Even though we publish new blogs daily from your intrepid editor and from a number of well-known writers, sometimes it's good to have a look back at some of our articles from the recent past that were well received.
Audio seems to be a popular topic among engineers. Here is one that discusses class-G audio power amplifiers. Class-G amplifiers share some traits with the more well-known class-D amplifiers — notably, better power efficiency. Better efficiency makes them ideal for battery operated portable devices. They provide this efficiency while maintaining high levels of performance.
This article is in two parts. Part 1 looks at the general details of different classes of amplifiers and compares their performance. Then it moves into the specific details of how class-G works.
Part 2 gets into the class-G performance specifics.
Let us know about your experiences working with audio in general and these newer classes of amplifiers in particular.
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Hi Brad,
In the past I used a class B amplifier, the TDA1518 Phlips, good cost is a good power output.
It was a simple, one amp audio for gaming equipment, in every way to achieve maximum power had a distortion signal too big, anyway, it was good but we needed to solve some small details HW, especially with the power power, which was to be linear with a loud noise.
Another point that was already waiting for something to arrive at the maximum the integrated heated too much, then a good aréa dissipation was created.
There was something with a content tencnológio very large, but in the end application had an excellent result, I must stress the small details given above.
Another very good experience now with energized circuit voltage lower typical 3v, this is the ISD4002 is a ci for recording audio, a few seconds, lol enough to let me say “bald” … I had many problems with the filters and the loss of the messages that were in memory of the uC, anyway after a good fight could improve perfomace, the output signal was white, no noise, it worked well …
Until …. the internal battery is discharged, as there was limited output signal so that the consumer was less …
Finally after much beating unable to handle the situation detection system using a low battery power and limit the ISD …
I learned a lot, but got …
Thanks for sharing this Brad.
The Class-G are surely helpful in reducing the power. The programming of the supply power according to the audio peak is very helpful.
As shown in Fig 2 above the supply is ramped up and down immediately, will it not introduce any click and pop noise?
The DC-DC will be switching and switching at frequency higher, say 10 times the audio range. Does this noise get filtered out by the speaker inductances?
Does Class-G architecture hold good for different speaker loads?
Does having Class-G architecture good only for lower loads, since current is a function of voltage ratio (VBAT/VSUP)?
When you start talking audio, when you get to guitar amplifiers, you immediately get to the tube vs. SS questions. There are still lots of Class A and AB guitar amps sold based on tubes in some sections, like the preamp.
A couple of years ago I started hearing there was a solid state device that had been engineered to match the characteristics of 12AX7 tubes. I saw some articles saying a company tubemodules.com was producing limited quantities. I even found a picture of one:
12AX7 solid state drop in replacement
Any comments on the ever-lasting tubes vs. SS in power amps like guitar amps? Has anyone seen or used one of these alleged replacements?
@eafpres – looks like s/o made a few of those in the basement (or garage) – does not inspire confidence.
@amrutah – no – the ramping of the supply voltage will not pass thru to the speaker – as long as it has a little bit of actual ramp time. Any good amplifier is designed to have pretty good power supply rejection ration (PSRR), so if the supply doesn't ramp too quickly, the dv/dt won't pass thru. Also, switching noise is sufficiently high so that it won't show up at the speaker.
@amrutah – it would be appropriate for and work well with various speaker load impedances.
Note that for high impedance loads, you may not realize much overall power savings.