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#1
Maxing bass amp cab capacity.
Just a question if my cab can support 300watts, would maxing it out with a 300watt head damage it?
#2
At higher volumes yes
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#6
They say if you can aford it, the peak wattage your amp should beable to hand shoudl be atleast twice what yoru head can put out.

However, you can get away with as few as a 10% difference. But the further they are, the better!

Also, make sure that the impendance matches!
#7
I dont really understand what you just said.
Did you say that my cab should be able to handle twice it's listed capable wattage?
#8
Nope.

I said if yo can afford the REALLY nice cabs, you shoudl get one that can handle atleast twice what your head puts out.

But you can go as safe as a 10% difference (90W head on a 100W cabnet), but you shoudl try and make the difference as much as you can afford!
#9
my cab is 300w at 8ohms. but it doesent say how much at 4 ohms, and most amps are listed under 4 ohms, is there a way to determine how much it can handle at 4 0hms?
#10
If your cab is rated 300 watts at 8ohms then it's 300 watts RMS. At 4 ohms it will be around 600 RMS. That is still not the peak handling capacity of your cab though. The peak handling will be much higher than the RMS handling. You won't damage it (even at high volumes) with a 300 watt head. Don't worry about it, and just use the 300 watt head.
#11
So get a head that's 300watts at 8 ohms, or 600 watts at 4 ohms, and i'll still be safe?
#13
Alrite... im just getting confused right now... I already have a 300w @ 8 ohms cab, whats the safest highest possible wattage in 8 ohms head that i can buy for it, and whats the safest highest possible in 4 ohms (im not even sure if i can buy a 4 ohm head for it, since the cab mentions nothing about 4 ohms)
#14
^ Doesn't 8+8=4? Yes I think it does because wired in parallel it would half the impedance. And yes half the ohmage you virtually double the wattage output. And I'm fairly sure a head doesn't have impedance because it doesn't take any charge out of the current the cab would have impedance because it is taking the power no? And then the head depending on the impedance of the cab puts out a set amount a energy and then the impedance would change how much of the energy gets transferred to straight wattage.

EDIT: Just saw the post. You could safely get away with a 300 watt head @ 8 ohms. A head doesn't have ohms (look above) so just make sure it says 300 watts @ 8 ohms. If it says 300 watts @ 4 ohms then beware it will only be about 150 watts @ 8 ohms.
Last edited by jazz_rock_feel at Feb 12, 2007,
#15
Quote by Fast_Bear
No it wont' be safe!

You get two cabnets at 4 ohms and wire them up!

Impendance is the electric term for resistance

So 4+4=8


No. 8 ohms + 8 ohms = 4 ohms, when wired in series. It is perfectly safe.
#16
Quote by jazz_rock_feel
^ Doesn't 8+8=4? Yes I think it does because wired in parallel it would half the impedance. And yes half the ohmage you virtually double the wattage output. And I'm fairly sure a head doesn't have impedance because it doesn't take any charge out of the current the cab would have impedance because it is taking the power no? And then the head depending on the impedance of the cab puts out a set amount a energy and then the impedance would change how much of the energy gets transferred to straight wattage.

EDIT: Just saw the post. You could safely get away with a 300 watt head @ 8 ohms. A head doesn't have ohms (look above) so just make sure it says 300 watts @ 8 ohms. If it says 300 watts @ 4 ohms then beware it will only be about 150 watts @ 8 ohms.

Ok. but when searching for heads most of them are listed at 4 ohms, so what would 300 at 8 ohms be in 4 ohms?
#18
Quote by kaossurge
Ok. but when searching for heads most of them are listed at 4 ohms, so what would 300 at 8 ohms be in 4 ohms?


If your head will push 300 watts into an 8 ohm cabinet then it will push about twice that amount into a 4 ohm cabinet.
#19
Quote by Bumper
If your head will push 300 watts into an 8 ohm cabinet then it will push about twice that amount into a 4 ohm cabinet.

no, my cab supports 300watts at 8 ohms, so what would it support in 4 ohms.
#20
I don't think you understand what you're talking about. The head doesn't have the ohm rating, the cabinet does. Your cabinet is rated at 8 ohms. You need to look for a head that will push 300 watts into 8 ohms. If you have a head that pushes 300 watts into 8 ohms, then you can buy another 8 ohm cabinet, wire it in series with the other cab, and your head will push about 600 watts into them.
#21
Quote by Bumper
I don't think you understand what you're talking about. The head doesn't have the ohm rating, the cabinet does. Your cabinet is rated at 8 ohms. You need to look for a head that will push 300 watts into 8 ohms. If you have a head that pushes 300 watts into 8 ohms, then you can buy another 8 ohm cabinet, wire it in series with the other cab, and your head will push about 600 watts into them.
Bumper you've got it the wrong way round, two 8 ohm cabs wired in parallel will give an impedence of 4 ohms, in series it would be 16 ohms.
I currently use a 450 watt amp driving a 300 watt 4 ohm 15" speaker. The speaker is safe because it is getting a good quality signal with no clipping.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#22
^AH! I thought for sure it was series! Ah well. Now all I have to do is go back....edit my posts.....delete this, and no one will ever know I made a mistake.
#24
i'm thinking of buying a 700 watt head and a 400 watt cab, bad idea or ok
I shot JR

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#26
Quote by smb
And I thought he was infallible...


I got one little word mixed up! Ah well......learn from your mistakes. I just wish I didn't have much more learning to do...
#28
^Ha, yeah, I know it. Ah well.....I think I can make a mistake or two and still keep a few shreds of dignity.
#29
Quote by Drmckool
i'm thinking of buying a 700 watt head and a 400 watt cab, bad idea or ok
One big thing to consider is the type of music it is to be used for; if it's for eighth note root bashing (no disrespect guys and gals) then it will be constantly producing high output/wattage levels so you could run into problems, if it is for Soft/Classic Rock, MOR/Pop then it could be ok with decent speakers, although I wouldn't trust far eastern speakers which do have a tendancy to fry when given too much power (often below their rated handling power).
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#30
ok... i dont care about all that i have 1 cab and only want 1 cab... 300watts at 8 ohms.... so the maximum head it can take is one that pushes 300watts at 8 ohms correct?
However, when looking for amps a lot of them say pushes x amount of wattage into 4 ohms, now if the amp is rated in 4 ohms, how much wattage can my cab take from a 4 ohms head. I might be completely misunderstanding the concept..
#31
Heads do not have ohm ratings. Only the cabinet does. Please....don't make me say it again. Now, since your cab is rated at 8 ohms, if you find a head that says "will run 600 watts at 4 ohms," simply divide the wattage number by two. A head that pushes about 600 into a four ohm cab will push about 300 into an 8 ohm cab, and about 150 into a 16 ohm cab. This also works in reverse, so one that pushes 600 watts into a 4 ohm cab will push about 1200 into a 2 ohm cab.
#32
Quote by kaossurge
ok... i dont care about all that i have 1 cab and only want 1 cab... 300watts at 8 ohms.... so the maximum head it can take is one that pushes 300watts at 8 ohms correct?
However, when looking for amps a lot of them say pushes x amount of wattage into 4 ohms, now if the amp is rated in 4 ohms, how much wattage can my cab take from a 4 ohms head. I might be completely misunderstanding the concept..
What it means is that you would need an amp that pushes about 450 Watts at 4 ohms to give you 300 watts at 8 ohms.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#33
^I thought it would about double it? I've always been taught that. I'm sure you're right, John....but is there any way you can elaborate for me on how you calculate that?
#34
Also sometimes when looking at descriptions of amp heads, it doesen't say 8 ohms or 4 ohms... it just says the wattage, should i infer that is 4 or 8 ohms?
#35
Quote by Bumper
^I thought it would about double it? I've always been taught that. I'm sure you're right, John....but is there any way you can elaborate for me on how you calculate that?
There is no hard and fast rule as far as I know but if you go to this site and click on the models you will see what I mean I use the 450 and 300 watt models.
http://www.bkelec.com/Modules/Amplifiers.htm
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#36
Quote by kaossurge
Also sometimes when looking at descriptions of amp heads, it doesen't say 8 ohms or 4 ohms... it just says the wattage, should i infer that is 4 or 8 ohms?
In the vast majority of cases the maximum wattage is at 4 ohms some at 2 ohm and some at 8 ohms but in most cases it is fair to assume 4 ohms
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#38
Bass cabs usually have two wattage designation: It's actual wattage (aka continuous, RMS), and it's peak power (aka program or peak). Typically, a 500W RMS cab has a peak power of 1000W. This means that if the power goes over 500W of output, it can handle a temporary spike (up to 1000W) without damaging. However, if you constantly go over the 500W, you can really damage the speakers.
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Last edited by thefitz at Feb 12, 2007,
#39
So if I have a head that runs 220W RMS into a cabinet that's 400W @ 8 Ohms, the head will only push ~100W into it?
#40
^You have your information mixed up a bit. If your head is rated to push 400 watts at 8 ohms, then you are running 400 watts RMS. If you are running through a 4 ohm cab, then you will be running a little more than 200 watts RMS.
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