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
atmasphere's avatar
atmasphere
11,637 posts
 

You have already stated that you thought op amps have no sound (are neutral). This has been refuted by hundreds of posts all over the net. Let us hear your story....if you think I am making up a story about you.

Opamps: the more important aspects are the open loop gain and Gain Bandwidth Product. These days most opamps have enough of either that as long as you don't ask more than about 20dB of gain then they will be neutral. Ask more and their 'sound' comes out. Older opamps from the 60s and 70s in particular weren't so good- so if repairing older guitar effects pedals you can mess up their 'sound' using newer opamps.

How GBP works is if you don't have enough, feedback falls off on a 6dB slope. When the feedback falls off distortion goes up. So when designing opamp circuits its a good idea to know these specs and their implications; otherwise expect colorations. Obviously 'hundreds' of posters are either using older opamps or don't know what they are doing.

none of my customers of my modded class D amps for 20 years have ever had a problem....

That you know of...

A lot of people new to class D are concerned about its noise interfering with other equipment. When you don't test, you don't know if your mod did damage on its way to trying to get the amp to sound better. I'm not saying you can't make an amp sound better but I am saying that if the amp injects more noise on the AC line or simply radiates more thru the air, it can interfere with other parts of the system, the TV in the next room, that sort of thing. I don't need a faraday cage to live in because we tested our amps...

Having built zero feedback class D amps (that is where we started) the thing we noticed is that as you have said, everything makes a difference since there is no correction. Noise is really hard to control; tiny changes you could hardly see in the board can have audible effects on the noise floor of the amp (as heard through the speakers). So I know Peachtree spent quite a lot of non-trivial time getting it right. They had to have been really careful about specs to make sure the parts they were using weren't shooting them in the back. If I were modding one of those amps, I'd want to know everything about it and have talked to the manufacturer (with whom I'd want to be on very good terms), before digging into their work. This might be because I respect how much work goes into the design, the designer that has done the work, and brought home the bacon. 

donnylovely
105 posts
 

@jerryg123 Cool story bro, go post it somewhere where people care.

donnylovely
105 posts
 

@atmasphere why don’t you test his mod if you don’t belive him, then tell us. Until then nobody cares, so go post your hate somewhere else.

kuribo
524 posts
 

Clearly there are indeed people here who care about real engineering, science, and facts. Sorry @donnylovely if the truth hurts.

atmasphere's avatar
atmasphere
11,637 posts
 

@donnylovely There's no hate involved. If that were so my posts would be a lot different 😉  The trick on the internet is to not take things personal. That's when you get into trouble. I don't claim to know everything either- but I've learned that if I have doubts to just not say anything.

We found that you have to have really expensive test equipment in order to see the waveforms that make noise in class D GaNFET amps! This is because they can switch at such incredibly high frequencies. Our equipment was right on the edge of that kind of resolution; we had to buy some really expensive probes and the like to be able to sort things out. Otherwise I don't think we'd have been able to meet EU Directives, which one must do in order to export to Europe. Most countries use similar rules (like the UK, China or Japan) so if you can use the CE mark then you're in good shape.

So I've trying to be helpful. If Ric did the measurements for noise (I'm not talking distortion, just RFI and noise radiated on the AC line) then its a guarantee that his mods would be more effective too. They go hand in hand.

 

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