Hello,
I made an amplifier using Hitachi HA13158a IC. Using this schematic:
For power supply I used SMPS from Logitech z533 2.1 pc speakers.
I cant tell much about it, but I know it was working normaly with the logitech amplifier. It outputs 17,7v.
I live in Europe and both the SMPS from amplifier and my TV don`t have earth connections.
Now I have problem with buzz.
If I turn on the amplifier without rca cables connected to it the buzz is really silent.
If I connect RCA cables to it (with nothing connected on the other side) buzz becomes loud, cables act like an antenna.
If I connect mobile phone to it buzz is almost gone. Really silent buzz remains.
But if I connect amplifier to the tv the buzz is much lounder than with the mobile phone.
If I turn off the tv the buzz becomest even louder.
I ordered TOSLINK to analog adapter mainly because I can`t control volume level of headphones jack without going into settings on tv, but it will also break possible ground loop to the tv.
But I have a feeling that the buzz will remain (because there is a slight buzz with the phone connected).
What can I do to solve the problem?
Thank you.
I made an amplifier using Hitachi HA13158a IC. Using this schematic:
For power supply I used SMPS from Logitech z533 2.1 pc speakers.
I cant tell much about it, but I know it was working normaly with the logitech amplifier. It outputs 17,7v.
I live in Europe and both the SMPS from amplifier and my TV don`t have earth connections.
Now I have problem with buzz.
If I turn on the amplifier without rca cables connected to it the buzz is really silent.
If I connect RCA cables to it (with nothing connected on the other side) buzz becomes loud, cables act like an antenna.
If I connect mobile phone to it buzz is almost gone. Really silent buzz remains.
But if I connect amplifier to the tv the buzz is much lounder than with the mobile phone.
If I turn off the tv the buzz becomest even louder.
I ordered TOSLINK to analog adapter mainly because I can`t control volume level of headphones jack without going into settings on tv, but it will also break possible ground loop to the tv.
But I have a feeling that the buzz will remain (because there is a slight buzz with the phone connected).
What can I do to solve the problem?
Thank you.
The operating voltage of the microcircuit is 13.7v.
The consumed current is more than 4A. Your power supply does not fit.
Connect via adapter.
The consumed current is more than 4A. Your power supply does not fit.
Connect via adapter.
Maximum is stated 18v in datasheet. Should I rather use 13.7v anyway?
You found out that 4A is maximum current for this psu? I searched on internet about it, but didn't find any info about it.
If that is the case I will find a transformer that I know I have somewhere and build 14v psu
Thank you
You found out that 4A is maximum current for this psu? I searched on internet about it, but didn't find any info about it.
If that is the case I will find a transformer that I know I have somewhere and build 14v psu
Thank you
This has been brought up in DIY Audio a couple of years ago -the chip is a car audio chip designed for automobiles and the several posters had the very same problem saying "its a standard fault in this and other car audio chips ".
If its any help the OP added a 15K grounding resistor ( line in to ground ) and moved R in rail further from V in capacitor .
That solved it for him.
If its any help the OP added a 15K grounding resistor ( line in to ground ) and moved R in rail further from V in capacitor .
That solved it for him.
This IC as most car amps have a separate input ground pin 12. May be grounding it with 50 ohms and getting the input ground of RCAs from pin 12 can help reduce the ground parasite, it is the case in cars.
Thank you, I will try that.
Each line in has 15k resistor towards the ground already, but I will try that anyway. I don`t understand what you mean by "moved R in rail further from V in capacitor". Do you mean he moved grounding resistor (15k) away from the power capacitor?
Thank you
I wasn`t aware that pin 12 is input grounding pin. Thank you I will try as you suggested. Just to make things clear... I should connect input ground directly to pin 12 and add 50ohm resistor between pin 12 and gnd?
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I would also like to ask what is the purpose of 2.2ohm resistors and 0.1uF capacitors going from each speaker output line going to gnd?
I recommend starting with this link Ground Loops- lots of great information. You must first understand where the hum comes from and then look for the causes. Good tools for fighting a hum are a headset or rms AC meter. Often moving a wire a few inches can reduce the hum by 0.5mV or even more...
Thank you all again for anwsers.
I added 15k pull down resistors, I disconnected pin 12 from gnd, added 50ohm resistor towards gnd and connected signal gnd from there. I connected one speaker to it and connected amplifier to computer and I can confirm that it is alot better. I can`t do full test with all the speakers and the tv right now, because it`s all at girlfriends house (I`m making soundbar for her tv). Will test tomorrow. Should I also connect all capacitors and resistors going from inputs to gnd (1n and 15k for each input from the schematic) to this new signal gnd instead?
I added 15k pull down resistors, I disconnected pin 12 from gnd, added 50ohm resistor towards gnd and connected signal gnd from there. I connected one speaker to it and connected amplifier to computer and I can confirm that it is alot better. I can`t do full test with all the speakers and the tv right now, because it`s all at girlfriends house (I`m making soundbar for her tv). Will test tomorrow. Should I also connect all capacitors and resistors going from inputs to gnd (1n and 15k for each input from the schematic) to this new signal gnd instead?
Get ride of the 15k and 1nF, it only needs 330nf polypropylene, in series coupling capacitor. Inside the IC there is 25k resistor linking the bias referenced to pin 12. To avoid plop on start up, you need 100uF grounding pin 10.
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can I use 470nF instead of 330nf? That`s what I have at home. No stores are open near me due to virus 🙁
Ok, I had managed to talk out the owner of the store where I buy everything electrical to supply me some goodies 🙂
I got resistors for zobel network, 120VA 12V toroidal and 35A greatz for power supply.
Any suggestions on what capacitors should I use?
I can`t find any good schematics for single rail psu...
I got resistors for zobel network, 120VA 12V toroidal and 35A greatz for power supply.
Any suggestions on what capacitors should I use?
I can`t find any good schematics for single rail psu...
As I removed 15k resistors and 0.1uf capacitors from inputs and soldered 470nf capacitors in series with inputs and 15k resistors (one for left one for right... i have 2 and 2 channels wired together) the buzz become louder.
That got me thinking before i had 15k resistor for each channel (2 on left and 2 on right) giving total resistance of 7.5ohm because of joined inputs thats why buzz was not as loud...
Can I try with 7.5k resistors and if it works call it job done?
How low can I go with resistance across input and gnd?
Also would it be better to add resistors directly to inputs of ic or before 470nf caps?
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