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

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#61
Using no FB makes an class D amp load dependent... i.e. it will sound different with different speakers.

The only thing that is different is the length of the wire between the DAC and and the amp. Here it is short - thats good 🙂

You have swallowed the ad story - sorry...

It's not a "digital amp" - its an amp with a digital interface.. quite a big difference...

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#62
TNT said:
Using no FB makes an class D amp load dependent... i.e. it will sound different with different speakers.
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We have to wait on that call, to see what are the measured output impedance (damping factor) of these amps are as that's yet to be revealed.
As the ones that have heard them have said the bass is deep, dynamic and well controled, that says to me ouput impedance is quite low.

Cheers George
 
#63
TNT said:
Using no FB makes an class D amp load dependent... i.e. it will sound different with different speakers.

The only thing that is different is the length of the wire between the DAC and and the amp. Here it is short - thats good 🙂

You have swallowed the ad story - sorry...

It's not a "digital amp" - its an amp with a digital interface.. quite a big difference...

//
Click to expand...
Why it is load dependent?
 
#65
georgehifi said:
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
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Why would higher speed and smaller deadtime lead to lower distortion? That doesn't make sense to me.
But maybe I am missing something?

Jan
 
#66
HAYK said:
Why it is load dependent?
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An amplifier with no feedback has a Zout which is often at the same order of magnitude or higher than the intended load impedance.
That makes the output voltage load dependent.
Fb can lower the Zout by many orders or magnitude making Vout independent of the load, within the amp's current capacility of course.

Jan
 
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#67
I asked the question to TNT.

The switches link the load to ground or +V with few milliohms. The output impedance is that of supply at switching frequency. Whether the load is 1ohm or 100ohm, the PWM has the same amplitude. Only the damping of the output filter makes the difference but the feedback of standard class D exclude the filter.
 
#73
https://e2e.ti.com/blogs_/b/powerhouse/posts/the-sound-of-gan
Says less deadtime, less distortion, but I don't know if this i applicable for all cases of use?
"GaN’s inherent characteristics provide a more ideal model of a small-signal PWM, driving the output filter. Along with this, the absence of a body diode eliminates reverse-recovery charge, which enables increased output linearity. Both characteristics allow GaN to minimize THD and ultimately create higher-quality sound."

Så not independent from the load but GAN " provide a more ideal model of a small-signal PWM, driving the output filter."
 
#74
Integrating the driver still don't make dem digital devices, but a mixed signal one: https://www.ti.com/product/LMG2100R044.
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#76
TNT said:
"Just 24 bits".... 24 bits is massive... no problem at all and superior to any analog pot if done right...

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Surely not.
24 bits is only 16 8 more than the signal, so you can't reduce to a low level before compromising source material.
The dynamic range of a 24 bit signal is not the issue, however linear or balanced the control is compared to an analog pot.
32 would be OK, I believe.

Not everyone lives alone, in a detached property, and has a big room.

Mod edit: member requested change in text in first line :cop:
 
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#79
jmansion said:
Surely not.
24 bits is only 16 more than the signal, so you can't reduce to a low level before compromising source material.
The dynamic range of a 24 bit signal is not the issue, however linear or balanced the control is compared to an analog pot.
32 would be OK, I believe.

Not everyone lives alone, in a detached property, and has a big room.
Click to expand...
I don't think you have a clue how it works actually.

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