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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
atmasphere's avatar
atmasphere
11,841 posts
 

@atmasphere do you care to comment? I think the removal of an output filter for Class-D will be very measurable. I guess when you don't have to worry about compliance testing, anything is possible. @atmasphere what would happen if you hooked these up to a big electrostatic speaker or something like a Magnepan? Aren't these switching at frequencies right in the middle of the AM band and then hooked up to all that wire in the speakers?  Aren't those speakers big capacitors? What is going to happen without those filters?

The extra output coils mentioned are only part of the filter. Certainly the result will be measurable, and likely audible as well. As best I can make out, the output filter choke remains. The amp would not function without it!

A zero feedback class D amplifier will exhibit an electrical resonance when used on an ESL; this being the result of the choke inductance and the capacitive load of the speaker. I've seen this resonance cause some class D amplifiers to fail.

I'm sure those series inductors are there for a reason. For example, most solid state amplifiers have a resistor/inductor network across their speaker terminals to increase stability at ultrasonic frequencies. In a class D, the concern is always radiated noise. To this end, with any changes made to the amplifier, its a very good idea to test the radiated noise to the AC line, since that noise can leak into other parts of the system (such as digital devices) and really mess with them. That is why its important to not just meet EU Directives, but to actually have noise figures well below that, since a lot of consumer digital devices aren't that good at dealing with switching noise in the AC power. Radiated noise which might emit from the speaker cables (behaving as an antenna) can also get into other equipment, increasing noise in the system.

Because most class D amps (if designed competently) are meant to meet EU Directives and similar emissions ratings of other countries, its often a Bad Idea to mess with the components in the output filter since they are often chosen for their noise characteristics; for example many capacitors have leads which have inductance; if the inductance is increased you can wind up with parasitics, which in turn if they don't mess with the amp directly can mess with other parts of the system. 

Put another way, reducing noise in a class D can have a very direct improvement on how it sounds!

 

 

donnylovely
105 posts
 

The output inductors he’s taking about, is a ferrite on the speaker wire outputs, the speaker wire is coiled around it. Not a coil on the power supply. Looks like the know it alls, don’t know it all. This we don’t listen to people that have never seen the product. 

cbugbee
4 posts
 

@ricevs  Referencing your recent post (3/8 @ 9:08 pm), you state that the stock amp "Did not sound good stock.....very grainy, dry and harsh.". I find this statement hypocritical, since the beginning of this thread you and others have indicated that the GAN1 is an exceptional amp. I understand how your mods may make it better, but many of the opinions on this thread and others indicate that it is an exceptional amp stock. I realize that you may not have actually heard it until recently, but i am amazed that your opinion differs so drastically from others. I understand that you are interested in modding thes amps, but some of your readers may only want to buy the stock unit.

atmasphere's avatar
atmasphere
11,841 posts
 

The output inductors he’s taking about, is a ferrite on the speaker wire outputs, the speaker wire is coiled around it. Not a coil on the power supply.

@donnylovely Yes- that was very clear in his prior post. FWIW, the choke used in a class D is not in the power supply; I don’t think anyone here had thoughts otherwise! A choke used in series with the speaker output (as mentioned prior) wouldn’t be part of the power supply either.

However if the amplifier suffers parasitics on either account, those can cause noise to be radiated via the power supply.

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