hm... it seems my computer PSU doesn't have it safety earth connected to circuit at all, only to chassis and nothing further connection.
I'm thinking by integrating star grounding without the safety earth have any connection to circuit (safety earth to chassis only)
AND using chassis connect to safety earth and circuit ground (0V rail, common)
AND using chassis connected to safet earth and loop breaker circuit(rectifier+capacitor+resistor )
What does different between them ? (advantage & disadvantage)
I'm thinking by integrating star grounding without the safety earth have any connection to circuit (safety earth to chassis only)
AND using chassis connect to safety earth and circuit ground (0V rail, common)
AND using chassis connected to safet earth and loop breaker circuit(rectifier+capacitor+resistor )
What does different between them ? (advantage & disadvantage)
Could you elaborate more ? as I couldn't get what you meant. How to check the above statement ?
I didn't see your amp. As I know ground problems mainly appears in multichannel amps, especially with separate PSU for every single channel. Your ground reference may have higher or not enough low resistance in comparison to voltage rails. Weird noise also might appear when there is a voltage difference in every PSU in multichannel amp, likewise as a result of ground loop.
measure the resistance from channel 1 input socket barrel to channel 2 input socket barrel.
Is the resistance (after correcting for measuring probe self resistance) less than 0r2?
You have a ground loop.
Measure the resistance from the channel 1 Spkr Return terminal to channel 2 Spkr Return terminal. You have potential for a ground loop.
Measure the resistance from the channel 1 input socket barrel to the channel 1 Spkr Return terminal. You have potential for a ground loop.
Is the resistance (after correcting for measuring probe self resistance) less than 0r2?
You have a ground loop.
Measure the resistance from the channel 1 Spkr Return terminal to channel 2 Spkr Return terminal. You have potential for a ground loop.
Measure the resistance from the channel 1 input socket barrel to the channel 1 Spkr Return terminal. You have potential for a ground loop.
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hm...about thoe measurement, i will take it later (busying other things)
But i have tried before, only test one side, by shorting the left channel input. This makes the noise not intruded into left channel output (or too small for audible different, since the amplifier itself also have some buzz)
But i have tried before, only test one side, by shorting the left channel input. This makes the noise not intruded into left channel output (or too small for audible different, since the amplifier itself also have some buzz)
Euro plugs
didn't find it in here so I'm posting my way to connect any schuko (cee 7/4 or cee 7/7) plugs in Euro countries that don't have the means to know where Line or Neutral is "actually" present (think an extension cord for instance)....
Before switching the power on, one can see the led/neon light up if the polarity is "wrong" ... and turn the plug the other way
this is a variation from a circuit found on rstaudio.de (really nice diy projects btw).
Uploaded with ImageShack.us
didn't find it in here so I'm posting my way to connect any schuko (cee 7/4 or cee 7/7) plugs in Euro countries that don't have the means to know where Line or Neutral is "actually" present (think an extension cord for instance)....
Before switching the power on, one can see the led/neon light up if the polarity is "wrong" ... and turn the plug the other way
this is a variation from a circuit found on rstaudio.de (really nice diy projects btw).
An externally hosted image should be here but it was not working when we last tested it.
Uploaded with ImageShack.us
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Hi guys,
Most of times to avoid the GROUND loops we talk about using STAR Grounds, But What about the VCC's and VEE's? For instance what If we have gor tow amplifiers connected to each others? I know that chips grounds, the input grounds and the output grounds and so on must be connected to a start ground (or alternatively connected to a good ground plane), But what about the VCC's and VEE's? I guess that the laters can generate some degree of potentioal difference (voltage) if the traces do not have a reference. So...?
Most of times to avoid the GROUND loops we talk about using STAR Grounds, But What about the VCC's and VEE's? For instance what If we have gor tow amplifiers connected to each others? I know that chips grounds, the input grounds and the output grounds and so on must be connected to a start ground (or alternatively connected to a good ground plane), But what about the VCC's and VEE's? I guess that the laters can generate some degree of potentioal difference (voltage) if the traces do not have a reference. So...?
"star gnd" is just shorthand - look at all current paths/loops
current always flows in closed loops
just looking at the "gnd" wire doesn't help
always trace the current loop(s) complete paths - from PS, supply wiring, Chip Amp pins, amp output, to load, load return, amp ps gnd
then there are 2 main concerns:
magnetic field radiation/coupling
+/- supply V wires for each amp should be twisted - this "sums" the Class AB currents so that their radiated mag field looks more linear
and their loop area with the gnd return for each amp+load should be minimized by keeping them close to the gnd return for that amp/load too
a very common mistake in Chip Amp board/module layout is to put +/- power entry, routing on opposite edges of the PCB
if you "follow the current" you should see that minimizing nonlinear mag field radiation also requires they be kept close on the board too
the other concern is Verror from currents flowing in common impedance paths
with multiple channels a problem arises with the source typically sharing analog signal gnd while "star gnd" will have each amp module's input signal gnd at a different "gnd", offest by load return current x Z of the amp's "star" gnd wire
current always flows in closed loops
just looking at the "gnd" wire doesn't help
always trace the current loop(s) complete paths - from PS, supply wiring, Chip Amp pins, amp output, to load, load return, amp ps gnd
then there are 2 main concerns:
magnetic field radiation/coupling
+/- supply V wires for each amp should be twisted - this "sums" the Class AB currents so that their radiated mag field looks more linear
and their loop area with the gnd return for each amp+load should be minimized by keeping them close to the gnd return for that amp/load too
a very common mistake in Chip Amp board/module layout is to put +/- power entry, routing on opposite edges of the PCB
if you "follow the current" you should see that minimizing nonlinear mag field radiation also requires they be kept close on the board too
the other concern is Verror from currents flowing in common impedance paths
with multiple channels a problem arises with the source typically sharing analog signal gnd while "star gnd" will have each amp module's input signal gnd at a different "gnd", offest by load return current x Z of the amp's "star" gnd wire
with chip amps maybe so, as they are usually very compact
but with bigger SS board layout, supply lines are bound to split up somewhere, in the end, right ?
I read somewhere that with sensible low level signal, and digital, and using double layer boards, its important that ground return is placed right below power supply line
or else I think 'ground plane' was suggested
No, it is not inevitable that the power rails and the Power ground need to be split up somewhere.
Run the Power traces together and the Power Ground on the top side of the PCB and you can keep them together until they reach the biggest current consumer/s on the PCB. There it becomes important to keep the loop around the output devices that runs from +ve feed to speaker and from -ve feed to speaker as short and as compact as possible. Incorporate the HF decoupling into this compact arrangement such that the caps can actually supply transient currents to the speakers through the output devices. One of our Members suggested we think of these tiny caps as being the sole supply for the speaker current. Imagine the HF decoupling as tiny batteries that will last for 1us.
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Interestingly and confusingly quite often the terms bypassing and decoupling are used synonymously, and lots of info regarding capacitors (and somtimes ferites) used in this way will use either term interactively. There is also confusion when using the terms as seperate entities. Even the experts on the subject use the terms either interactively or have opposite views on de-coupling capacitors and bypassing capacitors. Basicly if its a small value capacitor on a power pin it is both supplying the instantaneous power requirements and shunting high frequency noice down to the (low impedance) return current path (GND). There is an absolute ton of info on the web regarding this subject, there are a couple in this lot of links.
http://www.ti.com/lit/an/sloa069/sloa069.pdf
http://www.analog.com/static/imported-files/tutorials/MT-101.pdf
http://www.cvel.clemson.edu/Presentation_Slides/PowerBus-Decoupling.pdf
PCB007 Quiet Power: Resonances in Power Planes
PCB007 Quiet Power: How Thin Laminates Suppress Resonances
PCB007 Do Not Perforate Planes Unnecessarily
http://www.ipblox.com/pubs/DesignCon_2011/11-TA3Paper_Weir_color.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-6.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-7.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-8.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-9.pdf
http://www.electrical-integrity.com/Paper_download_files/EPEP98_DET.pdf
Ground Pours: To Pour or Not to Pour?
http://www.goldphoenixpcb.biz/pdf/Loop_Area_Decoupling.pdf
http://www.ti.com/lit/an/sloa069/sloa069.pdf
http://www.analog.com/static/imported-files/tutorials/MT-101.pdf
http://www.cvel.clemson.edu/Presentation_Slides/PowerBus-Decoupling.pdf
PCB007 Quiet Power: Resonances in Power Planes
PCB007 Quiet Power: How Thin Laminates Suppress Resonances
PCB007 Do Not Perforate Planes Unnecessarily
http://www.ipblox.com/pubs/DesignCon_2011/11-TA3Paper_Weir_color.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-6.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-7.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-8.pdf
http://electrical-integrity.com/Quietpower_files/Quietpower-9.pdf
http://www.electrical-integrity.com/Paper_download_files/EPEP98_DET.pdf
Ground Pours: To Pour or Not to Pour?
http://www.goldphoenixpcb.biz/pdf/Loop_Area_Decoupling.pdf