O.k... i tried numerous things.. this, that.. nothing helped.....
Than i reversed everything to how it is suposed to be by schematic and for some reason buzzing stopped in one channel... following that road i figured that even if i have input wires shielded, they were to close to power lines having AC rectified.... with over 2A of total current flowing there, it was more then enough to trigger my amp to buzz.... moving those input wires away from those power lines, reduced the buzz significantly....
Also, i figured that my interconnect between my dac/preamp and F5 is simply old and it's shielding is not firmly connected to rca jacks on one end and i had to resolder this ....
...
So, my amp is looking like a Frankenstein's newborn now.... (not that is was a masterpiece of desing to start from either)...
so, i have to disconnect everything, try to make the filtering caps board smaller (to remove it further from my amp pcb's), reroute the wires and hopefully, this time, it will work without buzzing 🤣🤣
Than i reversed everything to how it is suposed to be by schematic and for some reason buzzing stopped in one channel... following that road i figured that even if i have input wires shielded, they were to close to power lines having AC rectified.... with over 2A of total current flowing there, it was more then enough to trigger my amp to buzz.... moving those input wires away from those power lines, reduced the buzz significantly....
Also, i figured that my interconnect between my dac/preamp and F5 is simply old and it's shielding is not firmly connected to rca jacks on one end and i had to resolder this ....
...
So, my amp is looking like a Frankenstein's newborn now.... (not that is was a masterpiece of desing to start from either)...
so, i have to disconnect everything, try to make the filtering caps board smaller (to remove it further from my amp pcb's), reroute the wires and hopefully, this time, it will work without buzzing 🤣🤣
O.k...
Rewired everything top to bottom.
Changed input cables to cheap Vivanco coaxial.... buzzing was lowered significantly....
... it is stil there when i connect the input cables of the amplifier to the source... when amplifier is disconnected or with grounded input, buzzing stops.... then it is dead quiet... only when i connect input cables, buzzing starts again....
Since it is small now but enough to be heard from sitting position when everything is quiet - i am asking this - would lowering the input resistor to ground (47k now) to 10-15k do any good in lowering the buzzing even further?
Rewired everything top to bottom.
Changed input cables to cheap Vivanco coaxial.... buzzing was lowered significantly....
... it is stil there when i connect the input cables of the amplifier to the source... when amplifier is disconnected or with grounded input, buzzing stops.... then it is dead quiet... only when i connect input cables, buzzing starts again....
Since it is small now but enough to be heard from sitting position when everything is quiet - i am asking this - would lowering the input resistor to ground (47k now) to 10-15k do any good in lowering the buzzing even further?
Does anyone knows how lowering the input reistance.might affect buzzing... my tweeters are really sensitive 108dB/W attenuated a bit, they react to everything...
Lowering the inout resistance of the amplifier might lower (not hum but) buzz... since all this is not easy to do (not to much space around), i am rather asking and then working 🤣😁 ....
Funny is that it is only buzzing when i connect the interconnect cables to the source...... if i connect only one channel, it does not buzz, two channels it buzzes.... clearly a ground loop towards the source and back again... but all amos have that and it is not a problem... here it is a problem....
Killing me here...
..thank you all for your effort
Lowering the inout resistance of the amplifier might lower (not hum but) buzz... since all this is not easy to do (not to much space around), i am rather asking and then working 🤣😁 ....
Funny is that it is only buzzing when i connect the interconnect cables to the source...... if i connect only one channel, it does not buzz, two channels it buzzes.... clearly a ground loop towards the source and back again... but all amos have that and it is not a problem... here it is a problem....
Killing me here...
..thank you all for your effort
You could try to tie the left and right rca’s ground and ground them to the same point. It would make the loop smaller
It is really.small - what bothers me is that the amp is completely dead quiet until i connect inzerconnect cables to the source.....
So it can be quiet but for some reason it is not.... arrrgh 🤣
So it can be quiet but for some reason it is not.... arrrgh 🤣
Having high sensitivity speakers definitely allows very low level noise to be audible.
Do you have another source to try?
Also be sure to plug the source into the same AC wall outlet as your amplifier for smallest ground loop area.
Have a look at diyAudio member Bonsai's article on amplfier noise and grounding. Some debugging information is near the end of the article on page 68. It seems you have a case of cross channel ground loop. You can test to see whether it is inside your amplifier or caused by your source.
Do you have another source to try?
Also be sure to plug the source into the same AC wall outlet as your amplifier for smallest ground loop area.
Have a look at diyAudio member Bonsai's article on amplfier noise and grounding. Some debugging information is near the end of the article on page 68. It seems you have a case of cross channel ground loop. You can test to see whether it is inside your amplifier or caused by your source.
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i tried a passive preamp connected to my cd's analogue output... same thing.... also my equipment is on the same outlet....
...
thank you for sharing the pdf.... yeah - seems to me you are right about cross channel loop - will check the pdf and see if i can solve it or at least learn something more to be able to ask questions from there.......
...
thank you for sharing the pdf.... yeah - seems to me you are right about cross channel loop - will check the pdf and see if i can solve it or at least learn something more to be able to ask questions from there.......
It is most cross channel loop - will be back with what i have found - question is if it is inside or outside the amp - i would bet inside... but will let you all know....
printed the pdf (thank you Ben), will be back....
printed the pdf (thank you Ben), will be back....
Checked through that pdf - great material
.. to cut the things short - i havd a list of "to do" things i need to make - basically i am starting the wiring from ground up for the third time 🤣🤣🤣🤣
Will keep you all posted
.. to cut the things short - i havd a list of "to do" things i need to make - basically i am starting the wiring from ground up for the third time 🤣🤣🤣🤣
Will keep you all posted
O.k.... finally mannaged to make everything i wanted from my "to do" list based on that *.pdf file Ben Mah was kind enough to share (great material once again)...
Removed the protection circuit completely and for the sake of having things a bit easier - i removed the resistors in power supply that form C-R-C filtration... I left only caps there and from that central point i hooked everything i had to connect there.....
So twisted everything, tried to minimize loops - IT IS BUZZING LIKE IT WAS BEFORE.....
...
so, now i really don't know what to do....
i can listen to it, it sounds o.k. - it does not have enough hours of working to listen to it more seriously....
the buzz is around the level of when everything in the room is quiet you can hear it... when you sit on your listening position, i can hear it clearly....
now - my tweeters are 108dB/w, mid's are around 95dB i think... maybe to lower the input impedance resistor to have something like 10-15kohm?
.
amp is dead quiet as long as i have it with grounded inputs, no inputs, one RCA input connector connected - the moment i connect the second channel input i got buzzing sound .... no matter what i did so far it did not stop - only one time it did and i don't know what was the reason for stopping (at first i thought that input wires were to close to my power supply wires and i moved them away but that did not correct the problem so i am clueless what made it dissapear that time, in one channel only.....).....
...
i really don't know what do to more...
Removed the protection circuit completely and for the sake of having things a bit easier - i removed the resistors in power supply that form C-R-C filtration... I left only caps there and from that central point i hooked everything i had to connect there.....
So twisted everything, tried to minimize loops - IT IS BUZZING LIKE IT WAS BEFORE.....
...
so, now i really don't know what to do....
i can listen to it, it sounds o.k. - it does not have enough hours of working to listen to it more seriously....
the buzz is around the level of when everything in the room is quiet you can hear it... when you sit on your listening position, i can hear it clearly....
now - my tweeters are 108dB/w, mid's are around 95dB i think... maybe to lower the input impedance resistor to have something like 10-15kohm?
.
amp is dead quiet as long as i have it with grounded inputs, no inputs, one RCA input connector connected - the moment i connect the second channel input i got buzzing sound .... no matter what i did so far it did not stop - only one time it did and i don't know what was the reason for stopping (at first i thought that input wires were to close to my power supply wires and i moved them away but that did not correct the problem so i am clueless what made it dissapear that time, in one channel only.....).....
...
i really don't know what do to more...
The R in the CRC filter should reduce noise, not cause noise, so it is best to put them back in. Also the centre of the power supply board is not best location for taking the power from the power supply. So I suggest putting the resistors back in and taking the power from the end of the board as designed.
New pictures of your amplifier may be helpful in debugging. Include some overhead shots that show the whole amplifier.
Did you go through the Debugging procedure outlined in Bonsai's article?
New pictures of your amplifier may be helpful in debugging. Include some overhead shots that show the whole amplifier.
Did you go through the Debugging procedure outlined in Bonsai's article?
Attachments
Ben - thank you so much for your try to helping me..
CRC filtering was there in every version i did so far - it was buzzing every time ... now, following that pdf you shared, i wanted to make one middle point to connect everything there similar to what is in the pdf file. when i had CRC or when i have this now - buzzing is the same... when i disconnect the source in either way, amplifier is dead quiet - no problem with filtering or having CRC or just a bank of caps there.... imho...
will upload new pic's of what i did last a bit later....
.....
I went through that debugging procedure and it is a proble with cross channel ground loop... that is why i used HBR resistors at the input of the board on signal ground... buzzing did not change in any way.
Also when i disconnect my dac/pre from mains power and have both channels connected between source and power amp, it is stil buzzing the minute i connect both channels.... when i have only one connected, it does not buzz at all....
so, according to that pdf, it is a problem outside of the amplifier (most likely)....
however, not one of the power amplifiers or integrated amplifiers i connected to my M2Tech Young DSD dac/pre did not buzz... only F5 is buzzing - so, i can hardly say that the problem is outside of the amplifier but probably inside - where is the question..... i don't know...
I also tried to use a passive preamp driving that F5 from a cd player from Marantz - it did not stop buzzing.... behaved the same way as with my dac/pre.... so, changing the source to a passive device and cd if front of that, does not do anything .... it buzz the minute i connect the second channel....
....
CRC filtering was there in every version i did so far - it was buzzing every time ... now, following that pdf you shared, i wanted to make one middle point to connect everything there similar to what is in the pdf file. when i had CRC or when i have this now - buzzing is the same... when i disconnect the source in either way, amplifier is dead quiet - no problem with filtering or having CRC or just a bank of caps there.... imho...
will upload new pic's of what i did last a bit later....
.....
I went through that debugging procedure and it is a proble with cross channel ground loop... that is why i used HBR resistors at the input of the board on signal ground... buzzing did not change in any way.
Also when i disconnect my dac/pre from mains power and have both channels connected between source and power amp, it is stil buzzing the minute i connect both channels.... when i have only one connected, it does not buzz at all....
so, according to that pdf, it is a problem outside of the amplifier (most likely)....
however, not one of the power amplifiers or integrated amplifiers i connected to my M2Tech Young DSD dac/pre did not buzz... only F5 is buzzing - so, i can hardly say that the problem is outside of the amplifier but probably inside - where is the question..... i don't know...
I also tried to use a passive preamp driving that F5 from a cd player from Marantz - it did not stop buzzing.... behaved the same way as with my dac/pre.... so, changing the source to a passive device and cd if front of that, does not do anything .... it buzz the minute i connect the second channel....
....
in between the transformer and electronics inside is 4mm aluminium black in color plate (on the outside and on the inside is the iron plate connected to the ground to shield the electronics from the transformer on top.... i even used the iron pot (used magnet to see if it is magnetic) and put over the transformer - the buzzing did not change at all....
...
also, interconnect cables and bind together with zipties to minimize the surface area on the outside ... this also did not do anything - it is buzzing as usual.....
...
also, interconnect cables and bind together with zipties to minimize the surface area on the outside ... this also did not do anything - it is buzzing as usual.....
It looks like the ground from the input jack goes through paralleled 22 ohm resistors to the board. Do you have a ground lift resistor between the power supply ground and the chassis which is connected to the mains ground. That's where the ground lift should be.
Since the underside of the power supply filter board is not visible, I do not know whether there are issues there or not. A picture or drawing of the wiring of the power supply board would be informative.
It looks like you placed the HBR at the INground input of the amplifier board. That is not the correct location. The ground of the input circuitry on the board needs to be isolated from the power supply ground on the amplifier board. Traces need to be cut to accomplish that. I also could not tell from the photos of the pcb that I found on the web how resistor R2 is connected to ground, but that connection needs to be undone in order to install the HBR.
I do not have a F5 so I have no personal experience with F5 hum. I have 103dB speakers (not quite 108dB) so I do have experience in building quiet audio components. This is my take on Bonsai's HBR implementation.
Edit: revised HBR scheme
It looks like you placed the HBR at the INground input of the amplifier board. That is not the correct location. The ground of the input circuitry on the board needs to be isolated from the power supply ground on the amplifier board. Traces need to be cut to accomplish that. I also could not tell from the photos of the pcb that I found on the web how resistor R2 is connected to ground, but that connection needs to be undone in order to install the HBR.
I do not have a F5 so I have no personal experience with F5 hum. I have 103dB speakers (not quite 108dB) so I do have experience in building quiet audio components. This is my take on Bonsai's HBR implementation.
Edit: revised HBR scheme
Attachments
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from what i understand NTC is doing that like on the schematic of the F5 power supply... you can see it on the last picture i posted ...