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Puritan Audio PSM156 Review (AC Filter)

D

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Yeah, the crossing angle of the cables is important of course. I'm limited because the cables come parallel at the back, I've done what I can. The turntable is grounded and all possible ground loops have been avoided.

The noise was there even before I incorporated a DAC into my setup. The problematic chain is turntable -> preamp -> amplifier -> speakers. And I'm sure that the noise enters the system through the RCA cables between the turntable and the preamp.

Thanks to everyone for digging into this issue, but I considered it solved long ago. The current level of noise is low enough to be labeled as background. I'm only curious into finding if a filter like the measured on this thread or a cheaper one like many have shown could solve issues like this that present real listenable artifacts.

The following is more or less a guess based on the information that there is a cable bundle of rca and power cables.
In this case the noise possibly is generated by one of the power supplies of the devices, e.g. a poorly damped reonance that coupled into all cables. You would notice it in the turntable the most (or only) because that signal is most amplified. You'd likely also notice it in a microphone cable going to a preamp.
- The likely easiest way to fix it is to separate signal from power cables (running power cables close to digital is always discouraged, even in digital)
- If you cannot move the cables, an option is to put the phono preamp close to the turntable and run the hotter output signal in the bundle.
- Last resort would be to identify the problematic device and replace it.
I don't see many alternatives. A power conditioner may somewhat smooth the current that causes it but I'd be surprised if it fully solves it.

This would of course need further experimentation and I could be off but hope it is helpful..
 
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It's neither deceptive nor wrong.
It is a deceptive argument that fooled even researchers for a long time but science is moving away from looking at currents..

The 'flattening' of the top of the sine wave is caused by devices having a rectifier. What will be defined is how much flattening is allowed.
Correct, the flattening of the voltage profile is the problem because this means the device is distorting the voltage for everyone else.
The result is immediately visible in harmonics and THD. There are stringent limits to both metrics (IEEE has also current TDD limits).
This is why a lot of devices, except low power, now use a PFC stage.

And no this is not a problem.
Sorry, I could not makes sense of this in the context of your response.


PS. I agree with your statements in the original post:
When troubled with ticks and noises... first get the equipment and interlinks sorted out (not easy to do) and only then start with power supply conditioning.
One can only gain so much starting out with mains filtering.

See mains filtering as a last resort instead of a starting point for improving a flawed audio system.
I would even go so far to say that mains filtering is not a solution; just a patch for an underlying problem.
Regarding my answer, I just pointed out that rectifier current (or grid current in general) is usually not the problem (grid voltage is) but you can certainly find scenarios where current is the problem.
 
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solderdude

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Current shape isn't the problem unless the average current exceeds the fuse rating or is out of phase too much (the latter is not an issue with rectifiers that much)

Power is voltage x current ... I don't think science is moving away from that. As soon as rectifiers are used the drawn current is pulse shaped. Science also is not moving away from that either.
Aside from a few heaters and filament light bulbs nearly every device has a rectifier in it. Its the reason why mains is flattened.
Why would science move away from that fact ?

Could you explain to a noob why that is deceptive ?
 
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ShinMolina

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The following is more or less a guess based on the information that there is a cable bundle of rca and power cables.
In this case the noise possibly is generated by one of the power supplies of the devices, e.g. a poorly damped reonance that coupled into all cables. You would notice it in the turntable the most (or only) because that signal is most amplified. You'd likely also notice it in a microphone cable going to a preamp.
- The likely easiest way to fix it is to separate signal from power cables (running power cables close to digital is always discouraged, even in digital)
- If you cannot move the cables, an option is to put the phono preamp close to the turntable and run the hotter output signal in the bundle.
- Last resort would be to identify the problematic device and replace it.
I don't see many alternatives. A power conditioner may somewhat smooth the current that causes it but I'd be surprised if it fully solves it.

This would of course need further experimentation and I could be off but hope it is helpful..
That's already what I did months ago and that's why I consider it solved. I have updated every device in the setup: the preamp, speaker amplifier, the turntable and all the RCA cables. The only things that helped was the replacement of the RCA cables by properly shielded ones and making some cable management.

The noise is present whenever I put the RCA cables from the turtable close to any power cord carrying 220V AC. I don't know if there is an specific problematic power supply in my setup, so far every of the power cables going to a device in the setup causes the problem and there have been many: BRZHIFI TPA3255A amplifier, SMSL DA-9, Cambridge Audio Alva Solo and an old Technics power amplifier. I doubt that all of those device's power supplies are problematic since their devices differ in everything possible.

I haven't measured the 8 kHz noise with the current setup, but it is much lower than the turntable rumble comming from the speakers. You need to put your ear against the speaker to hear it and even then is very faint.
Easy to check for near no money:

https://www.aliexpress.com/item/32880545504.html?spm=a2g0s.9042311.0.0.27424c4dYIvajh

https://www.amazon.com/Filtering-Frequency-Two-stage-Low-pass-Optional/dp/B07T55RCLW?th=1

But only recommended for people who know what they do. High chance of getting electrocuted when fiddling with this stuff!
Yeah! Those are the ones I have looked at. I haven't bought them because I don't want the possibility of wasting more money since I like my setup now.
 

pma

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The noise is present whenever I put the RCA cables from the turtable close to any power cord carrying 220V AC

Have you minimized the area between L and R channel RCA cables? It should be as low as possible, you may try to twist them.
 

ShinMolina

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Have you minimized the area between L and R channel RCA cables? It should be as low as possible, you may try to twist them.
They are touching along all the way, so the area is as minimal as possible to reduce the antenna effect. I use velcro to keep my cables tidy. The only close AC line I have is the one at the back of the preamp.

Apart from that, every other power line is as far as I can get them. The RCA cable is quite thick and the length is exact, if I twist them they won't reach.
 
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Current shape isn't the problem unless the average current exceeds the fuse rating or is out of phase too much (the latter is not an issue with rectifiers that much)
The grid in our homes is a voltage source with series inductance (and resistance but that is small and can be ignored for all intends and purposes).
We say the grid is strong, when the inductance is small (usually in cities or close to substations) or a weak grid has a high inductance (usually in rural areas with long lines).
Loads with a certain current/power draw can distort the voltage (because there is the series inductance). Grid standards are increasingly restricting anything that distorts the grid voltage (because it affects every device in the neighborhood), less so the current because it does not do much (unless it affects the "source", i.e. voltage).
That being said, the grid codes on voltage are increasingly stringent and effectively imply that devices need to generate near-sinusoidal currents.

Power is voltage x current ... I don't think science is moving away from that. As soon as rectifiers are used the drawn current is pulse shaped. Science also is not moving away from that either.
Aside from a few heaters and filament light bulbs nearly every device has a rectifier in it. Its the reason why mains is flattened.
Why would science move away from that fact ?
Actually, voltage x current is what we call "instantaneous power", which is largely inconsequential for power conversion.
What we care about is the "average power" over one fundamental 50/60Hzperiod. This is also what we consider the power rating of a device. Instantaneous power can much higher than average power over short periods.

Regarding rectifier currents. Rectifiers are increasingly combined with a power factor correction stage (PFC) due to more stringent grid codes. With PFC, rectifier currents are near sinusoidal. This is done largely to mitigate issues related due to flat peaks (results for example in torque oscillations in induction machines).
 
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That's already what I did months ago and that's why I consider it solved. I have updated every device in the setup: the preamp, speaker amplifier, the turntable and all the RCA cables. The only things that helped was the replacement of the RCA cables by properly shielded ones and making some cable management.

The noise is present whenever I put the RCA cables from the turtable close to any power cord carrying 220V AC. I don't know if there is an specific problematic power supply in my setup, so far every of the power cables going to a device in the setup causes the problem and there have been many: BRZHIFI TPA3255A amplifier, SMSL DA-9, Cambridge Audio Alva Solo and an old Technics power amplifier. I doubt that all of those device's power supplies are problematic since their devices differ in everything possible.

I haven't measured the 8 kHz noise with the current setup, but it is much lower than the turntable rumble comming from the speakers. You need to put your ear against the speaker to hear it and even then is very faint.

I think I'd need to see a scope measurement (ideally with fft) of the grid voltage and RCA at the phono preamp (when the tone is audible and when not) before I could say anything specific. A picture of the RCA/power bundle would be useful too. Otherwise, I'm just guessing...
 
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Regarding rectifier currents. Rectifiers are increasingly combined with a power factor correction stage (PFC) due to more stringent grid codes.
There is no uniform code or standard in US for power factor. Industrial users are the only ones charged and what is, is different from power company to power company. Residential customers are completely exempt so in the context of what we are talking about here, it is a non-factor. That said, power factor correction is good to have on high power equipment and for being a good citizen.

I have not seen much trend in incorporating PFC in consumer products as it increases costs and per above, it is next to impossible to establish value for it in the eyes of consumer.
 

solderdude

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The grid in our homes is a voltage source with series inductance (and resistance but that is small and can be ignored for all intends and purposes).
We say the grid is strong, when the inductance is small (usually in cities or close to substations) or a weak grid has a high inductance (usually in rural areas with long lines).
Loads with a certain current/power draw can distort the voltage (because there is the series inductance). Grid standards are increasingly restricting anything that distorts the grid voltage (because it affects every device in the neighborhood), less so the current because it does not do much (unless it affects the "source", i.e. voltage).
That being said, the grid codes on voltage are increasingly stringent and effectively imply that devices need to generate near-sinusoidal currents.

But what does it have to do with my statement being deceptive or wrong ?

Actually, voltage x current is what we call "instantaneous power", which is largely inconsequential for power conversion.
What we care about is the "average power" over one fundamental 50/60Hzperiod. This is also what we consider the power rating of a device. Instantaneous power can much higher than average power over short periods.

That's exactly what I explained... what was deceptive and wrong about it ?

Regarding rectifier currents. Rectifiers are increasingly combined with a power factor correction stage (PFC) due to more stringent grid codes. With PFC, rectifier currents are near sinusoidal. This is done largely to mitigate issues related due to flat peaks (results for example in torque oscillations in induction machines).

Not for audio equipment, maybe some high power class D power amp supplies though.
newer high powered UPS etc will have such circuitry.

What's it have to do with my posts being deceptive and wrong ?
 
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There is no uniform code or standard in US for power factor. Industrial users are the only ones charged and what is, is different from power company to power company. Residential customers are completely exempt so in the context of what we are talking about here, it is a non-factor. That said, power factor correction is good to have on high power equipment and for being a good citizen.

I have not seen much trend in incorporating PFC in consumer products as it increases costs and per above, it is next to impossible to establish value for it in the eyes of consumer.

True, the US grid is governed by de-facto requirements. UL certification is also not a requirement in general..
Anyhow, this is how PFCs gain value in the eyes of the customers (and they'll never know they have one):
https://www.apc.com/us/en/faqs/FA158939/
 
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But what does it have to do with my statement being deceptive or wrong ?

That's exactly what I explained... what was deceptive and wrong about it ?

Not for audio equipment, maybe some high power class D power amp supplies though.
newer high powered UPS etc will have such circuitry.

What's it have to do with my posts being deceptive and wrong ?
Your problem description was not accurate.
 

solderdude

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Your problem description was not accurate.

I wrote: There are a few things at play here and in audio all devices have rectifiers and no PFC.
All the power needed by the devices comes from short current peaks.
Few people realize that so that's what I pointed out in more detail amongst some other aspects.
There was nothing inaccurate nor misleading about that.
 

audio_tony

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At least it has more passives in it than this IsoTek 'Cleanline'!
 

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sarumbear

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By your definition ever electric motor or overhead line is a RF device.
Science tends to distinguish between high frequency (rf, emc, etc) and low frequency. While Maxwell's laws apply to both, different mechanisms are dominant.
8kHz is low frequency.
Electromagnetic radiation (EMR, not EMC) is waves of the electromagnetic (EM) field that are propagating through space, carrying electromagnetic radiant energy.
Radio frequency (RF) is the oscillation rate of a magnetic, electric or electromagnetic field or mechanical system or an AC current, voltage, above the audio frequency range to around 300 GHz.

The above are standard definitions of EMC and RF, not mine. If you had taken Phsyics101 you would know this.

So yes, all AC electric motors are RF devices. They are a designed to convert electric power to kinetic energy but they still generates some RF energy. Overhead lines are not RF devices because the frequency of AC power they carry (50-60Hz) is much lower than the RF range.
 
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Electromagnetic radiation (EMR, not EMC) is waves of the electromagnetic (EM) field that are propagating through space, carrying electromagnetic radiant energy.
Radio frequency (RF) is the oscillation rate of a magnetic, electric or electromagnetic field or mechanical system or an AC current, voltage, above the audio frequency range to around 300 GHz.

The above are standard definitions of EMC and RF, not mine. If you had taken Phsyics101 you would know this.

So yes, all AC electric motors are RF devices. They are a designed to convert electric power to kinetic energy but they still generates some RF energy. Overhead lines are not RF devices because the frequency of AC power they carry (50-60Hz) is much lower than the RF range.

NO!!!

Speaking of Physics 101, you may want to have a look at
https://en.wikipedia.org/wiki/Faraday's_law_of_induction
https://en.wikipedia.org/wiki/Inductive_coupling
 

sarumbear

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That applies to resistors.
The grid is a voltage source and lines are inductive (not! resistive).
Fyi, I'm starting to enjoy this ;)
There is no voltage source in the real world; all have self resistance.
The grid lines are resistive as inductive.
There is no conductor that has zero resistance (in the environment that we live).

Mains voltage in US is generated at around 120VAC but by the time it reaches your socket it is at 117VAC. That loss is due to the combined resistance and inductance of the various types of power lines carrying the power to your socket in the wall. Those power lines can and do act as an RF antennae. Not to mention that a leaky filter maybe passing on the utility company's communication signal artefacts which are in the range of 10kHz to 100kHz. Look what else is going on inside your "voltage source" mains...

You are using limited level of formulaic knowledge and applying to real world without experience.
 

sarumbear

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storing

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using material sourced from a crowd sourced publication

While I get your general point about not wanting to argue on this, it's also not like there are factually incorrect things on those specific pages, I think, and the references are there, so please let's not go down the slippery slope of dismissing arguments when they use wikipedia because it's not 'real' science.
 

nyxnyxnyx

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At this point I'm convinced that 99,99% of "filter" products will never get a recommendation here. Mainly because the results concluded that many products don't really filter sh!t and the ones that actually do are not truly improving the sound quality of our soundsystem.

But still, somewhere in my foolish heart, I still have a soft spot for those good-looking products. At least this one actually does something, and maybe if the price is cheaper more people might pick it up just for their random moments of sheer unsighted subjectivity, or as a decoration piece.
 
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