How to match head watts and cab watts?

[jpowell]

The more I have read in this forum the more confused I have become. I need accurate info on the above. I am a singer songwriter/acoustic guitarist that is also taking up bass. I have narrowed my choices to the following:

GK Backline 300W Amp - GK Goldline GLX 2x10 and 1x15 300W

GK 700RB11 480W Amp - Same as above

GK " " " GK RBX 2x10 400W and SBX 1x15 400W

I suppose I could pick up a used 1001RB11 if it would make any difference. Please respond if you feel you have ACCURATE info. Thanks!!

 

[alexclaber]

Don't worry about it. A 2:1 ratio in either direction could help narrow your choices but it really isn't very important at all. Your cab will tell you when you're putting too much power into it by getting more and more distorted.

Alex

 

[bongomania]

Right- the "accurate info" is that you need to listen to the speakers, and if they start flapping, buzzing, farting, etc. then you need you turn down the amp (and/or engage a limiter), dropping your peaks below the level that caused the speakers to fart/distort.

As long as you've got that in check, over/under doesn't matter. Also remember that the published specs are usually more of a "general guideline" than a "fact".

 

[jtc_hunter]

I have the same amp and if I were doing it all over again, I would get 2 Avatar 112's 8 ohm ea. in LineX. You would save money, have a lighter pack, and just as good , if not better sound, and more durable cabs.

 

[jpowell]

I have not purchased yet and do not want to test for distortion AFTER I have done the deal. This seems like a fairly straight forward question even though I can't confidently answer it yet. Thanks.

 

[billfitzmaurice]

I have not purchased yet and do not want to test for distortion AFTER I have done the deal. This seems like a fairly straight forward question even though I can't confidently answer it yet. Thanks.

Try before you buy. If the amp causes the speakers to fart out it's got plenty of power for them. OTOH if the amp when fully cranked won't cause the speakers to fart out chances are you need a larger amp.
BTW, a speaker's wattage rating does not tell you how much power it will take without farting out. The average figure is 20 to 40%.

 

[Richard Lindsey]

This seems like a fairly straight forward question even though I can't confidently answer it yet. Thanks.

Well, it's not, or at least not in the manner you seem to think it is. The "matching" you're talking about is really kind of a red herring--as many, many threads in this forum have explained in some detail.

The short answer is that the amp power:cab power handling ratio (whether 1:1, >1:1, or <1:1) is of no real importance as long as you (a) have enough amp power to do the gigs you do comfortably (without straining the amp) and (b) have enough cab power handling to handle the level of power you are actually using (as opposed to the amp's max rated power, which you should not be approaching on any regular basis). Re (b), remember that an amp's stated rating is usually its MAX output in a specified setting, and if you have enough amp for your gig, you will only be using some fraction of that maximum on a regular basis.

Practically speaking, you'd probably want to avoid extreme amp:cab ratios in either direction. But at the ratios you're talking about, it generally doesn't matter much.

The advice you've been given to try the rig out is sound. If possible, you should take it. See if the rig can get up to the volumes you think you'll need. How does it sound? Is the amp peaking or running out of gas? Are the speakers complaining? Is the tone what you want? Etc.

 

[CapnSev]

You will be fine with either of those setups. I would go the 700RB for the quality/extra features if you have the money. It won't blow either of those cabs, let alone the two of them together.

 

[Rick Auricchio]

The farting-out situation is based on the cabinet design. Even cabs of the same style from different companies can behave differently: don't assume that everyone builds them identically.

If it farts out, turn down volume or bottom end, otherwise you risk damaging the speakers.

As Bill said, try the setup. If you can make the cones fart, you have all the power you need.

 

[jpowell]

Thanks so far. I am leaning strongly towards the GK 700 head. Could I get some input on the speakers I mentioned in my first post? That would be great. Thanks again.

 

[georgestrings]

Well, it's not, or at least not in the manner you seem to think it is. The "matching" you're talking about is really kind of a red herring--as many, many threads in this forum have explained in some detail.

The short answer is that the amp power:cab power handling ratio (whether 1:1, >1:1, or <1:1) is of no real importance as long as you (a) have enough amp power to do the gigs you do comfortably (without straining the amp) and (b) have enough cab power handling to handle the level of power you are actually using (as opposed to the amp's max rated power, which you should not be approaching on any regular basis). Re (b), remember that an amp's stated rating is usually its MAX output in a specified setting, and if you have enough amp for your gig, you will only be using some fraction of that maximum on a regular basis.

Practically speaking, you'd probably want to avoid extreme amp:cab ratios in either direction. But at the ratios you're talking about, it generally doesn't matter much.

The advice you've been given to try the rig out is sound. If possible, you should take it. See if the rig can get up to the volumes you think you'll need. How does it sound? Is the amp peaking or running out of gas? Are the speakers complaining? Is the tone what you want? Etc.

Agree on all of the above, and would just add:


Speakers that are driven hard on a frequent basis do not last as long as speakers that are "moderately" driven - in my experience, if a rig or PA isn't loud enough, or marginally so - adding speakers is typically a better solution and throwing watts at the problem...



- georgestrings