Building a symmetrical PSU B1 buffer

[KatieandDad]

I couldn't hear any difference with running the SALAS Shunt Reg at currents above 300mA. In the end I opted for 160mA (ish), the MOS-FETs run cool and there is no danger of component cooking.

Irrelevant of the current the PSU is consuming, the B1's run at about 7-10mA each (determined by the Idss of the 2SK170BLs).

The 2E heatsinks run at a nice cool 30 degrees at 200mA but start to heat up rapidly above 300mA.

You will notice that I opted to use the SALAS Reg Supply part of the DCB1 but then used the B1 itself. I needed the capacitive coupling so the combination of the two suited my application perfectly.

 

[pinnocchio]

You will notice that I opted to use the SALAS Reg Supply part of the DCB1 but then used the B1 itself. I needed the capacitive coupling so the combination of the two suited my application perfectly.

Since I'll be running my setup in balanced mode, DC will not be an issue for me. But yeah, I agree with you, whatever suits your equipment need is what you should go for!

Ciao!
Do

 

[juanitox]

is worth to have separates regulator for right and left rails on B1 ?

 

[Salas]

Small subjective gain.

 

[Erlend Sæterdal]

I do not understand 21 V into 10 ohm resistors and 10 V out from supply and I can not feel any temperature rise at all.

 

[Salas]

That's very good sinking for 200mA or less. Have you got 1.6-2V voltage drop on the 10 Ohm resistors? If yes you surely run spec current. Maybe you can double up on them and drop them to 5 Ohm so to benefit from more current since you got nice dissipation bond to chassis.

 

[Erlend Sæterdal]

Yes 1,6 V across 10 ohm. I will follow your advice and use 2 more 10 ohm resistor.

What abuot the 10 V output ? Short circuit one Led in each side ?

 

[Salas]

Why? +/-10V is the spec.

 

[Erlend Sæterdal]

Oki I thought 12 V .

 

[umut1001]

Hello.I build dc coupled b1 preamp very simple, without regulators and potentiometer.I used 12volts empty 23AE type batteries(they measure about 10,5volts when empty)I used 100uf 10v rubycon za capacitors,dale hi end military resistors on pcb(i heard that rubycon za is very similar to rubycon blackgate caps)Buffer sounds excellent!Thanks Salas and Nelson for B1 buffer.
I matched 1% drain current with 9v batteries.Drain current is about 9,09ma for all fets.
I want to connect a battery for it,because i like battery for sound.Clean DC.Can i use +-12 volts lead acid battery with series resistors?Or maybe 9v lead acid batteries?Thank you

 

[AndrewT]

Pass specifies 18V for the B1.
You can try using 24V, but do expect there to be some, maybe small, difference in performance from a real B1.

 

[Salas]

You used those capacitors for what? Power rail's decoupling? Don't use series resistors with batteries, 9V or 12V are acceptable.

 

[umut1001]

I connected 100uf 10v rubycon za caps to legs of fets to make them reach better high frequency response.I think about bigger capacitors for power supply.But your circuit is +-10 volts and there is no +-10 volt lead acid battery.So how can make +-10 volts in a simple way?When connecting 200ohms 3w serial resistors to 12v accumulator , 10ma current of B1 preamp makes there will be a 2volts drop right?Is it not a true way?

 

[umut1001]

Or maybe a serial 2.2v 3w zener diode?

 

[AndrewT]

3W, why?
500mW 2.2V will pass 181mA all day. Yes it will be hot.
Two channels of B1 use ~20mA. That gives a dissipation across the Zener of just 44mW, not quite 10% but enough for good regulation of the dropping voltage.
Might be better to use a 400mW Zener. Or maybe a string of 3 diodes.

But listen to 24V first.

 

[umut1001]

I am using Salas DCB1 not nelsons circuit.12v batteries may be 12,8 volt at full charge so it makes 25,6volts so it is going to be too much.I will try serial diodes with accu,make about 2 volts drop on diodes and after that connect 10000uf 16v caps.So i think i will get +- 10,5 volts.I will buy 12v accumulators tomorrow i think.

 

[umut1001]

I now connected 9v sony nicad batteries for temporary listening.My denon amplifier was not clear enough but now it sounds clear like F5 amplifier.What a change!Guitars are better bass is better everything sound is more clear!
May be extremely clear sound with F5 amplifier.

 

[juanitox]

Pass specifies 18V for the B1.
You can try using 24V, but do expect there to be some, maybe small, difference in performance from a real B1.

i have 30V on my DC coupled B1 just because i have +15 and -15Vreg on hand .. sounds quite good and don"t fry yet

 

[AndrewT]

the DCB1 has a dc psu running at between 15Vdc and 25Vdc depending on mains and transformer.

The regulators of the DCB1 take that raw DC supply down to ~10Vdc into feed to the signal processing transistors.

If you think your DCB1 has 30V on the 2 little k170s then you have not looked at your schematic.

 

[ncc]

Hi everyone,

I've finished my Hypnotize B1, however it's not working now.

All Leds lit up, the current on one side is 40ma, on the other side, the current is 68ma.

I checked the voltage across the two 2SK170 for both channel, they're about 20.5V, so it seems that the voltage is correct. but I could not hear the relay click.

When I powered up, the green Led near the voltage regulator, lit up for half a minute then turned off completely.
I measured the voltage across the 10K bleeder resistor near the voltage regulator and saw that the votage dropped from 10V when powered up to 0v after 30"

I don't know if the voltage regulator (7812) working correctly? or something wrong?
Another thing is that since I did not have BC517, I replaced it with BC550.

Could you look into my problem and give me some advices.

Thank you very much!