Will I overpower my 115?

[ahjoyc2]

I have a Peavey Tour 700 head that runs parallel into an Acoustic 410 and an Acoustic 115.

The head is 700 watts @ 4 ohms.

The 410 is 400 watts RMS (8 ohms)

The 115 is 250 watts RMS (8 ohms)


So, if I were to, theoretically, run the amp as high as it will go, will it be pushing 350 watts into the 410 and 350 watts into the 115? And will this cause damage?

If so, does this mean I should never turn the amp up all the way?

 

[Christian Waiau]

unless you crank your head... you wont be using the full "700 watts" so you should be fine really.

 

[bongomania]

Partly yes, partly no. The 'yes' part is yes, the 4-ohm-rated power would be divided equally between both cabs. And it's true that 350W is higher than 250W.

The 'no' part is that amp and cab ratings are just loose guidelines, they are not a literal description of the impedance or wattage that is actually "happening" in real life. The wattage and impedance go up and down like yo-yo's depending on the notes you play and the strength of your instrument signal (i.e. much less wattage when you play a quiet note, and almost no wattage at all in between notes). Also the volume knob on the amp doesn't have a direct correlation to wattage. And diechris is right that most of the time you will not in fact be cranking the amp to max, because that would sound terrible.

So what you need to do is be aware that theoretically the amp could put out a bigger wattage spike than the 115 can handle, and listen to that cab while you play to be alert for any audible signs of strain on the speaker (farting, buzzing). If you hear those sounds, turn down the amp a bit, or play less aggressively.

 

[butchblack]

If you're going to run the head wide open you might blow the 115 speaker. If you're not wide open you're probably ok. If you're worried or you play wide open a lot you may be better off getting a different cab or finding a 15" speaker rated for 350W or higher and swapping speakers

 

[Kelly Lee]

Partly yes, partly no. The 'yes' part is yes, the 4-ohm-rated power would be divided equally between both cabs. And it's true that 350W is higher than 250W.

The 'no' part is that amp and cab ratings are just loose guidelines, they are not a literal description of the impedance or wattage that is actually "happening" in real life. The wattage and impedance go up and down like yo-yo's depending on the notes you play and the strength of your instrument signal (i.e. much less wattage when you play a quiet note, and almost no wattage at all in between notes). Also the volume knob on the amp doesn't have a direct correlation to wattage. And diechris is right that most of the time you will not in fact be cranking the amp to max, because that would sound terrible.

So what you need to do is be aware that theoretically the amp could put out a bigger wattage spike than the 115 can handle, and listen to that cab while you play to be alert for any audible signs of strain on the speaker (farting, buzzing). If you hear those sounds, turn down the amp a bit, or play less aggressively.

Ding! Ding! Ding! We have a winner and with that, this thread is closed.

To the OP, if you would like more info on this topic please check the FAQ's thread stickied at the top of the Amps forum. Here is a direct link: Amps FAQ *** Now with info on OHMS, PORTABLE RIGS, & Over/Underpowering Cabs & DIY! Go to the section on Overpowering/Underpowering speakers and you will find tons of great info.