Had a huge hum problem with 2 channels at the input. With only one nothing at all. Solution must be a little resistor in the gnd in?
Jims Pcb
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Please note the different symbols used for the chassis ground/Safety Earth/PE and the PSU power ground/PSU zero volts.
This is important.
Note also that the secondary centre tap goes directly to the first capacitor pair.
having got those bits wired correctly it becomes important to minimise the loop areas of the charging circuits to minimise the EMI.
This is important.
Note also that the secondary centre tap goes directly to the first capacitor pair.
having got those bits wired correctly it becomes important to minimise the loop areas of the charging circuits to minimise the EMI.
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Thanks Andrew but I use BUS. I realized it is not possible with only four rectifiers pr. channel. So I will use 8. The reason is common transformer. I think bus results in better sound.
Gnd enclosure
As my backplate is not metal I could have a problem with electrical connection of the enclosure parts. I'll connect the two heatsinks at the backplate with a copper 2 cm wide and ground my input to that trough 10 ohm and a capacitor. Do you think that's an idea? ? I can't post pictures even that I have paid Diyaudio 20 dollars for membership.
As my backplate is not metal I could have a problem with electrical connection of the enclosure parts. I'll connect the two heatsinks at the backplate with a copper 2 cm wide and ground my input to that trough 10 ohm and a capacitor. Do you think that's an idea? ? I can't post pictures even that I have paid Diyaudio 20 dollars for membership.
Don't post pictures.
Attach them !
How to attach images to your posts.
And registration here is free.
Thats what I try to.
Have anyone tried other rectifiers then MUR 3020 for the turbo? I think they are very bad sounding.
Have anyone tried other rectifiers then MUR 3020 for the turbo? I think they are very bad sounding.
As rectifiers in the PSU or parallel with the Mosfet sources?
Use what you wish in the PSU.
But change the diodes in the amp circuit with caution, the 3020's were chosen for their resistance vs. current curve.
Use what you wish in the PSU.
But change the diodes in the amp circuit with caution, the 3020's were chosen for their resistance vs. current curve.
A moderator must haVE DONE SOMETHING. nOW I CAN . This amp Just Hum whatever I do. If only one channel is connected to Pre it is ok.
I will rebuild it as monos,
A hum that only happens when you connect both channels is a signal ground loop and has nothing to do with your rectifiers.
With Monos there will be no ground loops.
I used the 3020 as rectifiers in another amp and I think they could be the reason for harshness in the turbo.
I used the 3020 as rectifiers in another amp and I think they could be the reason for harshness in the turbo.
The rectifier diodes are amongst the last thing I would change to address a perceived harshness, but feel free to change them if you like. As long as you use diodes of sufficient rating you will do no damage to the PSU.
Ahhhh, the hum breaking resistors... this seems to come up again and again with the F5. There were a few posts about modifying the diyAudio boards to add those resistors. Try searching for it.
By having an extremely low-impedance and low resistance ground. The easiest way to try it is attach ALL (including the signal input grounds) to one point on the PSU ground. Star-grounding is a common name for it.
Do this. Attach the speaker negatives and the input signal negatives to it as well. (Yes, the input from the RCA to the PCB will only be the positive!) The only ground connection from the amplifier boards will be the one wire attaching V+/gnd/V- to the PSU.
An externally hosted image should be here but it was not working when we last tested it.
Do this. Attach the speaker negatives and the input signal negatives to it as well. (Yes, the input from the RCA to the PCB will only be the positive!) The only ground connection from the amplifier boards will be the one wire attaching V+/gnd/V- to the PSU.