The Class TD Amplifiers

[opacheco]

Hi, do someone have any information about how the TD class amplifiers works? I have searching for this topic but I found nothing concrete about them.

Thanks in advance
opacheco

 

[opacheco]

any idea?

opacheco

 

[ccaudle]

any information about how the TD class amplifiers works?

I have never heard that term. Any references to where it is used? Is it a marketing term that one particular company came up with?

 

[opacheco]

I have never heard that term. Any references to where it is used? Is it a marketing term that one particular company came up with?

ccaudle Hello,

The Lab Gruppen company did this Technology reality in its famous Lab Gruppen FP-6400 and the same unit done for L Acoustic LA48, the same amplifier with minors differences; both TD class amplifier using a switching power amp in order to get more efficient amp and get a sound like the B class amplifier….but look like there aren’t more info in the web.

Thanks
opacheco

 

[OneRoomStudio]

I don’t know if “Class TD” is a real thing. Class D certainly is. For while, Tripath (a company that has made a number of nice Class D amplifiers) used the term “Class T” in their marketing, but it was purely marketing - all the “Class T” amps were Class D.

I’m guessing that got further confused and turned into “Class TD” somewhere along the way.

More info here: https://en.wikipedia.org/wiki/Class-T_amplifier

 

[ccaudle]

TD class amplifier using a switching power amp in order to get more efficient amp

OK, I think I see what they are doing.
It is like class H described on this page:
class G and H amplifiers

The power dissipated in the output stage is determined by the current through the output stage, and the voltage across the output devices.
A class D amplifier reduces the product of voltage and current by having the output devices either low impedance, fully on, so the voltage is low, or high impedance/off so the current is low, but the full power supply voltage is across the device.

Class H or TD gets the reduced power dissipation by reducing the power supply voltage when the signal amplitude is low, and raising the power supply voltage as the signal increases, so that the output device always has say 5V across it no matter the output voltage or current.
If the power supply voltage is changed using an analog regulator design, then the entire amplifier dissipation is still high, because now the power supply is dissipating power when the output stage is not.

Lab Gruppen just took the obvious approach of using a variable regulated SMPS for the power supply in a class H design to reduce the total power dissipation, then tasked their marketing department with coming up with something clever to call it.