I'd like to build a solid state guitar amp. I am confident in the preamp design, and the power amp schematic (as the power amp was swiped from the AC30VR), but it's the power supply for the power amp that concerns me. As I've read, the power supply is the most important factor in a successful power amp.

I'm happy with lower voltages, and I've built a few tube amps, but I'm not comfortable with designing my own layout that deals with mains wiring, so I'm trying to stay away from that. Thus, this AC wall wart idea was born (/stolen from the internet). To circumvent the issue of having mains inside the box, I thought I'd try to power an LM1875 using a 15VAC 2.5A wall wart using the following schematic:

https://imgur.com/a/bISQ7

The other option is a 24V 2.7A adaptor, but I guess each rail is really only going to have 1A available from the 78xxx and 79xx regulators.

So I guess, at +/- 24V or +/-15, is 1A per rail going to be enough? And what might be a predicted wattage of this set up / would the 3875 run on either of those power configurations with any better results?

Thank you very much

Hola - first post here!

I'm looking at chipamp poweramps and came across some posts about changing them from voltage amps to mixed voltage and current amps in order to make it a little more... forgiving, ala Project 56, Figure 2, at Rod Elliot's Sound Product site.

I won't pretend to understand a lot of what's going on here, but I've been looking at poweramps used in production models, such as the Marshall 8040, and trying to figure out why values were chosen.

I'm somewhat of a novice with LTSpice, so when I try to simulate figure 2 from ESP, I get the 18.8V output without the 8ohm load, but when I make the connection to an 8ohm resistor, I get a square wave at 200mV on the output of the amplifier. So before I can use the equations to figure out output impedance, I need to get that voltage under load somehow.

In any case, does anyone have any tips on how to figure out that voltage before I continue on the path of misunderstanding?

Also, I did what I would consider a pretty thorough search on chipamps set up like this for guitar amps, but I can't seem to find many comments any projects posted here, or elsewhere. Of course there are a ton of people using the datasheet examples of chipamps for power amps, but nothing similar to this. I thought that was a bit odd as prevalent as these chips are in current commercial amps. So if there is something similar going around, I'd love to know about it! Thank you.