Here's another intentionally simple idea I've been playing around with. Hope you like it. See here for a detailed explaination: http://www.riemer.us/cmos-power-amp (http://www.riemer.us/cmos-power-amp)
Neat amp. Any pics of a build? Sound clips? What about output, how many watts are we looking at? I'm guessing something like 5w RMS, am I close?
I'll have to get back to you on that. I'll try to get some sound clips soon. Right now, I've only got it breadboarded. I plan on doing a permanent build, but I'd like to configure it for a 24V supply first. It sounds plenty loud enough for my purposes at 12V, but I'd like a little more headroom for clean tones. Based on Multisim calculations, which of course will differ some from the real thing, it probably puts out about 1.5W clean and around 5 or 6 W dirty. If I had a function generator, I'd tell you how it works out with my current setup. I'll be out of town for a little more than a week, but when I get back, I'll work on the sound clips if everyone can excuse my guitar playing. Before I leave, I might have my wife bang away on my guitar while I measure the Vpp on my little oscilloscope. That might give a better idea about the real world power output.
Great, keep us updated :tu:
Here are some pics. Obviously I don't have this finished yet. The first pic shows the amp as it currently exists, just some components connected on a solder-less breaboard. The speaker is just some crappy 20W car stereo woofer. In the lower left corner, you can kinda see my preamp. There's obviously some stuff in the photo that has nothing to do with this project. My work area is quite cluttered. Maybe one day I'll clean it up.
The second shot is a close up of the amp on the bread board. Due to clutter, there's some non-related stuff on the breadboard. You can see the input buffer near the blue pot, which is used for biasing the MOSFET in the buffer stage. The two power MOSFET's are on a heat sink that I scavenged from an old atx power supply. The very large cap at the top of the board is just for killing power supply noise.
The third pic shows the inside of my preamp. This is the MOSFET Booster circuit that I posted about here: http://www.ssguitar.com/index.php?topic=1121.0 (http://www.ssguitar.com/index.php?topic=1121.0). It's breadboarded in my ProtoBox. I just got an aluminum enclosure and small breadboard from RadioShack. I mounted the breadboard inside, and drilled holes for various pots and jacks. When I eventually do a permanent build of this circuit, I'll use this ProtoBox for something else.
The last pic shows the front of the protobox.
I'm sure this isn't the finished product you were wanting to see. Hopefully I'll get this permanently built soon.
Here are some the sound clips I promised. Keep in mind that my recording setup is VERY CHEAP. On top of that, I'm using a crappy car stereo speaker. Hopefully soon, I'll get around to modifying my Combo amp to allow me to plug in different heads into the speakers. Also, I'm no Joe Satriani, so please excuse the guitar playing. :)
As I mentioned on my site, this circuit is a power amp, and needs a preamp. I used a MOSFET booster as a preamp. There are no tone controls, other than the tone knob on the guitars (Though there needs to be). On one clip, I'm using my Jackson 7 String ( I think a DR-7). On the other clips, I'm using my Ibanez RG5EX1.
I think playing this through real guitar speakers would improve the sound the most. If I had a tone control pedal, I would put it between the preamp and the CMOS Power Inverter amp. Maybe I'll build a ROG Tonemender for this.
I when playing clean, I was surprised how clear the sound was. The cheap mic didn't do it justice. Maybe I'll gut the mic housing and build a condenser mic.
http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20Jackson%207%20String%20-%20Mostly%20Clean.mp3 (http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20Jackson%207%20String%20-%20Mostly%20Clean.mp3)
http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20RG5EX1%20-%20Bridge%20Psudosingle%20-%20clean.mp3 (http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20RG5EX1%20-%20Bridge%20Psudosingle%20-%20clean.mp3)
http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20RG5EX1%20-%20Neck%20Humbucker%20-%20Overdrive%20-%20Simple%20Chording.mp3 (http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20RG5EX1%20-%20Neck%20Humbucker%20-%20Overdrive%20-%20Simple%20Chording.mp3)
http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20RG5EX1%20-%20Neck%20Humbucker%20-%20Overdrive.mp3 (http://www.riemer.us/sound/CMOS_Power_Inverter_12V/CMOS%20Power%20Inverter%20Demo%20-%20RG5EX1%20-%20Neck%20Humbucker%20-%20Overdrive.mp3)
Nice job is it finished yet?
I like the schematic to recording deal, makes it easy for someone like me to repeat.
The schematic for the power amp is at the top, and you can get the schematic for the preamp here: http://www.ssguitar.com/index.php?topic=1121.0 (http://www.ssguitar.com/index.php?topic=1121.0). I don't have a combined schematic for both, and I might experiment with different preamps before I build a finished amp, though I might just build the power amp separately for a more modular approach. If you decide to build this setup, let me know how it works out for you.
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-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-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.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 (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 (http://www.riemer.us/sounds/cmos_power_inverter_12v-1)
Thanks for posting the clips again !
I think the sound is very promising. :)
What gain/damping factor did you use?
What do you think about the sound you get with this amp compared with the sound you get from your preamp using other amps?
I like the simplistic approch of your amp, it reminds me of the "Zen amplifiers" (Single-Stage Single-Ended Class A HiFi amp):
(http://www.tubecad.com/2004/image135.gif)
Best Regards,
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.
Hi rowdy_riemer, thanks a lot for the info.
I attach the 'my version' of the CMOS configuration as an attachment to this post.
Please note that this is a principal schematic!
Transistors, OPs are not optimal and dc-servo is missing etc.
Do you see any problems with this way of handling the bias current?
How much bias will I need?
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.