Mark Johnson Noir Class A Amp (aka T2)

I built this 2 watt Class A smp several months ago and thought I would share it with you all, its a really great first time into DIY building and works very well with low to high impedance headphones. Details of mine and several others build is locatated at : https://www.diyaudio.com/forums/headphone-systems/343616-noir-transistor-headphone-amp-class-single-150ma-bias.html

Basically here are the design criteria:

  • Solid state, all discrete: no ICs, no vacuum tubes

  • Single ended, Class A circuit operating at 150 mA bias current (exceptionally high for a headphone amp)

  • No mains voltage inside the DIY chassis. Power is supplied by a commercial, safety rated, wall wart @ 24V DC

  • All thru-hole parts, mounted on a single PCB with generous spacing between components

  • Very easy to stuff and solder; suitable for first time DIYers. Component IDs and component values printed on PCB silkscreen.

  • Headphone output on front panel, linestage preamp output (RCA jacks) on rear panel

  • Pre-made front and rear panels, drilled and silkscreened, for DIYers who prefer not to do metalwork themselves. These are black PCBs, 2.0mm thick, cut to match the diyAudio Store “1U Galaxy” chassis front & rear panels.

  • Detailed, 37 page .pdf file named “Noir Build Instructions” walks you through the assembly process with plenty of photos. It’s 4.7 megabytes long, over the size limit for attachments here on the Forum, but is available for download on the sales page of the Store.

Here are some of my pix:




I replaced the front panel with the recently re-named T2 to “Noir” to prevent a name conflict with an existing device.

I have a hundred hours with this amp across a wide variety of headphones, low to high impedance and all work very well. Very euphonic amp, it adds a slight warmth IMO, but very tasteful and the soundstage is really wide and deep, a very satisfying amp using “normal” old school parts…

A great introduction into DIY for headphone amps, a kit is available over at the diy store as well…

Alex

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Very nice clean looking build.

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Thanks!

I didnt like the wiring and since then went back and redid it to make it more “professional”…didnt affect the sound :grinning:

Diy is fun and its great when it works for the first time, but buggers when it doesnt…builds patience and character and increases you 4-letter vocabulary!!

:kissing_smiling_eyes:

Alex

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Manual dexterity and patience are a must I would imagine. I admire anyone who can put together such things. I keep saying that I am going to try my hand at a Bottlehead Crack build. I am sure I will in the future.

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The Crack is a great DIY kit for sure…had mine for about three years, and even though there are “better” amps technically, spec wise etc this is a special amp…works very well with HD600/800’s etc…just a simple design the BH boys have perfected at this level and price point.

If you take your time and really read the good directions your build will be great…most folks that have issues due to not really reading well on where things go and poor soldering abilities.

Solder is what I call an “electric glue” but it takes a little understanding on how to do it well and some practice.

So if you go there get a soldering iron and buy some cheap parts like resistors and terminal strips and practice winding and crimping these to terminal strips to learn how much heat and how to melt the solder for a good electrcial connection.

Alex

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Thanks Alex. I am interested in the BC for use with my HD650’s. I understand that the ‘Synergy’ is really great.

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Well since I have the new Bifrost 2 and finally sold my Bifost 1 with a Unison USB card, I have been doing some comparing with several amps…going to sell some, my Mainline is up for sale…

Here is a shot of an all black stack I am using and comparing…listening to Johhy Cash, the man in black with a black stack ha!! sounds great! America IV The Man Comes Around…

The Monoprice THX AAA 887 has been in the stable for several weeks and I am comparing to other amps. The picture shows the B2 on top of the THX AAA and its on top of Mark Johnsons Noir DIY 2 watt Class A map…listening with HD600s presently.

Going back and forth I am very surprised how well the “Noir” amp hold up to the THX AAA amp, remember the THX AAA is running in Class AB with its novel way to reduce or eliminate the transconductance cross over distortion by differentially detecting and inverting and reinserting it to cancel out the distortion and help give those vanishingly low specification. While the Noir is just a brute force 2 transistor (well maybe 3) that oeprates in Class A 100% of the time…heat but no cross over issue.

But its been measured and has well mediocre measurements! BUT!!

It sounds just GREAT to my ears…regardless on those measurements! Ha!

So the unscientfic listening tests for the past hour is: They are very close, the edge goes to the THX AAA amp, its just a smidge clearer…but unless your really listening very closely you would be surprised!!

The THX amp is a $400 investment!! The Noir is a $29 pcb, case and parts…about $200 or so, The kit was available at the diyaudio store, but I dont see it listed as a kit, but the pcb is and case. EASY build. really EASY…highly recommended for a great Class A first time DIY project.

Alex

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