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
kuribo
524 posts
 

@donnylovely

Maybe this will help...

From:

https://sound-au.com/articles/pwm.htm

Class D Audio Amplifiers - Theory and Design

6 - Output Filter Design

The output filter is one of the most important parts of the circuit, as the overall efficiency, reliability and audio performance depends on it. As previously stated, a LC filter is the common approach, as it is (theoretically) lossless and has a -40dB/decade slope, allowing for a reasonable rejection of the carrier if the parameters of the filter and the switching frequency itself are properly designed.

The first thing to do is to design the transfer function for the filter. Usually, a Butterworth or similar frequency response is chosen, with a cutoff frequency slightly above the audio band (30-60KHz). Have in mind that one of the design parameters is the termination load, that is, the speaker impedance. Usually, a typical 4 or 8 ohm resistor is assumed, but that would produce variations in the measured frequency response in presence of different speakers. That must be compensated for by means of proper feedback network design. Some manufacturers simply leave it that way so the response is strongly dependent on the load. Surely a non-desirable thing.

7 -   Feedback

As I have stated previously, timing errors can lead to increased distortion and noise.  This cannot be skipped and the more precise it is kept, the better the design will perform.  Open loop Class-D amplifiers are not likely to satisfy demanding specifications, so negative feedback is almost mandatory.


And there you have it...

yyzsantabarbara
4,829 posts
 

@dolfan It could be ignorance on my part. I saw the blurb on Peachtree web site that said they have a new batch being built for Dec 2022. I will give them a call to see if they can put some SpeakON speaker termination for me. That way I can do a real apples-to-apples comparison with my Benchmark gear.

I will use the GAN1 amp for my KEF Blade 2 Meta (ordering in Feb 2023) until I get funds for a more powerful amp for the Blades. I was wondering what to do with the GAN1 amp afterwards. I realized that the GAN1 has the protentional to be a great headphone amp for my RAAL SR1a earphones. I want to get a headphone amp for the bedroom and the GAN1 could be a perfect low box count solution. I bought some very short used Audience AU24 SX speaker cables a few minutes ago for that purpose.

As a frame of reference, the best 2 channel gear I had on the RAAL SR1a earphones cost over $20K and I sold all of them since it was not as good as my RAAL VM-1a amp. The VM-1a only works on the SR1a and not speakers so it has some advantages in design.

So, I now have 2 comparisons to do with the GAN1.

1) Benchmark stack vs GAN1. I will have to downgrade my speaker cable for this comparison to Audience Conducter SE unless Peachtree can do SpeakON termination for me.

2) CODA 07x preamp | KRELL DUO175XD amp | Musetec 005 DAC | Audience FrontRow speaker cable vs GAN1. I still remember how this sounded since I listened for hours each night for over a year. I will use the just purchased Audience AU24 SX speaker cable which is one notch below the FrontRow so it should be a close approximation.

 

 

 

dolfan
109 posts
 

@wise Santa B

Hoping we both get ours next week. They told me last week I would hear sumn about testing and or shipping but nothing so far.

u have nice systems

Mine will be Gan 1, Node, Tekton Perfect Set, and Rythmik FV15HP. It's a TV and backround music set up.

I need a coax cable. Where would u start?

ricevs
1,543 posts
 

BTW, the GaN 1 digital board measures almost the same frequency response as the board in the GaN 400 (analog input board). It is one db down at 20K using a 4 ohm load. This will give less than one quarter db attenuation at 10K......no one can hear this. However, with a 2 ohm load it is 2db down at 20K.....so it will make 10K down one half db.....maybe you could hear this. OMG this is so horrible!!!! (Kuribo speaking here). There is maybe one person in 100 with a speaker that MAYBE you could hear the rolloff.......I don’t hear much above 10K myself. There are a couple of electrotats that have very low impedance at 20K and there are a handfull of regular speakers that have a 2 ohm tweeter load.......but very, very few. Just go to stereophile mag and read the measurements of various spekakers they have reviewed lately....only the Kef Blade 2 goes a little under 4 ohms at 10k.....all the rest are above 4 ohms......just not an issure.

So, thinking you need feedback and op amps and DACs and Preamps and analog cables so you do not have this very slight problem that practically no one will hear is simply silly. But, some people make mountains out of mole hills.....hey, I get excited for positive things.....some people get excited to put things down.

I like UP myself. I say Yes to life.....and Blessings to all......how about BLESSESS......Beautifully Love Every Single Soul Every Single Second

kuribo
524 posts
 

Speaker loads are rarely purely resistive nor are they flat.

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