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Connecting Mesa Powerhouse bass cabs

couzin2000

couzin2000

Oct 18, 2017
20
9
Sainte-Therese, Quebec, Canada
#1
So I have this Ampeg SVT III (non-PRO) rackmount head, churns out 300W @ 4ohms.
I also own a Mesa/Boogie 4x10 Powerhouse bass cab, rated 8ohms.

After asking around to figure it out, I now know that my cab is pushing about 150W, which is half the power I could be getting if I were running every thing at 4ohms.

So I decided to get an extra cab.
Enter Mesa/Boogie 2x10 Powerhouse bass cab, rated 8ohms.

In theory, combining both bass cabs would bring the circuit down to 4ohms rating, which will let my amp push its full 300W out.

HOWEVER: I'm trying to figure out which way is best to connect:
  • from Ampeg SVT left (1/4" jack) to 4x10 cab input, and from Ampeg SVT right (1/4" jack) to 2x10 cab input;
    OR
  • from Ampeg SVT left (1/4" jack) to 2x10 cab input, and from 2x10 parallel output (1/4" jack) to 4x10 cab input.
I've been looking for a manual in PDF form, but no such luck - unable to find.

If anyone knows how to, please reply here, or even post a link to the bass cab manuals!
thanks
 
#3
While either will work, note that your 210 cabinet's drivers will receive twice the power that your 410 cabinet drivers receive.

This means that each 210 driver will receive ~75 watts and each 410 driver will receive ~37-1/2 watts when operated in parallel

I think you will find the difference with the second cabinet underwhelming compared with a second 8 ohm 410, and maybe even the single 410.

Using just the 410, each driver receives ~50 watts.
 
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#4
Roland GR 88 said:
[Invalid or Expired Link Removed]

The two outputs are parallel so hook up your cabs in series. ie; daisy chain them together. At 8ohms your head is pushing 200w and at 4ohms it will do 350w.
Click to expand...
Your reasoning is sound. My only concern with this is that each of the cabs has a parallel output - doesn't that do the exact same thing as hooking up both cabs to each left and right amp output?
 
#5
agedhorse said:
While either will work, note that your 210 cabinet's drivers will receive twice the power that your 410 cabinet drivers receive.

This means that each 210 driver will receive ~75 watts and each 410 driver will receive ~37-1/2 watts when operated in parallel

I think you will find the difference with the second cabinet underwhelming compared with a second 8 ohm 410, and maybe even the single 410.

Using just the 410, each driver receives ~50 watts.
Click to expand...
So what you're saying is that each cab acts as an independant, in-a-series attenuator?
So with that in mind, I should be putting my 4x10 first in the chain... am I thinking the right way here?
 
#8
couzin2000 said:
Your reasoning is sound. My only concern with this is that each of the cabs has a parallel output - doesn't that do the exact same thing as hooking up both cabs to each left and right amp output?
Click to expand...
Perhaps see below....

Paulabass said:
That's not series, that's STILL parallel.
Click to expand...
Didn't catch the that .... thanks for the clarification :)
 
#9
couzin2000 said:
BTW, if anyone has a PDF manual for the cabs, link them here please :)
Click to expand...
It was in the very first response you got.

And it doesn't matter how you plug 'em in...all the jacks are parallel. It doesn't matter in what order you plug things in...each box will get half the power. One box will share that power between two drivers, the other between four drivers...there's no attenuation or anything like that involved. As @agedhorse pointed out, you're not likely to notice much difference with this arrangement. Is it loud enough with just the 410, but you're just angst-ing about how you're not getting/using all the power you have coming to you? If so, I wouldn't sweat it too much...loud is loud enough in my book.
 
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#11
agedhorse said:
While either will work, note that your 210 cabinet's drivers will receive twice the power that your 410 cabinet drivers receive.

This means that each 210 driver will receive ~75 watts and each 410 driver will receive ~37-1/2 watts when operated in parallel

I think you will find the difference with the second cabinet underwhelming compared with a second 8 ohm 410, and maybe even the single 410.

Using just the 410, each driver receives ~50 watts.
Click to expand...

I almost want to say it will not be as loud as the 410 by itself, as you will probably have to keep the volume down to go easy on the 210. Of course, I'm just going on a gut feeling here. :)

If you do this, (as always) keep an ear on the 210 speakers, as they will likely give up long before you get the 410 to its "sweet spot".

And while it may actually work, sound good enough, and NOT blow anything up, it's still not as efficient as running 2 410 cabs (or 2 210 cabs for that matter).

Maybe a 2nd 410 instead of the 210?

T$
 
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#13
Bassdirty said:
I almost want to say it will not be as loud as the 410 by itself, as you will probably have to keep the volume down to go easy on the 210. Of course, I'm just going on a gut feeling here. :)

If you do this, (as always) keep an ear on the 210 speakers, as they will likely give up long before you get the 410 to its "sweet spot".

And while it may actually work, sound good enough, and NOT blow anything up, it's still not as efficient as running 2 410 cabs (or 2 210 cabs for that matter).

Maybe a 2nd 410 instead of the 210?

T$
Click to expand...
In the end, what I want is the air displacement. I realize it won't really be LOUDER than what the 4x10 would be on its own - but I do want 2 things. 1, the flexibility of having a small cab for small venues or even home play. 2, I wanna use the 2 cabs to put less constant strain on the amp, because even if it has been rebuilt to factory standards recently, it's still old, and has to cope with me hammering the shag outta my bass.

More air being displaced results in a smoother sound as well, as far as I'm concerned.
Still, I wanna be clear on how I connect it, because at the price I'm paying, ain't no way I'm gonna let it be damaged.
 
#16
Redbrangus said:
And you think loading it with a lower impedance achieves this....how?
Click to expand...
I'm.... sure I... don't know. :oops:
I get there is science behind all this, I keep asking questions here because I need answers. My amp seems to be underwhelmed with the 4x10, I can't get a good bang out of it. It's got volume, but it's not "LOUD". (Before you ask, yes, the attenuator dial is "turned off" - no attenuation present.) I'm still cranking my volume all the way to 7-8 on the amp and it's not loud? I'm not sure I'm dealing with this amp the right way then.

Speaking of which - if I use amp into 4x10, but connect 1x 1/4" cable from left output to cab input, AND 1x 1/4" cable from right output to cab parallel out -- does the parallel out need to be connected and if so, does it attenuate the volume levels being output?
 
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#17
agedhorse said:
While either will work, note that your 210 cabinet's drivers will receive twice the power that your 410 cabinet drivers receive.

This means that each 210 driver will receive ~75 watts and each 410 driver will receive ~37-1/2 watts when operated in parallel

I think you will find the difference with the second cabinet underwhelming compared with a second 8 ohm 410, and maybe even the single 410.

Using just the 410, each driver receives ~50 watts.
Click to expand...
That was pretty much the input I was about to write.
 
#18
couzin2000 said:
I'm.... sure I... don't know. :oops:
I get there is science behind all this, I keep asking questions here because I need answers. My amp seems to be underwhelmed with the 4x10, I can't get a good bang out of it. It's got volume, but it's not "LOUD". (Before you ask, yes, the attenuator dial is "turned off" - no attenuation present.) I'm still cranking my volume all the way to 7-8 on the amp and it's not loud? I'm not sure I'm dealing with this amp the right way then.

Speaking of which - if I use amp into 4x10, but connect 1x 1/4" cable from left output to cab input, AND 1x 1/4" cable from right output to cab parallel out -- does the parallel out need to be connected and if so, does it attenuate the volume levels being output?
Click to expand...
Never connect two amplifier outputs to one speaker!!!!
Doing so is a certain recipe for equipment death!:dead::dead::dead::dead::dead:
 
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#19
couzin2000 said:
Speaking of which - if I use amp into 4x10, but connect 1x 1/4" cable from left output to cab input, AND 1x 1/4" cable from right output to cab parallel out -- does the parallel out need to be connected and if so, does it attenuate the volume levels being output?
Click to expand...
If I am reading this correctly it seems that you are asking about running a speaker cable from each of your amp's two output jacks to the two cab jacks.

There is no reason to do this...one cable does the job fine is the proper way to go. A cable connected to to any other jack in this scenario (i.e. it has a live signal on it) that is not connected to a cab is a serious safety hazard that will not change the total load the amp is seeing - but depending on what it touches may present a deadshort to your amp and/or a potentially serious shock to a person. I strongly recommend you do not do this, even as an experiment.

Power distribution follows a simple rules as cited in post #3 above. The power output of your head is based on the total connected load that it sees (one 8 Ohm cab is an 8 Ohm load, two 8 Ohm cabs create a 4 Ohm load).

In terms of total connected load, it does not matter to the head whether that load is connected using the two output jacks on the back of the head with cables each running to two different cabs, or if you run a single speaker cable from either output on the back of the head to one cab and then connect that cab to a second cab with another speaker cable. All of these types of connections are known as parallel in electrical terms.

I hope this helps.
 
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