No it is not. It is too much and it reflects in the filter transfer function measured. Q of the LC filters is affected.
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Puritan Audio PSM156 Review (AC Filter)
- Thread starter amirm
- Start date
No it is not. It is too much and it reflects in the filter transfer function measured. Q of the LC filters is affected.
OP
- Thread Starter
- #162
As if you know that your equipment has 50 ohm impedance to care? Let's dispense with fantasies here.
Honestly I had no idea that such a large portion of our senior members have bought into these useless things. Use it but don't waste my time with irrelevant comments like this.
solderdude
Grand Contributor
When the output of the DUT voltage was measured in parallel to a real world load I see no reason why the measurement would not be valid.
Maybe the transformer used to lower 110V to the measuring side should have an additional resistive load but that does not have to be 40 or 50 ohm IMO.
Amirs measurement goals are different from what others would like to see tested.
Amir does not have an EMC lab and even then the results would only mean something to folks that really understand what they mean and only test to certain levels (to which norm should be tested and which tests ?) and not to specific situations people moan about.
Folks.... realize Amir does NOT have an EMC lab, nor a makeshift one and even if he did he could not say this or that device will work well or may be plagued with gremlins in your particular situation.
One can see comments (and they do come in that form as well) as positive (instructive/informative/constructive) and negative (to put efforts or comments down).
The first type requires positive thinking and cooperation the second one only leads to threads going in the wrong direction.
Maybe the transformer used to lower 110V to the measuring side should have an additional resistive load but that does not have to be 40 or 50 ohm IMO.
Amirs measurement goals are different from what others would like to see tested.
Amir does not have an EMC lab and even then the results would only mean something to folks that really understand what they mean and only test to certain levels (to which norm should be tested and which tests ?) and not to specific situations people moan about.
Folks.... realize Amir does NOT have an EMC lab, nor a makeshift one and even if he did he could not say this or that device will work well or may be plagued with gremlins in your particular situation.
One can see comments (and they do come in that form as well) as positive (instructive/informative/constructive) and negative (to put efforts or comments down).
The first type requires positive thinking and cooperation the second one only leads to threads going in the wrong direction.
That's right so he should stick with measurements of output of the audio components only. This is where he has an equipment (and knowledge) for. AP is not suitable for measurements of AC mains power filters and the results measured by AP at conditions as described may be not precise enough and sometimes misleading.
solderdude
Grand Contributor
I would agree that to (probably) a lot of folks mixing audio output plots and mains FFT plots will be scrambled in their brains and misinterpret the results.
Yet, I feel when measuring the (differential ONLY) mains filtering effect plots help and show what at least some folks want to know.
The confusing part would be SINAD for mains measurements and the fact that folks won't understand why it is not of any consequence.
Yes, there are no common mode things which add much more audio-gremlins than differential mode (what is tested here) and yes the effect of things like DC offset are not shown but can be helpful in some cases where folks hear transformers hum and are annoyed.|
That doesn't mean its a pointless addition in a device that seems made to tackle mains related issues for which it is done.
I do agree with not trying to fix what does not need fixing and debunking the silly audio myths about improved fidelity which are not founded. For this the reviews are fine. They do not cover common mode issues which could be much more of an issue is correct criticism but we cannot demand Amir to also buy/have built an EMC lab or just 'wing' something to satisfy some folks.
My suggestion to @amirm would be to make the reporting a bit more suited for dummies as well and or elaborate a bit more or perhaps explain it in a video what the goal is and what is measured and why. Maybe this could result in less confusion and comments.
Yes, it will consume more time and thus one review less but may save everyone some stress...
Yet, I feel when measuring the (differential ONLY) mains filtering effect plots help and show what at least some folks want to know.
The confusing part would be SINAD for mains measurements and the fact that folks won't understand why it is not of any consequence.
Yes, there are no common mode things which add much more audio-gremlins than differential mode (what is tested here) and yes the effect of things like DC offset are not shown but can be helpful in some cases where folks hear transformers hum and are annoyed.|
That doesn't mean its a pointless addition in a device that seems made to tackle mains related issues for which it is done.
I do agree with not trying to fix what does not need fixing and debunking the silly audio myths about improved fidelity which are not founded. For this the reviews are fine. They do not cover common mode issues which could be much more of an issue is correct criticism but we cannot demand Amir to also buy/have built an EMC lab or just 'wing' something to satisfy some folks.
My suggestion to @amirm would be to make the reporting a bit more suited for dummies as well and or elaborate a bit more or perhaps explain it in a video what the goal is and what is measured and why. Maybe this could result in less confusion and comments.
Yes, it will consume more time and thus one review less but may save everyone some stress...
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This is the schematics of Schaffner FN2030-4 line filter. Current rated up to 4A.
In the schematic above, R1 is a generator output impedance and R3 is a load impedance. With 3kohm load, we have 17.6W power at 230Vac.
Now, let's change R1 (generator impedance) and see what happens with filter attenuation and resonance peak. R1 near zero would be the situation in the power mains net and R1 = 40 ohm is the AP generator situation.
With R1 = 40 ohm, we get lower resonance peak and better attenuation than in real life conditions.
In the schematic above, R1 is a generator output impedance and R3 is a load impedance. With 3kohm load, we have 17.6W power at 230Vac.
Now, let's change R1 (generator impedance) and see what happens with filter attenuation and resonance peak. R1 near zero would be the situation in the power mains net and R1 = 40 ohm is the AP generator situation.
With R1 = 40 ohm, we get lower resonance peak and better attenuation than in real life conditions.
Tks
Major Contributor
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Hey Amir, really quickly, do any of those now-discontinued Monster Power Conditioner's do literally anything of worth? My dad isn't an audiophile (he was an electrical technician working for a car factory before the advent of digital systems), and he claims these things are good at producing a cleaner sinewave at the end of the day. He doesn't think there is an audible benefit, but for older analogue devices due to the components they use, he thinks it does aid with preserving the lifespan of such products (like CRT's and Plasma's) And speaking of Plasma, he still has his Panasonic that he's used every day since like 07 or something with no hicups.
Any chance of those power conditioners at least delivering on stable power delivery if not the "cleaned up sine waves" as he assumes?
“Should”? I’m sorry but with what authority you can say that?
You showed us how Q of a filter changes with load resistance and that the load of AP may result around 5dB difference below -50dB attenuation at the arbitrarily selected 20kHz. I don’t know what the moderator will say but in my book it looks like arguing for the sake of arguing.
Science is not just maths.
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Please learn to read the posts and graphs before you comment. My post showed the effect of the generator output impedance, not the filter load impedance (I hope you understand the difference). The load impedance was kept constant 3kohm, which equals to 17.6W power at 230Vac mains, quite usual load of a bigger preamp or smaller power amp. 0 ohm generator output impedance is close to mains impedance (speaking about lower frequencies), 40 ohm AP generator impedance is far from reality. I would ask for some technical level of my opponents if they wish to argue.
I apologise miss-typing load instead of output, however nothing else I said has changed. You have simply demonstrated that the filter Q changes with resistance. So what? That’s what Q is about.
My comment and what the equipment test are about attenuation of the filter at it’s stop band. You showed that attenuation at 20kHz changes around 5dB at -50dB attenuation when the resistance is altered. It looks like you are arguing that such a small difference in the mains supply will cause an effect to the audio signal. I disagree as there is no reason for that to happen. So far you have not even tried to explain the reasons for that to happen other than finding peripheral issues at @amirm’s test setup.
FYI my technical level is summarised in the footer of all my posts with more in my about page. Maybe you care to tell us yours?
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Do you still hear the 8kHz signal when you disconnect the phono cable from the preamp?
ShinMolina
Active Member
No, I only hear the 8 kHz when the turntable is connected to the preamp. The noise is higher when the RCA cables are closer to the AC power cords, it is "funny" to play with them as I move them closer and further.
Then the phono cable (or the pickup, or both) act as antenna. No mains filter will fix this. You may need a better suited phono preamp. I'm not sure whether it's possible to design a filter for the input of your phono preamp. Is it MM or MC?
Have you tried to place a ferrite choke on the cable near the input to the amplifier?
ShinMolina
Active Member
I don't know what device or cable upgrades could eliminate this issue, I'm using Mogami cables and a Cambridge Audio Alva Solo. Both of them are top of the notch without going into expensive stuff.
The part that is acting line an antenna are the cables from the turntable to the preamp. As I said before I can increase the 8 kHz noise by getting the RCA cables closer to the AC power cords.
A properly designed AC filter with enough attenuation at 8 kHz could solve my problem if located at the start of the power cords that emit the noise. That way the power cord that goes close to the RCA cables at the back of the preamp won't be carrying any unwanted noise that could be radiated.
ShinMolina
Active Member
I have, but ferrite chokes do not offer enough attenuation in the kHz range, they usually are intended to reduce noise in the MHz range.
ShinMolina
Active Member
Do not go deep into the issue, I already solved it months ago by my standards when I bought the Mogami cables. The noise is only listenable with the ear at 20 cm or less from the speakers when at normal volume.
That's enough for me, I can't hear the sound when sitting at the couch and nothing playing. I didn't know that the vinyl world device chain would have been so finicky, it remembers me of electric guitar noise pickiness.
That's enough for me, I can't hear the sound when sitting at the couch and nothing playing. I didn't know that the vinyl world device chain would have been so finicky, it remembers me of electric guitar noise pickiness.
Most likely you have RF interference in the MHz range but the audio amplifier is converting that to an envelope modulation in the audio range which is what you are hearing. It is a relatively common occurrence. Otherwise, there’s no antennae long enough for a 8kHz RF signal to propagate in a building; the wavelength of 8kHz RF signal is almost 35km.
ShinMolina
Active Member
Well, I measured the AC mains with an oscilloscope and the only noticeable peak was that 8 kHz one. I measured up to 20 MHz if I remember correctly. I also think that it is quite strange, 8 kHz noise couldn't radiate as easily from a power cord.
Likewise, the ferrite choke didn't help at all, the noise is there with or without it.
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