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PostPosted: Tue Aug 21, 2018 6:33 am 
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Location: Markham, ON, CA
I found this article and thought I would share. It talks about sources of EMI, harmonics and its affects on REDUCING capacitance.....so those nasty computers, LED lights, etc are actually affecting the efficiency of capacitors in our crossovers, amplifiers etc.

https://electrical-engineering-portal.c ... mpensation

I found it interesting.....

Have a great day folks!
Tom

-- 21 Aug 2018 15:47 --

A couple of thoughts....

I wonder what sort of room is used to test THD etc on modern amplifiers and efficiency with speakers. My bet it is as insulated from background sources as possible

Should modern amplifiers, speakers etc now have some sort of filters installed upstream of the caps to ensure that this continual frequency bombardment be moderated? Are the good ones doing this? (my bet is yes).

What about speakers specifically. We spend a lot of money in design and testing, cables etc. If speakers are in the same house with computers, microwaves, (in my case, even welders), then the performance of these systems will be affected. Is this something we can design into cabling, or an actual mod of crossovers?

I added up all the separate transformers in use on just the main floor of my house (cell phone chargers, wall warts, laptop power supplies, LED transformers for the pot lights etc....and I came up with 18 separate power sources. In about 1,000 square feet. If you live in a condo, I bet your neighbours' power supplies and electrical components may also have an affect. Remember that the EMI sources are not just radio-driven, but also are driven through the shared power supplied on the wall. At best, most of us have second-degree separation of power supply....in condos it may be first order only.


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PostPosted: Tue Aug 21, 2018 6:56 am 
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Location: Kingston, ON, CA
This brings home my point about how anything with a pulse power supply design is at risk of premature power supply aging. As in - all of them.

As this is the primary method of operation of a class D amplifier, the scenario is doubled. Premature aging of the pulse power supply for the class D amp and the class D amp itself -- prematurely aging.

Besides the high levels of inharmonic distortions that impinge upon the given circuitry, that, in the final outcome...makes up the fundamental 'sound' of these devices. How many subs end up in the dump with their plate amps deemed unrepairable? A higher percentage than should be...One example out of many...

When we test cables and audio gear, everything in the given space/building is shut down. Lights, computers, all of it....where the power for the listening and evaluation system is connected via a ~475lb balanced AC transformer.

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PostPosted: Tue Aug 21, 2018 7:04 am 
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Location: Markham, ON, CA
Teo Audio wrote:
This brings home my point about how anything with a pulse power supply design is at risk of premature power supply aging. As in - all of them.

As this is the primary method of operation of a class D amplifier, the scenario is doubled. Premature aging of the pulse power supply for the class D amp and the class D amp itself -- prematurely aging.

Besides the high levels of inharmonic distortions that impinge upon the given circuitry, that, in the final outcome...makes up the fundamental 'sound' of these devices.

When we test cables and audio gear, everything in the given space/building is shut down. Lights, computers, all of it....where the power for the listening and evaluation system is connected via a ~475lb balanced AC transformer.



Ken, as the pulse supplies age, what would be the affect on the amp? Noise levels increasing, more THD?

Tom


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PostPosted: Tue Aug 21, 2018 11:06 am 
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Something like that. Gritty. Grungy, dirty, cloudy, harsh, dark, all at the same time.

The in-harmonic distortions can sometimes in some minds, be mistaken for new exposed detail.... when in fact, it is the exact opposite.

Happens all the time.

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(Ken Hotte, of) Teo Audio


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PostPosted: Tue Aug 21, 2018 1:23 pm 
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Joined: Wed Feb 06, 2008 2:04 pm
Posts: 756
Location: London, ON, CA
brownslane wrote:
I found this article and thought I would share. It talks about sources of EMI, harmonics and its affects on REDUCING capacitance.....so those nasty computers, LED lights, etc are actually affecting the efficiency of capacitors in our crossovers, amplifiers etc.

https://electrical-engineering-portal.c ... mpensation

I found it interesting.....

Have a great day folks!
Tom

-- 21 Aug 2018 15:47 --

A couple of thoughts....

I wonder what sort of room is used to test THD etc on modern amplifiers and efficiency with speakers. My bet it is as insulated from background sources as possible

Should modern amplifiers, speakers etc now have some sort of filters installed upstream of the caps to ensure that this continual frequency bombardment be moderated? Are the good ones doing this? (my bet is yes).

What about speakers specifically. We spend a lot of money in design and testing, cables etc. If speakers are in the same house with computers, microwaves, (in my case, even welders), then the performance of these systems will be affected. Is this something we can design into cabling, or an actual mod of crossovers?

I added up all the separate transformers in use on just the main floor of my house (cell phone chargers, wall warts, laptop power supplies, LED transformers for the pot lights etc....and I came up with 18 separate power sources. In about 1,000 square feet. If you live in a condo, I bet your neighbours' power supplies and electrical components may also have an affect. Remember that the EMI sources are not just radio-driven, but also are driven through the shared power supplied on the wall. At best, most of us have second-degree separation of power supply....in condos it may be first order only.

Might not be anything here to get your knickers in a knot....... :idea:

The article describes the effects of extraneous frequencies on components used to filter or resonate very, very high power electrical systems.

"The author Edvard Csanyi is an Electrical engineer, programmer and founder of EEP.
Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry facilities."
If my math is anywhere near right, that 6,300 Ampere current at a few thousand volts (LV) is Megawatts of electrical power.

The capacitors pictured in the large steel cabinets would have power line AC currents flowing through them (60, 120, 180 Hz, etc.)

Doesn't jump out at me that there is anything here that pertains to audio equipment :?:


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