• 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 freeLog in
    Want zero display ads or expanded classifieds tools? Compare plans.

4ohm 200w head and 8ohm 250w cab

Ya Boi

Guest
Sep 25, 2016
3
0
Hi everyone,

So I am new to bass and have don't know much about amplifiers. There is this rig I am looking at right now. It has a crate bx200 head which is rate 200w at 4ohms and and acoustic b115 which is rated 250w at 8ohms. Will this work?
 
Hi everyone,

So I am new to bass and have don't know much about amplifiers. There is this rig I am looking at right now. It has a crate bx200 head which is rate 200w at 4ohms and and acoustic b115 which is rated 250w at 8ohms. Will this work?
The head will give you 200 watts with a 4 ohm load, like with one 4 Ohm cab or two 8 Ohm cabs.
If you use one 8 Ohm cab, the amp will not supply as much power because it is not working as had as it can.
For instance, my Fender Rumble 200 combo is rated for 200 watts at 4 Ohms or 140 watts at 8 ohms.
Your's should be similar.
The wattage rating on the speaker is how much power it is designed to handle. (Though power is measured in different ways so a bit of caution is in order.) The ohms rating on the speaker is how much of a load it presents to an amp. The ohms rating on the amp says... make sure your total speaker load does not go lower than this.
In general, your 200 watt amp and your 250 watt speaker ought to go well together.

edit- Correction... Power is measured the same way. Power = Current X Voltage.
What I should have said above is that there can be different signal conditions in use when measuring power. Not all power specifications are derived under the same conditions.
 
Last edited:
I think the folks above covered it nicely. You're safe to operate in terms of nothing going wrong, but that single 15 will likely not get "cranked-up, rock and roll loud" and trying to push it too far with that amp would not be a great idea. Overall, if you let your ears be your guide, you should be just fine.
 
So I am new to bass and have don't know much about amplifiers. There is this rig I am looking at right now. It has a crate bx200 head which is rate 200w at 4ohms and and acoustic b115 which is rated 250w at 8ohms. Will this work?
This rig will be ok, but how loud do you need to play and what is your budget? Can you get to a shop to try out some amps and cabs? Is this the first amp you've bought?

If you're only playing at home or low volume rehearsing you can start with a combo, but separates are easier to upgrade. I'd also get my gear from the TB Classifieds.

If you're intending to start gigging then I'd get straight to the point and buy a 500 watt amp and maybe a 4 ohm 212 or 410.
 
I object to the term ''safe''. Pumping the bass EQ would likely stress the cab.
A fair criticism. I tried to qualify that in my answer and only meant "safe" from the standpoint of this isn't a "non-starter" issue such as plugging a 120 volt device into a 240 Volt power source, or using an 8 Ohm limited solid state amp to feed a 2 Ohm load.
 
So if I don't use EQ it would be okay?
Just don't go nuts by cranking the bass knob all the way to the right and then maxing out the volume/gain controls. Your ears will tell you when the speaker is moving out of its happy place.

Start with EQ controls at noon/neutral, volume/gain all the way off and then bring the volume/gain up to see how things sound. If you want more low end in your tone, use your EQ (drop highs and/or increase lows) and then check to see if the volume/gain needs to be adjusted a touch. Problems will become obvious quickly and you don't have to worry about a sudden disaster.

OBTW, this advice is good for any cab/amp combo. Sometimes a cautious approach, maintaining situational awareness and common sense will serve you at least as well, if not better, than hard and fast rules. To be fair though, hard and fast rules like not sticking a metal fork in a live electrical outlet are worth heeding. ;)