2. amps-preamps
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Peachtree GaN 1 Beta

Before I start my post here is my current system for reference:

Auarlic Aries G1 --> Denafrips Terminator or SW1X DAC --> Audio GD HE1 XLR preamp or Sachs preamp --> various tube amps --> Cube Nenuphar Mini's w/ a pair of REL S510 subs. Cables and power conditioning commensurate with the rest of the system.

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As warmer months approach I have been looking for a cool running amp to replace my Line Magnetic LM-518 and other tube amps for a few months as they run pretty hot.

I've been interested in the GaN FET amps and just purchased a used LSA Voyager 350 Gan FET amp which I should receive in a few days. I've tried class D amps before and while they checked a lot of boxes I just didn't feel drawn in. However, I like to explore so I figured I'd try the GanFET and since the amp has zero feedback and my speakers seem to prefer amps with little or no feedback I figured it be worth checking out.

Today, Peachtree Audio sent out an email inviting users to a beta of their new Gan 1 amp. Here are some excerpts from their email:

 

What is the GaN 1?

In basic terms it is a 200 Watts-Per-Channel (WPC) Power Amplifier designed to be the sole interface between your digital audio device with a variable output, like a Bluesound NODE, and your speakers. The GaN 1 is a simple, pure and cost-effective audio solution: connect the GaN 1 to a streamer and a pair of speakers and you have an amazing Hi-Fi system. That's it...no DAC, no preamp and no input switching. The signal path from the music to your speakers is remarkably short and free of artifacts. Want to hear the intricate details in your music that have always been there, but you couldn't quite make them all out before? Then the GaN 1 is for you!

What makes the GaN 1 so special?

First and foremost is the GaN-FET amplifier module. It has several inherent advantages in a power amplifier that even the best MOS-FET designs simply cannot achieve. A GaN-FET power stage provides a precise high-power reproduction of the Class-D PWM signal with extremely high linearity. This linearity eliminates the need for ANY feedback, ultimately allowing for the best possible audio quality providing clean, clear middle and high frequencies and a tight, solid reproduction of low frequencies. GaN-FETs track the complex audio waveforms MUCH more accurately than MOS-FETs, resulting in significantly more transparent and natural sound. The difference is something even a casual listener can hear and appreciate. The GaN 1 is also designed so that it does NOT require a digital-to-analog-converter (DAC). The digital audio signal at the input directs the amplifier outputs to drive the speakers. Although DACs have continued to improve over the years, there is no DAC better than NO DAC! This concept is not new as similar devices known as "Power DACs" made quite a splash in our industry years ago. But this time around, by executing the concept with GaN-FETs, the bar is raised to an entirely new level.

Key Features at a Glance:
▪ 200 WPC state-of-the-art GaN-FET module
▪ ZERO feedback design
▪ Regulated 450-Watt power supply
▪ Coaxial S/PDIF input with native support up to 24-bit / 192kHz
▪ DAC-less design
▪ Power on/off trigger port
▪ All aluminum chassis
▪ No cooling fans

 

This sounded really interesting to me and since I have a good streamer I signed up for the amp beta only. One aspect that intrigues me is to create an extremely minimal signal path. My speakers are single driver, crossover-less design. Employing the GaN 1 will mean the system will be Auralic Aries --> GaN 1 --> Cube Nenuphar Mini's. Will that lead to a more engaging sound vs the full system? Will the Voyager GaN 350 outperform a tube amp in the full system? Who knows, should be fun to find out....

Now, I have no idea how either of these GaN FET amps will work with my speakers. The Cube Nenuphars seem to prefer amps with low damping and no negative feedback, which is more common with SET tube amps and Class A solid state amps. I'm not sure of the damping factor of the GaN FET amps, but both are Zero feedback designs, and both have way more wattage than I need. For reference, I have a 1.5 wpc 45 tube amp that sounds amazing with the Cubes, so high wattage is not required. I am interested though in what these amps will sound like compared to my tube amps, and I am particularly interested in what the streamer direct to amp Peachtree will sound like.

I am also looking to acquire a First Watt SIT-3, which is a great match with the Cubes, but now that they are no longer produced prices have gone above my current comfort level. If I can get one I will throw it into the experiment.

The Peachtree won't be shipped until sometime in June, or possibly later. In the meantime I will get the LSA Voyager in the next few days. I might even be able to get it hooked up this weekend so stay tuned, should be an interesting experiment...
abd1
newbluesuit's avatar
newbluesuit
3 posts
 

I'm intrigued!

The only input is digital with a maximum depth of 24 bits. There is no internal volume control. So the only way to control the volume is in the digital domain, within the 24-bit range.

On my current system (NAD M12 and M22 V1), I am generally setting my preamp somewhere between −48 and −30 dB for ‘active’ listening (depending on how loud the source has been mastered), and this even though my speakers (PMC fact·12) are quite ‘hungry.’

If I did that in the digital domain within 24 bits, I would effectively end up with a 16- to 19-bit signal. I can imagine situations (listening more quietly and/or with more effective speakers) where one would end up with even less (i.e., less than CD quality in terms of bit depth).

Wouldn't that offset whatever benefits this amplifier has? Or do I misunderstand the way volume is handled in that system?

In any case I'll be interested in reading what you have to say about this amp when you receive it! (I'm not in the US so can't take part in the beta testing.)

mbolek
168 posts
 

@newbluesuit Volume will be controlled by the streamer.  You will not lose any resolution (signal) going through the GaN1.   In theory, this will be the most direct way to amplify a digital source.

newbluesuit's avatar
newbluesuit
3 posts
 

You won't lose anything inside the amplifier, but you will lose some (possibly a lot of) bit depth in the streamer when you control the volume in the digital domain.

My NAD M12 controls the volume in the digital domain as well, but it does so at a much higher bit depth, and then the signal is converted to analog to feed the M22 V1.

It would certainly be great if a digital signal with a very high bit depth could be fed into the GaN 1, but since the input is limited to 24 bits I'm very skeptical. You lose 1 bit of depth every time you lower the volume by 6 dB.

unsound
7,329 posts
 

While I really like this concept, of skipping what might be the superfluous conversion stage from PCM to analog (and to many, perhaps a most critical conversion stage) before ultimately being converted to PWM, @newbluesuit brings up an excellent point. Perhaps, if this device started with a higher bit depth such as the ubiquitous 32-bit rates now available this might work out better.

Furthermore, I would like to see this amp spec’d into 4- and 2-Ohm outputs.

newbluesuit's avatar
newbluesuit
3 posts
 

@unsound S/PDIF does not support anything above 24 bits, unfortunately. You'd need something like USB to accept a higher bit depth, but that would probably require more processing inside the amplifier to recover the raw PCM signal. And you would need the source (where the volume is actually controlled) to be able to output a 32-bit (or more) signal as well.

It seems to me that this concept would work better in an integrated unit, so that the manufacturer could use whatever connection is most appropriate between the digital preamp and the class-d amp (separates with some kind of proprietary connector between the two would also work). Peachtree's self-imposed decision to make a standalone power amp costing less than $2000 would not have allowed this, but I hope we'll see something like this from them or another reputable company soon.

For now my plan is still to replace my NAD M22 V1 with an M23 when that becomes available (haven't seen it anywhere in Switzerland yet…). I'll have to ‘live with’ an analog connection between the preamp and the amp for a bit longer!

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