on the thread
http://www.diyaudio.com/forums/powe...d-transformers-what-right-17.html#post4305992
are to find new observations concerning the remove of unwanted hum.
http://www.diyaudio.com/forums/powe...d-transformers-what-right-17.html#post4305992
are to find new observations concerning the remove of unwanted hum.
I'm sure you know it
Z = 1/(2*pi*f*C)=> 1/(2*3,14*50*470e-6) = 339 ohm.
In my world you'll need > 4700 uF More is better.
The next question is:
What current can the capacitor pass, that ensures the capacitor voltage drop does not exceed the diode turn on voltage?
What current can the capacitor pass, that ensures the capacitor voltage drop does not exceed the diode turn on voltage?
The choice of the capacitor size is a trade off between physical size, how high sound from the speakers you must have in order to hide the transformer hum. Normally you will only need current through the caps up to a couple of watts out. You can have huge caps but it will not serve any purpose. For a true class A amp you will need bigger caps since you have a high idle current.
Tube systems also need high standby current. With 8 6c33c tubes & another 8 signal tubes i need around 375VA in filament current alone.
" i need around 375VA in filament current alone. "
Keeps your house warm too?
470µF is not enough for that one.
Keeps your house warm too?
470µF is not enough for that one.
This is an old threat, and I did read it all.
I have a Roland musical instrument keyboard that buzzed like crazy. Today I decided to try to fix it as easy as possible.
Not many seemes to notice Nelson Pass idea in the start of the thread.
I have respect Nelson a lot, and opted for that solution. Just a thermistor seriel in the live
power line, and the buzzing was gone.
Best regards
Arthur.
I have a Roland musical instrument keyboard that buzzed like crazy. Today I decided to try to fix it as easy as possible.
Not many seemes to notice Nelson Pass idea in the start of the thread.
I have respect Nelson a lot, and opted for that solution. Just a thermistor seriel in the live
power line, and the buzzing was gone.
Best regards
Arthur.
i tried the thermistor solution also but never reported back - unfortunately, it didn't work for me.
however, the cap-based dc blocker worked perfectly; no buzzing at all for the last several years.
mlloyd1
however, the cap-based dc blocker worked perfectly; no buzzing at all for the last several years.
mlloyd1
Maybe the perfect specs for the thermistor are not so obvious...I tried them on a couple of isolation Tx and they helped significantly, not to total silence but anyway they reduced audible noise and improved sound quality (noise floor, detail retrieval, dynamics...etc) to an extent higher than anticipated. As if the attached power supplies were happier now 😀
I plan to test with higher values until I find the optimal for my environment.
Cheers,
M.
check out the interview between reviewer for The Absolute Sound and Mr. James Bongiorno, developer for SAE, SUMO and some other company - go to
https://www.diyaudio.com/forums/pow...bar-mains-dc-mains-voltage-2.html#post6455330
https://www.diyaudio.com/forums/pow...bar-mains-dc-mains-voltage-2.html#post6455330
Hi guys. I was hoping to get some help.
I have recently noticed the transformers in all of my amps humming. Some louder than others but everyone is noisy. I thought to check what in the house had changed and found that two humidifiers we have running for the winter are the cause of the problem. I tried adding power line filters to the humidifiers but no difference. I than reversed the phase of one of the units and my amps transformers are quiet as long as both humidifiers are turned on. I’m not so sure this is a great solution.
My question is how to stop the dc from going back into the wall from the humidifiers or if it’s ok to run one unit out of phase.
Thanks for reading my long winded post.
I have recently noticed the transformers in all of my amps humming. Some louder than others but everyone is noisy. I thought to check what in the house had changed and found that two humidifiers we have running for the winter are the cause of the problem. I tried adding power line filters to the humidifiers but no difference. I than reversed the phase of one of the units and my amps transformers are quiet as long as both humidifiers are turned on. I’m not so sure this is a great solution.
My question is how to stop the dc from going back into the wall from the humidifiers or if it’s ok to run one unit out of phase.
Thanks for reading my long winded post.
If you disconnect the humidifiers, any change? If you take the amp and connect it in a very different location, still humming?
Both humidifiers unplugged and the transformers are quiet. Doesn’t matter where in the house I plug them in the humidifiers or the amps. My audio equipment is on a dedicated circuit.
Then I suppose a DC filter would do the trick for the amps. I suppose your humidifiers is creating a lot of EMC.
I suppose it would. I was hoping to stop the problem at the source instead of building eight dc blockers. Yes my system is active and uses eight amps.
I think the main problem is that US has no(?) EMC regulations so you can these "polluters". In Europe you are not allowed to sell devices over a certain EMC emission level. You could use my DCT03 which is capable of 12 amps and connect as many amps you want with the restriction to current consumption.