• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Too much amp to cab power?

dystopiate

dystopiate

Feb 21, 2008
797
3
New York City
Disclosures
Endorsing Artist: Spector, Aguilar
#1
Is it possible to have too much amp to cab power?

I just got a Crown poweramp on clearance at MF. At 8 ohms it's 450W per channel or 1645W bridged. Most of the time I'll be running a 4x10 rated at 400W at 8 ohms.

Is there a reason I shouldn't run the poweramp bridged? I can use my ears to determine if I'll run it bridged regularly, but is there any sort of risk associated with trying to run it very overpowered?

Also, is there any reason I can't use a speakon to 1/4" speaker cable?

Thanks so much... I'm amp-tarded!
 
#3
Speakon -> 1/4" cables are fine for most purposes. There can be extreme instances where a 1/4" can't handle very high current as well as the Speakon can, but it prob. wouldn't be an issue in this case.

The thing to know about amp wattage is you do have control over how much of it is being used. Unfortunately it's nowhere near as simple as just setting the gain knob lower. In order to keep that much power from blowing your speakers you have to keep your playing dynamics under control and/or use a compressor to keep your peaks under control, and you have to listen for speaker distortion/farting out. If your dynamics (especially peaks and big low notes) are kept under control, and your speakers are not buzzing or farting, then you are using an amount of wattage that the speakers can handle. OTOH if you are putting out big peak spikes, cranking on the low B string etc., you will send "all" of that top wattage amount (give or take) into the speakers and blow them. And if your speakers are buzzing/farting, they are at risk of damage.

There is no reason you should need or want to bridge the amp though. Bridging will not give you better tone, and not bridging (using just one channel) won't hurt the amp at all.
 
#4
Bongo-
Thanks for the clarification. Does this mean that a 'master volume' on a power amp doesn't limit the amount of watts that's being sent to the cabinets?
The reason I ask is that I also have a power amp that I use at home with a small mixer and some 12" speakers. I just keep the master turned down it seems to work. But I don't want to damage the amp or set the house on fire!
 
#5
The master volume is part of the equation, as it regulates the amount of gain, but it does not in fact limit the amount of watts. For example even if you have the volume knob set to 50% (reducing the gain) the amp is still capable of putting out its full wattage if you feed a hot enough signal into it.

Check out this paper from our own Bob Lee: [Invalid or Expired Link Removed]
 
#7
Kelly Lee said:
No.

I advise doing a little research here as there are countless threads on this very topic. We have at least one new thread a week.
Click to expand...

Not to sound like a total goon, but I must be bad with the search function. I found some stuff about overpowering 2:1 for more headroom, but wasn't sure if something like 4:1 was just plain silly.

Bongomania: I am using a compressor, but you mentioned that overpowering won't affect my tone... is the "headroom" thing a fallacy?
 
#8
If you run 1600 odd watts into a 400W cabinet you will eventually blow it. Hypothetically if you switch the amp on and pick up your bass, slip and drop it or your bass falls over with the amp on, you will send a pulse of full pawer into the cabinet. That could very easily use your voice coils as fuses. Much better idea is to run the amp in parallel mono and connect your cabinet to just one channel. That will put 450W into a 400W cabinet and will be much safer. This is how I run my systems.

Paul
 
#9
Yes you can do it and, no you shouldn't hurt anything unless you get stupid and run the amp into clipping. Does the amp have any sort of db meter? 0 db bridged would be 1600W -3db would be 800W and, -6db would be 400W. etc. I bet you'll notice that it is loud as hell at -9 db (200W)
 
#11
I'm starting to think I've radically misunderstood a lot of what I was reading about amp:cab power!

I guess my question now is, will there be *any* difference in sound if I have more headroom, or is headroom just a way of pushing the amp less?
 
#13
Sort of along the lines of what Bongo said, attack and peaks will be much more crititcal in this situation and a comp/limiter is a real good idea in this case. Running one chanel makes it much less fool proof though. 450 watts is a screamin load of power under many scenarios.

That being said, if I had my choice I would want to run an overrated rig thn an underrated one. Clipping, distortion and the resultant square wave is much more dangerous for a speaker than simply more clean power. That kind of stuff equates to heat and that is what takes out voice coils quickly. Particularly when you're driving it hard.

JKT
 
#15
JKT said:
Sort of along the lines of what Bongo said, attack and peaks will be much more crititcal in this situation and a comp/limiter is a real good idea in this case. Running one chanel makes it much less fool proof though. 450 watts is a screamin load of power under many scenarios.

That being said, if I had my choice I would want to run an overrated rig thn an underrated one. Clipping, distortion and the resultant square wave is much more dangerous for a speaker than simply more clean power. That kind of stuff equates to heat and that is what takes out voice coils quickly. Particularly when you're driving it hard.

JKT
Click to expand...


Here we go again.....:hiding:

:D
 
#20
dystopiate said:
Thanks so much! I can't help but wonder why the whole 2:1 for more headroom thing gets parroted so much.
Click to expand...

Something else you need to understand is that headroom is not in any sense determined by the amp-to-cab ratio. It's determined by whether you have enough, not quite enough, or more than enough power to get the tone and volume you need in a given playing situation. There is no magic amp:cab ratio that confers headroom. The important ratio is that between the power you need and the power you actually have. Headroom is determined by the playing situation. If you have a lot of headroom with a 1200 W amp into a 600 W cab, you will have essentially the same amount of headroom with the same amp into a 1200 W cab of equal sensitivity and frequency response.

This of course means that headroom is not a constant thing but a dynamic one. With the same rig, you might have more than enough headroom in a coffee shop, but not nearly enough in a huge club without PA support.
 

Latest posts

Top Bottom
Back