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Expanding my rig . . . Will this work?

stringthrough

stringthrough

Supporting Member
Nov 26, 2011
3,031
5,491
The great state of New York
#1
Greetings.

I have a Markbass 300W Combo with an internal 8 Ohm 12" speaker rated at 300-400W RMS (not sure). The combo is able to push 500W when presented with a 4 Ohm speaker load. My plan is to add an external 8 Ohm 12" speaker, rated at 300W RMS which when combined in parallel with the internal speaker will present a combined 4 Ohm load to the amp. So far, so good. My question is, if I dime the amp (I'll be playing an outdoor gig in 3 weeks and will probably need all the volume my amp will generate because I will not be sending my amp's signal into a PA) will the amp potentially damage my 300W RMS rated speakers with its 500W signal or will its signal be split 250/ 250W across the 2 speakers, thus safely using the speakers within their power handling spec.

Thanks for the help in advance.
 
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#3
Adda 4-ohm speaker, bypass the internal speaker and not have to worry about it.
That's what I did with the 2x10 below.. handles 600w continuous ..
The combo sits on top and doesn't use the 12" at all..
I did use the 12" for smaller gigs..
Apologies for pic size..
IMAG0150.jpg
 
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#4
s0c9 said:
Adda 4-ohm speaker, bypass the internal speaker and not have to worry about it.
That's what I did with the 2x10 below.. handles 600w continuous ..
The combo sits on top and doesn't use the 12" at all..
I did use the 12" for smaller gigs..
Apologies for pic size..
View attachment 936472
Click to expand...

Thanks for the suggestion but my bad back demands that I keep my amps/ cabs very light (under 35 lbs) that's why I'm going with a 1x12" extension... Your 2x10" looks to weigh more than my limit.
 
#6
You may never be able to send full power to the cabinets, simply because many cabs reach their mechanical limit long before their thermal (wattage) limit. If they begin to fart out, you have to back off the volume, no matter how many watts the nameplate says.

And if you add a different model of external cabinet, be advised that one or the other cab may hit its limit first, while the other one could still take more. You still have to stop there.
 
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#10
You'll be amazed how much louder it is just by adding the second cab. I wouldn't worry about needing to 'dime' it but I would be aware of what the speakers are doing as you turn it up as others have said. Theoretically, the two 12" speakers you have should move enough air to allow you to be heard outside without the need to push them real hard. Good luck!
 
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#12
The power coming out of the amp will be split evenly between the two speaker cabs presuming they are both 8 ohm and the connection is a parallel connection. Parallel connections are the standard of the industry and unless it says otherwise on the amp or in your manual, you should be good.

If you hear your speakers making farting noises, first drop the bass EQ a few notches and if that doesn't stop it, you'll need to drop the master until the farting goes away. If you play with the speakers making that noise, they will first crease, and then perhaps tear the cone or melt the voice coil, depending upon whether you are exceeding maximum extension or just plain sending too much power to the voice coils of the speakers. I would expect with that set up if you have any trouble it would be because you are exceeding the max extension on the speakers. Should be fine with the power at 250-watts per speaker. You'll probably be fine outdoors with two 12's as long as the guitars and drums don't get carried away. Two of the 112's always sounds better than just one.
 
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#14
As important as "how much power?" is "what does it do with that power?" It's a question of sensitivity; will both speakers produce the same/complimentary sound when driven with the same source? And phase; are both speakers wired to work together or is one our of polarity, essentially cancelling each other out. All things you probably need to address specifically before the show requiring a second cabinet
 
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#16
The cabs will each get the same power since the impedance is the same. Your real benefit in terms of volume is that extra speaker. Maxing out the volume control is neither advisable nor necessary, and won't give you much if any noticeable extra volume over running at safer levels.

If you're hurting for volume with 500 Watts, you really need more speaker and not another twist on the volume knob. Good luck and as a back-up I'd see if you couldn't get at least a little help from the PA/FOH system. Even without subs, a typical PA set-up can often give you some push in frequency ranges that are quite useful.
 
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#17
Warning: I have met many people who have had the same problem that I encountered with my markbass combo. When using an extension cabinet, any markbass combo has potential issues with blowing a fuse. I have had this happen with both a 1x12 combo and a 2x10 combo.

By no means am I knocking Markbass. This is a well-documented issue with their combo amps. Instead of using a combo, I switched over to a Little Mark III, traveler 1x12 and traveler 2x10 to avoid any possibility of blowout.
 
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#18
miggychunt said:
Warning: I have met many people who have had the same problem that I encountered with my markbass combo. When using an extension cabinet, any markbass combo has potential issues with blowing a fuse. I have had this happen with both a 1x12 combo and a 2x10 combo.

By no means am I knocking Markbass. This is a well-documented issue with their combo amps. Instead of using a combo, I switched over to a Little Mark III, traveler 1x12 and traveler 2x10 to avoid any possibility of blowout.
Click to expand...

That's pretty scary news, especially since I've just ordered a Hartke Hydrive 112 as an extension cab. Guess I'll bring a spare fuse to my dual-bottom gigs and hope that you experience and those of others you've come across are rare exceptions.

Thanks for the info.
 
#19
miggychunt said:
Warning: I have met many people who have had the same problem that I encountered with my markbass combo. When using an extension cabinet, any markbass combo has potential issues with blowing a fuse. I have had this happen with both a 1x12 combo and a 2x10 combo.

By no means am I knocking Markbass. This is a well-documented issue with their combo amps. Instead of using a combo, I switched over to a Little Mark III, traveler 1x12 and traveler 2x10 to avoid any possibility of blowout.
Click to expand...
I have never run extension cabs along side the built in on my Markbass 121.
I disconnect the internal speaker and only run the external... used it live for about 2 yrs and never had an issue with fuses. Still had the factory original in there.
4-Ohm 2x10 600w continuous fed by the 121 - as you see above in the pic.

My guess is that folks blowing fuses are putting less than a 4-ohm total load on the amp..
 
#20
s0c9 said:
I have never run extension cabs along side the built in on my Markbass 121.
I disconnect the internal speaker and only run the external... used it live for about 2 yrs and never had an issue with fuses. Still had the factory original in there.
4-Ohm 2x10 600w continuous fed by the 121 - as you see above in the pic.

My guess is that folks blowing fuses are putting less than a 4-ohm total load on the amp..
Click to expand...
Well both my combos that blew out were only running 4 ohms so I'm not really sure.
 

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