Do you have everything housed in a grounded metal housing? The buffer is for frequency response, and I do not think it will reduce the noise.

I recently built a Dr. Boogey using the info from Gauss Markov's site. It pretty much rocks. However, I think the bass response is a little lacking. I really like Mensur's adaptation of this circuit. See http://www.ssguitar.com/index.php?topic=991.0 . His sound clips are F#*$ing awesome. He's using an 18V supply and lower gain FET's. He also adds a source follower buffer after the tone stack, which allows for low impedance output. The Gauss Markov version has a scaled down version of the tone stack for low output impedance. While I do not have a build of Mensur's version to compare it to, I imaging the Source Follower buffer is a much better solution.


--EDIT--

Oops, he's using a 24V supply.

I leave the back open, though I should probably see how it sounds when its closed.

Ok, here's a discription of the Little Gem MkII I built (Thanks ROG for a great circuit). For those unfamiliar with the Little Gem MkII, it is a dual LM386 version of the Little Gem http://runoffgroove.com/littlegem.html. I used Pablo De Luca's PCB layout. Everything is housed in an old school intercom speaker box. A friend of mine was working a construction job at a school were a few of these were being thrown out, so he gave me a couple. The speaker is an 8 inch speaker that I removed from my Peavy Valveking Royal 8 (which now has a Jensen Mod 8 ). I have no idea who manufactures the speaker. Its probably some no name Chinese made speaker. If I had another spare Mod 8, I would probably use it for this project too.

This amp is about as simple as an amp can be. There are no controls other than what you have on your guitar. There is a single jack that also functions as the on-off switch. I'm using 6 D-cell batteries to supply 9 V. This amp seems to behave better when using D cells rather than a single 9V battery. For now, there is no external power jack.

Here are some links to some pics and sound samples. Please forgive the sloppy playing.


Pics:

http://www.riemer.us/littlegemmkii/LittleGemMkII.jpg

Front: http://www.riemer.us/littlegemmkii/LittleGemMkII_front.jpg

Top: http://www.riemer.us/littlegemmkii/LittleGemMkII_top.jpg

Inside: http://www.riemer.us/littlegemmkii/LittleGemMkII_inside.jpg

Circuit Board: http://www.riemer.us/littlegemmkii/LittleGemMkII_circuit_board.jpg


Sound Clips:

For all of these, I used my Ibanez RG5EX1 with a cheap ass Behringer Tube Ultragain Mic100(which just as well be all solidstate) mic preamp and a Nady SPC-25 condensor mic. None of this is top of the line equipment, but is fine for my purposes and fits my budget. I used Audacity for recording. I think my greatest limitation here is my lack of recording experience rather than the limitations of the equipment.

Bridge pickup in single coil mode: http://www.riemer.us/littlegemmkii/LGMK2-RG5EX1-BridgeSCMode.mp3

Bridge pickup in humbucker mode: http://www.riemer.us/littlegemmkii/LGMK2-RG5EX1-BridgeHBMode.mp3

Bridge pickup - Overdriven http://www.riemer.us/littlegemmkii/LGMK2-RG5EX1-OverDriven-BridgeHBMode.mp3

For whatever reason, I have a hard time overdriving this amp with just the output from the guitar. I certainly do not have this problem with the Ruby. I've read somewhere where someone modified the Little Gem MkII circuit with a dual pot for gain control. Such a mod might make this amp better. For the last sound clip, I used a pedal for some clean boost to overdrive the amp. I liked the sound of this amp better than with any Ruby/Speaker setup I've personally done so far, though I've heard some really good Ruby setups on youtube. Maybe turning the gain pot down on a Ruby and using a booster pedal or preamp would have similar results.

No prob. That works much better now. BTW, you're amp looks pretty cool.  :tu:

Dude, filefactory really seems to suck. You can host these for free with google sites. http://sites.google.com

Well, how about this, I'll take some pics today and post them along with the not-so-well recorded clip I've got at the moment. Then, if I get done with any changes before the 1 Feb deadline, I'll post those. I've got some much abused LM386's on the board right now that I recorded with. They sound not so well when overdriven. The ones that were originally on the board were fried when I accidentally wired up a battery back to it with the wrong polarity. I'm gonna try to pick up some more LM386's during my lunch break along with a 2 D cell battery holder to add to my 4 D cell holder. If I can do that, I can probably get some decent overdriven sounds for to add to my previously recorded sound clip.

JFETs aren't rare. I would imagine they are as easy to find as an LM386.

Here's a couple of listings for mpf102's from Hong Kong suppliers:

http://www3.hkinventory.com/public/OfferInventResult.asp?search=offerinvent&MainCate=&SubCate=&Order=&keywords=&words=3&SearchType=offer&pnums=mpf102&btnSubmit=Search

http://hk.farnell.com/jsp/search/browse.jsp?N=500002+1002727&Ntk=gensearch_001&Ntt=mpf102&Ntx=mode+matchallpartial

It also looks like mouser isn't a bad bet either. http://hk.mouser.com/Search/Refine.aspx?Keyword=mpf102

Well, JFET's are transistors. If you mean bipolar transistor, then yes, but it will have to be biased differently. Your best bet is to try to order what you need online from mouser.com or jameco.com or any other electronics part vendor. Of course shipping might be a little pricey for you if you order from jameco or mouser or any other American supplier, but I bet you can find an online parts supplier reasonably close. If you do use a bi-polar transistor, be sure to research how to bias them. http://en.wikipedia.org/wiki/Bipolar_transistor_biasing . Any low current BJT  in an emitter follower configuration should be fine. However, you will not have the high impedance that you would have with the jfet input. In fact, you might not get much better results then you would have by leaving out the buffer stage all together, like with the Little Gem. You could also use an op-amp buffer instead of a source follower or emitter follower. It would be best to find a jfet with the same pinout as the mpf102. Then, you will be able to use the PCB layout  provided by ROG. Good luck on the parts search.

I haven't checked out all those, but I would definately leave in the emitter follower buffer stages. Removing those might have a bad effect on your tone. You could certainly build your circuit of choice on a solderless breadboard and experiment.

I would suggest looking for a separate circuit for the headphone out. Also, if you don't do some sort of speaker cab simulation for the headphone out, the sound of a high gain preamp will sound like complete crap. You might check out the condor project on runoffgroove.com. Also, while many of the circuits on ROG might not be suitable for metal, you might like the Thor. You should probably also build a separate good clean preamp for clean tones and switch between the two rather than one that tries to do both. I designed a simple expandable mixer circuit, though I hesitate to post it as I've only tested the design in simulation, and I'm sure there are some good proven designs. btw, it's cool to see another Electronics student on the site. I'm slowly working on an EE degree myself, and taking electronic classes is what got me interested in amp building, which got me back into playing guitar.

I'll post some pictures of the Little Gem Mk II I recently built. It's not quite finished, but is currently functional as is.

You might consider a TDA2040 based amp. I've run a TDA2040 at 12v and it was much louder than a ruby(if I remember right). It no doubt used more current, but with a car battery, no prob. (btw, I've got a project that's been on hold forever to use a TDA2040 for a car PA system, so my wife can yell at bad drivers.) You can do something like this: http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=59&Itemid=200 . You'll need a preamp circuit, but that shouldn't be a big deal.

Like this? http://www.drtube.com/schematics/marshall/3005.gif