did you tried correcting that offset ?
do you know how?
anyway , your build is full with problems and you're not helping much - pictures and explanations are necessary so we can deduce what's problem and how to easier explain to you
if you need help , you need to learn either how to post pics here or successfully link them here
do you know how?
anyway , your build is full with problems and you're not helping much - pictures and explanations are necessary so we can deduce what's problem and how to easier explain to you
if you need help , you need to learn either how to post pics here or successfully link them here
Whaaaat? Between l and r channel? Who measures that.
DC on output is measured at speaker terminal, live to ground.
We care what DC our expensive speakers and headphones will get, its detrimental to them.
Here's a link to Teabags blog if you haven't already seen it.
M2Clone boards with 120mm UMS spacing - diyAudio
M2Clone boards with 120mm UMS spacing - diyAudio
answer to Syl20m
Hello Syl20m,
for me this sounds like you did no offset adjustment.
To do this:
DMM - you want to measure Volts - millivolts! at your speakeroutput
You put the red probe of your DMM to speakerout + and DMM black probe
to speakerout - (you do this first ONLY! on the left channel)
Now you adjust your trimpot for offset adjustment on the main pcb (left channel!) till you get close as possible to 0,0 mV on your DMM. Turn slow!
You will not get 0,0mV but try to get close. All below 1mV is super, below 10mV acceptable. Up to 50mV is my personal absolut maximum.
Now go to right channel:
same procedure
Greets Dirk
Hello Syl20m,
for me this sounds like you did no offset adjustment.
To do this:
DMM - you want to measure Volts - millivolts! at your speakeroutput
You put the red probe of your DMM to speakerout + and DMM black probe
to speakerout - (you do this first ONLY! on the left channel)
Now you adjust your trimpot for offset adjustment on the main pcb (left channel!) till you get close as possible to 0,0 mV on your DMM. Turn slow!
You will not get 0,0mV but try to get close. All below 1mV is super, below 10mV acceptable. Up to 50mV is my personal absolut maximum.
Now go to right channel:
same procedure
Greets Dirk
Hi all,
I have replaced r7 to 52.3k on both channels to get more window for tuning the offset.
After running the amp for 20 Minutes, I have set both channels below 0.5mV . It is now occilating between 0 and 0.5!
I will check it again when the amp is fully warm!
I will check temperature of the components again tomorrow!
I have noticed that the amp seems to take about 4-8seconds to load the capacitors when powered up which result of bad sound if the source is already playing!
I supposed the CL-60 inrush limiter i put at primary of the transformer is one of the reasons for this long charging!
Also the CL-60 is quite hot, I was not able to measure , but I guess above 50 degrees
Is that a problem?
You gonna tell the that I should power up the amp and them turn the source On after a while. Which I would normally do!
I have been using a cl-60 also between ground of chassis and ground of power sypply!
The toroidy transformer 500w 2x18vac I am using is not dead silent, there is very small vibrating sound coming form it, it does not seems to spread up to the speakers at least.
Any advises are welcome !
I have replaced r7 to 52.3k on both channels to get more window for tuning the offset.
After running the amp for 20 Minutes, I have set both channels below 0.5mV . It is now occilating between 0 and 0.5!
I will check it again when the amp is fully warm!
I will check temperature of the components again tomorrow!
I have noticed that the amp seems to take about 4-8seconds to load the capacitors when powered up which result of bad sound if the source is already playing!
I supposed the CL-60 inrush limiter i put at primary of the transformer is one of the reasons for this long charging!
Also the CL-60 is quite hot, I was not able to measure , but I guess above 50 degrees
Is that a problem?
You gonna tell the that I should power up the amp and them turn the source On after a while. Which I would normally do!
I have been using a cl-60 also between ground of chassis and ground of power sypply!
The toroidy transformer 500w 2x18vac I am using is not dead silent, there is very small vibrating sound coming form it, it does not seems to spread up to the speakers at least.
Any advises are welcome !
