Amp and 2 cabs setup

[jsthvfn2000]

Hey all! Great Forum and real glad I found it.

I have a Crate G1500 150W 4ohm amp, a Crate GS412 4ohm cab, and a Peavey 8 ohm cab. I want to use them for our first show on Friday night but am concerned with the setup.

Is it best to run each cab on its own speaker output?

OR

Go from the amp to the Crate cab and then directly to the Peavey cab?

I know this ohm stuff is real easy for alot of you but for whatever reason, I just don't get it. The amp has a minimum ohm rating of 2.

By the way, tried to talk to some guys at Randall amps and this guy Jay answered. What a jerk! I will never buy any of their products because of him.

Thanks in advance,

Dan

[Lordathestrings]

You really don't want to parallel anything along with that 4-Ohm cab!!! You could trash your amp.

Please take the time to absorb this discussion (click here (http://www.guitartricks.com/forum/showthread.php?threadid=3383)).

[hairbndrckr]

Well I wouldn't parallel the cabinets either because you could seriously screw up your amp. I mean you are talking about a 2.66 ohm load to the amp. It's probably rated at 4 ohms max...But it WOULD be hella loud for a little while.

I can't even tell you how to rewire to make it work. You would have to series the 2 cabinets which would probably underpower your amp and not sound as loud. Since you can't hear in anything short of 3 decibel increments, you probably wouldn't hear a difference between a single cab and both cabs running.

Just use one cab, probably the 4 ohm as long as the crate will handle the load, because that would give you maximum output. Put the other one on stage with it for the "coolness" effect of having 2 cabinets. Make sure you put them side by side and position the head between the 2 for the full effect.

I used to have 3 soldano stacks on stage with me for the "coolness" effect. They were all fakes. I had a Mesa Mark IV sitting off the stage that was miked for all my sound! I even had one of the soldano cabinets miked!
Hey it got the oohs and aahhs it was supposed to do.

Oh I just noticed that you said the amp has a minimum ohm rating of 2 ohms. I've learned long ago that just because it says it can do it, doesn't mean you are gonna do any better with it. Stick with the 1 cabinet.

[Edited by hairbndrckr on 05-13-2003 at 09:54 PM]

[jsthvfn2000]

Thanks for the feedback!

So, I could run both cabs in series but the 8 ohm cab will not be as loud as the 4 ohm cab. Will doing this hurt my amp?

Also, 3 stacks mainly for show? Awesome! I wish I could do that.

[Lordathestrings]

Originally posted by jsthvfn2000
...So, I could run both cabs in series but the 8 ohm cab will not be as loud as the 4 ohm cab. Will doing this hurt my amp?...If you have a tube amp you must adjust the output transformer to match the load. They don't have a setting for a 12-Ohm load.

A transistor amp is OK with just about any load that is greater than the rated minimum.

In a series circuit, the current is the same all the way through, but the voltage will divide up in proportion to the impedance. Since Power = Voltage x Current, the 8-Ohm cab will get twice as much of the power as the 4-Ohm cab.

Whether it sounds any louder depends on how efficient it is, compared to the other cab. Most people can't distinguish a difference that is smaller than 3 dB - that means you have to double (or half) the power before it becomes noticeable.

[hairbndrckr]

Technically yeah you could run them, but why.
If you are miking through a PA you're only gonna mic one speaker in the cab anyways, unless you are running a stereo rig.
Also the only real reason for all that would be for stage volume, which if you need that, then buy monitors.

Also in reality, the 4 ohm cabinet would make twice the power than the 8 ohm. The lower the resistance, the more power the amp would make. And in sonic nirvana, you should be able to wire 100 4 ohm cabs together and get 1.1 gigawatts out the 150 watt head, but since circuit tolerances and such have their limits, that is why you have a 2 ohm limit on your amp. Also if I am not mistaken, that is probably the only way you are making 150 watts, but I could be wrong considering a guitar amp is probably a lot more stiffly regulated than something like, for instance, a car stereo amplifier. well now come to think of it the only way around that is if you can manually set the amp up for a specific load. Then it's possible to get full power no matter which cab you use. I would still only use either one cab or the other. Not both.

[Edited by hairbndrckr on 05-14-2003 at 10:36 PM]

[Lordathestrings]

Originally posted by hairbndrckr
...Also in reality, the 4 ohm cabinet would make twice the power than the 8 ohm. The lower the resistance, the more power the amp would make...This is true for running one cabinet or the other. I was talking about how the power would be divided between the cabs if they were wired in series.

By all means, yes, use the 4-Ohm cab if you want max power from the amp.