• 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.

500 Watt head and 400 Watt Cabinet

P

pmarq655

Feb 28, 2019
15
7
#1
I know this is probably a really stupid question but I am a relative newbie and know virtually nothing about electricity, watts, ohms, etc.

I have gotten to a point where I want to upgrade from my combo amp and I was wondering if it's possible to run a 500 watt amp (4 ohms) through a 400 Watt Cabinet (8 ohms) without destroying either?
 
#7
pmarq655 said:
I know this is probably a really stupid question but I am a relative newbie and know virtually nothing about electricity, watts, ohms, etc.

I have gotten to a point where I want to upgrade from my combo amp and I was wondering if it's possible to run a 500 watt amp (4 ohms) through a 400 Watt Cabinet (8 ohms) without destroying either?
Click to expand...

Your amp requires a minimum 4 ohm load and your cab gives it an 8 ohm load - that's great. When we try to run amps below their minimum resistance ratings, they can get cooked.

If you had a pair of 8 ohm cabs connected to your amp, you'd still be okay. That would give the amp a 4 ohm load - the two 8 ohm cabs together cut the resistance in half.

Also keep in mind that we don't need umptee-thousand watts from an amp to make decent volume when playing in a mix with a band. We need enough speaker(s) to push the air along with maybe a few hundred watts of power on hand. Some cabs will make big sound better than others (really great ones are pricey), but an essential factor for making "enough" sound is to have enough speaker area to work with.
 
  • Like
Reactions: chris_b
#10
What is the cab? What is the amp?

A 500 watt amp will put around 250 watts into an 8 ohm rated cab. But 99% of all amps will not sound good if you are running them flat out, so if your amp is designed correctly (and hopefully it is), you will be putting about 125 watts into this cab with the volume controls pointing to 12 o'clock. 125 watts into a 400 watt cab is a good ratio for keeping everything safe.

I play in loud bands with a 500 watt amp. I'd be surprised if you needed more power than that. If you want to go louder, more watts will not help as much as you would think. Adding cabs will always do a much better job. For instance, going from 1 112 cab to 2 112 cabs (same for all matching cabs) will improve the volume (moving more air) and improve your tone (moving more air), ie make you louder whilst making you sound better.

You sometimes get stupid answers, but there is no such thing as a stupid question. Keep asking until you understand what it is you want to know.
 
  • Like
Reactions: King Charles, Blind Lemon Sam, bste9 and 1 other person
#11
pmarq655 said:
Will effects pedals change the equation?
Click to expand...

I was told by an amp repair guy that volume doesn't kill speakers as much as tone does. That means a middy/high tone can drive a speaker to a higher volume level than a fat, low-end boosted bass tone. Pedals can overdrive your signal and cause problems for your speakers. I you hear problems with your sound, reduce your volume or buy that extra cab.
 
#12
chris_b said:
What is the cab? What is the amp?

A 500 watt amp will put around 250 watts into an 8 ohm rated cab. But 99% of all amps will not sound good if you are running them flat out, so if your amp is designed correctly (and hopefully it is), you will be putting about 125 watts into this cab with the volume controls pointing to 12 o'clock. 125 watts into a 400 watt cab is a good ratio for keeping everything safe.

I play in loud bands with a 500 watt amp. I'd be surprised if you needed more power than that. If you want to go louder, more watts will not help as much as you would think. Adding cabs will always do a much better job. For instance, going from 1 112 cab to 2 112 cabs (same for all matching cabs) will improve the volume (moving more air) and improve your tone (moving more air), ie make you louder whilst making you sound better.

You sometimes get stupid answers, but there is no such thing as a stupid question. Keep asking until you understand what it is you want to know.
Click to expand...
Thank you for the help!!! I got everything set up, and so far so good! I'm also using MXR 85 Bass and Black Cat Super Fuzz distortion pedals, and a Cry Baby wah pedal for bass. Will using any of these increase (or even lower) the wattage I am putting into the cabinet? My fear is that using the pedals will put the wattage going into the cabinet above the 400 it is able to handle.

The rig is a Gallien-Krueger MB Fusion 500 Watt head (4 ohms) and a 2X10 400 watt Gallien-Krueger cabinet (8 ohms).
 
Last edited:
#13
pmarq655 said:
Thank you for the help!!! I got everything set up, and so far so good! I'm also using MXR 85 Bass and Black Cat Super Fuzz distortion pedals, and a Cry Baby wah pedal for bass. Will using any of these increase (or even lower) the wattage I am putting into the cabinet? My fear is that using the pedals will put the wattage going into the cabinet above the 400 it is able to handle.

The rig is a Gallien-Krueger MB Fusion 500 Watt head (4 ohms) and a 2X10 400 watt Gallien-Krueger cabinet (8 ohms).
Click to expand...
The bigger danger with distortion fx is masking the overdrive of the low end trying to shred your speakers.
 
#14
pmarq655 said:
Thank you for the help!!! I got everything set up, and so far so good! I'm also using MXR 85 Bass and Black Cat Super Fuzz distortion pedals, and a Cry Baby wah pedal for bass. Will using any of these increase (or even lower) the wattage I am putting into the cabinet? My fear is that using the pedals will put the wattage going into the cabinet above the 400 it is able to handle.

The rig is a Gallien-Krueger MB Fusion 500 Watt head (4 ohms) and a 2X10 400 watt Gallien-Krueger cabinet (8 ohms).
Click to expand...

What combo were you using? Are you intending to play at louder volume levels? Are you playing at home or gigging?

The idea is to keep within the safe volume levels of your cab. As guys have said, your pedals will boost frequencies, so if you are playing close to the maximum of your cab that could push your sound into damaging the speaker, but you'd have to be pretty aggressive to do that. Many players don't come near to maxing out a 400 watt cab, but it is possible, so you are right to be asking the question.

If I was playing your gear I'd probably have the volume of the amp at no more than 1 o'clock and if I wanted to be louder I'd get that extra cab. At 1 o'clock I'd expect your amp to be putting around 130-ish watts into your cab. I'd expect your cab to handle that, even with a highly distorted sound. The problem is we can't be 100% certain, because we're not there. That's why the big advice is always to listen and if you hear signs you cab is distress, ie sounding bad then you turn it down. With a highly distorted sound, it's much more difficult to hear the driver when it's in distress.

It would help to know what combo you are upgrading from.
 
  • Like
Reactions: Blind Lemon Sam
#17
pmarq655 said:
Thank you for the help!!! I got everything set up, and so far so good! I'm also using MXR 85 Bass and Black Cat Super Fuzz distortion pedals, and a Cry Baby wah pedal for bass. Will using any of these increase (or even lower) the wattage I am putting into the cabinet? My fear is that using the pedals will put the wattage going into the cabinet above the 400 it is able to handle.

The rig is a Gallien-Krueger MB Fusion 500 Watt head (4 ohms) and a 2X10 400 watt Gallien-Krueger cabinet (8 ohms).
Click to expand...
Your pedals can't add power. The amp can't make more than 500 watts with a 4ohm speaker, or in your case about 250-300 watts with an 8ohm speaker. Which, by the way is getting close to what that speaker can handle. If you're gonna be loud, make sure the speaker is tilted or elevated so you can hear it clearly. You'll probably be just fine but, listen for 'bad' noises. You'll know.
 
#18
It is true that pedals can't add power but They can create distortion (even non distortion/dirt pedals can) and the position of the knobs on the amp means nothing in relation to power being produced It is a very rough guesstimate at best. Also Low boosted signal will shred a speaker much faster than a High/Mid boosted signal. The key is use your ears and common sense if it sounds good then it is if it sounds distorted then back off. And there is almost no speaker made for Bass Guitar that can pass for subs. So careful use of low boost is the key.
 
  • Like
Reactions: Omega Monkey
#19
David Jayne said:
Your pedals can't add power. The amp can't make more than 500 watts with a 4ohm speaker, or in your case about 250-300 watts with an 8ohm speaker. Which, by the way is getting close to what that speaker can handle. If you're gonna be loud, make sure the speaker is tilted or elevated so you can hear it clearly. You'll probably be just fine but, listen for 'bad' noises. You'll know.
Click to expand...
Pedals can indeed cause the amp to make MOAR power out of a distorted signal than possible with clean sounds.

Those sorts of sounds can sound similar to actual speaker overdrive caused by trying to make it sound like a PA stack at the same time.

Careful as ye go.
 
#20
It's good not to feed too much power to your cab, but don't think you can't blow a speaker with fewer watts than it's rated for. If you find you need to push things volume wise to the point where it starts to sound bad / the speakers sounds farty / strained, you're about to blow your speaker. You can add a second 8 ohm cab for more volume if you need it. A high pass filter can help protect your speakers if you're going to play loud AF.

Above all else, use your ears, not wattage ratings. Sounds like the speaker's unhappy? Turn the amp down.
 

Latest posts

Top Bottom
Back