Hi.
I'm currently experimenting with a class d board I bought on eBay and experiencing some noise.
I assume (I'm a noob) that the reason for this is that I just connected the board to a preamp attached power and a speaker to the board.
There is no central shield / ground from the board. Maybe someone can point me into the right direction because simply googling it turned not to be as successful as expected. But maybe I searched the wrong terms 🙂
In case I decide to use a metal housing, my questions are:
1) Do I need to connect the power supplies minus/ground to the metal housing ?
2) Do I need to connected the inputs minus to ground aswell ? I opened up some plastic distortion pedals to compare and it seems like their inputs are not wired to ground..
3) Do I have to do the same for the output / to speaker minus ?
4) If the above needs ground, do I need an additional groung wire to connect the (metal) input jacks to ground, or is it sufficient enough to use the connection to the metal housing they already have?
5) Can I simply add a low-pass filter cutting off at 6Khz before attaching a speaker or is filtering better on the input ?
6) If I'd like to amplify only 100hz to 6-7Khz to the class d board, restricting it with a passive bandpass, would it be better to do it on the input or output ?
I'm sorry if these questions may appear somehow stupid, but I hope someone can guide me into the right direction or provide some answers/clarification.
Have a nice and sunny day and thanks in advance!
audi0n00b
I'm currently experimenting with a class d board I bought on eBay and experiencing some noise.
I assume (I'm a noob) that the reason for this is that I just connected the board to a preamp attached power and a speaker to the board.
There is no central shield / ground from the board. Maybe someone can point me into the right direction because simply googling it turned not to be as successful as expected. But maybe I searched the wrong terms 🙂
In case I decide to use a metal housing, my questions are:
1) Do I need to connect the power supplies minus/ground to the metal housing ?
2) Do I need to connected the inputs minus to ground aswell ? I opened up some plastic distortion pedals to compare and it seems like their inputs are not wired to ground..
3) Do I have to do the same for the output / to speaker minus ?
4) If the above needs ground, do I need an additional groung wire to connect the (metal) input jacks to ground, or is it sufficient enough to use the connection to the metal housing they already have?
5) Can I simply add a low-pass filter cutting off at 6Khz before attaching a speaker or is filtering better on the input ?
6) If I'd like to amplify only 100hz to 6-7Khz to the class d board, restricting it with a passive bandpass, would it be better to do it on the input or output ?
I'm sorry if these questions may appear somehow stupid, but I hope someone can guide me into the right direction or provide some answers/clarification.
Have a nice and sunny day and thanks in advance!
audi0n00b
audi0n00b,
We may be able to give more accurate advices if we know what particular "class-D board" you are using right now, even better with pictures included 😉
K.
We may be able to give more accurate advices if we know what particular "class-D board" you are using right now, even better with pictures included 😉
K.
Be aware that a lot of class D amp are the so called bridge-tied, which means that the (-) terminal is not ground; i.e. same as the (-) of the power supply.
Do you have a DMM? You can check continuity between the power supply (-) and the input (-). If it beeps, probably safe to connect the power supply (-) to a metal chassis / enclosure. Let the input (-) "float" off the chassis, by using some sort of isolation / isolated connector when you mount it to the chassis.
Oh, input is always easier for such, as the impedance there is much higher. You can use smaller components which are less costly to do the same thing.
Hey @
Have a nice evening.
Kind regards
jjasniew
I don't really know what a DMM is, so I can't answer. But thanks regarding your "-" tipps. I will try that. If I got you right you mean, that if the minus of the PSU and the signal minus are connected (checking with an Ohm-meter) it'll be safe to ground ONLY the PSU-minus on a metal-chassis, right ? But if they're connected, why do I need to isolate the Signal-Minus ? Doesn't it then also carry ground signal ? Sorry, but this confuses me a bit....Have a nice evening.
Kind regards
You have not described the noise.
No one knows what noise needs eliminating.
You also have not stated the power supply to the board. Batteries, laptop brick......
DMM = Digital multimeter.
More than one connection to ground (e.g. input grounded at the jack and via the power supply ground connection) may cause a ground loop and hum.
No one knows what noise needs eliminating.
You also have not stated the power supply to the board. Batteries, laptop brick......
DMM = Digital multimeter.
More than one connection to ground (e.g. input grounded at the jack and via the power supply ground connection) may cause a ground loop and hum.
1) Yes, but for a dual power supply you need to connect the 0V (instead of the negative terminal) to the chassis.
2) No, you wire the inputs to the PCB, not the chassis.
3) No, you just wire the speaker to the correct points on the PCB, while also observing the correct polarity.
4) Basically, you need to wire the core / ground of the source to the core / ground on the receiving unit, using a shielded cable. All grounding is done inside the amplifier cabinet.
5) No, you do any filtering at the input of the amplifier.
6) Same as 5) above.
There is nothing stupid here, these're all regular questions that everyone must have had in mind at some time or other.