Hi Bonsai,
Yes, the feedback resistors.
Only reason I picked up the discrepancy is because I had counted out the quantity from Anand's BOM and found I was short 1 for each PCB.
Thanks for all your help Bonsai.
I'll order the parts and should have some feedback in a week or so.
Best regards,
Sorry, strike that remark. the 6th resistor was R25 (15R or 22R) not 1K8.
My mistake making assumptions from the layout.
Need a 'bench light'.
Source for KX.
Hello.
After 2 months long hiatus : ]
After 2 months of procrastination to test my Ripple Eater (which aren't done till today), i have ordered E1DA fully digital usb source with 400mW Ballanced output. (I have headphones but want to use it as a source)
I am not affraid that KX will have enough power because i have 96dB speakers.
I'm concerned if KX will be stable with no feedback digital output of that powerDAC. Had anyone previously tested anything similar?
Hello.
After 2 months long hiatus : ]
After 2 months of procrastination to test my Ripple Eater (which aren't done till today), i have ordered E1DA fully digital usb source with 400mW Ballanced output. (I have headphones but want to use it as a source)
I am not affraid that KX will have enough power because i have 96dB speakers.
I'm concerned if KX will be stable with no feedback digital output of that powerDAC. Had anyone previously tested anything similar?
I don’t understand your question. What I can say is the amplifier will only reproduce what’s on its input - so if you feed it with an open loop source it won’t make any difference to how the kx behaves.
kx amp
Perhaps I am not updated but on Jim's Amp PCBs, D2 anode seems to be floating..
Best Regards
Farooq
Perhaps I am not updated but on Jim's Amp PCBs, D2 anode seems to be floating..
Best Regards
Farooq
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1) When twisting the power supply lines, between the PSU and PCB, together is it OK to also twist the ZN line in too (to make it neater) - or should the Zobel line be kept separate?
2) Is 'braiding' the lines together as good as twisting?
Thanks
2) Is 'braiding' the lines together as good as twisting?
Thanks
Hello again. And again I have stupid question.
I can't show on schematic my tests, but will try to describe:
i've supplied 2x 23V to Ripple Eater, my two dummy loads (2 parallel 330ohm 5w ceramic res) were connected to vneg-0 and vpos-0
vneg-0 and vpos-0 are both steadily growing up to 32V- i understand that's what's intended.
but when i connected probe to vneg and vpos tab Then I see 130V AC. should there be any AC on exit?
I had not checked if i have AC on vpos-0 and vneg-0
I can't show on schematic my tests, but will try to describe:
i've supplied 2x 23V to Ripple Eater, my two dummy loads (2 parallel 330ohm 5w ceramic res) were connected to vneg-0 and vpos-0
vneg-0 and vpos-0 are both steadily growing up to 32V- i understand that's what's intended.
but when i connected probe to vneg and vpos tab Then I see 130V AC. should there be any AC on exit?
I had not checked if i have AC on vpos-0 and vneg-0
Thank for tip, that was half right.
I did resoldering, d2 was indeed one side soldered. Resoldered rest of diodes and still 135-140v AC on vneg-vpos. I've found no AC on vneg-0 and vpos-0.
I did resoldering, d2 was indeed one side soldered. Resoldered rest of diodes and still 135-140v AC on vneg-vpos. I've found no AC on vneg-0 and vpos-0.
I'm only loading and testing RE with dummy load 2x 330ohm paralell.
I think I don't understand how to measure dropout.
I think I don't understand how to measure dropout.
Meassurement of the input voltage, meassurement of the output voltage. The difference is the dropout...
You should not be reading anything like 130 VAC. Please check you wiring carefully - that does not sound good.
At full load, tne ripple eater will drop 2V across each pass transistor.
At full load, tne ripple eater will drop 2V across each pass transistor.
I seem to remember that there was a 'setting' for the offset output voltage adjustment, VR2, prior to initial 'power-up' but can't seem to find the reference.
Amps are being used in AAB mode @ ±33V
Can anyone please advise?
For reference:
I have completed both channels of the xK and have been checking the required voltages stage by stage (all components added except transistors)
First stage was with all the BC transistors (550/560) only (no driver or power transistors) and this worked out OK using my bench power supply and then the ripple eaters.
Adding the 4 driver resistors (2SA/2SC) to one board and powering up via my Digimess dual voltage supply resulted in a 'smoking' R19 (33R) resistor between Q10/Q11 emitters (one channel only attempted) ...
Removing Q11, Q10 from the boards and retrying I found the output to Q10 base at circa +23.5V on both boards. Q11 base was circa -1.24V. Both with respect to ground.
VR2 on both boards was set 'fully clockwise' - max resistance between R6 and D4 (min resistance between R6/D5).
Adjusting VR2 anticlockwise I've found that I can reduce both Q10/Q11 base voltages.
Unfortunately my Digimess is not working properly at the moment - output voltage is max 25V at ± 10 to 20 mA (spec is ±30V @ 3 Amps) - but the voltage fluctuates up and down - thus taking accurate measurements is not possible.
However, the current limit function still seems to be working which is why I'm persisting with it before 'hitting' a board with 33V @ 10 Amps.
Amps are being used in AAB mode @ ±33V
Can anyone please advise?
For reference:
I have completed both channels of the xK and have been checking the required voltages stage by stage (all components added except transistors)
First stage was with all the BC transistors (550/560) only (no driver or power transistors) and this worked out OK using my bench power supply and then the ripple eaters.
Adding the 4 driver resistors (2SA/2SC) to one board and powering up via my Digimess dual voltage supply resulted in a 'smoking' R19 (33R) resistor between Q10/Q11 emitters (one channel only attempted) ...
Removing Q11, Q10 from the boards and retrying I found the output to Q10 base at circa +23.5V on both boards. Q11 base was circa -1.24V. Both with respect to ground.
VR2 on both boards was set 'fully clockwise' - max resistance between R6 and D4 (min resistance between R6/D5).
Adjusting VR2 anticlockwise I've found that I can reduce both Q10/Q11 base voltages.
Unfortunately my Digimess is not working properly at the moment - output voltage is max 25V at ± 10 to 20 mA (spec is ±30V @ 3 Amps) - but the voltage fluctuates up and down - thus taking accurate measurements is not possible.
However, the current limit function still seems to be working which is why I'm persisting with it before 'hitting' a board with 33V @ 10 Amps.
Tony,
You should assemble the boards completely. You will not get readings of any use otherwise.
Power each amplifier module up separately in class AAB mode. You should then get the voltages indicated on the circuit diagram and the current draw should be about 600 mA for the module.
Set your power supply current limit to about 700-800 mA. Your modules will need to be mounted on the heat sinks.
Once you’ve done the above, let us know how it’s going and if needs be we can do some further debugging.
Re the offset, you simply adjust it for 0V on the output with the input to the amp shorted.
You should assemble the boards completely. You will not get readings of any use otherwise.
Power each amplifier module up separately in class AAB mode. You should then get the voltages indicated on the circuit diagram and the current draw should be about 600 mA for the module.
Set your power supply current limit to about 700-800 mA. Your modules will need to be mounted on the heat sinks.
Once you’ve done the above, let us know how it’s going and if needs be we can do some further debugging.
Re the offset, you simply adjust it for 0V on the output with the input to the amp shorted.