Hey everyone,
Please note I’m not an expert and this could be an obvious issue. Please take that into consideration as I’m learning.
So I’m putting together an amp using a wondom jab5 and a mean well gst160a
I know the amp is working because when I use a different power supply (mean well rsp 230 27) it works fine, there is a very faint white noise coming from the speakers but it’s very quiet.
But when I use the gst160a I get slightly louder white noise and if I connect an aux cable I get a horrible electronic squeal.
More info:
The power supply is connected using a kpjx panel mount to a power switch and then to amp.
My amp enclosure is plastic. It’s a 3d printed part.
I’ve also tested it outside of the enclosure with just all the parts loose and far away from each other.
I believe it’s related to the power supply as my other power supply doesn’t have this issue. (Note I don’t want to use the other power supply as it has a noisy fan which drives me mad).
Any ideas would be very helpful.
The jab 5 manual recommends the mean well gst160a so I’m suprised it wasn’t just plug and play.
Thanks so much
Will
Please note I’m not an expert and this could be an obvious issue. Please take that into consideration as I’m learning.
So I’m putting together an amp using a wondom jab5 and a mean well gst160a
I know the amp is working because when I use a different power supply (mean well rsp 230 27) it works fine, there is a very faint white noise coming from the speakers but it’s very quiet.
But when I use the gst160a I get slightly louder white noise and if I connect an aux cable I get a horrible electronic squeal.
More info:
The power supply is connected using a kpjx panel mount to a power switch and then to amp.
My amp enclosure is plastic. It’s a 3d printed part.
I’ve also tested it outside of the enclosure with just all the parts loose and far away from each other.
I believe it’s related to the power supply as my other power supply doesn’t have this issue. (Note I don’t want to use the other power supply as it has a noisy fan which drives me mad).
Any ideas would be very helpful.
The jab 5 manual recommends the mean well gst160a so I’m suprised it wasn’t just plug and play.
Thanks so much
Will
It might be a mixing product between the switching frequencies of the power supply and the class D amplifier. Is there any way to synchronize them, or to just change the switching frequency of one of the two?
Hi Will,
I think we are in the same boat.
I have built a Pellerano's Zen headphone amp for a friend from work (check out Pass Gallery forum). I want to run it on a 24V laptop brick power supply.
I tested the amp with my lab supply and it is working fine, no noise in any of my cans.
Then I have connected the a HP 24V power supply. It has a 3pin input (L,N and Earth). The E pin is connected to -V output. The powered on amp is quiet with nothing connected.
Then I connect a DAC which is also powered with a smps, also 3pins input and E connected to -V and then the whistling starts.
I suppose I am getting a ground loop via the ground connection.
Indeed if I break the E connection (do it at your own risk! can be lethal!) the whistling goes away.
I can also run the whole setup noise free powering the DAC with a small phone charger (2 pins input), hence no loop through the safety ground wire.
Also running the amp with a Lenovo 2pin supply is noise free. I have also another Lenovo supply which has 3pin input but -V is not connected to the safety ground and it is also fine.
I think your issue might be similar.
I wonder if a different smps would solve the issue.
I googled MeanWell GST120A24 ( I do not think it is that much different from the one your are trying to use) which widely used for the Pass ACA amp. People seem to be happy with it. Yet after consulting the documentation I see that the E pin is also connected to -V.
Since I have a metal enclosure for my amp I would like to have a PS with E connection and ideally I would like to connect the E to the chassis and have -V floating or lifted with respect to ground.
Yet I have not seen a laptop PS like this yet.
My experiments agree with what you are saying about mean well rsp 230 27 - I do not think E is connected to -V in this one, you are free to connect it to the chassis of your amp (or not - yours is plastic, right? ;-) )
I think we are in the same boat.
I have built a Pellerano's Zen headphone amp for a friend from work (check out Pass Gallery forum). I want to run it on a 24V laptop brick power supply.
I tested the amp with my lab supply and it is working fine, no noise in any of my cans.
Then I have connected the a HP 24V power supply. It has a 3pin input (L,N and Earth). The E pin is connected to -V output. The powered on amp is quiet with nothing connected.
Then I connect a DAC which is also powered with a smps, also 3pins input and E connected to -V and then the whistling starts.
I suppose I am getting a ground loop via the ground connection.
Indeed if I break the E connection (do it at your own risk! can be lethal!) the whistling goes away.
I can also run the whole setup noise free powering the DAC with a small phone charger (2 pins input), hence no loop through the safety ground wire.
Also running the amp with a Lenovo 2pin supply is noise free. I have also another Lenovo supply which has 3pin input but -V is not connected to the safety ground and it is also fine.
I think your issue might be similar.
I wonder if a different smps would solve the issue.
I googled MeanWell GST120A24 ( I do not think it is that much different from the one your are trying to use) which widely used for the Pass ACA amp. People seem to be happy with it. Yet after consulting the documentation I see that the E pin is also connected to -V.
Since I have a metal enclosure for my amp I would like to have a PS with E connection and ideally I would like to connect the E to the chassis and have -V floating or lifted with respect to ground.
Yet I have not seen a laptop PS like this yet.
My experiments agree with what you are saying about mean well rsp 230 27 - I do not think E is connected to -V in this one, you are free to connect it to the chassis of your amp (or not - yours is plastic, right? ;-) )
Yes I think your issue sounds similar, and yes the chassis here is plastic which is where I think the problem lies as there is no chassis ground.
I’ve since noticed on the Kpjx connector that there are two small pins on the side which I imagine would attach to the metal chassis so maybe this is my issue.
Not sure how to resolve in my case as like I say the enclosure is plastic. I wonder if I can connect it to the -v? The power supply is connected to uk mains so has a ground there.
I’m not savvy enough to know if this is safe or not
I’ve since noticed on the Kpjx connector that there are two small pins on the side which I imagine would attach to the metal chassis so maybe this is my issue.
Not sure how to resolve in my case as like I say the enclosure is plastic. I wonder if I can connect it to the -v? The power supply is connected to uk mains so has a ground there.
I’m not savvy enough to know if this is safe or not
The specs of MeanWell GST60A say -V is not connected to GND.
But then 60W might be not enough for you as you are powering an amp not a headphone amp.
But then 60W might be not enough for you as you are powering an amp not a headphone amp.
Good to know so the ground is the issue. Also just to confirm I’m using the GST160a which sure recommend for this amp.
I guess the solution is to buy a metal enclosure
I guess the solution is to buy a metal enclosure