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NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=1799
Page 15 of 167

Author:  roggom [ 22 Jun 2010, 10:22 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Great job guys,

I have only had to build one low voltage clean supply and basically RC'd until I got the correct voltage and ripple (used on my Tori amp). For the NP-100 I lucked out with a good wal wart and never looked back.
Pete's power supply will solve so many issues for the new builders.

Thanks
Rogers

Author:  robot797 [ 22 Jun 2010, 13:32 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

can i use 2 ef42 tubes as a replacment of the ecc82?

Author:  roggom [ 22 Jun 2010, 19:11 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

robot797 wrote:
can i use 2 ef42 tubes as a replacment of the ecc82?

Robot, welcome to the forum :headphones:
In short, it is possible but not recommended for this project. The Pentode (http://en.wikipedia.org/wiki/Pentode) filaments will draw too much current. If you have advanced knowledge of tube circuits you can use those tubes in a triode strapped mode and make a nice desktop amp > i did similar with some TV deflection tubes
viewtopic.php?f=9&t=607

Rogers

Author:  robot797 [ 22 Jun 2010, 23:54 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

are there any other types of tubes were i can use 2 for this amp
(2 tubes look epic)

Author:  roggom [ 23 Jun 2010, 09:42 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

robot797 wrote:
are there any other types of tubes were i can use 2 for this amp
(2 tubes look epic)

There are a few ways to go about this.

The easiest with virtually no changes is to build the amp, with 2 12AU7's and use one triode from tube 1 and 1 triode from tube 2. They will still glow and look the same, just have a wall wart that puts out about 1.5 A.

The other would be to use tubes like 6J1 or EF91 EF92 EF95 and triode strap these. They are 7 pin tubes and have totally different pinouts. These are the tubes in use with the little dot amps.

Again that is a little bit astray from the original project so If you went this route, we could help but please start another thread.

Author:  mikeyancey [ 23 Jun 2010, 09:52 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

roggom wrote:
robot797 wrote:
are there any other types of tubes were i can use 2 for this amp
(2 tubes look epic)

The easiest with virtually no changes is to build the amp, with 2 12AU7's and use one triode from tube 1 and 1 triode from tube 2. They will still glow and look the same, just have a wall wart that puts out about 1.5 A.

Heh - yes, two tubes would consume twice the filament current, plus some.

The beauty here is in the simplicity. You get two channels with only one filament heating cost - cost as in: heat, power, and 'support' items like a second socket, a larger enclosure, extra wiring, etc.

I *do* recommend the Millet Max, and there are several two-tube projects out there - but once you launch in that direction, the co$t goes up as well. I think the bill of materials for a Millet Max is about $150. Mine's 'down' right now, to change to the higher gain tubes, so this 12AU7/IRF510 version is now in daily use on my desk at work.

Mike Y
Dallas, Texas

Author:  jaume [ 25 Jun 2010, 04:24 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Quote:
Well, as they say, amateurs plagiarize, and professionals steal *cough* here I've stolen the Millet Max regulator circuit (see: http://www.diyforums.org/MAX/schematic/MAXsch75.jpg).

Image

I've filled in the component values, which are kept on a separate MillettMAX BOM.

For the (listed) 4 x 1000uf/50V filtering capacitors at CR1A-D - this is way overkill - I used 3; you can probably get away with 2... depends on how clean the input. Use what ya have...

The Millet Max uses a raw, 24 VAC input, rectified, and also uses more current, so there's reason for 4 there. If you're wall-wart is even somewhat filtered, you can do with much less here.

I have assembled this circuit with 18V input, but it is impossible to regulate the proper voltage (12.6 V). I changed the value of RR2.
1k, can adjust between 9v and 17v.

Greetings!

Author:  Giammarco [ 28 Jun 2010, 06:57 ]
Post subject:  12Au7 / IRF510 Head Amp

Due to an accidental spike, I burnt the irf510. I then replaced irf510 with irf630 (I run out of 510 and had replacements). The thing works, it sounds like the high are somewhat flattened. I'm going to replace the 630s soon.. Do you guys have any experience w/ 630s? I believe irf510 are better in terms of dynamics and hi openness.
Attachment:
12AU7-IRF630-LM317-headphone-amplifier.JPG

Actually the fets are irf630 (at the present time). Takman 2W resistors, metal film everywhere except for the cathode resistors, which are carbon films (the pink ones). Solen film cap and Elna Silmic II. Apart from the irfs, the sound is great. Still waiting to complete capacitor's burn-in.

Author:  Gio [ 28 Jun 2010, 19:09 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

Hi Giammarco,

The IRF630 will roll off the highs as noted on the project page and in this post: viewtopic.php?p=15465#p15465

Try replacing the IRF630 with IRF510, IRF610, IRF611 or IRF612. I've tried them all with the exception of IRF611 and they all work and sound great.
Cheers

Author:  robot797 [ 28 Jun 2010, 22:56 ]
Post subject:  Re: NP-100v12 - 12AU7 / IRF510 HeadAmp Support Thread

i found a tube

the ecc85
but the distrorcion is very heel erg

and my second build doesnt work at all

all is checked and controlled and it does not woerk

i use a irf520

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