Questions about busboards

hello all;)

Come here with a little question about euro psu and busboard,
actually i own 6u 84hp case psu is meanwell rt 65-b and busboard is d.machinery,
my problem is that i have undesired noise,into the audio output.
And i was asking my self if it can come from the bus board 'cause when i look to other brand of busboard manufacturer,
i see some capacitors are they there for filtering noise from the psu?
As i will make a new case soon 9U 104HP ,i would know if i keep them or swap it for something else.

thanks in advance

Which module emits noise?

The noise filtering is much more efficient if it’s done closer to the components i.e. inside the modules. The capacitor inside the modules together with the inductive nature of a regular cable (or a bus-board in this case) works as a LPF to remove the noise. It doesn’t always make things better by making the busboard more capacitive (by adding capacitors), it could even make things worse.

Some modules tend to pick up noise more than others. I know some people had problems with Meanwell PSUs and certain digital modules, or the hexinverter vcnoize. The Harvestman Polivoks filter also seems to be prone to pick up noise from certain modules that somehow create noise even with linear PSUs. But this is just examples… So, I know it’s a lot of work, but you need to add one module at a time and try to find out which one is misbehaving.

Is it noise or is it hum? Hum is usually caused by a ground loop.

thanks guys for you quick replies

@pichnettes,don’t know which modules exactly cause it ,i tried with different sound sources always the same.

@barksten,didn’t know that,so i can eliminate this question.

@rumplefilter,i will give a try tonight about what you said,like this i can target which one make this problem.

@the slowgrowth,will check that also,and will try on another plug in my house.

i will come back later with the results.

I have four of those busboards and am in the process of installing another smaller busboard and three RT-65B power supplies. I was using T60s. The only thing that caused some odd noise was when one of the power supplies started to fail and the -12V line was at -6V. At that point I was overloading the supply, and I think that caused the noise. Make sure you have enough power for your modules, on all of the relevant lines (12V, -12V and 5V).

well as Mr.Hinton sais, ground loops are part of every circuit, the problem often is more wrong grounding.
check this thread here also:

@piscione,already checked this,no problem from there.

@rumplefilter,oh seems that i missed this…what a shame!

so if i get it right busboard need a ground connections directly after the main power intlet?
can i take a wire and attach it from earth point on the intlet to my bus board GND point?
or i still miss a point?

sorry for my ignorance,thanks you all

I’m in Canada, not sure how grounding is handled everywhere else but I went from the mains ground to the power supply ground and used the power supply Common to supply ground to the busboards. No issues with noise. I’d be nervous about hooking the busboard directly to any part of the mains for any reason.

Hinton has great advice but I find it to be a bit over-the-top for my use.

i wired it same as you piscione but after reading the post that linked rumplefilter…
it’s a hum definitely and it comes out from all sound sources i tried.
and as it’s a hum i made research on the forum for ground problem and feel more confusing,
so if someone have a clear,understandable and safe explications about how to wire properly should be very kind.

have a good night;)

If it is a “hum”, do you know what frequency it is? In my case, a 60hz hum would indicate a ground issue somewhere, or something not connected that should be. I think pichenettes is right (no surprise of course), you should check every module one at a time. Disconnect everything and then put each module back one at a time. You need to know where the actual problem is coming from for sure. Can you post a photo of your power supply/busboards wiring?

@piscione it’s higher than 60hz,i pushed the investigation further last night,and when i crank up the gain on the mixer it looked like leds bleeding,so i went to this:

i found that the problem was,after i tried the one by one method describe above by rumplefilter,that it depend on which order i attach module on the busboard so i reorganized everything and it’s left.
also i found a thread don t remember where…that was describing the same problem and suggest to change the order of the module on the bus board.

so thanks you all for your suggestions and help,really kind

a last question,who is using a meanwell and the mr hinton ground scheme ?