Watts question (?)

Dudelike89 · #1 10-26-2010, 06:13 PM

Okay so I have an amp that will output 550 watts at 4 omhs. If I have a 1200 watt cab at 8 ohms and a 600 watt cab at 8 ohms (combined together = 4 ohms load on amp), will I risk blowing the 600 watt cab?

I ask because I simply don't know. And I'm thinking about buying a new amp that is said to put out 600 watts at 4 ohms. If you're wondering, I'm talking about mesa boogie cabs if any of you know the quality. Not sure if it makes a difference here though.

will33 · #2 10-26-2010, 06:56 PM

Quote:

Originally Posted by Dudelike89

Okay so I have an amp that will output 550 watts at 4 omhs. If I have a 1200 watt cab at 8 ohms and a 600 watt cab at 8 ohms (combined together = 4 ohms load on amp), will I risk blowing the 600 watt cab?

No. You have 550 watts (only if it's cranked up) and it's split between 2 cabs so each one would get a little less than 300 (again, only if it's cranked up). Wattage ratings aren't everything, the displacement limit is likely far less than the wattage rating but in any case, just listen to your cabs. If they start to sound distorted or farty, back off a little, otherwise just play.

Steveaux · #3 10-26-2010, 08:49 PM

Education time ...

AMPS FAQ!! Info on OHMS, Allsize RIGS-OverUnderPowerCabs DIY TechTalk-Links

Dudelike89 · #4 10-26-2010, 10:09 PM

Okay so I read something about some number that the amps have that shows how much louder they will go in certain situations. One guy said a 1200 watt amp had a certain rating or something that was at 2 dbs so the amp would produce 2000 watts seeing as 3 dbs is a double wattage. I'm wondering how I would find that number for an amp.

Also, so it looks like an amp that drives 550 watts at 4 ohms would send 275 watts to each speaker. So 600 watt handling power is rather huge. I guess this was confusing to me because I'm currently sending 550 watts to 2 speakers, and they are crapping out tremendously at low volumes. Happens more with the bass all the way up. I think I understand now. I still would like to know that rating that shows the decibel amount the amp may go over of it's max.

JimmyM · #5 10-26-2010, 10:41 PM

you're talking about rms vs peak power. generally amps will have the potential for twice their rms power in peak power. often not an issue in solid state amps since distortion in them sounds very ratty and nasty, but there are solid state and hybrids where it sounds pretty good. but it's generally not a big deal if you watch what you're doing.

Dudelike89 · #6 10-26-2010, 10:47 PM

So hypothetically speaking I could have my amp blasting two 8 ohm cabs at 550 watts, so the peak power would be around 1100 watts. So both speakers would be receiving about 550 watts at peak power, which is still below the 600 watt rating. Sweet. This all makes sense now. Thanks for all the help.

Of course if I'm not understanding, please correct me.

JimmyM · #7 10-26-2010, 10:57 PM

Quote:

Originally Posted by Dudelike89

So hypothetically speaking I could have my amp blasting two 8 ohm cabs at 550 watts, so the peak power would be around 1100 watts. So both speakers would be receiving about 550 watts at peak power, which is still below the 600 watt rating. Sweet. This all makes sense now. Thanks for all the help.

Of course if I'm not understanding, please correct me.

in theory that would be correct. in real life it don't work that way. most cabs will start to make farty sounds way before the point that they blow, and that can be damaging to them. so your best course of action is always using your ears and listening for signs of trouble, and back off if you think your cab might blow, because it probably will.

Dudelike89 · #8 10-27-2010, 12:39 AM

Yeah, okay. I was just making sure I understood. I have these ampeg cabs currently that are "farting" at 50% volume with bass on 100% on my amp. I'm thinking about mesa powerhouse cabs that are ported, unlike my current ampeg cabs.

Thanks again for all your help. I no longer feel like I'm going to vastly overpower a cab just because my wattage rating is close to the peak performance of that one cab.

Von Felgenhauer · #9 11-03-2010, 07:25 AM

if it's farting out with bass @ 100% and volume @ 50%, turn down the bass. It doesnt really travel as far as you think it does, you are just working your speakers harder then normal.

Mr. Foxen · #10 11-03-2010, 07:45 AM

Not sure if he means the bass knob on the amp, or the volume on his bass instrument. Instrument on full is happy, bass knob on your amp should only really get turned up if you are playing very quietly, usually lack of bass is down to the cab rather than eq.