2 amps 2 cabs 1 amp 2 cabs

Yes.

 

810 cabs are loud... the limiting factor is usually the power, so having twice the power will indeed yield more loudness. The same might not hold true for every other 2 amp 2 cab combination though.

 

Carrots

 

Loudness is measured in deciBels, and is generated by speaker cones vibrating in boxes.

Depending on how many cones are vibrating, how much they displace, and the characteristics of the box(es) they’re in, the set of drivers will be capable of a theoretical maximum amount of dB output.

Getting the drivers to that point will require a certain amount of electrical energy, usually expressed in watts. The more efficient the driver(s), the fewer watts are needed to reach the same dB loudness.

Delivering those watts is the job of the amplifier(s). If a single amplifier isn’t capable of delivering those watts, then splitting the job between two amps (each driving its own cab(s) ) will increase the dB output. But if a single amplifier is up to the task, then adding another amp buys you nothing (except the increased likelihood of damaging drivers).

 

or if you love tube goodness how about four SVT CL (or VR) heads into two 8x10 cabs

 

A modern Ampeg SVT 810 is 800 watts... the SVT2PRO head is 300 watts... in the OP's scenario it's practically ideal to run both amps if the goal is to be as loud as possible.

 

As a general rule, more speaker area will increase volume more than more watts.

 

Is anyone currently running such a rig? Gotta ask.......why?
Adding the second head adds a theoretical 3dB, just a barely noticeable increase in perceived volume over the one head powering both cabs.

And using even a 2nd 810 begs the same question. Unless you are playing huge ballrooms w/o PA support, why?

 

If only it were that simple.

Wattage ratings on cabs are very nearly meaningless, as they don’t tell you about frequency response, they don’t tell you about efficiency (how many watts are actually producing sound versus how many watts are wasted as heat), and they don’t specify any sort of acceptable distortion level.

And that’s just off the top of my head.

If the concern is loudness, then the unit of analysis is deciBels, not watts.

 

This is true, but this doesn't change the answer to the OP's question. doubling the power into two very power hungry cabs will definitely provide more useful headroom volume-wise than half the power into the same two cabs.

 

The SVT2 Pro, being a tube amp, will deliver 300 Watts regardless of the attached load.
So in the scenario with one head and two cabs, the 300 Watts will be shared between the two cabinets while in the scenario with two heads each cab receives the full 300 Watts.

So the scenario with two heads will be 3dB louder.

Replace that amp with a SS head and the load difference will more or less balance that issue.

 

Unless the power overwhelms the cab.

 

True again... but not a problem with the gear that the OP is referencing...

 

I would help to know what the OPs goals are.

If he wants a rig twice as loud, it's not as simple as adding a second head. You need to add 10dB to get twice as much perceived volume. Many ways to do that. I'll illustrate one way below:
(Since we're talking tube heads, no need to worry about running at 4 ohms putting out more power than running at 8 ohms that SS heads do.)

Base rig- SVT + 'Fridge. You're a rock god of bassdom

SVT + 2 'Fridges = +3dB. An SVT will adequately power two 'Fridges.

SVT + 2 'Fridges plus another SVT + 2 'Fridges = +6dB. That's a ton of gear and we haven't yet doubled the amount of perceived volume yet.

Should we go on?

 

No, I don't think so... if the same power source, tubes or not, is connected to multiple drivers the wattage will be divided amongst them. If what you propose is true then how is it that each driver isn't getting it's own 300 watts?

 

Four amps into two cabinets is a recipe for letting the magic smoke out!

 

Doubling the amount of drivers (even with the amp putting out the exact same amount of power as before) yields a theoretical increase of 3dB. Simple physics at work here.

We always use dBs when addressing loudness or perceived volume.

 

‘Fridges can be split via a connection on the rear so one amp can drive the top four drivers and another amp can drive the bottom four drivers.

And the SVT can drive 2ohm loads.

So you could have 4 SVTs and 2 ‘Fridges for an increase of 6dB over our base rig of 1 SVT with 1 ‘Fridge.

 

The modern SVT 8x10 cab is basically two 400 watt 4x10's... no problem at all feeding each 8x10 with two 300 watt SVT2PRO amps.

I am pretty sure that doubling power is what calculates to the rule-of-thumb 3db increase. Doubling the amount of drivers should make a much more substantial difference.