Kalimera, Kirie Salas!
Just one question about your shuntreg: why did you use such a beefy TO247 mosfet for the CCS and the parallel device? It's only 120 mA for the first one and much less for the second. Wasn't a TO220 mosfet (such as IRF9610) enough for this purpose?
(OK, OK, I know one possible answer: I picked up what was available in my drawer.....)
P.S. I like the idea of a P device for the shunt, while many others use N devices that amplify the noise.
Just one question about your shuntreg: why did you use such a beefy TO247 mosfet for the CCS and the parallel device? It's only 120 mA for the first one and much less for the second. Wasn't a TO220 mosfet (such as IRF9610) enough for this purpose?
(OK, OK, I know one possible answer: I picked up what was available in my drawer.....)
P.S. I like the idea of a P device for the shunt, while many others use N devices that amplify the noise.
Beefy usually sounds...errr...beefy.
Plus it will not create instability so easily as a very fast one, plus low Rds On (9610=3 Ohm, 9240=0.5 Ohm). In my initial concept explanation I talked about faster TO220 Mosfets too and that many devices will do. Open to experiments. Also we may run Amperes even if we feel like spending money and space on transformer and heatsinks. It will sound different maybe. Also 9240 has good availability.
As it is now, the sound opens very noticeably in dimensional scale, cleans up a lot, the focus of each instrument becomes very certain, and the overall musical detail gain is breathtaking.
The concept is easy, please experiment with Mosfet types and capacitor values and qualities as much as you can.
Plus it will not create instability so easily as a very fast one, plus low Rds On (9610=3 Ohm, 9240=0.5 Ohm). In my initial concept explanation I talked about faster TO220 Mosfets too and that many devices will do. Open to experiments. Also we may run Amperes even if we feel like spending money and space on transformer and heatsinks. It will sound different maybe. Also 9240 has good availability. As it is now, the sound opens very noticeably in dimensional scale, cleans up a lot, the focus of each instrument becomes very certain, and the overall musical detail gain is breathtaking.
The concept is easy, please experiment with Mosfet types and capacitor values and qualities as much as you can.
One last thing. For those who are going to use RIAA versions requiring under 30V B+ better use 4.7k resistors for the current source BC560 instead of the 6.8k ones in the 37V B+ example. That way its current stays about the same level as in the example. Taken that the Vin is +6 to 8V up Vreg.
And a hint. Auricaps sound nicely warm and beefy at the final output coupling capacitor position in my RIAA. But that is a system match and preference area. You know all that.
And a hint. Auricaps sound nicely warm and beefy at the final output coupling capacitor position in my RIAA. But that is a system match and preference area. You know all that.
Today I finally found time to build this circuit. Unfortunately, I am not getting any sound output.
Being pretty noobish, I have a noobish question if you don't mind. I'd just like to check that I have the FET's and transistor the correct way round. Which pins on Q6 are tied together please? And is it pin 1 of Q3 (bc550) that connects to Q1?
Cheers, Lee.
(Confused as to why it won't work)
Being pretty noobish, I have a noobish question if you don't mind. I'd just like to check that I have the FET's and transistor the correct way round. Which pins on Q6 are tied together please? And is it pin 1 of Q3 (bc550) that connects to Q1?
Cheers, Lee.
(Confused as to why it won't work)
Hi, it is possible that your last Q (buffer NJFET) has higher than calculated Idss and drops its Vd too much, Vg under its Vs, so it won't work. Given that all your parts are correctly oriented (most possibly) I would use a smaller resistor on its RC filter (R20) maybe 470R, same for R19, and see if I get sound. Measure the DC on its gate and source please. See that the gate sits slightly higher than the source.
Hi Salas, thanks for your help. The voltage on Gate of Q5 is oscillating wildly from ~4v - ~12v. Source is ~9v.
I matched these fets using the method shown in an earlier post, and this is making me question the accuracy of my meter.
I will try as you suggested and reduce the value of those two resistors.
Regards, Lee.
I matched these fets using the method shown in an earlier post, and this is making me question the accuracy of my meter.
I will try as you suggested and reduce the value of those two resistors.
Regards, Lee.