It Goes To 11

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Comment by rich gallagher 7 hours ago

with battery (they're wired for adaptor,but haven't tried them with it) yes, the ruby does have the input buffer and then the 10k pot - i'm looking at specific preamps for piezo guitars now - some very simple, but i live in the middle of nowhere and don't have the correct parts - going to the nearest town tomm maybe i can score them at the shack

Comment by Mark aka. Junk Box Instruments 13 hours ago

Are you powering your amps with a battery or a mains adaptor? If it's a mains transformer then I wonder if there's noise from the power supply.

Re: Input pots...if I recall correctly the Ruby has an input buffer stage with a FET and the 10k pot comes after that. I guess it's possible there might be problems at the input buffer if the signal from a piezo isn't reined in somehow (my electronics knowledge isn't goodenough for me to say).

Comment by rich gallagher 15 hours ago

wait! the ruby has a 10k pot on the input - how do i get rid of this obnoxious noise!

Comment by rich gallagher 15 hours ago

mark, thanks for the schematic - i'll wire one of these up and try it out - i'm still messing with my rubys to get them to work with piezo - i'll try the idea in your schematic - have put a 250k pot in a piezo cbg and cut out the noise/feedback(?) but sounds like crap now muddy and fuzzy

Comment by Mark aka. Junk Box Instruments 20 hours ago

Nice amp. Even though 1/2 watt doesn't sound much it can be surprisingly loud if you put it through the right speaker in the right enclosure.

Having built a few LM386 circuits I think I've got the basics of the circuitry sussed - but now I'm beginning to focus on the details of the box and speaker because I've come to realise what a difference those can make to the sound.

I'm curious to know what the tone is like with your amp Eric. It looks like a smallish speaker, which I'd figure would be "trebly", but I guess a reasonable sized closed box, like you've got there, might compensate a bit.

Whatever the case, the most important thing with these amps is to have fun with them!

Comment by Eric Johnson 1 day ago

I just finished building a cigar box amp today, also a LM386 design. Got the basic schematic out of MAKE magazine, though they put it in a cracker box. Not too terribly loud, but decent for noodling in the house.

Comment by Bill Ludeman 1 day ago

Not sure if this will help anyone out or not... I started out with a 20 dollar Honeytone amp from Guitar Center - its fun and tiny - runs on a ninevolt and quits working when the battery gets low. Easy to fix - change the battery! Then i got a used first act practice amp. Little bugger and kinda fun. Paid twenty for it too. Probably a great learning point for not much money. Next i ordered a Lm386 board to build my own and rediscovered that electronics are tiny and my hands are big and busted. On the shelf for now. Last weekend we took fourteen instruments to a music swap meet down by Orlando Fl. I didn't sell anything but did buy stuff. If anyone needs training on losing money just email me.... I bought a fifteen amp Radio Shack amp that the owner said he bought new about fifteen years ago and had just up and quit. Paid five bucks for it!! Took it apart as soon as I got home, four screws and unplug the speaker and it was wide open. Great looking electronics widely spaced and clearly marked. Made in Taiwan which means better quality than China to me. And there in the corner was an old style glass fuse and it was open. The speaker had rattled it apart after fifteen years of thumping and banging. Cost me three bucks for a package of ten and I have played with six or seven different instruments with it. One piezo pickup didly bows and two piezo pickup three string slide blues all sound great in it. Plenty loud and only running half volume and a quarter turn on gain. Enough amp for most of us amateur types maybe?? Now fot the icing on the top. I bouught a Roland Micro amp. Its rated at two watts?!?! its got a bunch of knobs on it that do things I didn't know about. Phazzer and delay and stuff. It runs on batteries or plug in and after fooling around with it I realized it has nearly the same power as the old Rado Shack 15 watt. I plugged this thing up and tried all the settings and combo's i could think of and had an absolute blast. Most fun I have had in decades. This contraption made me sound like I know what the h_ll I am doing!! Wore myself out inventing bluesy sounds and generally having fun. I can whole heartedly recommend this particular contraption., I got a great deal on it but there were three others for sale all in the seventy five dollar range. New they are 130 bucks. I would have loved to have read this story before I started out on my amp quest so I hope it helps someone else get to the fun spot. I haven't figured out how to do messaging on this website but if anyone wants to ask any questions post a comment on my page. Thanks Bill

Comment by Mark aka. Junk Box Instruments on March 16, 2010 at 7:10pm

Here's a circuit diagram:

The input attenuation is about as simple as you could get - it's the pot labelled R2. Just a basic volume control that allows you to turn down the signal going into the amp.

Comment by rich gallagher on March 15, 2010 at 11:41am

nice looking amp - could you tell me about the attenuation? that might solve my problem with rubys and piezo pups

Comment by Mark aka. Junk Box Instruments on March 11, 2010 at 11:23am

My latest build



A simple LM386 circuit (ie. similar to Little Gem or Smoky) teamed with the biggest speaker I could get into a small box. Controls are gain and input attenuation (aka. input level). I think having that input control makes a useful difference - especially when using piezos or other pickups that can be a bit wild.

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