Affordable GaN FET amp from Peachtree Audio

@barts ,

It’s over my head as well but here’s this from their site:

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 so 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 even 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 a new one as similar devices often referred to as "Power DACs" made quite a splash in our industry years ago, but this time around, using the concept with GaN-FETs raises the bar to an entirely new level.

 

There’s also this from Twittermachines on the Technics SU-R1000 (which uses GaN FETS:

It’s also worth pointing out that there’s no DAC, no digital to analog conversion, taking place inside the SU-R1000. Incoming digital signals are upsampled (to 32-bit/768kHz), sent through a 1-bit Delta-Sigma converter, followed by another stage, the PWM converter, which forms a so-called “ternary” (2-bit) signal out of the 1.5MHz 1-bit signal. So each transistor only has to handle a switching speed of 768kHz/1-bit which is easier to handle in terms of the natural response time of a GaN-FET. I include this information knowing full well that few people will really understand it, yours truly included, so let’s just say that digital remains digital right up to the speaker binding posts.

I read somewhere that Wadia did a similar thing all those years ago but was stymied by the limits of the output devices they had then. It’s still over my head but I can definitely hear the results with my Technics SU-G700. I still prefer going analog in from my SACD player but it’s a close enough call to make me know that a better coax cable can level the playing field, or, maybe not.

All the best,
Nonoise

OK, color me curious...How in the world can a GaN amp be fed a digital signal and amplify that signal and have it be an analog output without a D to A conversion taking place?

And if that D to A conversion is taking place (me thinks it has to be) then the GaN amp is incorporating a DAC (of whatever strip you wish to call it).

By extension does this mean that any GaN amp doesn’t need a DAC and can be fed a straight up digital signal.

ralph at atmasphere or others working with these technologies can probably answer better ...

...but to my understanding the class d amps use pulse width modulation of the output transistors... so the input into that form of power transistor control scheme is digitized by nature... so when you put an analog signal into these units, it actually goes through a-to-d conversion initially, so that the amp module is working off a digital signal it needs to its modulation (downstream control) scheme - and then the amplified output is delivered to the output taps (speaker terminals) in analog form, thus playing music

amps and integrated amps like those from devialet, lyngdorf et al all work this way - you feed in an analog signal, it converts to digital at the input... then the amplification module converts it back to analog with the juice behind it to drive the speakers...

so this peachtree product is simplifying the scheme by taking the digital in only at the spdif rca port... to a-to-d conversion is being done for any inputs

https://digilent.com/blog/whats-the-point-of-a-dac-and-why-do-i-care/

https://www.adam-audio.com/en/technology/pwm/

https://www.eetimes.com/class-d-audio-amplifiers-what-why-and-how-part-5/

@nonoise 

If you use the digital output of the Bluesound Node, you ARE using it's internal DAC. The only way to it is to use the analog outputs, which there are not analog inputs on the Peachtree amp.

I'm sorry sir however, you have that exactly backwards. The analog outputs from the Node2i have passed through the internal DAC of the Node2i. That's why they are an analog signal: They've been converted from 1's and 0's to an analog waveform with left and right channels.

The digital output from the Node2i has NOT be converted as it is by-passing the internal DAC in favor of an outboard DAC or other component which can accept a digital signal.

So the question remains, if I use the digital output of my Lumin streamer into this amp, what device is doing the digital to analog conversion? No DAC needed according to the OP, but I'm having a hard time figuring that one out.

Well I went back to their ad copy in which they state: "The GaN 1 is also designed so that it does NOT even require a digital-to-analog-converter (DAC). "

I too fail to see how you can put out an analog signal to speakers unless somewhere along the way you convert those little 1's and 0's to an analog waveform. Peachtree are doing that, they're simply just not saying they're doing it.

Also, I stand corrected: I forgot the Node2i does have analog inputs so I suppose you could use a phono preamp into it for a TT, thus using the Node2i as a "preamp" of sorts but I'm skeptical as to the sound quality.

I like the Node2i, but I'm not going to hand my TT over to it. 😉

Happy listening.

@jjss49 

Ah thank you for the citations and clarification on this process! 👌

So the D to A process is still happening, they're being creative with the design to do it with. Slick.

Happy listening.

@musicfan2349

That quote you attributed to me was not mine.
It was ozzy62’s.

All the best,
Nonoise