Russell, what's the math for that amp calculation? I know it's probably basic, but I'd like to make sure from you so that I can apply the calculation in the future. I often need to know how many amps an item is going to require.
I know I know, it's probably Ohm's Law isn't it? Something ridiculously well-known like that, which I've never really paid much attention to. ;D
JL's equation is right but he must of hit a wrong button when entering the numbers. 250w/8ohms is 31.25 so the square root of that is 5.5 amps.
Ah, so the calculation is SQR ( Watts / ohms). Thanks!
So for a 2 watt amp producing 8 ohms:
2 / 8 = .25
SqrRt = .5 Ah requirement
Is that correct?
Yes...except an amp doesn't produce ohms LOL
Ah, I stand technically corrected. I take it the amp is "rated" at 8 ohms rather than producing 8 ohms. So you'd use the rated ohms in the equation?
0.5 amps, not 0.5 Ah (amp hours is used to rate how long a battery runs at nominal design current)
an amplifier is rated at wattage, the combination of volts/amps it can put out without burning, which depends on how many ohms the speaker has. more ohms in the speaker, less amps from the amplifier, less ohms in the speaker, more amps from the amplifier, short the speaker wires for zero ohms and the amplifier burns.
yup I goofed, forgot to carry the 2, lol
I remember getting bit but not killed by a speaker cabinet wire, 5 amps 50 amps BIG DIFFERNECE, thanks
The great thing about being able to use small amps with large speakers is this neat concept:
One can build an amplifier right into a CBG. Just take along a speaker box with a 1/4" jack built into it.
What's the advantage of this? It would be a rare instance, but if you're ever near a speaker cab and want to plug directly into it without going through an amp head... you could do so.
Other than that, it's simply kewl to have an amp circuit built into your guitar. Add an equalizer system and hubba hubba. Equalizer systems are far more fun than simple tone pots.
All I can say is I'm glad I didn't know all this years ago when I started to build & just wired some up I guess its the old no rules thing
It's not that it won't work but it may not work to everyone's expectation. Loud enough for one person might be too soft for another. I'm sure this particular amp and speaker combo work fine or Gitty would not be selling them. Not sure about how it would work with car speakers. Have you or anybody tried this with a car speaker yet? Would be interested in how it turned out.
I can see the appeal of building your own amp but I have a Blackstar Fly 3 battery powered amp that is awesome and is only $59
I hear you Wes. If there's one thing that building CBGs, amps and pickups have all three taught me: learn the rules, but don't be afraid to break them. Sometimes stuff I'm absolutely sure won't work winds up working better than how it "should be done". When I first started I read posts here and elsewhere that piezos can't possible sound "as good as" mag pups (proved that wrong), that "the more wraps in a pickup the better" (nope, nope, nope), I thought that keeping the bridge away from the tail of the guitar was the best way to build (found out there is no "best" way to build), and that cardboard doesn't make a good git (I have one and am getting ready to build another out of a pink Mary Kay box. :D) .
Thinking way outside the box and not being afraid to try something ridiculous is how we make incredible discoveries. Who would have guessed that a single copper wire surrounding a magnet would make a terrific home-brew pickup?
So when it comes to car speakers being used as an amp, my from-the-gut answer would be, "Depends on the speaker and the amp circuit".
It is my personal experience however, that a car amplifier with regular speakers does not make for a quality amp. Seems the amp circuit itself really needs to be a guitar amp circuit. Mind you, it's not that you can't get a good CBG amp from spare parts. It's just that a guitar amp circuit is made for guitars Overall I'll have to agree that a guitar amp circuit and a guitar-intended speaker is the way to go, but that doesn't mean a seat-of-yer-pants setup won't work. It's always worth a try, especially if the parts are just sitting around.