Noobie Question: How many watts and the output impedance of Ruby

[exztinct01]

Hi i'm a noobie hir. I'm planning to build the Ruby Amp but I don't know its output impedance and the watts it can deliver. I read of some comments in this forum stating that they're using 4 x 12 cabs so I expect that it can drive speakers like the Celestion G12M 25 watts???
Should I pair it with (how many watts) of speaker and impedance of (what? 4? 8? 16 ohms?) Please help me here. Thanks

[Kipper4]

Hello and welcome to the forum.
It's customary to post a schematic so we know what you are working from.
I think the ruby is a 1watt amp and it will drive a 25watt speaker.
As a general rule I double the wattage. So 15watt amp---30watt speaker.
Anything over 2watt speaker should be fine for the ruby.
Output impedance not sure without a schematic and even then.........
Help us out.
Rich

[anotherjim]

You don't really need to worry about matching output impedance. That's really when there's a transformer on the amp output (as is usual in tube amps). You do have to consider power rating. Important here is which grade of 386 is in the amp. Across the range the different versions trade off supply voltage against load impedance and different power handling.
See "Models" table here...
https://en.wikipedia.org/wiki/LM386
Power handling isn't more than 1 watt!

I think with a -4 version and guessing it can output about 8v peak to peak from 9v supply, you're just about safe with a 16ohm load, although the chip should safely self limit if overloaded.
Personally, I wouldn't use a speaker larger than 8" with a 1 Watt amp, but if some like the sound of a 4x12 being tickled along at 1w, I'm not going to argue.

[PRR]

The '386 chip at 9V supply will make a bit more than One Half Watt clean in 8 Ohms. A bit *less* in 4 Ohms, but at this level, that's no big deal. Drives 16 Ohms happily at lower power.

Extended sets of heavy power-chords into the 0.3 Watt speaker from a pocket radio will toast the speaker.

Any larger speaker "can" be used.

High Fidelity speakers don't make much sound for the Watts you put in, may not be impressive outside a small bedroom.

Any for-guitar speaker will do fine. Yes, even a full-stack of eight 150W E-V EVM12Ls! And that would be a bodacious sound, except poor economics. $2 of amplifier into $2,000 of speakers.... you could get the same amount of sound in the room with a $20 amplifier and a single $90 speaker.

But if you have the full-stack, or twin, or even a single 12", just use it.

[exztinct01]

thanks for your replies.
I think I'll go with a single Greenback G12M 8 ohms cab, anyway I'm also planning to build an 18 watt Marshall clone which will also benefit with the cab I'm going to build