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Old 18th August 2010, 04:07 PM   #1901
Malka07 is offline Malka07  England
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Originally Posted by dudaindc View Post
To effectively reduce the vibration issue you described, you need to mechanically decouple the fan from the cabinet cover - a rubber gasket is a good start.
Thanks Dudaindc I will give that a try.
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Old 18th August 2010, 04:10 PM   #1902
Salas is online now Salas  Greece
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Your capacitor filters are still electrically OK for ripple at those currents, I wouldn't argue against trying higher if easy though.
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Old 18th August 2010, 04:22 PM   #1903
Malka07 is offline Malka07  England
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Originally Posted by Salas View Post


Your capacitor filters are still electrically OK for ripple at those currents, I wouldn't argue against trying higher if easy though.
Thanks Salas, I was thinking of trying some 10,000uf Mundorf Mlytic Titanium caps
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Old 18th August 2010, 08:09 PM   #1904
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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
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Old 18th August 2010, 08:28 PM   #1905
Zigis is offline Zigis  Latvia
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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 by Zigis; 18th August 2010 at 08:35 PM.
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Old 19th August 2010, 05:25 PM   #1906
Malka07 is offline Malka07  England
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Quote:
Originally Posted by regiregi22 View Post
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
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
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Old 19th August 2010, 05:33 PM   #1907
Malka07 is offline Malka07  England
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Originally Posted by Zigis View Post
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.
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
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Old 19th August 2010, 05:52 PM   #1908
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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
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Old 19th August 2010, 08:58 PM   #1909
Zigis is offline Zigis  Latvia
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Quote:
Originally Posted by Malka07 View Post
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
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
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Old 19th August 2010, 09:50 PM   #1910
Malka07 is offline Malka07  England
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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
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