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SINGLE ENDED CLASS A FET HEADPHONE AMPLIFIER
ZERO FEEDBACK | SINGLE VOLTAGE GAIN STAGE

 

Asgard 2 is the next generation of one of the most popular headphone amps in the world, boasting higher performance and convenience features such as switchable gain and preamp outputs. It’s a versatile control center for your desktop system, ideal for most headphones from IEMs to orthos, and with pre outs for powered desktop speakers.

Significantly Improved Performance
We used what we learned in Mjolnir to significantly improve Asgard 2’s performance. A high-voltage, cascoded JFET gain stage feeds a high-current Class A MOSFET output section. The 80V rails on the gain stage allow us to reduce distortion, while retaining Asgard’s no-overall-feedback design in high-gain mode.

Additional Versatility: From IEMs to Orthos to Active Monitors
Asgard 2 offers two gain settings. The low-gain mode is perfect for high-sensitivity IEMs, while the high-gain mode is ideal for most other headphones, up to and including many orthodynamics. In addition, the preamp outputs can easily be connected to powered speakers, for a complete desktop system.

Made in USA
By “made in USA,” we mean made in USA. The vast majority of the total production cost of Asgard 2—chassis, boards, transformers, assembly, etc—goes to US companies manufacturing in the US. Our board house is 20 minutes away from our office in Newhall. Our chassis guys are just over the hill in the Valley.

 

Specifications*

Frequency Response: 20Hz-20Khz, -0.1db, 2Hz-400KHz, -3dB
Maximum Power, 32 ohms: 1.0W
Maximum Power, 50 ohms: 1.0W
Maximum Power, 300 ohms: 380mW
Maximum Power, 600 ohms: 190mW
THD: Less than 0.008%, 20Hz-20KHz, at 1V RMS, high gain mode (worst case)
IMD: Less than 0.010%, CCIR at 1V RMS, high gain mode (worst case)
SNR: More than 102db, unweighted, referenced to 1V RMS, in low gain mode
Crosstalk: Less than -72dB, 20Hz-20KHz
Output Impedance: Less than 2 ohms
Gain: High = 6 (15.6db) or Low = 1.5 (3.5db), via rear switch
Topology: Fully discrete, single-ended Class A with single voltage gain stage, no overall feedback in high gain mode, 12dB feedback in low gain mode
Protection: standard muting relay for delayed turn-on and fast turn-off
Power Supply: Internal power transformer with 4 separate power supply rails and over 20,000uf of filter capacitance
Power Consumption: 30W
Size: 9 x 6 x 2.25”
Weight: 5 lbs

*All measurements made on a Stanford Research SR1+ Audio Analyzer

 

Wait a minute! You upgraded Asgard?
Yes. Change is the only constant in life, and all that.

I loved the original. Why’d you do that?
Because we hate you. No. Just kidding. Asgard was a great amp for its time, but time has moved on. More people want to run powered monitors on their desktops, which means preamp outputs are important. More people want to use custom IEMs, so switchable gain is important. And we learned so much in the development of Mjolnir, we really wanted to share.

So is this a circlotron?
Nope. It’s still a single-ended Class A amp. It retains all the essential character of what made an Asgard an Asgard. But it now has Mjolnir’s high-voltage trick with a cascoded JFET input stage. Running very high voltage is one way to linearize circuits without using negative feedback. Which means Asgard 2’s distortion performance is much better than the original Asgard. We also eliminated Asgard’s output coupling capacitors, so this amp is DC in, and DC out.

So does it sound different?
Yes, it does, but it retains Asgard’s relaxed, natural character, together with additional transparency and dynamics.

But I hear all amps sound the same!
That’s cool. We think you can get a good deal on a headphone amp from Amazon for like $39. Or just use your receiver outputs and save even more money.

I hear you are using terms like “no feedback” and “Class A” to baffle us with audiophile bullshit, what’s up with that?
It’s no different than using the terms “precision operational amplifier” or “capacitor coupled gain stage” when describing a circuit. Describing the Asgard as a “no overall feedback, Class A” amp is accurate and relevant. If you think this is a value judgment on other topologies, or that we’re trying to obfuscate and confuse, well, what can we say, other than there are a ton of other options out there?

Will Asgard 2 drive orthos?
Many of them, yes. The HiFiMan HE400 and HE500 do well with Asgard 2, as well as the Audeze LCD2. The popular Fostex T50RP mods (Mad Dog, Paradox) are also well-served by Asgard 2.

And IEMs?
Yes. We’ve tested extensively with IEMs, and Asgard 2’s is excellent for them, in low gain mode.

And other headphones?
Of course. It may be the only amp you ever need, unless you want to get into tubes, or balanced amps.

So can I leave my headphones plugged in all the time, or do I have to do the unplug-and replug thing every time I turn Asgard 2 off and on?
You can leave them plugged in all the time. Asgard 2 has a muting relay which delays output on first turn-on, and mutes the output on turn-off.

Does the volume control adjust the preamp outputs?
Yes.

Can I turn off the headphone outs when I’m using the preamp outputs?
Plugging in headphones automatically disconnects the pre-outs.

How do I switch the gain?
There’s a toggle switch on the back of the amp.

What does Class A really mean?
For us, Class A means Class A—that is, the output stage is running its maximum current all the time. This is a real Class A amp, biased by a current source. It can never go out of Class A. Protip: running a Class A amp hard into a difficult load actually causes it to run cooler. Please note this is not an invitation to destroy your hearing. This is just a bit of trivia. We probably should be telling you to practice safe listening, use a condom, sign this disclaimer before you turn up Asgard 2, don’t use the lawnmower as a hedge trimmer, coffee is hot, blah blah, but we don’t roll that way.

So, this thing runs damn hot, like Asgard?
If by “damn hot” you mean 40-45 degrees C, then yes.

And you’re not concerned with that?
Nope. The entire chassis is a heat sink, and we’re running the outputs well within their safe operating area, even derating for the operational temperature. Sorry, some engineerese crept in there.

But it still runs hot!
And technically, that’s still not a question. If you want an amp that runs cold, it’s best to look elsewhere.