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OHM I GOD...WATT THE FACK (POWER ISSUES)

S

SpreadinButter

Jan 26, 2009
42
0
#1
Sup dudes,

I am currently designing a rig for myself and had a few power handling issues I needed help with:

Right now I have

Goliath Jr. III (8 OHMs 400 Watts)
Big Ben (8 OHMs 400 watts)

That gives me a total of 4 OHM impedance correct?

If the Xti1000 power amp I am looking at says it gives:

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500 Watts at Stereo, 4 ohms (per ch.)

Does that mean I will be endangering my speakers with that amp since they each are 400 Watts?

Or will this combination only give 250 Watts to each cabinet...

Real confused here, I think I understand the OHM part somewhat but I'm at a loss Wattage wise.

Also my goliath jr's have an input as well as an output on the back, where as my big ben only has 1 input (must be an older model). Thinking about buying a real nice tube pre-amp as well. How would one suggest I set this rig up?
 
#2
500W per channel at 4 ohms means each output of the power amp will independently put out 500W into a 4 ohm load (separate 4 ohm loads per output).

You have two 8 ohm cabs, so you need to look for the spec that says how much wattage it will put out per channel at 8 ohms. Or if it can bridge, look for the spec that says how much power it puts out into 4 ohms bridged.

The 500W into a 400W cab thing is not a problem. Just listen for any sign of speaker distortion (farting, buzzing, etc.) and turn down the amp if you hear any.
 
#3
Well for me it is always better to be safe than sorry. It would be best to one, get a compatible cab or two a compatible head. Oh and the Watts stay the same however, the power is distributed equally to boith sides
 
#4
Stereo, 2 ohms (per ch.) 700W
Stereo, 4 ohms (per ch.) 500W
Stereo, 8 ohms (per ch.) 275W
Bridge-Mono, 4 ohms 1400W 1% THD
Bridge-Mono, 8 ohms 1000W

Soooo that would mean too much power at 4 OHMs Bridged mono?

Come to think of it I don't know how I would run stereo anyway unless I split the signal somehow. So I guess I am looking at bridging.
 
#6
SpreadinButter said:
Bridge-Mono, 4 ohms 1400W 1% THD

Soooo that would mean too much power at 4 OHMs Bridged mono?
Click to expand...

in a way yes. your amp puts out 1400w, and your cabs handle 800w. but it´s good to have power available, so your amp doesn´t max out before your cabs. in the case your amp clips, it´ll send square-wave signal to your cabs, and destroy them in no time.

so, listen for cone-cry, and back off the volume a tad if you hear some.

btw, nice setup:)
 
#7
I just had a setup with preamp and an xti2000. It didn't sound as 2000 watts. It had a 4ohm load to work with and was bridged. Db750 had MUCH more headroom. Just to warn you that those switching amp might not be as effective as the wattage specs. might tell you.

Just my 2 cents
 

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