Solid State Mode, Low Gain

THD: < 0.0015%, 20Hz-20KHz, at 2V RMS, 32 ohms
IMD: < 0.001%, CCIR at 2V RMS, 32 ohms
SNR: > 115db, unweighted, referenced to 2V RMS
Crosstalk: < -72dB, 20Hz-20KHz, 32 ohms
Output Impedance: 0.4 ohms

Tube Mode, Low Gain

THD: < 0.003%, 20Hz-20KHz, at 2V RMS, 32 ohms
IMD: < 0.003%, CCIR at 2V RMS
SNR: > 111db, unweighted, referenced to 2V RMS
Crosstalk: < -70dB, 20Hz-20KHz, 32 ohms
Output Impedance: 0.4 ohms

Solid State Mode, High Gain

THD: < 0.003%, 20Hz-20KHz, at 2V RMS, 300 ohms
IMD: < 0.003%, CCIR at 2V RMS
SNR: > 102db, unweighted, referenced to 2V RMS
Crosstalk: < -85dB, 20Hz-20KHz
Output Impedance: 0.6 ohms

Tube Mode, High Gain

THD: < 0.004%, 20Hz-20KHz, at 1V RMS, 32 ohms
IMD: < 0.005%, CCIR at 1V RMS
SNR: > 97db, unweighted, referenced to 2V RMS
Crosstalk: < -85dB, 20Hz-20KHz
Output Impedance: 0.6 ohms

Preamp Output, Low Gain, Solid State

THD: < 0.0003%, 20Hz-20KHz, at 2V RMS
IMD: < 0.0003%, CCIR at 2V RMS
SNR: > 118db, unweighted, referenced to 2V RMS
Crosstalk: < -95dB, 20Hz-20KHz
Output Impedance: 75 ohms

Preamp Output, Low Gain, Tube

THD: < 0.0025%, 20Hz-20KHz, at 2V RMS
IMD: < 0.002%, CCIR at 2V RMS
SNR: > 112db, unweighted, referenced to 2V RMS
Crosstalk: < -90dB, 20Hz-20KHz
Output Impedance: 75 ohms

All Tube and Solid State Modes

Frequency Response: 20Hz-20Khz, +/-0.08db

Maximum Power, 16 ohms: 9.0W RMS per channel
Maximum Power, 32 ohms: 6.0W RMS per channel
Maximum Power, 50 ohms: 4.0W RMS per channel
Maximum Power, 300 ohms: 900mW RMS per channel
Maximum Power, 600 ohms: 450mW RMS per channel

Gain: High 5.7 (15dB), Low 1.2 (1.35dB)

Topology: Coherence ™ fully discrete, current-mode noninverting 6SN7/bipolar hybrid with constant transconductance output stage with Fusion Architecture™ depletion MOSFET gain fallback, 64-step relay ladder volume control

Protection: microprocessor oversight for high DC, over-current, and tube presence; mute on any fault and management of tube and solid state gain modes

Power Supply: two internal power transformers with 72VA total rating, plus with over 55,000uf of filter capacitance; two discrete regulated +/-100V supplies, two high-current +/-26V supplies, four regulated oversight supplies—20V, +/-15V, 5V

Power Consumption: 30W

Size: 9 x 6 x 2”

Weight: 6 lbs

APx555 Report for Lyr+

Are you saying you can run tube gain or solid state gain on one amp?
Yes!

And if I don’t put in a tube, it switches to solid state, without me doing anything?
Absolutely correct.

Holy moly, my head just exploded.
Yeah. We know. It’s OK. When we were developing this amp, we called it the “where is your god” circuit, because you could turn it off, pull the tube out, turn it back on, and it’d go on as if nothing had happened. But we figured “Fusion Architecture” was a bit more tasteful, so there you go.

I’ve seen other amps with tube and solid state options. How is this different?
There’s a huuuuuuge difference between simply throwing in a separate solid state section, and replacing the tube with depletion MOSFETs in the same exact topology. The first approach is completely separate from the tube stage, and probably doesn’t perform (or sound) anything like it. The second approach is completely nuts, and it retains the overall simple tube topology (in this case, our own Coherence™ hybrid topology), changing only the active gain devices. This is the only way you can retain the inherent qualities of a tube architecture—and directly compare tube and solid state gain.

How do I know you’re not just running solid state all the time, and the tube’s just for show?
The noise and gain characteristics do change between solid state and tube. When you’re running tube gain, you’re running 100% tube gain. Which means you can roll tubes, and expect the tube rolling to result in the same sonic changes that you would have expected, say, on Lyr 3. In tube mode, Lyr+ is very similar to Lyr 3, in fact. However, when there’s no tube installed, Lyr+ will switch back to its internal depletion-mode MOSFET solid state gain stage, which gives you a convenient tube alternative.

So does the MOSFET gain stage sound like a tube?
We don’t comment on that. You tell us.

Ah come on!
Here’s the thing: we don’t really comment on how things sound. That’s for you to say. What we can say is that a depletion-mode MOSFET operates most like a tube, at least among gettable devices these days. This is reflected in the distortion profile of the amp—the MOSFETs look a lot like tubes. That’s why we chose them as an alternate.

When I’m using tubes, is it only a tube amp?
When you’re using a tube, it’s 100% tube gain, coupled with a discrete Continuity™ bipolar output stage. So it’s technically a hybrid, like all Lyrs from the beginning, almost a dozen years ago.

And when I’m using solid state…
Then it’s 100% solid state, with depletion MOSFETs swapping out for tubes in our Coherence™ architecture. Same output stage. Still 100% discrete.

Do I have to pull the tube out to switch modes?
No. If you have a tube installed, you can switch between tube and solid state modes via the remote. You can also press and hold the gain switch for 4 seconds, and when you release the button, it will switch modes. With no tube installed, Lyr+ only allows you to use solid state, of course.

Why’d you give me so many choices?
Well, we don’t know if you’ve noticed, but tubes are getting harder to get. It’s particularly difficult for us to get thousands of good, new-production tubes to put in our products. But we still like tubes. And we know it’s a lot easier for you to find one tube than for us to find 10,000. So we created Lyr+, so you can experiment with lots of really nice tubes, with the convenience of only using one at a time…or you can run solid-state, if your tube happens to get noisy, or if you simply prefer it from time to time. We think choices are good. We hope you think so too!

Why is this more expensive than previous Lyrs?
Because we wanted to give you the best tube hybrid desktop headphone amp and preamp we ever made. So we created an entirely new Fusion Architecture for seamless tube and solid state gain. Plus we added new high-end features, like a relay-ladder volume control for perfect channel matching, all the way up and down the dial. And to top it off, we incorporated remote control, because you might want to use this off you desktop. Finally, microprocessor oversight provides exceptional convenience and safety. Bottom line, Lyr+ is the most advanced desktop-sized headphone amp and preamp we’ve ever made.

So why not balanced?
You tell us where to put the balanced connections and supporting circuitry, and we’ll make it happen.

Seriously?
Come on, look at the chassis. It’s full. Sorry, if you want balanced, we have Jotunheim 2, which is an amazing headphone amp and preamp in its own right.

But I want balanced and tubes and—
Yeah. We did that. It was called Mjolnir. It was big and inconvenient and we couldn’t move it with bran.

Sigh. Okay, so let’s talk about your buzzword bingo. What is Fusion Architecture?
In case you missed it above, it’s our way of allowing you to use tube gain or solid state gain, and to manage the modes. Think of it as a tube hybrid amp that always has a fallback. Or a solid state amp that always has the option for a tube.

And Coherence™?
This is our unique current-mode, noninverting tube/BJT hybrid topology that eliminates the need for interstage coupling capacitors. These two disparate devices work seamlessly together in this topology, hence the name.

And the Continuity™ output stage?
Sit down and buckle up, because this is important—maybe the most important subject for a Class AB amplifier, like, ever.

• Transconductance nonlinearity in the transition from Class A to Class B is an inherent problem baked into literally every Class AB amp. Take a look at Bob Cordell’s amplifier design book for a great tutorial on the subject. Also, online, reference John Broskie. Both have written many words about the problem of transconductance nonlinearity. 
• When you bias a Class AB amplifier, both transistors conduct at low levels. When the output goes outside of this low level, though, only one half conducts. Effective transconductance is halved. You can pursue an optimum biasing strategy for Class AB that minimizes this transconductance discontinuity, but it is absolutely there. You can squint your eyes and say that the emitter resistors swamp the effects, but it’s still there. You can use a ton of feedback to squash it flat, but, again, it is absolutely still there. Sumo addressed this with its Transconductance Linearization error servo based on the work of Hawksford and Cordell. This was a complicated way to get around it, but it did work. Another way to address the problem is to bolt on huge heatsinks and crank everything as far into Class A as possible, so the transconductance is always doubled. That’s great, except for the fact you end up with huge, heavy, hot amplifiers.
• Our Continuity™ constant transconductance output stage is a serious attempt to solve this problem. It uses both N-channel and P-channel devices on both positive and negative sides of the power supply, all conducting at the same time, and it uses additional devices that linearize the transconductance outside of the Class A bias region. It addresses both the problem of transconductance doubling and of mismatch between N-and P-channel devices. 
• This isn’t just hand-waving—the Continuity output stage measures 10dB better THD to clipping.

Let’s talk practicality. Is this quiet enough for IEMs?
Many of them, in low gain mode.

And it has enough power for…
…any headphone, yes.

And it has remote control?
Yes.

Can I control the preamp outputs remotely?
Yes. The remote does volume, input, preamp on/off, tube or solid state, and gain hi/low. As long as you don’t have a ton of inputs, this is a great preamp as well as a headphone amp.

You know this sucker runs warm, right?
Yes, about 10W more at idle than Jotunheim. This is well within the capability of the parts we’re using, so there you go. 

What is Lyr?
In Norse mythology, Lyr is Menglad’s hall in Jotunheim, land of the giants.

Lyr+ Manual