The simplistic Salas low voltage shunt regulator

[alibear]

Hi all, this is my first post to this excellent thread.
I am going to construct +ve and -Ve Version 1 regulators for the input stage,VAS and pre-driver stage of a Krell clone I am building (still )and would like some advice please.
Would it advisable to build a + and - regulator for each channel eg 4 regulators or would one pair be OK for both channels?
What would be a ball park figure for biasing the CCS?
Would a 35-0-35 transformer be suitable, I want an output between 30V and 37V (Yet to be decided )
Thanks for your help.
Alan

[agussug]

Originally Posted by Phisci

More questions if I may: Can I run several loads off 1 shunt reg (for example 74hc74 flip flop as well as a DAC (+5V))?
What about using one transformer with multiple secondaries to power several of the shunt regs?

Yes you can put several loads on 1 regulator. But I think it's not good idea to power the logic IC and the DAC especially the analog part from 1 regulator.
No problem in my experience to use multiple secondary trans to power several regulators.

Regards

[Salas]

Originally Posted by alibear

Hi all, this is my first post to this excellent thread.
I am going to construct +ve and -Ve Version 1 regulators for the input stage,VAS and pre-driver stage of a Krell clone I am building (still )and would like some advice please.
Would it advisable to build a + and - regulator for each channel eg 4 regulators or would one pair be OK for both channels?
What would be a ball park figure for biasing the CCS?
Would a 35-0-35 transformer be suitable, I want an output between 30V and 37V (Yet to be decided )
Thanks for your help.
Alan

Hi, Alan

One pair can go 90% the way, if the driver stages are heavily biased so they don't move individual current consumption too much.
150mA more than load consumption is a good point. You should decide config and know/measure the consumption of what it will feed.
The Tx sounds adequate for enough Vin to Vout distance.

[alibear]

Hi Salas, thanks for the reply.The drivers for the output stage will be supplied from the high current supply that also feeds the output transistors. The PCB's I have for the Krell look easy to split the tracks before the drivers, so the shunt regulator will only be feeding the input and VAS. Sorry if my wording is confusing.
Thanks
Alan

[Salas]

Alright, use a small resistor in series like 0.1 to 1R when you will do the split of what you have to use the regs for, with a dvm and the drop across that resistor when you drive with a 1khz sine wave just before clip see with Ohm's law what those stages draw for current. Sum what is for each reg to feed, add 150mA for CCS setting figure.

[Kazuo Ozawa]

Originally Posted by Salas

Lets hope it will open the Mosfet gate less capacitive at least.

The gate is fully open at last.
I implemented STP55NF06L into Reflektor as Salas suggested, getting great improvement.
When I used with 2SK2586, the sound was harsh. Now there is nothing, but clear ,smooth and dynamic. Especially transparency and 3-D reality is remarkable.

I have adopted four wire configuration for the first time, and surprised that the effect is very big comparing to two wire.

Zobel value is not optimized for sound quality whereas there is no oscillation at all.

Thanks Salas and other Reflektor lovers.

[Salas]

Great. Zobel is 'not' optimized, or is 'now' optimized?

P.S. Is there a Z Foil resistor in the picture between trimmer and a BJTs pair?

[Phisci]

Salas, in the REFLEKTOR, just to confirm:
1. that the CCS current is (2N4403)Vbe/R1?
2. And this should be = load current plus shunt current
3. The dissipation on 9610 mosfet is (Vin-Vout)*(CCS current)
4. The dissipation on 640 mosfet is (Vout)*(CCS current-Load current)

Thus when adjusting the Reflektor for different optinal currents, the best way would be to change R1?

Your help much appreciated.

[Salas]

Confirming all points above.

[Phisci]

Excellent, thanks,
Forgot 1 more: Total CCS should be equal to at least 150mA + load current?
And 1 more: why does Kazuo get better results with a STP55NF06L? What chnages in going from 640? What alternatives would you suggest to STP55NF06L if not available?