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Old 23rd September 2018, 07:58 AM   #1
saf is offline saf  Portugal
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Default Stir the pot - AC signal and AKSA processing

This has been quiet, how about some academic work for the mind?

I decided to bring back an old problem to the table, i never got rid of it so i have been till trying to find the cause. I suspect my AC power is a piece of S***.

I have noticed with the Mayas that i have a very susceptible system, being the transparent speakers, the amp or whatever.

Some times during the day or night, i get a buzz from speakers that last 5-10 seconds. Sometimes this occurs 3 or 4 times in a row and then stop for a few hours (to happen again). So a small disturbance in the AC line i thought....from whatever cause....

ITs difficult to catalog the pitch sound, maybe some 200Hz to 500Hz.

I have had a PS AUdio PPP (power regenerator) for a while now, and i can confidently say that when the amps are connected to it, the buzz is much smaller. So it is kind of fixing 70% of whatever is coming in from the line. It is still there.
But with the amps connected directly to the wall..it is much louder.

So in enters a new kid on the block. A PS Audio P10. This is a monster of a regenerator. Its big, heavy and expensive. I bought this after much consideration, i got a good deal on one and went for it. I still did not plug my amps to it....but it comes with a new feature that led me to write THIS.

It has an embedded oscilloscope !What a cool feature. It cannot zoom in , or change scale, but nevertheless is quite nice. I plugged it in, to a wall socket next to the PPP. So both are connected but only the PPP is powering the amps.

Now....the other night the speakers started buzzing and i rush to the P10 to see the AC wave form and distortion values....i got to record 3 seconds of the distorted AC wave !!!! Here it is :

YouTube

The anomaly is the first 3 seconds. I recorded with my phone. After this i kept recording to see if it happened again, no "luck".

Now...WTF is that ??? What kind of harmonics are in the AC line to produce such a distorted ac wave ? Funny..if one counts the peaks, there seems to be from 10-12 each cycle....which would translate into 300HZ harmonics ? 6th order?
Is this the sound i am hearing ?

Ok, now academic for Hugh :

1. Why do the Mayas show the buzz on the speakers, and another commercial amp does not ? I used to own Marantz and Denon products and never "heard" the buzz. I can connect a Cyrus amp i have in the closet and be SURE of this. I would have to have both connected to identical speakers to make a 100% assumption.

Maybe the commercial amps have some kind of filtering ? I find that hard to believe as there is no better and complex filter than the PS AUdio itself and it still lets some noise pass.

Maybe the topology of the Maya is too transparent?

DO you think this noise is coming from outside my house, or something within ?
I contacted my electricity company, that says is going to install a "analyser" in my house for 8 days to measure and record data. Maybe this will show them the distorted wave and they something to offer here.

I have talked a lot....i will let you think now
All the best
Filipe
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Old 23rd September 2018, 10:22 AM   #2
analog_sa is offline analog_sa  Europe
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Stir the pot - AC signal and AKSA processing
Have you considered the possibility that the interference enters your system in other ways too? Perhaps the disturbance is close to you and there is a strong radiation component as well which enters your system through an input. Is it possible to test with the amp inputs short-circuited?
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Old 23rd September 2018, 11:19 AM   #3
saf is offline saf  Portugal
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Whatever happens inside the amp is downstream.
My problem is upstream, as noted at the input voltage wave in the PS AUDIO regenerator.
This P10 is only connected to the wall socket, nothing else. IT shows the AC sine wave completly distorted.

The fact that this noise is traveling through the AC input, to the amp circuit is another thing.
But the problem remains in the AC input.
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Old 23rd September 2018, 11:58 AM   #4
AKSA is offline AKSA  Australia
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SAF.
I have just returned from weekend away and I will respond tomorrow. At present I cannot give a good answer - I have to think hard and get back to you.....
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Old 24th September 2018, 04:59 AM   #5
rabbitz is offline rabbitz  Australia
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We have problems with off-peak ripple control signals at 1050Hz but only effects ceiling fans in the early hours of the morning.

To make sure that's all it was I ended up unplugging everything and turned them on 1 by one to eliminate them as a noise source.

Doesn't help you but looking for external sources can help to find the culprit.
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Old 24th September 2018, 07:10 AM   #6
meanman1964 is offline meanman1964  Belgium
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SAF , Can you check if the transformer is generating noise when you here the buzz ?
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Old 24th September 2018, 08:06 AM   #7
saf is offline saf  Portugal
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Originally Posted by meanman1964 View Post
SAF , Can you check if the transformer is generating noise when you here the buzz ?
Yes it is ( i heard it at least 2 times, dont know for sure if its 100% of the times).
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Old 24th September 2018, 08:12 AM   #8
saf is offline saf  Portugal
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Originally Posted by rabbitz View Post
We have problems with off-peak ripple control signals at 1050Hz but only effects ceiling fans in the early hours of the morning.

To make sure that's all it was I ended up unplugging everything and turned them on 1 by one to eliminate them as a noise source.

Doesn't help you but looking for external sources can help to find the culprit.
Are you saying your ceiling fans were generating the noise in the AC line?
I am trying to find the culprit, but its kinda hard because i dont know when it will happen and when it does, its for 5-10 seconds.

Funny enough, last night i was testing a new amp build (old LifeForce brought back to life) and i all i had connected to it was my Smartphone.
So, no common ground on the rca input, just floating from smartphone.
I heard the PSAUDIO tripping into protection, and immediatly put my hear to the speaker and paused the music : NO NOISE

This got me thinking, is the AC noise getting in the line level input through some other equipment on my rack, or router , or tv, or whatever.....
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Old 24th September 2018, 01:24 PM   #9
meanman1964 is offline meanman1964  Belgium
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Quote:
Originally Posted by saf View Post
Yes it is ( i heard it at least 2 times, dont know for sure if its 100% of the times).
I think you've the same problem I was having with my N80 . A dc blocker was the solution .
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Old 25th September 2018, 07:45 AM   #10
rabbitz is offline rabbitz  Australia
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Quote:
Originally Posted by saf View Post
Are you saying your ceiling fans were generating the noise in the AC line?
No. The fans were receiving the noise from the ripple control signals. They occurred the same time of the day.... 12.40am etc.

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