PS Audio (Paul McGowan) you tube “Phase Linear Gear”
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- Halfbiass...Electron Herder and Backass Woof
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- Halfbiass...Electron Herder and Backass Woof
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Yessir! On the PL400, I use Mouser P/N 5989-400V.01-F, they are 400VDC .01uF film caps. For the PL700, I use Mouser P/N 598-103MWR630K, they are 630VDC .01uF metalized polyester film caps. They are axial leaded 11mm long cylindrical caps and they tuck down between the PL700 large bulk capacitors nicely.
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Bypass caps are well known solution to reduce noise due to RF
so two questions :
1) Can you hear the difference in sound ?
2) In PL400/ PL700 service manual it' written to add 4 caps across the rectifier
in case of RF interference , so what's the best solution ?
Probably for AM ( very popular in US )?
Ciao
Marco
PS: I would only like the understand and learn .
so two questions :
1) Can you hear the difference in sound ?
2) In PL400/ PL700 service manual it' written to add 4 caps across the rectifier
in case of RF interference , so what's the best solution ?
Probably for AM ( very popular in US )?
Ciao
Marco
PS: I would only like the understand and learn .
The polyester film caps do not have an AC rating. They are being applied on the rectifier. I'm not suggesting they are misapplied. They may be fine.
Ceramic discs have been used for decades and have both an AC and DC rating. They are recommended, as are mylar film types in the service bulletin section of the 400 and 700B for RF abatement.
I have seen 1000VDC film caps fail dramatically on 208VAC. Granted across the line is a different application then across the rectifier. A suitable alternative to the film would be Mouser ceramic disc. These are intended for line filters for automotive electric vehicle chargers. At $0.50 each the price is hard to beat.
Ceramic discs have been used for decades and have both an AC and DC rating. They are recommended, as are mylar film types in the service bulletin section of the 400 and 700B for RF abatement.
I have seen 1000VDC film caps fail dramatically on 208VAC. Granted across the line is a different application then across the rectifier. A suitable alternative to the film would be Mouser ceramic disc. These are intended for line filters for automotive electric vehicle chargers. At $0.50 each the price is hard to beat.
My opinion regarding amplifier noise, supported by theory and some facts in RF wave propagation is this:
Much of the noise interference occurs in the frequency bands above the threshold of human hearing, generally considered to be 20kHz, but most people cannot hear average-level sound above 16kHz. However, there are lower or higher frequency harmonics generated outside the amplifier that may interfere with the input or amplified signal, such as a AM or HAM radio in the LF band (30kHz to 300kHz). If it is part of the input signal, it gets amplified along with everything else and can cause musical signals to sound "smeared" or otherwise unclear, unless a capacitor cuts off anything above the audible spectrum.
Of course the worst offender is any noise in the audible spectrum, such as 60Hz (heard at 120Hz) that is radiated into the amplifier can be heard in the background of the musical signal. This could be hum or ringing sounds, especially if the amplifier is not shielded and the source of the interference is external, such as a fluorescent light ballast, or a noisy switch mode power supply. If the amplifier power supply is not operating correctly, it can be the source of interference, too.
What we can do:
For external RF noise interference in the power lines, ensure the metal case around the amplifier is grounded. This will drain noise to ground on a low impedance path. Extreme cases might require a low pass filter to cut off the offending frequency, this is best done with a resistor-capacitor (RC) filter in the power supply such as: Mouser P/N 80-PMR210MB5220M100 $3.81ea. Possibly a power conditioner to plug the amplifier into, but it will have to be a large one, our WOPL amps can draw 2000Watts.
For AC (60Hz) hum on the power line (if you have noise on all components plugged into that circuit), try and find the source (often a defective or low quality appliance) with an AM radio tuned off-station and walk around the house. It it turns out to be everywhere, it could be a noisy power line transformer. Good news, the utility company will come out and replace it for free and usually very quickly.
Bypass other sources of AC noise (power strips, fluorescent light ballasts, switch mode power supplies (SMPS), etc.) with AC-rated (labeled X2) capacitors of sufficient voltage. I like these: Mouser P/N 539-104MACQRL150 $8.32ea.
Then, bypass sources inside the amplifier such as switches, bridge rectifiers, relays, etc. (WOA Backplane Boards also accomplish this).
I always do more than the minimum, who knows where the amplifier might end up, some guys garage next to an old battery charger, don't ask?
Much of the noise interference occurs in the frequency bands above the threshold of human hearing, generally considered to be 20kHz, but most people cannot hear average-level sound above 16kHz. However, there are lower or higher frequency harmonics generated outside the amplifier that may interfere with the input or amplified signal, such as a AM or HAM radio in the LF band (30kHz to 300kHz). If it is part of the input signal, it gets amplified along with everything else and can cause musical signals to sound "smeared" or otherwise unclear, unless a capacitor cuts off anything above the audible spectrum.
Of course the worst offender is any noise in the audible spectrum, such as 60Hz (heard at 120Hz) that is radiated into the amplifier can be heard in the background of the musical signal. This could be hum or ringing sounds, especially if the amplifier is not shielded and the source of the interference is external, such as a fluorescent light ballast, or a noisy switch mode power supply. If the amplifier power supply is not operating correctly, it can be the source of interference, too.
What we can do:
For external RF noise interference in the power lines, ensure the metal case around the amplifier is grounded. This will drain noise to ground on a low impedance path. Extreme cases might require a low pass filter to cut off the offending frequency, this is best done with a resistor-capacitor (RC) filter in the power supply such as: Mouser P/N 80-PMR210MB5220M100 $3.81ea. Possibly a power conditioner to plug the amplifier into, but it will have to be a large one, our WOPL amps can draw 2000Watts.
For AC (60Hz) hum on the power line (if you have noise on all components plugged into that circuit), try and find the source (often a defective or low quality appliance) with an AM radio tuned off-station and walk around the house. It it turns out to be everywhere, it could be a noisy power line transformer. Good news, the utility company will come out and replace it for free and usually very quickly.
Bypass other sources of AC noise (power strips, fluorescent light ballasts, switch mode power supplies (SMPS), etc.) with AC-rated (labeled X2) capacitors of sufficient voltage. I like these: Mouser P/N 539-104MACQRL150 $8.32ea.
Then, bypass sources inside the amplifier such as switches, bridge rectifiers, relays, etc. (WOA Backplane Boards also accomplish this).
I always do more than the minimum, who knows where the amplifier might end up, some guys garage next to an old battery charger, don't ask?
These do, Mouser P/N 598-103MWR630K. At the 630VDC rating, the AC rating is 220VAC; more than adequate for use across the rectifier terminal pairs which should never see more than 200VAC.
Datasheet attached.
Funny you picked this one: A suitable alternative to the film would be Mouser ceramic disc. P/N 72-AY2103M61Y5VS63L0
I have been using this AC-rated ceramic capacitor across the power switch for a long time. P/N 72-VY2103M63Y5US63V0
It is a Y2 300VAC rated capacitor, and the price is $0.48ea. I honestly can't tell what the difference is between the two.
Datasheet attached.
Funny you picked this one: A suitable alternative to the film would be Mouser ceramic disc. P/N 72-AY2103M61Y5VS63L0
I have been using this AC-rated ceramic capacitor across the power switch for a long time. P/N 72-VY2103M63Y5US63V0
It is a Y2 300VAC rated capacitor, and the price is $0.48ea. I honestly can't tell what the difference is between the two.
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According to my experience in hifi systems ,
I saw these problems for noise :
- ground loops ( NAD 4150 grounded )
Cause :a mistake by Nad that sent to Italy some units for UK market
Solution : I disconnected the ground
- motorboating ( Dynaco FM 5 )
Cause : Power line ethernet
Solution : I added a 0.1 uF 630 V on 230 Vac .
The problem is fo find the " guilty " They took me very much time .
Generally I consider hi fi gears well designed for noise .
Ciao
Marco
I saw these problems for noise :
- ground loops ( NAD 4150 grounded )
Cause :a mistake by Nad that sent to Italy some units for UK market
Solution : I disconnected the ground
- motorboating ( Dynaco FM 5 )
Cause : Power line ethernet
Solution : I added a 0.1 uF 630 V on 230 Vac .
The problem is fo find the " guilty " They took me very much time .
Generally I consider hi fi gears well designed for noise .
Ciao
Marco