The simplicity and low component type make the ROG Ruby a MUST for any diy-er. Had my project on the shelf for too long, just couldn't figure out the problem -- I build it twice to make sure. In the end the opamp turned out to be bad.
I listed my voltages below, so check below the vids.



It's a simple 9 volt amp with VOLUME and GAIN controls and can just be hooked up to about any speaker. The quality of the sound will be dependent on the speaker used, in the sense that tiny speakers give tiny sound. There is no problem hooking the amp to a big cabinet or a 10" or 12" guitar amp speaker.

I built mine onto an old, detachable. tape recorder speaker. What's more exciting even is that the speaker is date coded 08 66 (August 1966), so real vintage :D






Had to take the amp outside with my longest 10m cable. This thing is LOUD




I had a hard time debuggin mine because I didn't find any correct pin voltages to check. If you build yours could can use the below voltages as a guideline. Dependent on your battery voltage they should be comparable. My battery measured 9.18V

2N5457 JFET:
Drain = 9.18V;
Source = 0.84V;
Gate = 0.00V

LM386 opamp:
1 = 1.34V;
2, 3 and 4 = 0.00V;
5 = 4.56V;
6 = 9.18V;
7 = 4.64V;
8 = 1.34V