Quote from: R.G. on February 13, 2007, 06:35:39 PM
Just curious - since a SS amp is great at just doing what it's told at anywhere less than clipping, why wouldn't you do an entire soft clipping circuit ahead of the power amp and then just feed that to the accurate power amp?

The soft clipper only has to soft clip the input at a voltage less than would drive the power amp to clipping. As long as that happens, the power amp is completely unaware what's happening to it.

As long as a SS amp never clips, it never sounds ugly, just accurate. It's possible to follow a soft clipped signal accurately.

Thanks for the words of wisdom R.G., it couldn't have been said better.

A good ss power amp circuit will not color the sound, will not alter it in any way other than making it louder.  So what you do is make your preamp do the clipping, soft clipping or whatever you want.  Or, run a pedal into it.  This is part of the reason why tube/ss amp combos are so popular.  If you can get a tube preamp to sound really amazing, then hook it to a good ss power amp, it sounds great.  Keep in mind thats not the best example however, because a real tube amp has a tube preamp as well as tube power amp and tube power amps DO color the sound.  So to get a tube/ss hybrid to sound the same as a tube amp, you need to get the preamp to sound the same as a tube preamp and a tube power amp!

Regardless, listen to what R.G. said and you'll be good to go.

Wow, thats a lot to read!

Basically what it boils down to is that changing the chip on your current board will be pretty much impossible unless there was a clone chip (sometimes chips are identical except power output) and even then you'd need to at least upgrade your caps and transformer to allow for more power.  The best way to get more power out of it would be to ditch the current poweramp setup and just build a new one altogether and run your current preamp into that.

Of course you can always just replace your burnt out chip with a new one and go with that.

jameco.com and partsexpress.com are the two places I recommend get your chips.  If you want a whole poweramp setup I would consider chipamp.com

In my experience it has generally been that each coil puts out roughly 250mV.  So a single humbucker would put out 500mV, two humbuckers, 1v etc.

Power chips are a few dollars a piece.  Are you going to try to find one that is "plug 'n play" so to speak, or are you building a new poweramp circuit?

It can be taken a little simpler than that.  Basically you have your max rating on the chip (30w RMS), normally peak is double that (it's good to find out for sure though) but lets assume it is.  So 60w PEAK, and then you want to multiply by 1.5 or so for inefficiencys to make sure you won't blow your fuse under regular use.  So, that'd be 90watts you are dealing with.  To get amps you divide watts/volts.  So on 110v you'd want a 0.81amp fuse (1 amp would be fine obviously) and get a slow-blow fuse, its great for this type of application. 

This has always worked great for me.

You could just use a LM4780 which is essentially two LM3886's on one chip.  But if you wanted to, you could use two LM3886 chips.  It's up to you.

100w RMS is fine for pretty much any "stage" use as far as I'm concerned.  But it does depend on what you mean by stage.  In a small club you could use anything from 25-50w RMS and you'd be fine, in a larger club you'd want 50-100w RMS probably.  But if you are playing the halftime show at the superbowl, you'd need a lot more than 100w RMS (of course I'm assuming you would probably just hook into the "house" system at that point anyway).  It also depends on the type of music you are playing/who you are playing with.  If you are by yourself, it won't take much.  If you are with another guitar, a bass and a loud drummer...well, you get the idea.

Quote from: teemuk on February 06, 2007, 07:13:04 AM
See the first figure in the article.
http://sound.westhost.com/project04.htm

Sweet, thats exactly what I needed to know.  I'll probably do that basically.  When it's done I'll get some pics up in here, its going to be pretty wicked.

So you can split the transformer to run two amp PSU boards?

That does look like a monster, cool find.

I still think it's a really cool thing.  As much as I like chip amps, discrete circuits are just so damn cool.

The picture isn't loading.  I will say, however, that star grounding is the way to go.

Running at 35 watts you *might* be ok passively, with a fan it would be perfect.  You could always try it and see, the chip has thermal protection so it will shut down before damage occurs.

How's it sound Joe?  I'd love to hear some clips and maybe see some pics of the final revision.

And maybe you could add this to the wiki, or if you want, I could add it for you.

The problem is with a solid piece of metal is that it will only work for a certain amount of time without shutting down.  It will basically absorb heat, but not disperse the heat into the air.  Fins are really required to get the job done well.