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NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=1799
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Author:  mcmillant [ 04 Apr 2019, 11:01 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

yay she lights up finally :)) i did a pcb myself via easydea and somehow it not work T.T , so i have to roll back to original pcb.

Image

A lot of hum from power and when i touch to volum pot hum come louder, any tips? i plant to build a power filter for her , maybe power schematic from milletmax (which i read from another forum is quite good )

Author:  john55 [ 05 Apr 2019, 06:11 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

What are you using for a power supply?

Author:  vixr [ 05 Apr 2019, 07:01 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

mcmillant wrote:
yay she lights up finally :)) i did a pcb myself via easydea and somehow it not work T.T , so i have to roll back to original pcb.

Image

A lot of hum from power and when i touch to volum pot hum come louder, any tips? i plant to build a power filter for her , maybe power schematic from milletmax (which i read from another forum is quite good )


solder a wire from the ground plane to the metal body of the volume pot, you may have to rough up the area on the pot where you try to solder to. Tin the wire and the pot, then fuse them together.

Author:  ILoveHiFi [ 05 Apr 2019, 15:50 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

I've notcied your using MKS4 capacitors, those are metalised polyester.
Almost always metalised plolypropene has better sound quality, can consider upgrading in furure to some.
Pulse x is very fancy and not too expensive and tight on a budget any metalised polypropene will also sound good.

Author:  mcmillant [ 06 Apr 2019, 04:18 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

vixr wrote:
solder a wire from the ground plane to the metal body of the volume pot, you may have to rough up the area on the pot where you try to solder to. Tin the wire and the pot, then fuse them together.

ty i will try it right after finish my power filter :thumbsup:


ILoveHiFi wrote:
I've notcied your using MKS4 capacitors, those are metalised polyester.
Almost always metalised plolypropene has better sound quality, can consider upgrading in furure to some.
Pulse x is very fancy and not too expensive and tight on a budget any metalised polypropene will also sound good.

Yea, mks4 is the only good choise i can find in my local store :) i will try to get some pulse x when have change to order it :beerchug:

john55 wrote:
What are you using for a power supply?

a hp print power, it have 35v and 15v, i use only 15v from it.

ps: Can i ask if i do a power by myself (using a ac power transformer 220v-~13v then convert it to dc like millet's schematic) , Is this type have more power hungry than my hp printer power supply ?

Author:  ILoveHiFi [ 06 Apr 2019, 16:46 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Using transfomers then using diodes and converting to dc is much less efficent and uses more power. Efficency arround 50-60% typically

If you use the hp print power I imagine it is a swithcing power supply with lots of high frequency noise and is cuasing some plorbems.
You may try a voltage regulator or use a very large capacitor direcly on the output of smps to help reduce noise.

Author:  mcmillant [ 08 Apr 2019, 11:14 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

ILoveHiFi wrote:
Using transfomers then using diodes and converting to dc is much less efficent and uses more power. Efficency arround 50-60% typically

If you use the hp print power I imagine it is a swithcing power supply with lots of high frequency noise and is cuasing some plorbems.
You may try a voltage regulator or use a very large capacitor direcly on the output of smps to help reduce noise.


hi , i am trying a regualator schematic from milletmax , after finish i check it run about 13v (i trim my rr3 1kpot but nothing happend ! still 13v). Then i plug in amplifier, it not works at all, i check the volt out put dance around ~11v to 0v :eek: ... i check everything but seem i wired right... , the sound have no hummmmm (a long hum) but a "discrete" hum :2c: .... btw the volt dance around 10V~ to 0V cant run amplifier ....

Anyone have experience with this case :bawling: :cold: ...
ps: i using cheap compoments but checked quality is quite good

Author:  ILoveHiFi [ 08 Apr 2019, 16:38 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Only connect 12 or 23 of the pot.
If you don't do this and you short the 21 of the pot then you don't have any adjustments avalible or have very limitted.

Also never use the metal case of lm317 to output any voltage. always use the tabs on to-220.
Very easy to get poor contact and plorbems

Author:  mcmillant [ 11 Apr 2019, 12:53 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

ILoveHiFi wrote:
Only connect 12 or 23 of the pot.
If you don't do this and you short the 21 of the pot then you don't have any adjustments avalible or have very limitted.

ty thast's why i cant control my out put volt , now i can do it better

After some test i relized i had more problem with noise sound, not only hum from power, but ground noise , i short metal case of volum pot to gnd but seem i just help a little bit, when i touch to the gnd this beezzz noise become lower and lower depend on how hard i touch it, i learned ppl call it ground loop noise. So the noise from power and noise from gnd is my main problem, i am tryingto get noise filter simple as posible and studied there too many way (pi filter, caps ect), but when google it show too many advertising and i found nothing about how to setup or caculate it correctly.
I have zero experience with electric things so can you give me some advices to eliminate that noise ?

Thanks!

*Update 1: I add a diode bridge to input of lm317 regulator no matter input is dc or ac, the hum reducte critical but still can noticed. The buzz noise from ground i still have no idea to deal with but touch my figure to gnd :( more strong i touch it more noise reducte, but still notice too

Author:  ILoveHiFi [ 11 Apr 2019, 15:37 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

You need to use coax cables for input wires, not twisted pairs as offers very litte or zero proetion against noise pick up.

viewtopic.php?f=9&t=6392&start=70
Theres also quite a few plorbems which you also may be doing which I disscussed with another dude in this thread.

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