds a buck (or linear if you're so inclined) regulator outputting 5-12 V. From this, low-noise LDO regulators provide the voltages (usually 3.3-5 V) required by various components. The noise seen by the critical circuits is mainly determined by the local regulator, not the external power supply, provided the latter is of reasonable quality.

Further to this, the main DC power that is distributed is often 12V or greater (15V is popular and sometime as high as 44V, generally below 50 then you don't have to worry about SELV requirements.)

If you use a cable for 12V it will pick up a certain amount of rf noise depending on the cable construction, the same cable carrying 3V will pick up the same noise, but with a far worse SNR. So if you are providing external DC, a main high voltage with local regulation as Mansr described is the best way in EMC terms. Providing multiple low voltage feeds via external cables increases the risk of cross-talk, rf pick up and other EMC issues. Then there is the cost and problem of filtering all these supplies when they enter the box being supplied. Filtering at the point of entry is the rule here.

I will dig into my notes and stuff on this, plenty off stuff from Henry Ott, Ralph Morrison, Keith Armstrong etc as well as many examples I can look at, there is a whole variety of filtering DC inputs and different components even active modules.

Sorry if you think its a bit OT but looking at the whole area of DC distribution will benefit the discussion. It could be the lack of proper filtering, bad wire layout etc. that does cause issues with some systems and noise pick up.

[marce]

Some interesting tomes (textbooks almost☹️) to promote discussion...

https://www.analog.com/media/en/training-seminars/tutorials/MT-095.pdf

 

 

If anyones got the kit.

http://www.hottconsultants.com/techtips/tips-cm.html

 

Based on a larger scale, but the ideas do filter down, we have motors being driven by amps and control gear for the amp (DAC), also shows good wiring techniques.

https://dl.mitsubishielectric.com/dl/fa/document/manual/plc/bqn-p0e100083e/bqnp0e100083e.pdf

 

Or if your really serious... a great Textbook:

https://www.amazon.co.uk/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304

or

https://www.amazon.com/Grounding-Shielding-Interference-Ralph-Morrison/dp/0470097728

 

And here a whole wealth fo practical advice and information.

http://www.emcia.org/keitharmstrong.aspx

 

 

 

[John Dyson]

All too many 'improvements' using things like special power cables or any kind of interconnect (modulo certain kinds of speaker cables -- some very bad, some slightly better), these are due to EMI issues or as noted before -- working around exceptionally poor design.  It is a lot like the difference between the way that lossless file formats sound -- there are virtually ALWAYS uncontrolled variables that encourage misunderstanding what is really going on.

 

I do believe that electrical/electronic noise sources are grossly underestimated as the actual cause for sound differences attributed to interconnect/file formats.  (When I speak of 'noise', most of the time I am not speaking of Johnson or other VERY low level noise for power supplies -- I am speaking of things like noise from CPUS or other fast digital circuits that have current surges in the order of Amps and transition speeds of nsecs or less.) 

It really isn't being 'scientific' to blow off claims of unlikely behaviors -- but it is also unscientific to ignore careful experimental control.

WRT power supply quality -- less noise-creation, less noise-susceptability,less output impedance, less power-loss, better transient-recovery, more available current -- these and other things are all good.  A real-world design balances these attributes against cost, and purists seem to bias their goals away from the 'cost' and try to optimize the positive attributes.  Improving the positive attributes are 'good' things from a technical standpoint, but might not actually be helping the sound...  The 'fix' might actually have been improving the resistance of a cold solder joint (as a simple example.)  All of the heroic electronic 'shotgun improvements' might have overshadowed the actual circuit improvement.

 

The problem is -- do these 'improvements' make actual technical sound quality improvement, or is it a (respectfully) mental thing?  The correct way of doing things -- if the technical improvements cannot be clearly shown to provide better audio, then do an actual scientific, statistically meaningful comparison.  (ABX is a good kind of thing in this regard, for example.)

 

From very painful experience, I have found 'learning by feeling' is tantamount to acting like 'The Three Stooges' or 'herding cats'.   Gotta control those experiments so that next time a better targeted solution can be created  (maybe should really focus on the actual improvement(s), rather than a shotgun approach or a rather silly chase of many 'cats.')

 

John

[photonman]

The circuit designer of the Chord Qutest states that he has accounted for these power supply issues with filtering and regulation and that the supplied wall wart cannot be improved upon.  So one example of product that was designed with DC power supply quality in mind.  I recently went back to the wall wart and plugged it directly into the wall outlet.

[marce]

10 hours ago, John Dyson said:

- I am speaking of things like noise from CPUS or other fast digital circuits that have current surges in the order of Amps and transition speeds of nsecs or less.) 

 

https://blogs.mentor.com/hyperblog/blog/2015/06/02/simultaneously-switching-noise-an-overview/

Simultaneous switching noise, the digital power delivery system is designed to cater for this and the initial high dI/dt requirements, the on chip capacitance and local decoupling capacitors cater for the initial charge, then the on board reservoir caps. scattered about and finally the power supply as the power supply cannot handle the current requirements on its own.

We have to remember this noise is not stored in any digital files...

[Ralf11]

16 hours ago, marce said:

Further to this, the main DC power that is distributed is often 12V or greater (15V is popular and sometime as high as 44V, generally below 50 then you don't have to worry about SELV requirements.)

If you use a cable for 12V it will pick up a certain amount of rf noise depending on the cable construction, the same cable carrying 3V will pick up the same noise, but with a far worse SNR. So if you are providing external DC, a main high voltage with local regulation as Mansr described is the best way in EMC terms. Providing multiple low voltage feeds via external cables increases the risk of cross-talk, rf pick up and other EMC issues. Then there is the cost and problem of filtering all these supplies when they enter the box being supplied. Filtering at the point of entry is the rule here.

I will dig into my notes and stuff on this, plenty off stuff from Henry Ott, Ralph Morrison, Keith Armstrong etc as well as many examples I can look at, there is a whole variety of filtering DC inputs and different components even active modules.

Sorry if you think its a bit OT but looking at the whole area of DC distribution will benefit the discussion. It could be the lack of proper filtering, bad wire layout etc. that does cause issues with some systems and noise pick up.

 

I'm looking forward to it.

 

If something puts noise 120 dB down we can likely move on...

 

 

[Speedskater]

9 minutes ago, Ralf11 said:

I'm looking forward to it.

If something puts noise 120 dB down we can likely move on...

From an external basic supply, we can move on long, long before that!

[Ralf11]

Let's keep on track with DC power supplies.

 

Sandy - if you start your own thread on noise in the disc or on an SD card, etc. then you will have control of it.

[Ralf11]

I created a thread for this issue:

 

 

Please post there and do not derail this thread.

[The Computer Audiophile]

3 minutes ago, sandyk said:

 I have already made it perfectly clear that I am not interested.

Go talk to yourself and Kumakuma in your new thread, and without favouritism remove the off topic replies in this thread that you created.

BYE !

Sandy - If you can't converse with people without losing your cool, you just can't hang around here. You are constantly offended. Feel free to say whatever you want in your own threads. 

[sandyk]

9 minutes ago, The Computer Audiophile said:

Sandy - If you can't converse with people without losing your cool, you just can't hang around here. You are constantly offended. Feel free to say whatever you want in your own threads. 

 Chris

 I have made it clear on several occasions that I no longer wish to continue this off topic discussion in Ralf11's thread..The OP already knew when he created the new thread that I was not interested in participating..

[Ralf11]

then shut the fk up

[Hugo9000]

1 hour ago, sandyk said:

 Chris

 I have made it clear on several occasions that I no longer wish to continue this off topic discussion in Ralf11's thread..The OP already knew when he created the new thread that I was not interested in participating..

Who keeps forcing you to reply against your will?  

 

Please create your own threads and stop thread-crapping everywhere on the site, and particularly every single thread started by one of the people you keep complaining about and attacking.

 

Ignoring you doesn't work, since you are everywhere, and it makes every thread completely disjointed.  By your own posts stating your age, you are a mature person, please show it with your behavior and exercise a little restraint.  If you can't stand these E.E.s or "anti-audiophiles" you constantly rail about, then ignore them and stay away from threads they start.

[mansr]

10 hours ago, The Computer Audiophile said:

Sandy - If you can't converse with people without losing your cool, you just can't hang around here. You are constantly offended. Feel free to say whatever you want in your own threads. 

Maybe a compulsory break from the forum would do him (or us) some good.