Puritan Audio PSM156 Review (AC Filter)

[antcollinet]

It is very difficult to see how it can be doing any sort of power factor correction - let alone adaptive correction without (as far as I can see) any active power switching devices.

It seems to have (again as far as I can see) only an EMC filter and some transient suppression devices. And given the wire size on that choke, I'd be concerned about its power delivery capability on 4x 1000W outputs. The only proviso is I have no idea what the two cylindrical components marked LAB12 are. I assume capacitors - but who knows.

Most of the circuit seems to be devoted to power analysis - but not much point in doing that if you can't fix anything.

Needless to say - it will provide zero improvement to your audio.

OK - looking again, what they are calling power factor correction is achieved at the left hand side of the board. I'm guessing it is switching in/out of circuit the two white capacitors using the relays.

I'm expecting they can "adapt" 4 levels of capacitance : none, small, large, small+large.

The problem is that this type of correction is used when driving inductive loads (such as motors), by compensating the inductive phase shift with capacitive phase shift. Further, it is intended to correct the power factor of the system seen by the mains supply, not by the connected devices.

It will do nothing to correct the power factor of typical audio kit power supplies, and in any case power factor correction doesn't help the devices which are generating the power factor issue. So, I'm not seeing any benefit for any connected audio equipment in doing this.

 

[Vhond]

Found some measurements:

Lab 12 Gordian | Power Line Filter/Quality Analyzer | Review Lab Evaluation - AVMENTOR.net

Lab 12 Gordian, Review Lab Evaluation, Read Interesting Stories and Reviews about Audio, Hi-Fi, 2-channel, stereo, and multichannel technologies

www.avmentor.net

 

[Toku]

Found some measurements:

Lab 12 Gordian | Power Line Filter/Quality Analyzer | Review Lab Evaluation - AVMENTOR.net

Lab 12 Gordian, Review Lab Evaluation, Read Interesting Stories and Reviews about Audio, Hi-Fi, 2-channel, stereo, and multichannel technologies

www.avmentor.net

Unfortunately, when I look at the graph of the results, I can't find any points for improvement.

 

[Papillon]

This thing works quite well and is exactly doing what we expect from the mains filter. The meaningful test would be with several audio components connected to its plugs and mutually interconnected to make an audio chain. Especially if some of them use SMPS power supplies. This would show if there is an effect to reduce switching frequency intermodulations. The test with single component like DAC or preamp is meaningless.

Hello
I have a device with smps power
Connected on the psm156, we noticed that it was sending noise to the other sockets of the psm!
Measures with an emi line meter
I don’t know if this is normal

 

[antcollinet]

Hello
I have a device with smps power
Connected on the psm156, we noticed that it was sending noise to the other sockets of the psm!
Measures with an emi line meter
I don’t know if this is normal

I would say normal. The device is designed to filter noise from the mains, not from one device to another. Even then it only reduces noise at the higher frequency end by about 10dB

There is a small filter for each socket which will filter some cross contamination - but presumably only provides a small amount of that 10dB.

No filter removes all noise - there is only ever attenuation.


Having said this - it really does't matter. Noise on the mains input to your device is very unlikely (if the device is decently designed) to find its way to the audio output in any audible form.

 

[Papillon]

Thanks a lot for your answer.
I am concerned though that the smps power supply then sends noise on the circuit which can't be something beneficial.
but perhaps it's not that important

 

[antcollinet]

Thanks a lot for your answer.
I am concerned though that the smps power supply then sends noise on the circuit which can't be something beneficial.
but perhaps it's not that important

Every** mains powered device emits EMI on the mains - there are even standards that state how much EMI they are allowed to emit, as well as how much EMI a device must tolerate. Typically devices must tolerate 10x the EMI that other devices are allowed to emit.

It really is not that important unless you are experiencing audible noise. Then you need to investigate further - though more often than not, that will be ground loops rather than mains EMI.

** with some few exceptions - eg totally passive devices such as fanless electric bar fires.