Building a symmetrical PSU B1 buffer

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#1,904
I love that preamp Malka, definitly one of the bests shown here.
A shunt regulated dedicated supply for the LDR attenuator....yeeeehaaaa!!!. Make yourself a favour and get a Noctua fan. They are the less noisier ones of the market, they are targeted for computer use. Made for 12v, put one of them at something between 5v and 9v and it will not make a decibel. And even moving big flows of air. A bit pricey for a fan, but sure worths it considering the total cost of the project. Don't forget some of those rubber "things" that hold the fans in place as if they were screws, but only using elastical force.

I would place more capacitance, but not "as is", butwith a series resistor to form an RC filter network. I would put 2x 10.000uF followed by a series 0.1 ohm power resistor in each rail, and then the 2x 4700uF. Ask for an schematic if you need to.

Regards,
Regi
 
#1,905
Silent fan is good thing, on low voltage and with rubber "things" even better, however best fan is no fan 🙂
Malka, I see you have nice large, massive enclosure. Why not to use it like large heatsink? Without fan.
Nice build.
 
Last edited:
#1,906
regiregi22 said:
I love that preamp Malka, definitly one of the bests shown here.
A shunt regulated dedicated supply for the LDR attenuator....yeeeehaaaa!!!. Make yourself a favour and get a Noctua fan. They are the less noisier ones of the market, they are targeted for computer use. Made for 12v, put one of them at something between 5v and 9v and it will not make a decibel. And even moving big flows of air. A bit pricey for a fan, but sure worths it considering the total cost of the project. Don't forget some of those rubber "things" that hold the fans in place as if they were screws, but only using elastical force.

I would place more capacitance, but not "as is", butwith a series resistor to form an RC filter network. I would put 2x 10.000uF followed by a series 0.1 ohm power resistor in each rail, and then the 2x 4700uF. Ask for an schematic if you need to.

Regards,
Regi
Click to expand...

WOW thanks Regiregi22, that is high praise indeed 🙂 considering the quality of some of the builds on this thread. Think my personal fav is William2001's build...Thanks for the advice as well, i had a look into the Noctua fan, and i might just get myself one of those. With regard the Capacitors, would it just be a case of having the 10,000uf caps connected in parallel to the 4700uf caps? with a 0.1ohm resistor going positive to positive, and a wire from negative to negative? This way the 4700uf caps stay on the board, and i can have the 10,000uf caps off board.

Alon
 
#1,907
Zigis said:
Silent fan is good thing, on low voltage and with rubber "things" even better, however best fan is no fan 🙂
Malka, I see you have nice large, massive enclosure. Why not to use it like large heatsink? Without fan.
Nice build.
Click to expand...

Hi Zigis, you are probably correct, however, i installed the dcb1 board so close to the edge(so that the input/output wires are kept as short as possible) that there isn't enough room to bend the mosfets back to the chassis floor, so it would involve drilling new holes and relocating the dcb1 board and changing all the length of wires...also i cut the legs of the mosfets quite short, so again i would need to desolder these and refit new ones...Also with the fan running at 5v, it really is almost silent, im sure when i add the rubber gastket, and maybe change to a Noctua Fan, it will be silent. Also i like the fact that im running at 350ma and the fan keeps the mosfets just warm, so im able to maybe run the mosfets at 500ma 😉 we will see.

Alon
 
#1,908
You're right, connect the capacitors like in the attached schematic.

My PC only runs with a very big cpu heatsink going passive, two noctua running very slow attached to the case and the fan of the PSU. Extremely silent with a damped case. I have a pais of these ones:
Noctua NF-S12B-FLX-1200 120x120 1200rpm NH-S12B FLX - Ventilador 12 cm

or you can get this model for a bit more of sucking air power and more or less the same amount of noise:
Noctua NF-P12 120x120 1300 RPM Ultra-Low-Noise NF-P12 - Ventilador 12 cm

Now I look like a noctua vendor 😀
 
#1,909
Malka07 said:
Hi Zigis, you are probably correct, however, i installed the dcb1 board so close to the edge(so that the input/output wires are kept as short as possible) that there isn't enough room to bend the mosfets back to the chassis floor, so it would involve drilling new holes and relocating the dcb1 board and changing all the length of wires...also i cut the legs of the mosfets quite short, so again i would need to desolder these and refit new ones...Also with the fan running at 5v, it really is almost silent, im sure when i add the rubber gastket, and maybe change to a Noctua Fan, it will be silent. Also i like the fact that im running at 350ma and the fan keeps the mosfets just warm, so im able to maybe run the mosfets at 500ma 😉 we will see.

Alon
Click to expand...

You can bolt aluminium angle to chasis floor and to mosfets, as a heatsink.

Right now I am working on PC based audio player for cheap, and my largest enemy are different fans noise, so probably I react too sickly, wen see fan 🙂
I get old Pentium 2 based pc, 300Mhz, looks laughable today, but this is enough for XP and Foobar 2000. Pentium 2 is on large heatsink, without fan at all. Still PS is with noisy fan 🙁
 
#1,910
Well i Just Changed the Fan power supply from:
12v 292ma-diode bridge-3300uf-82.4ohm-3300uf
TO
12v 292ma-diode bridge-4700uf-Salas Shunt Reg(5v)

I wasn't expecting an improvement in SQ, i only did it because (1) I had a spare Shunt Reg and (2) I read somewhere that a clean power supply can help keep a fan quiet...so i thought id give it a go...

When i tell you all that the SQ did indeed improve, you will probably think im nuts!!! but its true...the sound is now soooo Transparent, and dynamic, it seems like im hearing every single bit of detail...I dont understand this???
How does improving the power supply to the Fan, improve the sound!!! am i really going nuts??!!(thats a rhetoricle question!!!)

The transformer i use has two 12v secondaries, i use 1 into the salas 5v shunt feeding the Optivol, and the 2nd now goes into another 5v salas shunt which feeds the fan.

Can someone explain the improvement in sound???

Alon
 
#1,914
Today, ive been trying to sort out my ground loop problem...i previously fixed this, by lifting the earth from the chassis, but this was only meant to be a temporary fix. So today after trying numerous things, i found that disconnecting the input grounds from the optivol board, got rid of the loud hum...however when i put my ears up to the speakers i can still hear some buzz from the tweeters and some hum from the woofers (not loud...quiet, but still there) I also got this level of buzz and hum, when the earth was lifted. So there appears to be another problem?? I tried switching the preamp and poweramp on while the cd player was connected but off...and also when the cd player was disconnected...but both times the hum and buzz was still there.
Does anyone have an idea, as to what i can try next?

Thanks

Alon
 
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