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Power conditioning vs DC blockers


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I am Looking at an ifi DC blocker or audio lab DC block unit. I’ve read that power conditioners are felt by many to negatively affect the liveliness  Of recordings. I don’t want to get into a debate about PC or not but are DC blockers less intrusive in this regard, anyone with listening experience? Have you tried either of these new and cheap dc blocking units?

Edited by Mjj
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You have confoosed me, Michael by referring to:

  • the iFi DC blocker on one hand
  • and a 'USB unit' on the other?

The iFi DC blocker operates like a 'normal' DC blocker ... in that it is fed by a mains cable ... and plugs into a component's IEC socket.  It's purpose is to stop any DC which might be on your mains ... from upsetting the mains power transformer in the component.  (DC can cause the power transformer to mechanically hum.)  The only comment I would make about the iFi unit ... is that it seems very small to be able to do a good/safe job?

 

So where does a 'USB unit' come into the picture?

 

Andy

 

Edited by andyr
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Andy, sorry it was a spell correct, I’ve edited the original post. 

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2 hours ago, Mjj said:

Andy, sorry it was a spell correct, I’ve edited the original post. 

 

OK then answering your original Qus:

  • some power conditioners do indeed negatively affect the SQ..  :(
  • my experience is that a good DC blocker will not.

Note: my definition of a "good DC blocker" is one that is able to pass the full 10a that a wall-socket can deliver.

 

Andy

 

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16 minutes ago, andyr said:

some power conditioners do indeed negatively affect the SQ

Maybe. However some are definitely very beneficial.

John

 

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34 minutes ago, andyr said:

 

OK then answering your original Qus:

  • some power conditioners do indeed negatively affect the SQ..  :(
  • my experience is that a good DC blocker will not.

Note: my definition of a "good DC blocker" is one that is able to pass the full 10a that a wall-socket can deliver.

 

Andy

 


 

https://www.audiosciencereview.com/forum/index.php?threads/equitech-1-5rq-balanced-power-review.24948/

 

I can safely assume that the above link to this product is an isolation transformer that has the potential to block DC?  Stand corrected if I’m wrong.  If you look at the scope on the input, Amir didn’t specify whether the probes are set to DC or AC, due to the mains test,  assume he’s set his probe to AC measurements, if he’s done that then he would have switched a in-line cap on the probe to filter out DC.  Regardless, you can see that the mains is actually distorting at the peaks on the left of the scope,  inline FFT you can see the measurement for distortion on the analyser….pretty horrific amounts of distortion!    Note also that the mains distortion is at both end of the +ve and -ve peaks are are almost identical,  therefore there is no DC offset resulting from the waveform!   
Note also when he sticks a amplifier on the end of the mains and note the distortion analysers for audio output!    Saids a lot for any “mains reconditioning products  or any DC blocker “ that’s on the market!  
As I’ve always outlined, even if you look at a linear PSU the audio isn’t even in the same circuit as the mains, they are in Line with the filter caps, bridge rectifier and secondary of the transformer…. And if there was any DC on the mains, your transformer will heat up quicker than normal, note that is a fact not fiction.  

Edited by Addicted to music
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9 minutes ago, Assisi said:

Maybe. However some are definitely very beneficial.

John

 

I'm not disagreeing with you, John.  :)

 

Andy

 

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Thanks for your comments gentlemen.

Reason I was asking as I have a humming Naim transformer and cannot trace the cause, separate power line. I looked at review of audiolab dc blocker from dealer on YouTube and was suggested it led to improved sq too. So at $229, I thought even sq improvement without stopping hum might be good. Paul McGowan from PSaudio commented that he found conditioners seemed to have a positive effect at first for him but robbed the sound of its “live feel” and he went back to socket only. I know the real answer is to try/listen myself and am searching for a means of doing that or finding a seller with a good returns policy.

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4 minutes ago, Mjj said:

Thanks for your comments gentlemen.

Reason I was asking as I have a humming Naim transformer and cannot trace the cause, separate power line. I looked at review of audiolab dc blocker from dealer on YouTube and was suggested it led to improved sq too. So at $229, I thought even sq improvement without stopping hum might be good. Paul McGowan from PSaudio commented that he found conditioners seemed to have a positive effect at first for him but robbed the sound of its “live feel” and he went back to socket only. I know the real answer is to try/listen myself and am searching for a means of doing that or finding a seller with a good returns policy.

 

I see you're in Melbourne, Michael - which makes it easy.

 

I can come over to your place (well, when the lockdown finishes!  :( ) and install one of my (10a) DC blockers - so you can immediately see whether or not it stops the humming coming from that Naim transformer.

 

I always recommend trialling before buying - because sometimes stopping DC doesn't stop the hum. 

 

It'll cost you more than $229 if you decide you want it, tho'.

 

PM me if you're interested.

 

Andy

 

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1 hour ago, Mjj said:

Thanks for your comments gentlemen.

Reason I was asking as I have a humming Naim transformer and cannot trace the cause, separate power line. I looked at review of audiolab dc blocker from dealer on YouTube and was suggested it led to improved sq too. So at $229, I thought even sq improvement without stopping hum might be good. Paul McGowan from PSaudio commented that he found conditioners seemed to have a positive effect at first for him but robbed the sound of its “live feel” and he went back to socket only. I know the real answer is to try/listen myself and am searching for a means of doing that or finding a seller with a good returns policy.


I would be sceptical of Paul McGowans intentions, PS Audio sells power conditioners.

 

There are many reasons why transformers hum,  DC on the mains is pure myth in 95% of cases.   Reasons could include,  over mains Voltage 230vAC +  faulty transformers,  electrolytic caps passing there life,  even other equipment that’s in the house that’s put your audio a receptive Device to there emissions… Also circuit failure in the electronics that’s drawing more current than usual will cause transformers to hum or buzz.   Definitely look at things you can eliminate yourself b4 you go spending on marketing hype.  

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Reason I was asking as I have a humming Naim transformer and cannot trace the cause, separate power line. I looked at review of audiolab dc blocker from dealer on YouTube and was suggested it led to improved sq too. So at $229, I thought even sq improvement without stopping hum might be good. 

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I agree, re-hype and cautions re online opinions and reviews, couldn’t cover every aspect of my thinking in original post.
 

Interesting comment on overvoltage, I consistently have greater than 230v here. Currently 235v. 

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17 minutes ago, Mjj said:

I agree, re-hype and cautions re online opinions and reviews, couldn’t cover every aspect of my thinking in original post.
 

Interesting comment on overvoltage, I consistently have greater than 230v here. Currently 235v. 

That could well be the lowest overvoltage in the country. 

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I have the top model power conditioner from PS Audio. Somehow despite all its fancy regeneration from scratch with an allegedly perfect low impedance sine wave, it manages to not block DC.

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Just sharing my experience and agree that you need to try with your particular gear as there can be many reasons for hum.  I was interested in trying a balanced transformer as a low cost alternative to a power conditioner and after reading things like this. 

 

I sourced an Airlink BT. After initially hearing some benefits mentioned in the thread, I also sporadically would hear some hum buzz from the Balanced transformer.  I thought this is strange as it was not constant and at times there was no noise at all. So I bypassed the BT and listened for hum from the rest of my gear and I indeed could hear a little bit coming from my amplifier transformer which I hadnt noticed previously but it had the same characteristics. Once the BT was connected again I couldnt hear any noise from the amp but it was also hard to hear over the BT noise as we are talking pretty low level noise.  I then tried a dc blocker in front of the BT and from then it was quiet and didnt make any further noise and also the amp.

 

Since then my understanding is that the BT will block DC to downstream components but can be affected by DC itself as it is usually a big transformer.  So long story short the dc blocker stopped hum.  the unit you mention has an RFI filter so that may affect sq. Definitely take up @andyr's offer or some other way of trying a dc blocker at no/low cost to at least determine if a dc blocker will help as @Addicted to music is very right to point out it may be a separate unrelated issue altogether. 

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32 minutes ago, Ittaku said:

I have the top model power conditioner from PS Audio. Somehow despite all its fancy regeneration from scratch with an allegedly perfect low impedance sine wave, it manages to not block DC.

 

That is odd as my lowly recently procured PS-10 does not hum itself  and neither do the downstream components whereas I know I have significant dc on my lines at various times as mentioned above. Although I have read that PS10's themselves are not immune to hum and may require a dc blocker I havent heard of them passing on DC. Just wondering how you have come to that conclusion . Did you measure or some other way of determining?

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1 hour ago, Addicted to music said:

PS Audio sells power conditioners.

My understanding is that PS Audio manufactures/sells regenerators.  Not conditioners.  They are different products.

John

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13 hours ago, andyr said:

 

I'm not disagreeing with you, John.  :)

 

Andy

 

Andy, Maybe I was being a little bit pedantic.  I should also have said that the Conditioner that I have has as a feature:

“…DC Offset Blocker – a circuit eliminating unwanted DC component of the power grid.”

Whatever that means.  I am told it is benefit.

John

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3 hours ago, andyr said:

 

I see you're in Melbourne, Michael - which makes it easy.

 

I can come over to your place (well, when the lockdown finishes!  :( ) and install one of my (10a) DC blockers - so you can immediately see whether or not it stops the humming coming from that Naim transformer.

 

I always recommend trialling before buying - because sometimes stopping DC doesn't stop the hum. 

 

It'll cost you more than $229 if you decide you want it, tho'.

 

PM me if you're interested.

 

Andy

 

I'd go with this offer from Andy, as it is risk free trial, so you can see for yourself it a DC Blocker will benefit you and apply to the issue you have.

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@Hydrology have you tried this unit? Or know someone who has? Yes it says 150watt 2ch max. My amp is around 70watts per ch 8 ohm.

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Ive tried it with my Hegel H390 and found no issues. It neither improved nor deteriorated sound quality, but did remove a slight transformer hum. I have also used the bigger IsoTek DC Synchro units (16A?) with great success

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Posted (edited)

That’s encouraging.. there’s a YouTube review with a H590 that’s really positive. I’M presuming the isotek is quite a lot a more $$ ?- what did the isotek do for you?

 

Edited by Mjj
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I lived in a semi-detached house, whose poor wiring no doubt led to all my power amplifiers having a slight buzz/hum.

 

All the DC blockers I had (3 different ones) worked, they reduced the hum a lot (90%) and made the sound better. But they also took something away. DC blockers sit on the peak transient for bass impact and speed. Possibly the cap bank in your average commercial DC blocker needs to be a lot bigger.

 

Anyway when I got into a new house I had it fully rewired top to bottom and now there is no hum whatsoever. The DC blocker in this new place was just a net negative to audio system performance.

 

If you put in a DC blocker and it improves things, try taking it out later as well. You may find it makes things quieter but also makes things a bit flat. I hear the same things with DC blockers as with ferrite cores. They initially seem to improve things but upon later removal you realise what was lost.

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