Do you have fuses in the power amp rails or some other way of powering up just the filter? Disconnect the filter output from the amp input.
With just the filter powered and no source connected measure the AC and DC output of the filter relative to ground. They should both be 0.
Connect your discman to the filter input (no music playing), repeat. Still 0?
Connect to your computer to the filter input (no music playing). Still 0?
Now pull power to the filter. Power up the amp. Output hum? Measure the output AC and DC voltage. As long as DC is less than 100 mV it's ok. AC should be 0.
Connect the computer directly to the amp input (no music playing). Hum? Still the same 0VAC and DC voltages?
If this all checks out, reconnect it computer to filter to amp. Pay attention that all grounds go to the same star ground point. The input jack should be isolated from the chassis and its shell connected to the star. There should be one lead from the filter board to the star. All filter board grounds connect to this one lead.
With just the filter powered and no source connected measure the AC and DC output of the filter relative to ground. They should both be 0.
Connect your discman to the filter input (no music playing), repeat. Still 0?
Connect to your computer to the filter input (no music playing). Still 0?
Now pull power to the filter. Power up the amp. Output hum? Measure the output AC and DC voltage. As long as DC is less than 100 mV it's ok. AC should be 0.
Connect the computer directly to the amp input (no music playing). Hum? Still the same 0VAC and DC voltages?
If this all checks out, reconnect it computer to filter to amp. Pay attention that all grounds go to the same star ground point. The input jack should be isolated from the chassis and its shell connected to the star. There should be one lead from the filter board to the star. All filter board grounds connect to this one lead.
I did the whole thing an all checked out
but I didn't understand your last paragraph
my box is made of wood and it doesn't have any metal for chassis
but I didn't understand your last paragraph
my box is made of wood and it doesn't have any metal for chassis
BTW when I directly connect the amplifier to computer it doesn't have any sound ( even a little hum or hiss )
But when I connect the filter to the amp and power up the amp it has a bit humm
But when I connect the filter to the amp and power up the amp it has a bit humm
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All the grounds need to connect to a common point, called the star ground because of the way numerous connections are made to it. I often use a bolt for my star ground and all the leads connecting to the bolt have ring terminals that I place on the bolt and hold in place with toothed washers and a nut.
The amp board has at least one ground connection, maybe two that connect to the star.
The amp's transformer winding center tap should connect to the common point between the filter capacitors, which in turn should connect to the star.
The amp's output ground should connect to the star. (assuming a standard topology, not bridged)
The center tap of the filter power winding connects to the star. The common point of the filter's power supply connects to the star.
The filter board's ground should connect to the star.
The input signal connector's ground lead should connect to the star.
The mains power safety ground lead should connect to the star. This can either be a direct connection or through a ground loop breaker such as a CL60.
If any of the grounds are not connected as above, you can have issues.
OK, how about when you connect the amplifier to the filter but nothing connected to the filter input?
The amp board has at least one ground connection, maybe two that connect to the star.
The amp's transformer winding center tap should connect to the common point between the filter capacitors, which in turn should connect to the star.
The amp's output ground should connect to the star. (assuming a standard topology, not bridged)
The center tap of the filter power winding connects to the star. The common point of the filter's power supply connects to the star.
The filter board's ground should connect to the star.
The input signal connector's ground lead should connect to the star.
The mains power safety ground lead should connect to the star. This can either be a direct connection or through a ground loop breaker such as a CL60.
If any of the grounds are not connected as above, you can have issues.
OK, how about when you connect the amplifier to the filter but nothing connected to the filter input?
Hi BobEllis
I tried the what you said but when I connected the following wires I have a serious problem :
Ground on the filter + Ground on amplifier + Center point of filter's trans + Center point of Amplifier's trans
When I connect these 4 wires together I hear a fairly loud Hum on the subwoofer. but when I power up the amplifier I can hear the song just like before with its buzz+upper hum
I tried the what you said but when I connected the following wires I have a serious problem :
Ground on the filter + Ground on amplifier + Center point of filter's trans + Center point of Amplifier's trans
When I connect these 4 wires together I hear a fairly loud Hum on the subwoofer. but when I power up the amplifier I can hear the song just like before with its buzz+upper hum
Are the amp and filter PSU grounds connected to the same point?
If that still hums, there is something else at play that I cannot identify remotely. Do you know anyone who might be able to help or have an electronic repair shop nearby?
If that still hums, there is something else at play that I cannot identify remotely. Do you know anyone who might be able to help or have an electronic repair shop nearby?
Before I star I want to thank you for your all advices and attentions
I built that Sony filter which I sent you before
It was quite good, But it had a problem and it was that I could not hear the frequencies that the singer voices was on it ( I mean hum part of singer voice ) and it just had thump ( I think lower than 120Hz )
Than I used Linkwitz-Riley crossover calculator that you introduced me to make a 24db/octave low pass filter for my present filter that I'm using ( before my filter )
and the response was fantastic. and I'm so happy to reach what I want.
Thank u so much for all your help BobEllis.
As I guessed before the buzz from my subs was from themselves. because I tested them with two other amplifier and I still got that buzz.
my only problem from this sub system is that when I power up the amp (the sound from computer is not played ) I hear a bit hum from subs and I don't have a oscilloscope to see the output of the amp and find out the frequency of this hum so I could remove it from my amp output by a filter.
If you could help me to remove this hum from my sub, you helped me a lot and I'll never forget that
Thank you
I built that Sony filter which I sent you before
It was quite good, But it had a problem and it was that I could not hear the frequencies that the singer voices was on it ( I mean hum part of singer voice ) and it just had thump ( I think lower than 120Hz )
Than I used Linkwitz-Riley crossover calculator that you introduced me to make a 24db/octave low pass filter for my present filter that I'm using ( before my filter )
and the response was fantastic. and I'm so happy to reach what I want.
Thank u so much for all your help BobEllis.
As I guessed before the buzz from my subs was from themselves. because I tested them with two other amplifier and I still got that buzz.
my only problem from this sub system is that when I power up the amp (the sound from computer is not played ) I hear a bit hum from subs and I don't have a oscilloscope to see the output of the amp and find out the frequency of this hum so I could remove it from my amp output by a filter.
If you could help me to remove this hum from my sub, you helped me a lot and I'll never forget that
Thank you
Hi,
One last test.
Unplug from the mains.
Disconnect the wire from chassis to main ground star. DO NOT disconnect the PERMANENT connection from chassis to the third wire in the mains power lead.
Attach a resistance meter to chassis and main ground star.
What is the resistance reading?
One last test.
Unplug from the mains.
Disconnect the wire from chassis to main ground star. DO NOT disconnect the PERMANENT connection from chassis to the third wire in the mains power lead.
Attach a resistance meter to chassis and main ground star.
What is the resistance reading?
Hi Andrew T
I said already that I don't have any chassis because my amplifier box is made of wood
Do I have to mount any metal to my box as chassis
I don't have to connect the ground of home outlet ( ground on the high voltage of trans) to the star? do I?
I said already that I don't have any chassis because my amplifier box is made of wood
Do I have to mount any metal to my box as chassis
I don't have to connect the ground of home outlet ( ground on the high voltage of trans) to the star? do I?
don't worry
I'll take the responsibility of this job
I'm an electrician
Just tell me what to do
do I have to mount a chassis?
I'll take the responsibility of this job
I'm an electrician
Just tell me what to do
do I have to mount a chassis?
You are an electrician, then tell us how you protect an operator from electric shock if using a piece of faulty mains powered equipment.
How do you wire up the PE?
How do you wire up the PE?
I live in Iran and in here we don't have third wire as Earth
So what do I have to do
Do I have to connect my chassis to the water pipe? or I must dig a hole in my room and I go down until I reach to wet ground and finally put my earth ground there?
You show me the way and tell me what to do
So what do I have to do
Do I have to connect my chassis to the water pipe? or I must dig a hole in my room and I go down until I reach to wet ground and finally put my earth ground there?
You show me the way and tell me what to do
apex design sub is verry good
Hi
I re
cently have built a 250W mosfet amplifier and I need a very good Low pass filter ( Sub filter ) for it to drive my sub
I tried this one
Low pass filter - Subwoofer
but I want something with higher performance
Please introduce me something that you've built and it did work
thanks
Please someone give me a reliable and tried schematic😕
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