2X12 guitar cab wiring help!

[Jax]

So I just got one of these little Crate Powerblock guitar amps - which is surprisingly tone-chunky for the price and size. The amp outputs are:

8 ohm mono @150W

4 ohm Left @ 75W
4 ohm Right @75W

How should I wire my 2x12 (loaded with two 8 ohm speakers - G12H30 and V30) so that it doesn't take a ton of level to drive the speakers into pushing some air? And, I don't get how to wire the speakers to the 4 ohm outs. Do I need two jacks on the back of the cab, or a Y cable? I don't know what I'm doing!

As you can see - I'm a novice when it comes to anything guitar related.

TIA

[tINY]

It's hard to say. Since that thing is solid state, you don't have to load each output with 4 ohms. You can wire the thing up for stereo (but you don't have a pan or balance, so you can't blend the speakers to taste), you could wire the speakers in parallel (4 ohms) and run them off of one side. Or, you could wire them in parallel and run them off of the bridged mono output.

I wouldn't wire them in series, as this amp seems to want to drive a low impedance and 2 x 8 ohms in series is 16 ohms.

From the block diagram, it looks like this thing has speaker simulators hardwired to the pre-amp and line in. Maybe this thing wants to drive full range speakers, not guitar cabinets......



-tINY

[Jax]

Thanks, Tiny. Turns out my cab is wired in parallel. I did some quick research and figured it out.

It sounds right connected to a single 4 ohm (75w) out, about as I'd expect, but in this configuration the speakers are not being driven to their power capacity (90w total). Am I sacrificing some desired speaker breakup? Can I damage the speakers by underpowering them?

[Jax]

Originally Posted by tINY

Maybe this thing wants to drive full range speakers, not guitar cabinets......

-tINY

Nah, it's designed to use with guitar cabs.

[barefoot]

It sounds like it actually has two internal amps. It might also have a built in stereo chorus or delay, no? Ideally, you would wire your cab with 2 jacks and drive each speaker with a separate output. This should give you the best amp performance as well as having the option of getting that spacious Roland JC120 effect.

[Jax]

Originally Posted by barefoot

It sounds like it actually has two internal amps. It might also have a built in stereo chorus or delay, no? Ideally, you would wire your cab with 2 jacks and drive each speaker with a separate output. This should give you the best amp performance as well as having the option of getting that spacious Roland JC120 effect.

Hey Thomas,

The amp has no efx - just a barebones but serious sounding little (and I mean tiny - no bigger than your shoe) amp.

It looks like you're describing a stereo wiring setup, but this amp doesn't have a balance or pan pot, and the speakers in my cab wouldn't handle the power evenly (one speaker is 60w, the other 30w). So I guess my choices are:

1) get another pair of speakers at 75w each,
2) use a different amp that puts out @ 100w at 4 ohms, or
3) wire the cab in series and use and use a different amp's 16 ohm out

too bad.. none of those choices include using what I already have.

Here's a shot of the rear panel to show the somewhat odd connection choices the amp uses:

By the way, I'm local and I'd love to hear what the barefoot's are capable of in my studio. I'd probably be tempted to sell half my studio to buy a pair though!

[barefoot]

Originally Posted by Jax

1) get another pair of speakers at 75w each,

More important than the power rating is the efficiency. Both speakers should have the same efficiency or the more efficient speaker will be doing all the work while the less efficient speaker is just a waste of space, no matter how you wire them. I would strongly suggest using two of the same speaker models.

Then I would still wire them with two jacks.

Thomas