I prefer to keep R4 ofpost2454. It better defines the output voltage of the multiplier.
The output voltage isVout = {Vin * R4 / [R3+R4] } - Vbe
The ratio determined by R4 can be varied over a very wide range to take account of the expected ripple on the supply when heavily loaded. R4 could be anywhere from 3times R1 to 100times R1.
Making R4 infinity defeats proper implementation of the capacitance multiplier.
The output voltage isVout = {Vin * R4 / [R3+R4] } - Vbe
The ratio determined by R4 can be varied over a very wide range to take account of the expected ripple on the supply when heavily loaded. R4 could be anywhere from 3times R1 to 100times R1.
Making R4 infinity defeats proper implementation of the capacitance multiplier.
Hi Salas,
Does my hiss can be related to 2SK117GRs IDSS mismatch?
Now I have a hesitation with regards to my testing/choosing of these 3 transistors.
It was difficult to measure IDSS on that set which I got as a mini-kit. Some, I measured twice or three times and every time I got different mA. Do I need to short all legs to "discharge" them between each measurement? I'm sure one of these 3 was about 6.4mA and I placed it at Q305. Does it make sense to un-solder these and to re-test precisely?
Also and and since I use your Raw DC circuit, I placed 470uF 50v (Nichicon KZ) for C305. Maybe I need more filtering there and I should to increase it to 1000uF?
Does my hiss can be related to 2SK117GRs IDSS mismatch?
Now I have a hesitation with regards to my testing/choosing of these 3 transistors.
It was difficult to measure IDSS on that set which I got as a mini-kit. Some, I measured twice or three times and every time I got different mA. Do I need to short all legs to "discharge" them between each measurement? I'm sure one of these 3 was about 6.4mA and I placed it at Q305. Does it make sense to un-solder these and to re-test precisely?
Also and and since I use your Raw DC circuit, I placed 470uF 50v (Nichicon KZ) for C305. Maybe I need more filtering there and I should to increase it to 1000uF?
No, the JFETs intrinsic noise will only vary slightly from sample to sample, leave it as is.
Just increase the filtering to see if its getting better, but it could be the hiss level increases due to some pick up in the cabling or just the bandwidth is too wide. Can't really nail it without testing data on oscope and/or FFT. Terminating with a 47uF normal ESR capacitor instead of the Zobel (R107 short, MKT out) can truncate the bandwidth.
Just increase the filtering to see if its getting better, but it could be the hiss level increases due to some pick up in the cabling or just the bandwidth is too wide. Can't really nail it without testing data on oscope and/or FFT. Terminating with a 47uF normal ESR capacitor instead of the Zobel (R107 short, MKT out) can truncate the bandwidth.
Hi Salas,
I replaced C305 with 1000uF 50v Elna RFS. Zobel shorted on R307 and 47uF 50v Rubycon none-polar electrolytic replaced previously installed 4.7uF MKT (do not have any polar or Elna for that value yet). Hiss dropped dramatically!!! Does it make sense to increase C303 farther to 68uF or 100uF to try to stop it more?
Thank you.
__________________
Alex
I replaced C305 with 1000uF 50v Elna RFS. Zobel shorted on R307 and 47uF 50v Rubycon none-polar electrolytic replaced previously installed 4.7uF MKT (do not have any polar or Elna for that value yet). Hiss dropped dramatically!!! Does it make sense to increase C303 farther to 68uF or 100uF to try to stop it more?
Thank you.
__________________
Alex
Oops, I can't trust that cap. Unfortunately, its edge is unknown (it might be 10+ years old). I'll get Elna RFS with the same value next week.
You know, hiss now is audible only in very high volume (above the level of my normal audition setup). So, I can live with it.
Later on, I'll compare that BHL to my new-unbuilt yet Folded and I'll make my choice between them. Thank you.
________________________________________
Alex
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Hi Salas,
I troubleshooted my hiss issue deeper and the remaining noise is coming from MC PSU.
I check it several times and finally made the decision and rebuild it from from the scratch.
I'm done now, but hiss is still there. I'm sure there is some AC component in it, like 100Hz or so. I'm attaching my schematic and my be you can advise me some RC or so...
Thank you.
I troubleshooted my hiss issue deeper and the remaining noise is coming from MC PSU.
I check it several times and finally made the decision and rebuild it from from the scratch.
I'm done now, but hiss is still there. I'm sure there is some AC component in it, like 100Hz or so. I'm attaching my schematic and my be you can advise me some RC or so...
Thank you.
Attachments
You can repeat another Cmult after the first in series. This thing makes 108dB kill @ 100HZ. After that mod whatever remains for hum is surely whatever it picks from cables, layout, & environment. Also whatever will remain for hiss it will be whatever the MC stage self produces, no doubt. Keep it nearest to the MC stage possible and use twisted pair cabling.
Add another 0.6V to the 317 output to compensate for the second cell loss. 1m and 2.2m mean 1000uF and 2200uF respectively. Vcc is the 317 output point.
Add another 0.6V to the 317 output to compensate for the second cell loss. 1m and 2.2m mean 1000uF and 2200uF respectively. Vcc is the 317 output point.
Attachments
I just completed a 15V bi-polar BIB 1.1 and am using it to power a Legato 3.1. I have a couple of questions.
For R101/201, I’m currently using the large black Mills CW-5 resistors (4R) and am thinking I would replace them with a slightly lower value (have 300mA CCS and wouldn’t mind going to 350mA). I wonder if using a “better” quality resistor here is warranted. Any suggestions?
I am using 22 gauge wire in the test setup. The 4 ground wires into the single Legato connector gets pretty tight and I don’t trust the connection. Is it OK to use smaller gauge wire, 24 maybe? Can I jumper the two sense grounds and run a single wire for both? Should the sense wires match the gauge of the force wires? These wires will be about 8cm long.
Big thanks to Salas and TeaBag for this!
For R101/201, I’m currently using the large black Mills CW-5 resistors (4R) and am thinking I would replace them with a slightly lower value (have 300mA CCS and wouldn’t mind going to 350mA). I wonder if using a “better” quality resistor here is warranted. Any suggestions?
I am using 22 gauge wire in the test setup. The 4 ground wires into the single Legato connector gets pretty tight and I don’t trust the connection. Is it OK to use smaller gauge wire, 24 maybe? Can I jumper the two sense grounds and run a single wire for both? Should the sense wires match the gauge of the force wires? These wires will be about 8cm long.
Big thanks to Salas and TeaBag for this!