WHoohooooo!!!!. Congrats, pyro. :tu:

I do not see any problems right off. Of course, I'm not quite an electronics guru just yet either, though I think I'm heading slowly in that direction. I do not know what the optimum bias current would be, but it definately needs to be enough to reduce crossover distortion to a minimum.

Thanks. If I remember correctly, I ran the power amp at  maximum gain, essentially with R5(the feedback control pot) essentially shunted.. I also think I made sure my preamp was not overdriven, so all of the distortion came from the two MOSFETs. I haven't used the preamp with many other amps. It definately sounds different with my little Valveking Royal 8, but that's mainly because it overdrives the hell out of that amp's preamp tubes. There's no effects loop with that, so I cannot test that preamp with just the output tube. I've used it with the effects loop to bypass the preamp of my Crate GFX 212, but I don't quite have the courage to piss the neighbors off by overdriving that. So I really do not have much to compare it too. It definitely sounds better to me than an overdriven Ruby. I think I'm using a different preamp with it now than I did when I recorded those sound clips. My current pre is just a few JFET stages setup similiar to the FETZER valve configuration shown on runoffgroove.com. I like the schematic you posted. This would certainly be more appropriate for higher voltages. It certainly allows for better current control. I like the Mu Follower configuration. With the CMOS configuration, you just about have to do a class AB bias to go with a supply voltage higher than 12 volts. A class AB bias with a CMOS configuration might be ok with a high bias current, especially if using the more expensive lateral MOSFETs.

Ok, I've reposted the sound clips.

The links to the sound clips above do not work anymore for some reason. Per kikey's request for sound clips, I'm reposting these. Now that I have a somewhat decent recording setup and a MOD 8 hooked up to this amp, I may record some different one's later.

http://www.riemer.us/sounds/cmos_power_inverter_12v-1/CMOSPowerInverterDemo-Jackson7String-MostlyClean.mp3?attredirects=0&d=1
http://www.riemer.us/sounds/cmos_power_inverter_12v-1/CMOSPowerInverterDemo-RG5EX1-BridgePsudosingle-clean.mp3?attredirects=0&d=1
http://www.riemer.us/sounds/cmos_power_inverter_12v-1/CMOSPowerInverterDemo-RG5EX1-NeckHumbucker-Overdrive.mp3?attredirects=0&d=1
http://www.riemer.us/sounds/cmos_power_inverter_12v-1/CMOSPowerInverterDemo-RG5EX1-NeckHumbucker-Overdrive-SimpleChording.mp3?attredirects=0&d=1

Also, you can find these links at http://www.riemer.us/sounds/cmos_power_inverter_12v-1

I posted some sound clips, but apparently the links do not work any more. I'll fix the links and let you know.

I'm not claiming it is. I'm just glad someone is interested in doing something with the design. All it really does is allow you to vary the negative feedback, so with little feedback, the damping factor is low, possibly making it sound a little more like a tube amp with no negative feedback. When the speaker impedance is low, it will load down the amp a bit limiting the current through the speaker, but there is, of course, no active current control.

QuoteI have been extremely sick this last couple of weeks,go back to DR in a couple of days.

BTW, hope you get to feeling better.

QuoteBTW I didnt want to sign up for yet another site to view those other pics of the second entry would you mind hosting them somewhere else so I can view them a little easier ?

I think I'm the second entry. These are hosted on my site and should require no one to sign up for anything. They should be easily accessible. If you still have problems viewing them, I'll post them from my local machine.

QuoteI find rowdy_riemer's 'CMOS amp' an interesting and simplistic approch for current drive.
http://www.ssguitar.com/index.php?topic=1177.0
I am working on an amp inspired of rowdy's amp.

Awesome!!! Let me know how it turns out.

Since you have already built a ruby, you might enter it into this contest, http://www.ssguitar.com/index.php?topic=1456.0 , and you might win what you need for a higher powered amp. :tu:

For your power requirements, you should try an LM3886. There's a lot of good info on this site about those. Also, see http://chipamp.com/lm3886.shtml . Using effects as a preamp should work fine. I've used my Dr. Boogey and other effects as a preamp on my Crate GFX 212  by plugging them into the effects loop to bypass the amps built-in preamp. It works fine.  I've also done this with my Digitech RP-70. Actually, just for the hell of it, I've plugged my guitar directly into the effects loop, and it was plenty loud enough. In fact, there is no technical reason not to consider most effects to be preamps depending on how you define the term. BTW, what did you think of the Dr. Boogey? To me, the bass response is somewhat lacking. Perhaps that's due to a bad solder job on my part  , but I wonder if anyone else has a similar opinion.

Quote1) for battery powered amps, i've understood that only the LM386 will do the job, is that right ?

I haven't tried any other chips for battery powered amps, but I know there are others that work. If you want to power the amp with a little nine volt battery,
you might should stick with the LM386. It all depends on the current requirement and how heavy you want the amplifier to be. Some of the amp chips used in car radios
or any chip that'll work with a 12V or lower supply would likely be fine with battery power. I'm sure others will have several good suggestions. When considering a chip, figure what the current requirement is, and make sure you use batteries that will supply the needed current.

Quote2) for mains powered amps, do i always need a trasformer and some heatsinks ??

Transformers - YES. heatsinks - depeneds. Even if you wanted a 120V supply, you would want a transformer for safety considerations. Now, using a transformer might mean using a walwart. For small amps, wall warts that supply enough current will work fine. Also, ATX power supplys from dead computers make great 12v supplies.

For heatsinks, that depends on how much power the amp chip dissapates. You can use the datasheet to figure this out by looking at the chip's thermal resistance.

Quote3) what's the max power i can obtain for a battery powered amp (say, using 9V) ?

That depends on a given batteries internal impedance, which will vary between batteries. I do not think you'll get much power from a 9V. I'm considering investigating this further. I've had ok results with 9v's for Ruby's. It seems that with my Little Gem MkII, the amp did better with D cells than with  a 9 V. I'm considering measuring the current through the LGMII using a 9v and D cells to see if the 9V is being loaded down significantly.

I'll check out the ""krank distortus maximus". Keep in mind that Q5 is setup as a source follower. There will be a voltage gain of a little less than 1 regardless of the FET used. However, I think you will have more current gain(lower output impedance) with the MPF102. Also, Vth(cutoff voltage) is lower for the J201. Some may disagree, but I think FET's in a source follower configuration should have as high a Vth as practical and as high a Idss as practical. Look on page 208 of Teemuk's book to see what he says about J201s in a source follower configuration.

By saying the Dr. Boogey rocks, I was saying it sounds really good.  I used j201's. If I did it over again, I might use an MPF102 for Q5.