Audience Adept Response AR6P.


The topic of PLCs has been hot lately, hence I feel it's a subject worth investigating further. With this post, I will attempt to demystify some of the technical aspect of PLCs. In hope that a more informed buyer is a smarter buyer.

There are basically four types of PLCs competing in the market today. They are:

1) Passive Filters - These are the earliest and technically the most basic of methods. It merely involves filter caps of various values, coupled with cryogenitically treated contacts and sometimes add choke filter in to the power line. The sound characteristics of this type of PLC is rather un intrusive, especially when the design uses low value filter caps of 0.1uf like the Shunyata Hydra. It basically retains the sound of the system powered by it, but with further refinements at the top end and perhaps add a little bloom to the mids. Sometimes, in circuits where a power factor cap of 4.7uf is installed in the schematics, the bass will probably also tightened up a bit. Some models like the Shunyata Hydra 8 and Audio Magic Stealth XXX has compound screening to further reduce the effects of airborne RFI and EMI interference. The most successful representation of this type are Shunyata Hydras, Audio Magic Stealth series and Audience Adept Response models.





Audio Magic Stealth XXX.


Shunyata Hydra 4 undressed. Note the red MOV, grey circuit breaker, black 0.1uf filter X-2 caps and the cyro ed bus bars connecting the duplex receptacles.

Shunyata Hydra 6.


2) Transformer Based - It's really baffling what the good ol' transformer, with it's various winding schemes can produce so many varieties of PLCs. You have parallel choke based types like the RGPC 400P, and there's also the balance transformer type like those made locally by Promithues Audio. Also available are the booster transformers employed by Isotek Titan and finally, we have isolation transformers like the famed Torus Power and RGPC Substation. AVRs can also be transformer based, just like the Soundstage brand sold by Tong Lee. As for the sound of the transformer based PLC is harder to tell, as each version will have their own characteristics. For example, a balance transformer winding splits the 240V input voltage to two 120V lines. Both are wind along side each other to cancel out noise, just like our balance XLR interconnects. Booster transformer can reproduce more ampere at output than what was feeding it at the input, hence it'll always sound muscular and in control. Isolation transformers isolate your audio system plugged thru it from the rest of your house, allowing your system to be heard at it's full glory.


Torus Power RM8A undressed, note the huge isolation transformer.


RGPC Substation, isolation transformer inside too! Claims to supply peak 4000W, double the Torus Power RM8A s, 2000W.


3) Re generators - Here, we have the most technically challenging, and in theory should be the most correct way of treating power line noises. It's like having the power station supplying direct power to your audio system. It takes power from the wall, converts them to DC voltage, either stored in batteries or huge storage capacitors, then amplify the DC back in to AC voltage just like a power amp would. With the new class D designs, you can get very high efficiency, hence very high out put from a very manageable package, it runs cool too! The sound aspect is very predictable too, to a certain degree. Both the PS Audio Power Plant Premier and Pure Power models have that characteristic balls out bass control, eerily quiet back grounds, wide band width transient response and out of this world micro and macro dynamics. It really totally takes over and changes the sound of your system substantially.


Pure Power AC re generator, UPS and offers full feature protection for your hifi!


PS Audio Power Plant Premier AC re generator.


4) Hybrids - Labeled as such, it means that the PLC uses more than one of the above three methods to treat power line noises. Isotek is one such example, like in my Sigmas model, you can actually find booster transformers, passive filter and power factor caps, married to choke filters to isolate each output.


Isotek Sigmas, a true hybrid for great performance.

Despite all the PLC technobable, I don't think it's any more help full at all, as PLC performance in any case, are hard to gauge for the following reasons.

a) They are reactive to the power quality of the area. Hence different areas will require different solutions to the problem. And if the power quality of an area is good to start with, you'll probably not hear much of improvements with the PLC, but if the power quality is poor to start with, the sound improvement perceived will certainly be more.

b) Different system places different demands on PLCs. Like ampere hungry tube power amps and mega watt class A rated solid state amps are the hardest to drive and will place very unreasonable loads upon PLCs. Smaller systems can in fact be more sensitive to changes with a PLC added.

c) Every audiophile, depending on his/her hifi journey have different expectations on PLC performance.

d) Setting up of PLCs, some will invariably respond better to tweaks, like isolation than others. Even the quality of input power cables and contact plugs matter too.

Technical merits aside, the final advise is still to try before you buy! No other way to guarantee you get the most suitable PLC for your system and budget requirements.

18 comments:

hifikaki said...

panzer,

Another masterpiece! You are our power-guru!

Anonymous said...

You have missed out a few more
1) Parallel Noise Filters using caps
eg
PS Audio Noise Harvertors
Blue Circle Noise Hounds
Alan Maher's Power Enhancers
2) Electromagnetic Frequency based Power conditioning
eg
QRT Symphony
Nordost Quantum
Acoustic Revive RR-77
Synergistic Research Powercell
3) Totally Passive Power Distributors ie
no on/off switch, L.E.D.s, fuses, surge suppressors, transformers, chokes, filters, bells, or whistles
eg
Oyaide MTB
Acoustic Revive RTP Ultimate
ORB Kyoto
AudioExcellence PowerWing
Walker Audio Velocitor
Just mainly based on control of resonance and absorption of EMI.

Felix said...

Good write up!

Very useful for me, at least!

Anonymous said...

I agree totally with hifikaki. You have given to those looking for plcs a more informed base to start with, which is most helpful. An exellent, unbiased and "DESIRABLE" write-up, keep it up.

Anonymous said...

You have missed out a few more
1) Parallel Noise Filters using caps
eg
PS Audio Noise Harvertors
Blue Circle Noise Hounds
Alan Maher's Power Enhancers
2) Electromagnetic Frequency based Power conditioning
eg
QRT Symphony
Nordost Quantum
Acoustic Revive RR-77
Synergistic Research Powercell
3) Totally Passive Power Distributors ie
no on/off switch, L.E.D.s, fuses, surge suppressors, transformers, chokes, filters, bells, or whistles
eg
Oyaide MTB
Acoustic Revive RTP Ultimate
ORB Kyoto
AudioExcellence PowerWing
Walker Audio Velocitor
Just mainly based on control of resonance and absorption of EMI.

Anonymous said...

Good piece, Mr Panzer ... there're so many PLCs in the market, it's getting confusing. Yes, trying before buying is the best advice.

Oh, what about those balanced power transformers made locally by AVIA?

Annoymouse

kiarch said...

Well researched papers that gives good & concised summary of the topic; welldone (again) Panzer.

Of course, in each and all 4 aforesaid types of PLC, there is issue of different levels of excellence in each that bear its desirability.

Ed said...

Just a few more types to add to the list
1) Parallel Noise Filters using mainly capacitors
eg
PS Audio Noise Harvertors
Blue Circle Noise Hounds
Alan Maher's Power Enhancers
2) Electromagnetic Frequency based Power conditioning
eg
QRT Symphony
Nordost Quantum
Acoustic Revive RR-77
Synergistic Research Powercell
3) Totally Passive Power Distributors ie
no on/off switch, L.E.D.s, fuses, surge suppressors, transformers, chokes, filters, bells, or whistles
eg
Oyaide MTB
Acoustic Revive RTP Ultimate
ORB Kyoto
AudioExcellence PowerWing
Walker Audio Velocitor
Just mainly based on control of resonance and absorption of EMI.

Panzer said...

Hey guys!

Thanks for the kind words, for which without this blog as my platform, I would not have the oppurtunity to explore and learn so much. It is my outmost pleasure to share what little knowledge that I have aquired.

hifikaki,

no power guru me.

Felix,

Glad that you've found this posting usefull.

Anonymous 11.12am

Thanks for the encouraging words.

Anonymous 2.45pm,

I felt confused too, hence the research. I have used the locally made AVIA tranformers before, they were good then, however then PLC technology has been moving on at a rather rapid pace. Having said that, the AVIA products are still decent if no longer outstanding.

kiarch,

You're right, all the diferent methodology, but in the end the result of the execution is more important. All are valid from a technical point of view, some better than others, but in the end, nothing beats good quality parts, workmanship and sensible engineering at it's best!

kiarch said...

Hi Panzer,

Perhaps its good to note that not all of the PLC available in hifi market are power stablizer eventhough they are all an isolator.

For those PLC that are both isolator and stablizer, the type of servo used to maintain constant voltage will affects the condition of the post current that our hifi is using. I realised much of the noise are generated by the built-in servo constantly adjusting to maintain the output voltage.

It is good to also take note that the voltage in Malaysia is NOT 240V +-10% as from April last year. We are now offically running 230v +-10% given by TNB.

The reason for the change from 240v to 230v, accordingly, there is less waste in power mainly because all electrical equipment runs better in 230V. I guess not many people know about this unless you are in the industry.

Anonymous said...

230V? In principle, maybe. I regularly get 250V right up to 260+V ...!!!

Panzer: Somehow, I've not been able to find a PLC that does not reduce the dynamics and drive of a big power amp. They work with sources and preamps, though ... on the other hand, the balanced AVIA transformer seems to work nicely for power amps.

cheers
Anonymouse

Panzer said...

kiarch,

Malaysia now runs on 230V+/- 10%??? Now that's news to me, thanks. No wonder my in coming is now so much more stable. I used to get a range to 221V - 268V. Now, the tolerance is somewhat lowered to 236V - 258V, which is a big improvement.

km ng said...

Hi Panzer,

Great write-up!

Out of the 4 types of PLC mentioned, may I include a 5th.

The one from Quantum called Quantum Resonance Technology (QRT).

Quantum has licensed its QRT passive technology to Walker Audio ("Velocitor"), Nordost ("Thor") and Combak/Harmonix ("Reimyo ALS-777") PLCs - all pretty expensive stuff.


How does the QRT works? I can't explain here in layman language and I'm afraid you have to search the WWW for additional information.

I've heard the Walker's Velocitor in a friend's system and my 2 words reaction...

Simply awesome!

Panzer said...

Anonymouse,

Very creative that! If you find the AVIA works for you, all is well. And thanks for sharing.

Ed,

Thanks for adding to the list. I just did main four of the most common ones in general available.

KM,

QRT, I've read about them but there have not been any technical papers on them which I could understand. Also did not have a chance to try them. But who knows???

Also to note, the Nordost Thor is essentially a re- worked Isotek Sigmas, with new face plate, internally re-wired with Nordost wires, and perhaps have a thing or two added in to it. Also one of the very reason I bought the Isotek Sigmas. If it's good enough for Nordost to use as a starting base, it's pretty good for me too.

Ken said...

Hi Panzer,

Just two question.

1. Does all plc protect the system from lightning or power surge?

2. If it does, how did it do so?

Panzer said...

Ken,

I think most PLCs don't protect from from lightning strikes, and I believe very few offer power surge protection.

Even if they do offer surge protection, it's usually within a tolerance of +/- 20% or so bandwidth. And from what I experienced with TNB power supply, that 20% is not always enough to save the day. In the end, it's still the fuses, be it in the 13 amp UK plug or the equipment it self that saves my equipment! Hence why I am not too keen on NEMA 5-15 std plugs just yet!

Having said that, I can confidently say that Pure Power is better at offering protection than most other PLCs. Whilst the Pure Power was in my system, I knew at one particular moment lightning struck, but music carried on!, with no equipment damaged. As for the intensity of the lightning? I can't be sure, but my home circuit breaker did trip.

Anonymous said...

Wah, some of the PLC are pretty empty inside but still charges 4 figures and some even more than RM10k.

We need some local products for PLC.

Anonymous said...

AVIA has balanced transformers?
Who sells them now?
I bought my AVIA Powertrans from the late John Lim.