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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:  gofast [ 11 Dec 2010, 02:32 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

thanks!

specially for the illustration :mrgreen:

the knob is off of an Akai reel deck from the 60's. dead motor..so i used the tube amp section to build a guitar amp and rest of the parts here and there.

Author:  santik [ 11 Dec 2010, 03:03 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

KrammeAcoustics, nice analogy with nice pics! :up:

hehe... :D

Author:  cm_dja [ 11 Dec 2010, 05:51 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

I've recently started to be interested in the audio equipments which involves vacuum tubes. As in the time from deciding components, learning about tubes to building in. I have several main issues that I want some advices.

First, the choose of power supply is so important. Linear PS is consider to be more preferred. I've heard that SMPS could easily get the switch-clicking noise if the filtering progress isn't perfect. But, in this project, it seems that a smps is acceptable or even recommended. I got a Mean Well SMPS 12V 1.25A. The result is - switching hum with clicking noise , it's minor but could be noticed.

How could I improve it to be cleaner ? By extra filtering?
I tested a 470UF 25V capacitor across the 12V+ and ground. It can reduce the noise to almost quiet !
But , I thought it's probably not a appropriate way to do. Give me some conceptions or explanation. THX !

Another problem is, the power on/off pop sound. I'm afraid it could damage the phones in long term using. Besides a relay to protect phones, is there any other solutions? Like adding a capacitor or else... varistor?
Thanks again!

Author:  ujkozavlanje [ 11 Dec 2010, 08:12 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

I'm finishing the assembly of my amp, but i've been havin problems with potentiometer routing. I've got alps dual amp, but i dunno how to wire it... :blush:
Please help!

Author:  koogar [ 11 Dec 2010, 08:50 ]
Post subject:  How to Wire a typical Potentiometer

ujkozavlanje wrote:
I'm finishing the assembly of my amp, but i've been havin problems with potentiometer routing. I've got alps dual amp, but i dunno how to wire it

This is how the majority of pots are wired up with some exceptions. The picture shows a dual gang for stereo applications

Image

The Input (Line IN from the source iPod ,PC ETC)

The wiper being the output to the tube end of the circuit

since we only have 1 ground for both channels short the grounds at the pot with a jumper wire across each pin then connect your grounds to one side

hope this helps

Koogar :smoking:

Author:  gofast [ 11 Dec 2010, 11:39 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

cm_dja wrote:
How could I improve it to be cleaner ? By extra filtering?

This post on Power Supply Filtering explains how to deal with the noise and filtering with unregulated power supplies. talk about the importance of clean power! I never realized it until this project.

Author:  cm_dja [ 11 Dec 2010, 12:12 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

cm_dja wrote:
How could I improve it to be cleaner ? By extra filtering?
gofast wrote:
This post on Power Supply Filtering explains how to deal with the noise and filtering with unregulated power supplies. talk about the importance of clean power! I never realized it until this project.

Thanks for the post of solutions! But..I just got the SMPS with absolute 12 Volts. According to the article, a higher voltage power supply will be better when it is filtered down to 12V. Does it mean that I have to find a another one ?

Author:  gofast [ 11 Dec 2010, 13:36 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

cm_dja wrote:
cm_dja wrote:
How could I improve it to be cleaner ? By extra filtering?
gofast wrote:
This post on Power Supply Filtering explains how to deal with the noise and filtering with unregulated power supplies. talk about the importance of clean power! I never realized it until this project.

Thanks for the post of solutions! But..I just got the SMPS with absolute 12 Volts. According to the article, a higher voltage power supply will be better when it is filtered down to 12V. Does it mean that I have to find a another one ?

i believe so....

18v - 24v smps is very common and can be found at thrift shops for $3 - $5. i got three different ones from goodwill the other day, and even on ebay, you can buy one for cheap.

Author:  ujkozavlanje [ 11 Dec 2010, 13:57 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

I've finished with the building the amp, although i've tested it with a ECC88(because my kid brother literally broke my ECC83, and please don't ask how :D ) it is has a hum in the background, but tommorrow i'm getting a new tube, either 82 or 83 and a case for the amp. So i'd like to thank all of you who helped me, i really do appreciate it. :thumbsup: :thumbsup: :thumbsup:

Author:  gofast [ 11 Dec 2010, 15:30 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

i've been fooling around with the amp for last several days, and i feel that this little amp is very sensitive to what tube you use. i've tried maybe a handful of tubes such as 12au7, 12au7a, 12ax7, 12at7, 12az7, 12bh7, 7316, 5963, 5814 and etc. so far, i like the rca black plate 12au7 and amperex 7316 the best. i'm sure it all depends on each tube and brand, but these two had the least noise and most clean sound with solid tight bass. 12ax7 and 12at7's are probably not appropriate for this circuit at all - too much noise and distortion. most 12au7a's i've tried didn't perform very well either for some odd reason....

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