Danelectro N-10 Honeytone

Gem Toaster amp

Don't know if you enjoy occasional story or not, but here one goes anyway. A friend at work was visiting his parents during easter holidays. His father is quite handy building stuff and while he had joined a local combo of fiddlers. He built himself a mandolin which was truly beautiful workmanship. Being handy as he is, he built himself a preamp for the guitar pickup housed inside the instrument. Due to his limited understanding of electronics, he tried his hardest to make the preamp drive a speaker. As we all know, that won't work. Or it will, but not in a manner that's even remotely usable. His biggest issue was that this setup ate up a lot of batteries and quick. The son told me about this case and wondered what could be done to remedy the situation. He figured that i might have an answer of some sort, being the guitar enthusiast i am. I thought about it for a while and my first instinct was to recommend a small tube combo. But the goal was to have the mandolin heard, not necesserily loud, just a bit louder. And this was the best to achieve with a single 9V battery - and that battery should last as long as possible. Although being a true craftman the money became the next issue. So a 9V battery and a decent level of volume on a decent frequency range on a budget. Lucky for me, the pickup used was a standard single coil, so no ridiculous input impedance numbers as with some high grade piezos were needed. I had drawn myself a "FYA Bone Toaster" circuit some months ago. This was aiming to be a JFET based preamp that could perform as a clean boost with minimal distortion and thus, perfect for jazzy tones. With controls of level and tone (not completely unlike big muff tone stack made active), i figured this could very well work as a preamp. And followed by yet another Ruby Amp with one cap value upped to keep the low frequencies in tact.

Took both schems and drew a layout up. The next thing was to draw the board so it could be mounted in a hand build combo cabinet with as little hazzle as possible. So i figured the pots should be board mounted. This sets a number of limitations to the board, but i think i managed to squeeze it in rather nicely. I've had a love/hate relationship with LM/JRC386 distortion and gain settings, so to keep this thing's gain at usable levels for a village fiddler, i used a 5K trimpot for power amp gain. This way the gain and volume pots could be maxed and then the trimmer used to tweak the best balance between low distortion and high volume. It's not possible to get both at the same time, so the trimmer comes in handy here.

I printed the layout out and gave it to my friend. Helped him with ordering parts and then we wait. I wanted to try the layout myself before i send a novice on a path of becoming electronics building addict with an unverified layout (and no guarantees it'll work). Built it and was rather pleased with the results. This circuit ran into 4ohm 15" element. Whoah.

For the pots, the gain and master volume could be logarithmic. For the rest of it.. Yup. A decent practice amp. For about 6-7 dollars/euros/pounds, it doesn't get much better than this. Now, if we have a handy wood worker to build up a beautiful combo...

(Do note that the power amp chip is "upside down")

Ruby Tuby

Request.  This is based around the Runoffgroove LM386 Ruby, but with an IC preamp, into a 12AX7 section, and then into the LM386-N3 power section.  Sounds pretty good in the clips which you can hear at:

http://www.sophtamps.ca/mambo/index.php?option=com_content&task=view&id=28&Itemid=39

This needs a 12VDC supply, so if you're using an unregulated one like the one mentioned in the circuit information then you may want to include a 12V regulator to stabilise it.

Tiny Giant Amp

Requested by a few people on the forum, this is a mini amp circuit by Taylor Livingston with a bit more ooomph than the others on here, giving 20 watts into a 4 ohm speaker, or 12 watts into an 8 ohm.

Designed to run off a laptop power supply which I'm sure we all have hanging around the house from old broken laptops, with a LM338T taking that down to a regulated 11.6V to supply the opamp and amplifier.  The pins of the TDA7240A will need offsetting slightly so it is suitable for vero, but it can be done easily enough, as checked by Lazy Swamis on the forum.

Details of the project can be found here, and there is plenty of discussion to read through if you want to at diystompboxes.

Short clip of the amp in use

MXR Headphone Amp

Not a lot of info around, but this one is apparently simple little box that allows you to play at nighttime - without disturbing the missus. Seemed like a quick and painless schematic, but took me a few hours to finish...

Sort-of-requested by PaulR. :) I think i won't be posting anything more today. :D

Noisy Cricket MkII

Runoffgroove and Beavis Audio have been great resources for the DIY audio community for a long time now, offering projects and guidance which has helped many people over the years, me included.  This is Dano's take on a ROG project, a nifty little 0.5W amp that has a lot of fans out there, but with an added Bass switch for additional tone control.

Info from Beavis about the amp:

Here’s a fun Beavis Audio project that lots of people love: the noisy cricket guitar amp. I started with the runoffgroove.com ruby amp, and then added a tone control and a ‘grit’ mod. This is a great project that will give you a very sweet sounding practice amp based on the 386 lower power amp chip.

More information can be found on the Beavis Audio site here.

Added optional headphone output daughterboard.  Don't forget to use a stereo socket for the headphone output and it will need to be a plastic body type socket, so the sleeve can be isolated from ground through the box:

And a switched headphone option.  An easier way of doing this would be to feed a switched headphone socket from the daughterboard, and the signal also going through the normally closed contact to the speaker output.  Then when a plug is in the headphone socket, the speaker will be diconnected automatically.

Ruby Amp