Peachtree new GaN-1 all "Digital Amplifier" the future?? (and it's not Class-D)

[cab]

Add to an open loop design load dependent frequency response.

 

[billshurv]

yes, hence the 'valve sound'. There are well regarded solid state amplifiers out there with no feedback around the output stage after all.

 

[cab]

More proof that there is no accounting for taste.

 

[billshurv]

It’s entertainment not dialysis!

 

[5th element]

See post 1.
On simulator using the same GaNs in bridge with 5ns dead time it measured 0.007% with 200khz carrier.

This is at least an order of magnitude worse than the state of the art.

Nevertheless the reduction of the dead time is a property of using the GaN devices not the digital input. Much better to use GaN in an analogue input class D with post filter feedback.

 

[torgeirs]

I know that at high speed, miltiple gigahertz analog solutions are needed most of the time. But are we really there with GAN audio amps?
I also know there are som very clever analog feedback designs out there. But is the speed/timing really that high? So those analog designs can’t be ported to digital domain

 

[davewantsmoore]

It can, if you re-define class D to fit your purpose. Watch.

GaN Systems use the phrase "Class-D" in reference to their amplifiers 26 times in their paper.

 

[drjlo]

There's no need to try and combine the two and TI have even given up on this concept with a lot of their single chip amps. Most of them now contain a traditional DAC plus class D amplifier together in the one package.

I still have the old Panasonic SA-XR55 "all digital" PWM amp using the TI chip. It still sounds darn good when fed a clean digital signal (forget about analogue inputs). I think these types of PWM amps have a great role when they are priced low and plenty available (like Panny was), so I wish TI would have continued to make such products.

Now what we have are "audiophile" companies making PWM products and charging orders of magnitude more money. "Audiophile grade" might as well spell "Hospital Grade" as far as pricing anomalities..

 

[torgeirs]

So those analog designs can’t be ported to digital domain

Should have been: So those analog designs can’t be ported to digital domain?

 

[torgeirs]

Don't have the SA-XR55, but i have the Sony STR-DB900 with analog inputs for each chanel like the panny.
Its from 2004. So should not the digital circuits have speeded up to cope with GAN in 2023?
This is the amp part from the service manual of the STR-DB900

 

[torgeirs]

Input from left side. Looks like they already figured it out in 2004. IC308 6-702-673-01 IC CXD9730Q. So looks like Sony legacy chip

 

[torgeirs]

Could have been updated to a GAN design with two of these for each chanel.
https://epc-co.com/epc/products/demo-boards/epc90143

 

[torgeirs]

Funny part is that the mosfets on the output is not analog parts they are boosters. Guess its «the same» with the GAN parts of GAN-1

 

[jan.didden]

They are the output devices. They operate in the voltage, current, time domain. That's analog.

Jan

 

[xrk971]

Have you guys ever seen a GaN FET go supernova? It’s quite impressive (and a bit scary) given the current densities and how small they are and sometimes they have very little heatsinking in place.

 

[torgeirs]

They are the output devices. They operate in the voltage, current, time domain. That's analog.

Jan

No, no. Digital boosters🤣

 

[torgeirs]

Wonder why the GAN marketers today think they can get away with the «all digital» as sony and panny tried 20 years ago

 

[georgehifi]

They are the output devices. They operate in the voltage, current, time domain. That's analog.

Correct, they're just doing a bit of marketing.
These Peachtree GaN-1 and Carina-GaN are digital all the way "up to the output stage", which is more digtal than anything else today.
Yes from what I've read the GaN output stage themselves the way Peachtree use them are analog, but because of their far superior switching speed and dead time figures, they allow the use of "everything before them to be totally digital", which Mosfets can't from what I gather. (correct me if I've understood it wrong)

Cheers George

 

[jan.didden]

Basically any class D that accepts analog or PCM or DSD or PWM are all analog amplifiers.
Only if the accept digital inputs like I2S or Toslink or S/PDIF can claim being a digital amp.
Many confuse switching with digital.

Jan

 

[georgehifi]

Another thing I should have added to the GaN output transistor superior switching speed and dead time figures over Mosfet, is it said that because of these advatages over Mosfets they can be used open loop (zero feedback) (as Peachtree do in these 2 amps) and yet still have great low distortion figure of .04% or was it .004%. Remember designers only use global feedback as a bandaid to bring distortion and output impedance down, most prefer and myself "the sound" of local feedback only if the distortion and output impedance are still kept low.

Cheers George