Power supplies and cables - observations, considerations & commentary

[vortecjr]

Hi John

 

Thanks for the clear explanation of leakage currents, definitely helps. Someone should tag your message as a reference on leakage currents.

 

A question:

 

Are leakage currents important after the DAC? Say in pre-amp or power-amp stage? When the signal leaves the DAC to pre-amp, can leakage currents back flow to the DAC via the interconnect from a pre-amp or power amp power supply?

 

I know you mention the following already - "..(leakage current) is entirely a product of the DC output of the supplies connected together through the USB cable.." but would like to clarify just in case since most pre and power amps have AC/DC convertors inside.

 

What about within pre-amps and power-amps in general, are leakage currents significant further along the audio signal path?

 

John may out for a few days so I'll provide some feedback until he returns and can expand on your questions. Leakage current in pre-amps can produce audible noise (the dreaded 50/60Hz hum coming from your speakers). I generally plug my amplifier right into the outlet and don't worry about it.

[vortecjr]

Thanks John, this absolutely helps. I completely understand the LPS-1 is the perfect power supply to complement the microRendu.

 

Just for my understanding, regarding "The above is NOT true if you use any other power supply to power the microRendu , then leakage currents come into the system through the power supply."

 

So a chain of mRendu-to-Intona-to-DAC won't break a low noice linear PSU's leakage currents as well as the LPS-1 supplying power to the microRendu?

Many thanks again for taking the time to explain this. It's greatly appreciated.

 

What he is saying is that a battery (without a charger connected to it) or a Uptone Audio LPS-1 will block leakage current from the AC line. Other power supplies will allow a certain amount of leakage currents from the AC line to the extent the design of the power supplies allows it. You then need to consider if the noise that gets in is audible or not and if the noise affects your system or not. Some systems are inherently better at dealing with the issue compared to others.

[lotriwer]

Received my mR couple of days ago. Very impressive piece of gear! Use it with Roon/HQplayer and T+A DAC 8 DSD. Even though T+A DAC does not play native DSD512 with Linux, it still sounds better with DSD128 DoP via mR over native DSD512 via USB (IMHO).

[JohnSwenson]

Hi John

 

Thanks for the clear explanation of leakage currents, definitely helps. Someone should tag your message as a reference on leakage currents.

 

A question:

 

Are leakage currents important after the DAC? Say in pre-amp or power-amp stage? When the signal leaves the DAC to pre-amp, can leakage currents back flow to the DAC via the interconnect from a pre-amp or power amp power supply?

 

I know you mention the following already - "..(leakage current) is entirely a product of the DC output of the supplies connected together through the USB cable.." but would like to clarify just in case since most pre and power amps have AC/DC convertors inside.

 

What about within pre-amps and power-amps in general, are leakage currents significant further along the audio signal path?

 

Yep, all AC line to DC power supplies (except LPS-1 and LIO) have leakage current, even ones in pre-amps and power-amps. LPS supplies generally have lower leakage than SMPS supplies so the effects of the LPS in pre/power amps is usually less than the leakage current involving digital systems which usually use SMPS. It is the almost universal use of SMPS in computer systems and the larger leakage current from such supplies which have made leakage current much more important to SQ than the leakage current in the rest of the chain.

 

John S.

[JohnSwenson]

Yep, all AC line to DC power supplies (except LPS-1 and LIO) have leakage current, even ones in pre-amps and power-amps. LPS supplies generally have lower leakage than SMPS supplies so the effects of the LPS in pre/power amps is usually less than the leakage current involving digital systems which usually use SMPS. It is the almost universal use of SMPS in computer systems and the larger leakage current from such supplies which have made leakage current much more important to SQ than the leakage current in the rest of the chain.

 

John S.

 

More info on preamps, most preamps have a volume control before a fixed gain stage, because the noise from a leakge loop goes through the ground, NOT the signal line, it bypasses the volume control in front of the gain stage. The result is that the preamp is amplifying the noise at its full gain, even if the volume control is turned down.

 

This can be why many people find that plugging a DAC into a preamp rather than direct into a poweramp sounds worse, the preamp is amplifying the noise.

 

A note on how this noise affects things. Leakage current going through preamp and poweramp is just lower frequency noise, usually not loud enough to be heard as tones by it self, but it can change how you hear the music (ie it doesn't "sound" as good)

 

Leakage current that goes through the DAC can have a different effect, the noise through the ground can increase jitter on the internal oscillator which causes increased distortion close in to the signal frequencies. This can have an effect on the "realness" of the sound.

 

It is extremely difficult to make absolute generalizations about any of this, how any of this affects a specific system is very dependent on what components are in the system, how the components are connected together and how the AC line connections are made. Remember my explanation is a LOOP which includes the AC line and the signal connections between boxes.

 

How your ac connections are done can have a very strong effect on leakage currents. One of the interesting parts of this is that many AC line "filters" that are supposed to filter out noise on the AC line, significantly increase leakage current. I have a feeling this is why many people feel that a lot of the filters "rob the sound of life", it is not that they restrict current, but they increase the leakage current.

 

I have some thoughts on how to setup your AC line system so as to decrease leakage currents, but this will take WAY WAY more time than I have right now.

 

John S.

[jamesg11]

"I have some thoughts on how to setup your AC line system so as to decrease leakage currents, but this will take WAY WAY more time than I have right now."

 

Yes, John, take your time with this ... but I bet I'm not alone in really looking forward to having these "thoughts" put before us!

[flkin]

Yep, all AC line to DC power supplies (except LPS-1 and LIO) have leakage current, even ones in pre-amps and power-amps. LPS supplies generally have lower leakage than SMPS supplies so the effects of the LPS in pre/power amps is usually less than the leakage current involving digital systems which usually use SMPS. It is the almost universal use of SMPS in computer systems and the larger leakage current from such supplies which have made leakage current much more important to SQ than the leakage current in the rest of the chain.

 

John S.

 

If leakage currents are being formed in power and pre-amps and can flow backwards up interconnects then it's just as crucial to investigate and eliminate these rogue currents as it will affect both the digital and analogue realms as described. There's no point caring so much about source and DAC power supplies while ignoring down line power supplies that contaminate upstream the same way. In fact, if I understand correctly, these rogue currents are amplified by the pre-amp and may be order/s of magnitude higher than before.

 

That said, if the source configuration is ethernet -> microRendu powered by LPS1 -> DAC powered by mR or battery, there isn't any direct connection to AC so no loop can form for this section of the audio chain even if there may be leakage currents in the pre-amp earth.

 

BUT if say, I dont use an isolated power supply like the LPS1, then the magnified leakage currents may flow from pre-amp back to the mR, through it's non-isolated power supply and into the AC thus forming the loop.

 

Is my understanding correct? If so it seems pretty critical to isolate (from AC) the source starting after the Ethernet point and down the signal path as far as possible.

[One and a half]

All the more reason to use XLR cables. Leakage currents are lucky to be non-symmetrical.

[JohnSwenson]

If leakage currents are being formed in power and pre-amps and can flow backwards up interconnects then it's just as crucial to investigate and eliminate these rogue currents as it will affect both the digital and analogue realms as described. There's no point caring so much about source and DAC power supplies while ignoring down line power supplies that contaminate upstream the same way. In fact, if I understand correctly, these rogue currents are amplified by the pre-amp and may be order/s of magnitude higher than before.

 

That said, if the source configuration is ethernet -> microRendu powered by LPS1 -> DAC powered by mR or battery, there isn't any direct connection to AC so no loop can form for this section of the audio chain even if there may be leakage currents in the pre-amp earth.

 

BUT if say, I dont use an isolated power supply like the LPS1, then the magnified leakage currents may flow from pre-amp back to the mR, through it's non-isolated power supply and into the AC thus forming the loop.

 

Is my understanding correct? If so it seems pretty critical to isolate (from AC) the source starting after the Ethernet point and down the signal path as far as possible.

 

We have to stop speculation on this now, this is still not clear, it has NOTHING to do with an EARTH connection. The leakage current does not get amplified by the preamp, the voltage noise caused by the leakage current flowing through a resistance ( interconnect shield in this case) is what gets amplified. So the preamp does not amplify the leakage current, just the noise.

 

I have gone over a lot of this in other posts here on CA, (mostly in the Sonore and UpTone sections, so please look them up and peruse them. I'm going to be on airplanes and airports all day today and then VERY busy for several days, so I won't be able to go into long explanations on any of this for several days.

 

Main upshot, the LPS-1 on a microRendu helps a LOT in almost any system, making generalizations beyond that is very difficult, and needs to be delved into on a system by system basis. There is a lot of education that needs to be done for people to understand how to analyze their own system and pinpoint where the most likely "problem points" may be and do things to improve them. Dealing with the digital side of things probably gets many systems 90% of the way there. Getting the remaining 10% cannot be done with a one size fits all approach.

 

John S.

[JohnSwenson]

All the more reason to use XLR cables. Leakage currents are lucky to be non-symmetrical.

 

Someone else did an in depth analysis of leakage currents and balanced systems and found that how much their effects were mitigated by the balanced system was heavily dependent on the implementation of the input receiver. some designs did a good job of decreasing the effects and others did not.

 

Unfortunately I cannot find the paper right now.

 

John S.

[vortecjr]

If leakage currents are being formed in power and pre-amps and can flow backwards up interconnects then it's just as crucial to investigate and eliminate these rogue currents as it will affect both the digital and analogue realms as described. There's no point caring so much about source and DAC power supplies while ignoring down line power supplies that contaminate upstream the same way. In fact, if I understand correctly, these rogue currents are amplified by the pre-amp and may be order/s of magnitude higher than before.

I don't believe this is a valid statement. Steve Nugent once said here something like I never met a system that didn't like a better source. We connect microRendu's to new systems everyday without knowing anything about what is happening downstream. I do believe that there are gremlins that need to investigated and eliminated because every system has them. That reminds me...I have to investigated and eliminated something that is rattling in my kitchen. If you currently have rogue currents amplified by the pre-amp that are order/s of magnitude higher than before I think you would know it.

 

That said, if the source configuration is ethernet -> microRendu powered by LPS1 -> DAC powered by mR or battery, there isn't any direct connection to AC so no loop can form for this section of the audio chain even if there may be leakage currents in the pre-amp earth.

 

BUT if say, I dont use an isolated power supply like the LPS1, then the magnified leakage currents may flow from pre-amp back to the mR, through it's non-isolated power supply and into the AC thus forming the loop.

The loop can form anyplace between two power supplies in the system. Not everyone is going to have a battery or an Uptone Audio LPS-1 so a good linear power supply is recommended. That said, there is a time and a place for everything and I have a system in my home with my trusty iFi iPower supply.

 

Is my understanding correct? If so it seems pretty critical to isolate (from AC) the source starting after the Ethernet point and down the signal path as far as possible.

A good start, although not very practical, would be to replace every power supply in your gear with an Uptone Audio LPS-1:)

[flkin]

...So the preamp does not amplify the leakage current, just the noise.

 

John S.

 

Ah ok, misread your earlier explanation. Thanks for the clarity.

[flkin]

...my trusty iFi iPower supply.

@&$!

[vortecjr]

@&$!

 

I have no clue what you mean by that.

[asdf1000]

Hi guys

 

Would something like these 2 items be a suitable power supply test for the mRendu + LPS-1? I generally only listen for 1-2hour maximum, so I plan is to fully re-charge this LiPo battery after each listening session. So I wouldn't think I'd approach dangerous low voltage (3V) for each individual cell after only 2 hours listening.

 

https://www.dfrobot.com/index.php?route=product/product&search=7.4v+lipo&description=true&product_id=489

 

and

 

https://www.dfrobot.com/index.php?route=product/product&search=7.4v+lipo&description=true&product_id=1212

 

Appreciate any advice. If this proved a good power supply for the mRendu, I'd then plan to go to the LPS-1 for sure.

 

Cheers!

[jaaptina]

Hi guys

Would something like these 2 items be a suitable power supply test for the mRendu + LPS-1?

 

 

I've been thinking along similar lines. Using 6 AA batteries now. Sounds great!

Recharging of the AA batteries is a hassle. Thought of buying a 7.2 V batterypack and a charger. Similar to what you propose.

 

However I've got two considerations:

1) You'll want to unplug the batteries when not listening. The microRendu might not like frequent unplugging.

2) Occasionly the battery power will drop below acceptable level and the microRendu will shut down. This might be damaging?

[JohnSwenson]

Hi guys

 

Would something like these 2 items be a suitable power supply test for the mRendu + LPS-1? I generally only listen for 1-2hour maximum, so I plan is to fully re-charge this LiPo battery after each listening session. So I wouldn't think I'd approach dangerous low voltage (3V) for each individual cell after only 2 hours listening.

 

https://www.dfrobot.com/index.php?route=product/product&search=7.4v+lipo&description=true&product_id=489

 

and

 

https://www.dfrobot.com/index.php?route=product/product&search=7.4v+lipo&description=true&product_id=1212

 

Appreciate any advice. If this proved a good power supply for the mRendu, I'd then plan to go to the LPS-1 for sure.

 

Cheers!

 

Be very careful with lithium packs like these. (This looks like a raw cell pack) Lithium batteries work very well as long as you don't discharge them below a certain voltage (the exact value varies by lithium chemistry type). If you DO discharge below the threshold a few times they stop working right and become useless as a battery. The microRendu does NOT have a circuit which will shut it down when the battery voltage gets too low so you can easily destroy your nice new battery pack very quickly.

 

The best bet is to get a battery pack which DOES include circuitry in the pack that does this monitoring and shuts down the output when it gets too low. If the description says it has a "chip" then you know it includes this circuitry.

 

A battery pack such as this can also produce extremely high currents, so a short can cause both the wires and the batteries themselves to get VERY hot, maybe even catch on fire, so you have to be very careful with them. The "chip" also limits the current so this does not happen.

 

John S.

[asdf1000]

Be very careful with lithium packs like these. (This looks like a raw cell pack) Lithium batteries work very well as long as you don't discharge them below a certain voltage (the exact value varies by lithium chemistry type). If you DO discharge below the threshold a few times they stop working right and become useless as a battery. The microRendu does NOT have a circuit which will shut it down when the battery voltage gets too low so you can easily destroy your nice new battery pack very quickly.

 

The best bet is to get a battery pack which DOES include circuitry in the pack that does this monitoring and shuts down the output when it gets too low. If the description says it has a "chip" then you know it includes this circuitry.

 

A battery pack such as this can also produce extremely high currents, so a short can cause both the wires and the batteries themselves to get VERY hot, maybe even catch on fire, so you have to be very careful with them. The "chip" also limits the current so this does not happen.

 

John S.

 

Thanks John.

[MrUnderhill]

SBooster LPSU 6v:

 

 

Got this last Friday. This is not a Damascene experience, in my system it does not change the character of what I hear; bare in mind that I am passing the mR output into a Mutec MC-3+USB. What the SBooster does do is:

 

 

 

1. Improve the quality of the high frequencies; and
   
2. Further uncover low level information in the music.
   

Example:

 

Signe from Eric Clapton Unplugged.

Standard test piece for me. Included in the supporting percussion are a triangle and wood blocks. These were evident before but, in the case of the triangle the emphasis was on the leading edge and it could almost sound truncated, and out of time in places; now you hear the rounded ring, it falls further back into the mix but you can here what the percussionist is doing. Similarly the wooden blocks are more of the piece and you can hear the resounding wooden sound, rather than a greater emphasis on the strike.

 

 

In summary, the Sbooster improves on what my system is doing right. This can almost sound minor, but in terms of what we are after in High Fidelity I suspect it is not - I just don't think it will supply this on its own. If your system is in good shape it will help focus what is already there.

 

 

M

[Al Jones]

A very accurate description of the improvements offered by the Sbooster range.

 

Yesterday, in another thread, I described the Sbooster sound as "quieter and cleaner, with more low level detail."

 

This is likely, in part, due to it being a single output LPS

 

In direct comparison of the 6V and 9V versions with the microrendu, I find that the 9V offers even more of the same.

 

This could be worth noting, for those considering an energizer PS for the LPS-1. Only the 9V is compatible.

[Confused]

SBooster LPSU 6v:

 

In summary, the Sbooster improves on what my system is doing right. This can almost sound minor, but in terms of what we are after in High Fidelity I suspect it is not - I just don't think it will supply this on its own. If your system is in good shape it will help focus what is already there.

 

 

M

Actually, this does not sound minor at all to me. I too am running a microRendu (with iFi) via a Mutec MC3+USB. To be honest, this combination sounds just so good that part of me was thinking that a linear PSU for the microRendu was unlikely to deliver any improvements. (less mains grunge accepted) So reading your post has perhaps nudged me the right way, if every thing is sounding good already, even the chance of the smallest of improvements is highly compelling! Thanks for sharing.

[vortecjr]

First post regarding the Uptone Audio LPS-1 Ultra Capacitor power supply with a Sonore microRendu:

 

http://www.computeraudiophile.com/f27-uptone-audio-sponsored/ultracap%99-linear-power-supply-1-launch-thread-29974/index8.html#post591892

[asdf1000]

Be very careful with lithium packs like these. (This looks like a raw cell pack) Lithium batteries work very well as long as you don't discharge them below a certain voltage (the exact value varies by lithium chemistry type). If you DO discharge below the threshold a few times they stop working right and become useless as a battery. The microRendu does NOT have a circuit which will shut it down when the battery voltage gets too low so you can easily destroy your nice new battery pack very quickly.

 

The best bet is to get a battery pack which DOES include circuitry in the pack that does this monitoring and shuts down the output when it gets too low. If the description says it has a "chip" then you know it includes this circuitry.

 

A battery pack such as this can also produce extremely high currents, so a short can cause both the wires and the batteries themselves to get VERY hot, maybe even catch on fire, so you have to be very careful with them. The "chip" also limits the current so this does not happen.

 

John S.

 

Hi John and JR @vortecjr and all

 

Is there danger with discharging alkaline batteries below a certain voltage, with the microRendu?

 

Or is this only a danger with lithium rechargeables?

 

So if i wanted to test my microRendu with 4 alkaline batteries in a battery holder like linked below, is there any danger to the batteries or to the microrendu if I use the alkaline batteries until the mirorendu stops getting the sufficient voltage it needs?

https://www.jaycar.com.au/4-x-aa-switched-battery-enclosure-with-2-1mm-dc-plug/p/PH9283

 

I'm looking to test with batteries before ordering the LPS-1 :-)

 

But I don't want to start a house fire in the process (batteries catching fire) or damage the microrendu due to low voltage supply !

 

Thanks in advance

[romaz]

Hi John and JR @vortecjr and all

 

Is there danger with discharging alkaline batteries below a certain voltage, with the microRendu?

 

Or is this only a danger with lithium rechargeables?

 

So if i wanted to test my microRendu with 4 alkaline batteries in a battery holder like linked below, is there any danger to the batteries or to the microrendu if I use the alkaline batteries until the mirorendu stops getting the sufficient voltage it needs?

https://www.jaycar.com.au/4-x-aa-switched-battery-enclosure-with-2-1mm-dc-plug/p/PH9283

 

I'm looking to test with batteries before ordering the LPS-1 :-)

 

But I don't want to start a house fire in the process (batteries catching fire) or damage the microrendu due to low voltage supply !

 

Thanks in advance

 

I tested and compared a regulated lithium battery supply against the LPS-1 with my mR. In my system anyway, leakage current was not that big of a deal. The battery supply against my iFi resulted in only a small improvement. The LPS-1 against my battery supply, however, resulted in a tremendous improvement. Small batteries without regulators are low noise but they are generally not low impedance and this appears to be what is most responsible for the LPS-1's magic in my system.

[asdf1000]

I tested and compared a regulated lithium battery supply against the LPS-1 with my mR. In my system anyway, leakage current was not that big of a deal. The battery supply against my iFi resulted in only a small improvement. The LPS-1 against my battery supply, however, resulted in a tremendous improvement. Small batteries without regulators are low noise but they are generally not low impedance and this appears to be what is most responsible for the LPS-1's magic in my system.

This is interesting. Of course it's all system dependent as you say but I have a low loise linear PSU powering my microRendu already (7V Gieseler).

 

I thought a 6V battery pack would be a good indicator for determining whether I should try the LPS-1 but your results suggest even if I hear no difference against my linear PSU (compared with a battery pack), I could still be in for a surprise with the LPS-1

 

Thank you for sharing.

 

PS: out of pure interest only, could you share your system chain?

 

Thanks again

 

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