what about calss D

[Joe Bee]

So you jumped at the chance and bought one of their modules - thats great! I just checked their website, they seem to be in Spain so shipping should not be too much trouble, is that correct?
Also, while 100€ is a bit of an investment (especially if you are after HiFi and need four or more modules) I guess it is far cheaper than brewing your own. I am just rather surprised you are not building your own switching supply for it, isn't that exactly the kind of thing you like doing?

Oh, and I'd love to hear more about your JFET preamp, did you find an effective way to fight the huge variance in parameters that other people who use JFETs seem to be fighting with?

[Steve Conner]

Hi Joe,

The Coldamp module seems good so far, but I've had a lot of "issues" with the SPS30 power supply! I think they overfill them with smoke at the factory

I could probably make a better one, but it would take up time and effort that I'd rather spend on parts of the project that actually affect tone. And I don't really need the full 400 watts of cone-shredding power. I just stuck a linear power supply in there and got on with something else. Besides, if I want to sell these amps, a linear power supply makes the EMC and safety approval issues slightly less of a nightmare.

Yes, I have a simple technique for getting round JFET parameter spread, but I'm not telling what it is!

[Shea]

Hi Joe,
Yes, I have a simple technique for getting round JFET parameter spread, but I'm not telling what it is!

Does it involve a constant current source?

[kldguitar]

switching powersupply is not good power supplier

I'm actually working on a Class-D amp just now. I bought a ready-made 400W power module from Coldamp and hooked it up to my own design of JFET preamp. It sounds surprisingly good, even on guitar overdriven with a boost pedal.

I ended up limiting it to 200W because I had trouble with the switching power supply I was using, and had to go back to a regular iron-cored transformer. A transformer big enough for 400W wouldn't fit in the size of case I wanted.

Switching power is not good power supplier ,It has many noise,But it is high efficience power supplier