Check out this odd different looking guitar practice amp. It looks like a professionally manufactured product but it certainly is not. [Bradley] made it himself, not just a little bit of it either, all of it.
One of the first things you notice is the quilted maple wood grain of the case. There is no veneer here, this started out as a solid maple block. The front radius was shaped and the recesses for the control knobs and input jack were bored out using a forstner bit. The case was sanded smooth and several coats of high gloss tung oil was rubbed on to give the wood a perfect finish. A small piece of grill cloth protects the speaker while adding a little more class to the amp. The bottom of the case is actually a cover for a computer hard drive. A rectangular hole cut in the hard drive cover makes way for a 9 volt battery compartment.
There are two control potentiometers, one for volume and one for gain. Any old knobs wouldn’t do for this project. [Bradley] knurled and turned his own aluminum knobs and they look awesome! The units power is turned on when the guitar cord is plugged in. An LED not only indicates that the power is on but it also gets brighter with the volume input from the guitar. The LED also pulses if two strings are out of tune with each other giving the guitarist an opportunity to tune one of the strings until the LED stops pulsing. When it is time for some private jamming headphones can be plugged into the amp and doing so cuts power to the speaker.
The electronic circuitry is [Bradley’s] design also, but unfortunately he doesn’t share the schematic. I suppose he wants to keep his amp one-of-a-kind.
What’s the difference between volume and gain?
In a proper amplifier? Not much. In a guitar amplifier? Volume is loud and gain is crunch.
It has to do with where in the amp circuit they are implemented. Gain is usually very early in the circuit where it boosts the input for the rest of the amp; the crunchy sound often associated with high gain on guitar amps is caused by the gain stage outputting a signal loud enough to cause clipping in the later stages. Volume is often put in at the end of the amp near the output and since it usually doesn’t feed into more amplification stages it cannot cause clipping.
gain is pre-eq
volume is post-eq
what’s the difference between ‘professionally made’ and ‘made to professional quality?’ Because honestly, it looks the same.
Not often you see a decent case around here.
Given the summary can’t decide if it’s ‘odd’ or ‘different’, apparently it’s been a while.
Case looks awesome. Circuit looks functional.
I was rather impressed he made his own knobs.
Oh, and as we all know HAD editors don’t RTFA; but toss him a dollar and he’ll send you the schematic & BOM.
For free I’ll give anyone a URL
http://www.electrosmash.com/ruby-amp-analysis
If that isn’t what they built it is what they should have.
Yup, got to be either a ruby or a little gem – the rheostat gives it away. But seriously Hackaday, if he’s not sharing, I’m not caring. $1 ‘donation’, wtf?
That’s how they did things in ancient times.
As @cliped pointed out, it’s from 7 years ago. According to the main page the site has been dead for over 4 years. PayPal link is probably dead as well.
I like that the input plug doubles as the power switch, it saves a part, a hole in the chassis, and it’s a big improvement in the user interface department as well. I wish my wife’s practice amp had this feature.
Easy enough to add, just use it to switch the DC, not 120VAC.
Looks like a dead simple LM386 circuit to me.
Not to be rude but this thing is really bad looking. Typicall “all over the place” design you often see by engineers/electronic enthusiasts.
After this I laid the Ruby Amplifier out in Eagle.
http://i.imgur.com/VQ39wr1.png
Looks neat enough to me, maybe not to etch, but as a drill guide for a point, to point, project. If I was to etch it I’d tweak the traces a bit more. This is just auto routed. I’m feeling that the parts layout is close now though, very close.
Posted on Hacked Gadgets seven years ago? That’s some fresh project!
someone plugged in a cable where they shouldnt have: http://i.imgur.com/uVES6YW.png