It was already previously connected, else that experiment would have increased the noise.
you are using your computer to control volume inside your music source !!!!!
Always set the digital volume controls to maximum so that you preserve as much of the digital information as possible.
Attenuate (volume control) the signal as late in the analogue system as possible.
yeah, i agree with you, andrew. Just because it was testing phase, so i use digital volume (i dont want to be deaf)
But it seems attenuation only solution to 'significantly' reduce the noise, but still post a problem (at least won't make my hearing 'motorboating'.
(thiss chip amp is too lousy, using digital volume control and analog control have no different, except the noise)
Do not alter/modify your computer PSU.
You as a beginner are relying on that PSU exporting safe power.
Ensure the computer PSU is properly and securely connected to PE in the mains wiring.
Normally the computer chassis is also connected to the PE. This doubles up the protection to the user in the event that a mains isolation fault develops.
I suggest you too, connect the power importing equipment to PE.
You never insert anything into those equipment to PE connections. NEVER EVER !!
Is that clear?
You as a beginner are relying on that PSU exporting safe power.
Ensure the computer PSU is properly and securely connected to PE in the mains wiring.
Normally the computer chassis is also connected to the PE. This doubles up the protection to the user in the event that a mains isolation fault develops.
I suggest you too, connect the power importing equipment to PE.
You never insert anything into those equipment to PE connections. NEVER EVER !!
Is that clear?
haha, yeah, sure. (its a confirmation question i asked) But how and what should i do solve my problem ? (try to avoid insulation transformer, costly... but will it be effective ?)
It seems more like a oscillation (noise pattern change when the attenuate VR changes) still wondering the real identity of the noise and root cause...
It seems more like a oscillation (noise pattern change when the attenuate VR changes) still wondering the real identity of the noise and root cause...
Cheapest solution:
A 3 conductor plug for amplifier power supply (enough conductors to include earth ground)
A 2 conductor cord for Amplifier power supply (see link in post 15 for double insulated amplifier power supply)
A 1 conductor cord from earth ground to amplifier enclosure/chassis AND ground loop breaker
A ground loop breaker from earth grounded enclosure/chassis to amplifier power ground
Although I personally favor wooden amplifier enclosures, Despite construction materials, safety requires that the ground loop breaker go from amplifier power ground to earth ground.
Review:
Earth ground connects to amplifier enclosure, aka chassis ground
Earth ground connects to Ground Loop Breaker
Ground Loop Breaker connects to amplifier power ground
Read that again, as if your life depends on it.
You can purchase a suitable replacement ac mains plug at the hardware store. Problem: The plug from the double insulated amplifier power pack linked in post 15 has an insufficient number of conductors. You need a replacement plug that has earth ground so you can cable earth ground to your amplifier enclosure/chassis and to your ground loop breaker.
Please also review related safety materials carefully.
Don't alter the computer.
For a highest quality, less haphazard, answer to your question, here is the list:
Input transformer.
end of list.
That may be safer than the cheapest solution.
A 3 conductor plug for amplifier power supply (enough conductors to include earth ground)
A 2 conductor cord for Amplifier power supply (see link in post 15 for double insulated amplifier power supply)
A 1 conductor cord from earth ground to amplifier enclosure/chassis AND ground loop breaker
A ground loop breaker from earth grounded enclosure/chassis to amplifier power ground
Although I personally favor wooden amplifier enclosures, Despite construction materials, safety requires that the ground loop breaker go from amplifier power ground to earth ground.
Review:
Earth ground connects to amplifier enclosure, aka chassis ground
Earth ground connects to Ground Loop Breaker
Ground Loop Breaker connects to amplifier power ground
Read that again, as if your life depends on it.
You can purchase a suitable replacement ac mains plug at the hardware store. Problem: The plug from the double insulated amplifier power pack linked in post 15 has an insufficient number of conductors. You need a replacement plug that has earth ground so you can cable earth ground to your amplifier enclosure/chassis and to your ground loop breaker.
Please also review related safety materials carefully.
Don't alter the computer.
For a highest quality, less haphazard, answer to your question, here is the list:
Input transformer.
end of list.
That may be safer than the cheapest solution.
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Terribly problematic to convey this information because the laptop computer and the car amplifier chip are running from two very similar models of SMPS power supply. These two power packs may be visually similar, but they have different jobs.
I wish to re-iterate: Don't modify the computer. Don't modify the computer's power supply.
When speaking of power supply, I was exclusively discussing the amplifier power supply. It may be necessary to purchase an appropriate power supply for the amplifier.
Again, add the ground loop breaker to the amplifier correctly and cable that ground loop breaker to safety earth ground. . . by upgrading the amplifier with a plug that facilitates using safety earth ground.
For installing the ground loop breaker--If you didn't have up upgrade the amplifier's mains plug (by going to the hardware store to purchase a full size plug that can ADD safety earth ground), then in that case you didn't purchase the right power supply for your amplifier. Please use a compatible power supply for your amplifier.
Attempting to discuss the matter safely, is, in of itself, also hazardous. It would surely be better to use the input transformer option because it is guaranteed to work while other options are not.
I wish to re-iterate: Don't modify the computer. Don't modify the computer's power supply.
When speaking of power supply, I was exclusively discussing the amplifier power supply. It may be necessary to purchase an appropriate power supply for the amplifier.
Again, add the ground loop breaker to the amplifier correctly and cable that ground loop breaker to safety earth ground. . . by upgrading the amplifier with a plug that facilitates using safety earth ground.
For installing the ground loop breaker--If you didn't have up upgrade the amplifier's mains plug (by going to the hardware store to purchase a full size plug that can ADD safety earth ground), then in that case you didn't purchase the right power supply for your amplifier. Please use a compatible power supply for your amplifier.
Attempting to discuss the matter safely, is, in of itself, also hazardous. It would surely be better to use the input transformer option because it is guaranteed to work while other options are not.
A very simple option that might work is to change the amplifier's bus ground topology over to a star ground topology.
The matter is definitely where pin 1 attaches to ground, definitely where input loads attach to ground, definitely where input jacks attach to ground, maybe also at pin 4 and maybe also at pin 2. The datasheet is not conclusive as to which pins are supposed to be a member of Signal Star ground.
Signal Star ground is created by adding a resistor of 4 ohms or 10 ohms or similar small amount. One end of that resistor is cabled to Power Star ground. The opposite end of that resistor creates the Signal Star ground.
Please review and compare other amplifier designs that use star grounding. Many of those are highly resistant to problems from computer source.
The matter is definitely where pin 1 attaches to ground, definitely where input loads attach to ground, definitely where input jacks attach to ground, maybe also at pin 4 and maybe also at pin 2. The datasheet is not conclusive as to which pins are supposed to be a member of Signal Star ground.
Signal Star ground is created by adding a resistor of 4 ohms or 10 ohms or similar small amount. One end of that resistor is cabled to Power Star ground. The opposite end of that resistor creates the Signal Star ground.
Please review and compare other amplifier designs that use star grounding. Many of those are highly resistant to problems from computer source.
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Problem: That may cause clipping in the typical cost effective computer sound chip. Solution: Proof? For guaranteed performance, just run the RightMark Audio Analyzer, RMAA, quality control software on that computer and leave the computer at whatever setting is proven to the lowest distortion.
Reference:
Audio Rightmark
The technique also applies to analog source. Hey, we're using solid state here. Facilitate clipping or cause it instead? Your choice.
Honestly, I don't care which of the two different approaches are used, as long as its clean, level and not dull. Really, I just wanted to mention the quality control software. Manufacturers of cost effective computers leave the step of audio quality control for the end-user.
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hm... understood. I'm going to build a power supply section for the amp, but not yet decide on material. What should in the construction ? unregulated power maybe suits it ? the PE just attach to the chassis, and loop breaker ?
Hm..... another point i'm not sure about is the 'signal star ground' you mentioned. So i just add a 4-10ohm resistor from the power star ground (which is power supply ground ?)
If i just put one end of resistor is input ground, opposite end is star ground ?
Hm..... another point i'm not sure about is the 'signal star ground' you mentioned. So i just add a 4-10ohm resistor from the power star ground (which is power supply ground ?)
If i just put one end of resistor is input ground, opposite end is star ground ?
haha, not a bad idea ! changing its name, only specialize use in computer !And now for some fun: We can change the language of amplifier input transformer to. . .
Computer sound audio output transformer. Wow! Now it is a computer audio upgrade!
Well.... at least my computer don't have crappy sound (listenable) and I also brought a custom manufactured higher quality external DAC ( i can significantly listen the different)
But the problem is still there when the AC charger is connected, maybe the noise a bit small in volume, no mayor different.
It also different than typical ground loop, which normally sound loud even the volume is at zero, but not mine. (the pattern, intensity changes when using a attenuation VR)
You can read the previous answer for the first time.
A link to the specific part is in post 15. Applying it and a ground loop breaker is post 28 and 29.
I cannot do better on a reiteration. Please review related safety grounding materials.
You can compare that with the many amplifier examples posted here at diyaudio.com Photographic and schematic examples are good.
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You may be looking at SMPS noise artifact. Have you yet added radio production environment style RF filtering?
The problem that you're describing is so weird:
The vague netbook with the iron and steel chassis having a lot of trouble driving the amplifier that does not yet have a power supply made for it.
Well, it does look like there should be a few caveats.
Please specify a lot better. Otherwise you narrow down your possible answers to: Replace problem equipment.
The problem that you're describing is so weird:
The vague netbook with the iron and steel chassis having a lot of trouble driving the amplifier that does not yet have a power supply made for it.
Well, it does look like there should be a few caveats.
Please specify a lot better. Otherwise you narrow down your possible answers to: Replace problem equipment.
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