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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:  mikeyancey [ 20 Apr 2010, 21:27 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

They are equivalent. NTE is a great source for replacements for OLD parts (i.e. old germanium transistors, odd-ball rectifiers, zeners or FETs) mostly to repair old solid-state electronics where the original part is... unobtainium.

But they supply equivalents for modern stuff as well and it's probably the identical thing - relabelled with NTE's number.

http://nteinc.com/

Cross-reference for IRF510:

http://nte01.nteinc.com/nte/NTExRefSemi ... teDocument

However, IRF510's are cheap and plentiful if you have a source...
Mouser.com has them for 53 cents each.

NTE fills a niche - Imagine how much really great, rare audio, and radio gear has been thrown into the landfill because someone thought they couldn't find a replacement transistor...

Mike Y
mxweas wrote:
I ordered some IRF510's at a local electronics shop and they gave me NTE66 MOSFETS will these work?

Author:  roggom [ 21 Apr 2010, 22:30 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

The NTE66 will work and are beefier. Not sure how they will sound, you will have to give them a try.

Looking at the datasheet, they can withstand more current and heat.

Let us know, or if you are in the US, you can pickup the IRF510 at Radio Shack. And if you really have a little time to wait, futurlec has them and many other parts very cheap. The only thing is they are out of Thailand. http://www.futurlec.com/

Author:  mikeyancey [ 22 Apr 2010, 20:16 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

I have a couple of dumb questions regarding the build:

1) In: Photograph 14: Setting the Bias "Adjust the two trim potentiometers to one-half of your supply voltage, 6 volts since we are using a 12v supply. "

Where should the 6v be tested for - at the junction of the FET Source and the LM317's 'IN'?
Heh - I've been testing AT the plate - only can get that down to about 9.2 volts or so... I'm guessing I'm testing in the wrong spot...

2) In: Photograph 8: Populating the PCB - I'm just guessing it's spec'ed for 470uf electrolytics, but only 220 uf was handy?

3) In: Schematic - 470uf needs a '+' toward the junction on the FET Source and the LM317's 'IN'.

Other than that, the more I listen to this amp, the more it grows on me - it's 'brighter' than some other other amps I have (Millet Max / tubes and AMB mini3 solid-state), yet the lows are still quite good.

Mike Y

Author:  roggom [ 22 Apr 2010, 21:17 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

mikeyancey wrote:
1) In: Photograph 14: Setting the Bias "Adjust the two trim potentiometers to one-half of your supply voltage, 6 volts since we are using a 12v supply. "

Where should the 6v be tested for - at the junction of the FET Source and the LM317's 'IN'?
Heh - I've been testing AT the plate - only can get that down to about 9.2 volts or so... I'm guessing I'm testing in the wrong spot...

Yes, or at the postiive lead of your output electrolytic.


2) In: Photograph 8: Populating the PCB - I'm just guessing it's spec'ed for 470uf electrolytics, but only 220 uf was handy?

Yes, per my other response, you can use 220 to 1000uF. These ones are audio quality Nichicons, I used up my 470uF Nichicon Muse on another amp. I must have 20 headamps laying around.


3) In: Schematic - 470uf needs a '+' toward the junction on the FET Source and the LM317's 'IN'.

You are correct, but just for futures sake, electrolytics, the positive tab goes toward the tube, both input and output.


Other than that, the more I listen to this amp, the more it grows on me - it's 'brighter' than some other other amps I have (Millet Max / tubes and AMB mini3 solid-state), yet the lows are still quite good.

Yes I have a Min3, really neat little amp. Thanks

Author:  mxweas [ 23 Apr 2010, 01:45 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

I'm not quite sure how you have the potentiometer wired to the board. I'd like to out my potentiometer and input/output jacks on the same board as my amp.

Thanks,
Max

Author:  roggom [ 23 Apr 2010, 08:32 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

mxweas wrote:
I'm not quite sure how you have the potentiometer wired to the board. I'd like to out my potentiometer and input/output jacks on the same board as my amp.

Max, If I understand correctly, you want to mount input and output jacks to your amplifier chassis and have an external potentiometer? If so that is fine as long as you wire the potentiometer to the input. If you put a potentiometer between this amp and another amp, it will increase the output impedance significantly. So a good circuit would be cd or mp3 - volume potentiometer (audio taper, not linear) NP-100 amp then headphones or power amp.

For a really small and cheap inline solution, I have used these for CMOYS and other little amps http://www.amazon.com/Koss-155954-VC20- ... B00001P4XH. Use them on the input of the NP100.

Author:  keechoon [ 23 Apr 2010, 12:03 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Rebuilt and shrank mine into a 7 x 9 cm protoboard :mrgreen:

Image

Image

Author:  tombethe [ 23 Apr 2010, 13:54 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Hi dgadling, Hi Rogers,

on the schematic if you plan to order a board, take a look on your jacks, how to connect them via eagle
Ground is the "square" at the end of the jacks...

The "+" from the input caps should show to the grid... It would be a good idea to use Polypropylene caps on the input.
Solen or i.e. Audyn caps would be fine.

@ keechoon - really nice build :up:.

Have fun ;-).

Author:  KrammeAcoustics [ 23 Apr 2010, 18:33 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

tombethe wrote:
The "+" from the input caps should show to the grid... It would be a good idea to use Polypropylene caps on the input.
Solen or i.e. Audyn caps would be fine.

Hi Tom

About the inputcaps, you wrote "+" ? After what i can see, it's bipolar caps ( non polar ).

The MMK Rogers are using, is not bad at all, they are much alike MKP's.

Hint: Even orange MKT Phillips, sounds ok, in this construction.

When it comes to MKP , my favorits are also AudynCaps ( Intertechnik ). I'm using AudynCaps for both amplifiers and loudspeaker crossovers. :trumpet:

Author:  tombethe [ 23 Apr 2010, 19:55 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Hi John,

just to wipe out confusions:

"dgadling" asked the members to check his Eagle based schematic he posted (20 Apr. '10).
The hint on the e-caps was for his schematic. He had drawn his e-caps with the "+"
to the input... Now - that were the things we suggested to change on dgadlings scheme...
I also suggested him (not Rogers) to use something like the Audyns instead of e-caps.
MKPs have the advantage that they block DC on both sides.
I mean possible DC from the amp and possible DC from the source...

Rogers surely knows what he does ;-)..
I'm also intrigued to build his amp... Time will see..
I have still a modified HV version in mind.. You know, we talked about it :idea:.


CU - Skol!

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