hello there!
i've build a tda7498e based multichannel power amp for my HT. i used this boards:
https://pt.aliexpress.com/item/4000...1;15.66;-1;-1@salePrice;EUR;search-mainSearch
for the power supply i've build a regulated linear psu based on a simple. the regulation is done with a opamp and power transistor
the AVR is a onkyo tx-nr656 and I've made some custom preout on it to connect the external amp.
so the problem is this:
the power amp is dead silent, but if i connect it to the AVR it makes some annoying hum and I'm having lots of problems eliminating it. I've changed the interconnect, i've connect the power amp to the earth ground' I've isolated the power amp from earth ground (no difference between the 2), i've disconnect all the cables (exept the interconnects to the power amp), i even bought some high level to level adapters and nothing works.... BUT if i connect a laptop or a phone to the power amp it plays without any annoying hum.
The hum i think is on the 60hz range.
about the custom preout on the avr: i've readded the service manual from it and the unit is the same as the tx-rz 610 but without preouts and i added the rca plugs with coupling capacitors from the jumper wire that is connecting to the power amp stage on the AVR. got it from the page 49 of the service manual.
what i need to know is if there is anything else i can do to make the hum disappear.
there are some photos of the build, it isn't beautiful but i think I've made things more or less well done. feel free to point thing to be done to make things better.
for last but not least, thanks to all the members of this forum that are sharing knowledge, teaching and helping this community.
i've build a tda7498e based multichannel power amp for my HT. i used this boards:
https://pt.aliexpress.com/item/4000...1;15.66;-1;-1@salePrice;EUR;search-mainSearch
for the power supply i've build a regulated linear psu based on a simple. the regulation is done with a opamp and power transistor
the AVR is a onkyo tx-nr656 and I've made some custom preout on it to connect the external amp.
so the problem is this:
the power amp is dead silent, but if i connect it to the AVR it makes some annoying hum and I'm having lots of problems eliminating it. I've changed the interconnect, i've connect the power amp to the earth ground' I've isolated the power amp from earth ground (no difference between the 2), i've disconnect all the cables (exept the interconnects to the power amp), i even bought some high level to level adapters and nothing works.... BUT if i connect a laptop or a phone to the power amp it plays without any annoying hum.
The hum i think is on the 60hz range.
about the custom preout on the avr: i've readded the service manual from it and the unit is the same as the tx-rz 610 but without preouts and i added the rca plugs with coupling capacitors from the jumper wire that is connecting to the power amp stage on the AVR. got it from the page 49 of the service manual.
what i need to know is if there is anything else i can do to make the hum disappear.
there are some photos of the build, it isn't beautiful but i think I've made things more or less well done. feel free to point thing to be done to make things better.
for last but not least, thanks to all the members of this forum that are sharing knowledge, teaching and helping this community.
