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Puritan Audio PSM156 Review (AC Filter)

tonycollinet

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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.

I've been reading your 8KHz noise issue with interest through this thread. In a previous life (before retirement) I worked professionally developing variable speed drives: Electronic devices that chop mains AC into variable frequency AC (VIA a DC Link) to turn AC motors at variable speed. A typical application for these devices is elevator control. And a typical "switching speed" (They use PWM to generate the variable AC) is 8KHz.

I would be almost certain the noise you are experiencing is 8KHz (and harmonics of) switching frequency conducted back from the drive and down the mains. This can be quite nasty because the 8KHz output from the drive is high voltage (probably 800V+ Peak to peak) with fast switching edges - so has lots of harmonics. In a proper installation these should be filtered out. I'd be very surprised if the companies statement that they are within limits is true. But your only recourse would be to try to get the power companies involved, and the effort would be disproportionate, especially as you seem to have got the noise under control.

As others have said, it will be magnetic coupling, especially into ground loops. To minimise, you should have all your power cords connected to one location (eg power strip) and have the individual power cords as close to each other as possible to minimise "swept area" of the ground loop.

Ideally you shouldn't have ANY loops in your signal interconnect (point to point or star arrangement). - eg if you have multiple devices connected to your amp or dac, avoid connections between the devices. If a loop is unavoidable - tie the looping cables together to minimise area between them. (From your description, you are already doing this)

The reason your turntable is suseptible will be the high impedance high gain input of the pre-amp. Minimising noise there, and on the low signal connections from the TT is critical. If you can put a filter on the power lead to the preamp that would be worth trying. It doesn't need to cost $1500 though ;). As a test, it might be worth trying to power your pre-amp from a battery, eg a power bank (if the pre-amp is normally powered from a low voltage wall wart).
 

ShinMolina

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I've been reading your 8KHz noise issue with interest through this thread. In a previous life (before retirement) I worked professionally developing variable speed drives: Electronic devices that chop mains AC into variable frequency AC (VIA a DC Link) to turn AC motors at variable speed. A typical application for these devices is elevator control. And a typical "switching speed" (They use PWM to generate the variable AC) is 8KHz.

I would be almost certain the noise you are experiencing is 8KHz (and harmonics of) switching frequency conducted back from the drive and down the mains. This can be quite nasty because the 8KHz output from the drive is high voltage (probably 800V+ Peak to peak) with fast switching edges - so has lots of harmonics. In a proper installation these should be filtered out. I'd be very surprised if the companies statement that they are within limits is true. But your only recourse would be to try to get the power companies involved, and the effort would be disproportionate, especially as you seem to have got the noise under control.

As others have said, it will be magnetic coupling, especially into ground loops. To minimise, you should have all your power cords connected to one location (eg power strip) and have the individual power cords as close to each other as possible to minimise "swept area" of the ground loop.

Ideally you shouldn't have ANY loops in your signal interconnect (point to point or star arrangement). - eg if you have multiple devices connected to your amp or dac, avoid connections between the devices. If a loop is unavoidable - tie the looping cables together to minimise area between them. (From your description, you are already doing this)

The reason your turntable is suseptible will be the high impedance high gain input of the pre-amp. Minimising noise there, and on the low signal connections from the TT is critical. If you can put a filter on the power lead to the preamp that would be worth trying. It doesn't need to cost $1500 though ;). As a test, it might be worth trying to power your pre-amp from a battery, eg a power bank (if the pre-amp is normally powered from a low voltage wall wart).
Thanks a lot for the reply! I see you control the subject at study and have brought a lot of useful information into it. With cable management, properly shielded cables and minimizing ground loop area the noise is pretty non existent.

Since I was already looking into a cheap mains filter, after your suggestion I will definitely try one to see if the noise vanishes completely. Thanks again for the contribution! :D
 

Geardaddy

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Entertaining thread. Interested to hear what Amir and others would consider prudent investments in power "conditioning,"
 

GXAlan

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Entertaining thread. Interested to hear what Amir and others would consider prudent investments in power "conditioning,"

AFCI circuit breakers and GFCI power plugs are the only prudent investments. :)
 

Rc Lobarniz

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Not trying to offend anyone, and not trying to defend Amir, I think he does not need it. But when I read some forum members questioning Amir's method and results after testing these different "boxes" and showing no apparent benefit of using them, I feel like I am reading flatearthers complaints.
Let me explain myself and please take this with a scientific mindset. If after following the same very method, that is thoroughly explained, if after inducing a highly noisy signal in another of the reviews, he gets the same result no matter what "box" he is testing, and he has shown that the filters in the Hifi units already take care of this noise, what more proof do you want?
Science progresses with science methods, if you want to disprove one of his tests go-ahead and following the scientific method prove your theory.
I lack the time and the resources to perform these tests but if anyone other tan Amir wants to perform such tests and gets different results, that is worth being published and a very good reason for constructive argument, that's how we advance in science.
Arguments per se are useless.
I hope no one takes this as an attack, it is an invitation.
 
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Layercake1

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Hi guys,
I am a mechanical engineer and so not qualified to really understand most of this stuff but ive just spent a weekend listening to a Puritan 156 (£1450 ) versus a Vertex AQ (Quiesent) Hi Rez taga (£2500) versus my Olsen sounds fantastic distribution block(£140) and the Puritan bests the Vertex by a little bit and also my humble Olsen powerblock by quite a noticeable amount. My system cost circa £20 K and compared to the Olsen, the Puritan definitely reduces the noise floor but more importantly, the sound of cymbals and strings is just more natural sounding.
It most definitely affects SQ contrary to the conclusions drawn from lab testing.
note testing was not done blind in answer to recent question
 
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LTig

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Hi guys,
I am a mechanical engineer and so not qualified to really understand most of this stuff but ive just spent a weekend listening to a Puritan 156 (£1450 versus a Vertex AQ (Quiesent) Hi Rez taga (£2500) versus my Olsen sounds fantastic (£140) and the Puritan bests the Vertex by a little bit and also my humble Olsen powerblock by quite a noticeable amount. My system cost circa £20 K and compared to the Olsen, the Puritan definitely reduces the noise floor but more importantly, the sound of cymbals and strings is just more natural sounding.
It most definitely affects SQ contrary to the conclusions drawn from lab testing.
Did you do the comparison sighted or blind?
 
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amirm

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Hi guys,
I am a mechanical engineer and so not qualified to really understand most of this stuff but ive just spent a weekend listening to a Puritan 156 (£1450 ) versus a Vertex AQ (Quiesent) Hi Rez taga (£2500) versus my Olsen sounds fantastic distribution block(£140) and the Puritan bests the Vertex by a little bit and also my humble Olsen powerblock by quite a noticeable amount. My system cost circa £20 K and compared to the Olsen, the Puritan definitely reduces the noise floor but more importantly, the sound of cymbals and strings is just more natural sounding.
It most definitely affects SQ contrary to the conclusions drawn from lab testing.
note testing was not done blind in answer to recent question
You don't need the sound of your system to change to observe those changes. I could have have taken all the guts out of Puritan, give it to you and you would still arrive at the same conclusion! It is the nature of that type of comparison.
 

Layercake1

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You don't need the sound of your system to change to observe those changes. I could have have taken all the guts out of Puritan, give it to you and you would still arrive at the same conclusion! It is the nature of that type of comparison.
Im just giving an honest assessment of what two of us heard. My mate who has a £100k system is trying it in his rig tomorrow versus my Olsen block and also just with his dedicated radial circuit with no conditioner / olson power block and will update the post in due course
 
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amirm

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Im just giving an honest assessment of what two of us heard. My mate who has a £100k system is trying it in his rig tomorrow versus my Olsen block and also just with his dedicated radial circuit with no conditioner / olson power block and will update the post in due course
I know you are being honest. That is not the question. It is just a matter of how our brain works. Many times I have thought two files sounded different only to later find that they were identical! Even after knowing this, I could make myself think there is a difference, or not, on demand! It is the difference between perception vs sound coming into our ear.

When you are comparing gear, your brain operates differently. It focuses on detail that it normally ignores. When it does this, it hears the attributes you described. This focus level varies from instance to instance and can create biasing. You hear the "change" when you swap something, and then when you go back, you think you don't hear it anymore because you listen differently.

This is why we run controlled test blind. This way, you don't know if a change has or has not been made. This takes out the above factor. To make sure guessing is not involved, we repeat the experiment a number of times (e.g. 10 times). We then do statistical analysis to see how likely it is that you heard a real difference. There is some work involved here but there is no substitute for it. No other experience is reliable I am afraid.

You can use your friend to do the above test. Swap in the Puritan sometimes, and sometimes not 10 times. Have him look away so he can't see. Write down his votes. If he gets 8 out of 10 times right, then you have something. Anything less means likely not. So even being right 5 out of 10 times is not useful proof.
 

LTig

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Sighted test , not blind but there were two of us listening and we were both in agreement.
That still doesn't count. Don't ignore the results of scientific research of the last 50+ years. You need to do subjective tests blind or double blind to get meaningful results.
 

Layercake1

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I had a third audiophile friend around today for a blind test and he is the third person now to say he preferred the SQ with the Puritan 156 versus the standard Olson (non conditioning) power block in my £20K system.
I have now purchased it and am very happy indeed. I don't think all three of us are deluding ourselves although I am sure you will disagree.
 

LTig

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I had a third audiophile friend around today for a blind test and he is the third person now to say he preferred the SQ with the Puritan 156 versus the standard Olson (non conditioning) power block in my £20K system.
I have now purchased it and am very happy indeed. I don't think all three of us are deluding ourselves although I am sure you will disagree.
How many blind tests have you done? Did you always switch or sometimes not?
 

MaxBuck

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I had a third audiophile friend around today for a blind test and he is the third person now to say he preferred the SQ with the Puritan 156 versus the standard Olson (non conditioning) power block in my £20K system.
I have now purchased it and am very happy indeed. I don't think all three of us are deluding ourselves although I am sure you will disagree.
You should go and enjoy your system. Why would you care what anyone else thinks if you're happy with it yourself?
 

Layercake1

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How many blind tests have you done? Did you always switch or sometimes not?
This line of questioning seems to be an attempt to discredit our findings.
If lab test results were the “be all and end all” then people would by transistor amps rather than valve amps.
I’ve been in this game for 40 years plus now and always trusted my ears.
I’m not anti science, I've been to University (twice) but just sharing our listening experiences which unfortunately doesn't match up with the lab tests performed.
 

Killingbeans

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This line of questioning seems to be an attempt to discredit our findings.

We are just pointing out that your conclusions are highly at risk of being erroneous.

The interaction between your auditory system and your brain is optimized for keeping you alive while using as little energy as possible, not for accurate data gathering. Most of what we are hearing is real, but much of it is just our brains taking shortcuts. It's unavoidable. You can however get a high "signal-to-noise ratio" be doing well designed tests with proper controls.

Like it has already been said, if your own conclusions are adequate to you and you're happy with the purchase, that's all that really matters. But please do not try to present it as reliable information.
 
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