Connect input GND to PSU GND...
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One quick question regarding the AX14 amp ground wiring options. I use a simple CRC psu boards (dual so each CRC for a single amp board). I also use a stereo speaker protection board. So the connections I have given is like:
1. Connected both the psu grounds (this is suggested as per the psu design). Use a single transformer but with 4 independent secondary winding.
2. Connected with a thick wire from psu ground using a thermistor in series to the chassis
3. RCA grounds connected to the each amp input grounds with RCA jacks being isolated from the chassis
4. Connected the psu ground to the speaker protection input ground from each psu (2 channels)
5. IEC ground not connected to the chassis. I have tried this connection to the same chassis ground connection but I get lots of hum.
With the above connections I still get hum with the inputs connected or not. Unable to get rid of the hum. Any suggestions here would be great.
Thanks
1. Connected both the psu grounds (this is suggested as per the psu design). Use a single transformer but with 4 independent secondary winding.
2. Connected with a thick wire from psu ground using a thermistor in series to the chassis
3. RCA grounds connected to the each amp input grounds with RCA jacks being isolated from the chassis
4. Connected the psu ground to the speaker protection input ground from each psu (2 channels)
5. IEC ground not connected to the chassis. I have tried this connection to the same chassis ground connection but I get lots of hum.
With the above connections I still get hum with the inputs connected or not. Unable to get rid of the hum. Any suggestions here would be great.
Thanks
Thanks Prasi, when I said 1 transformer but I have 4 independent secondaries and 2 of these power each psu board. With this same transformer and similar ground wiring in the same cabinet when I used the FH9HV amp boards of XRK it was completely hum free. Except the amp boards nothing has changed in this cabinet including the transformer, dual CRC psu boards, soft start, speaker protection boards.
When you say lift input ground via R23 with 10R resistor, what do you mean by this. Sorry I did not get this from your post.
Thanks again.
ok..
On this amp input ground is separate from PSU ground and is conneced via 2 diodes (D6/D7 ) and a resistor (R23).
Unless that resistor R23 is connected, your input ground will have no connection to PSU. This will lead to lot of trouble.
Alternative option is to leave out R23/D6/D7 and connect a separate wire from input ground to PSU ground on the clean side.
Third option is to short the R23 via jumper.
Try any of the above options and see if it helps with hum.
see here for stuffing guide.
100W Ultimate Fidelity Amplifier
Thanks Prasi now I understand why the AX14 board is different to the FH9HV. On my AX14 amp boards I have used the D6 and D7 along with the R23 resistors soldered. Now if I go with your 3rd option of removing R23 resistor and replace it with a jumper wire, then how should my ground wiring be?
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