Are there any low-power class D amplifiers that are not crap for guitar amplification

[dotneck335]

Originally Posted by maddins

I guess even if the micro cube schematics were available, they might not be very helpful since it's circuitry relies on an proprietary signal processor. I've had opened it up and couldn't find much discrete preamp parts on it that could be rebuilt.

Yes, it is true that the MicroCube's sound is mostly buried in the proprietary processing. I just want to modify mine with a Class-D amp (TDA7292), a LiOn battery, and a better speaker (Eminence 620H) to get more usable power. I'm thinking I can figure out the wiring from the other Cube schematics that bucks provided; but I'd still like to see the MicroCube's schematic.

[Printer2]

Originally Posted by john65b

Look at the top of the transistor - you should see a small rectangle on the seam joining the two parts - flat side and "d" side.

That little rectangle should be right smack in middle - centered on seam. Fakes are offset to one side on the 2SK170 and 2SK117.

Also, the Drain-Source resistance should be around 50 ohms for the 2SK170, unfortunately I cannot remember what it was on the 2SK117...

This may or may not be factual (I found all this out here on DIYAudio), but have no reason to not believe....made huge difference in my guitar preamp and a pacific phono stage that sounded ok/crappy for longest time due to "fake" 2SK170.

Seems they are fakes. Maybe change the bias? I'll have to try it some day.

[dotneck335]

The KEY to using ANY Class-D power amplifier is to NEVER NEVER EVER let it go into clipping! Class-D clipping is the most horrendous sound; much worse than any Class A or AB clipping. Put some sort of limiter in front of Class-D---even a pair of anti-parallel signal diodes would be an improvement---to avoid this.

[john65b]

Or just take the Roger Sanders (Innersound, Magtech, Sanders Sound Systems) approach and just use a suitable High-Power Class D amp so that you could never reach clipping before your ears give out.

After all, isn't the cost / size difference between low and high power Class D negligible? Is "Low Power Class D" just straw dog?