SWR Silverado Special Extension Cab Question

[triggerthehorizon]

Hello, I have a question regarding compatibility with my bass amp and potential extension cab acquisition.

My bass amp is an SWR Silverado Special Combo:

• 2X12" combo 
• 350 watts at 4 Ohms
• 450 watts at 2 Ohms
• Internal speaker impedence is 4 Ohms
• The manual says it can take a minimum load of 2 Ohms.

 

I am thinking of picking up an SWR Goliath JR III which is rated 8 Ohms.

From my calculations Ive found that the total load of the 4 Ohm internal speaker + 8 Ohm extension cab would be (((4*8)/(4+8))= 2.7 Ohms)) as they would be wired in parallel.

So I gather it would be safe considering 2.7 is greater than 2 Ohms. Is this correct?

 

My question is: should I hold out for a 4 Ohm extension cabinet or will this setup sound as good only with a little less volume on tap? I'm mostly looking for additional presence and clarity, not volume.

 

Thanks!

 

Edited March 31 by triggerthehorizon

[BassmanPaul]

If you are going to pick up an extension cabinet you would be better off buying a 4Ω box for the sake of power distribution. You may very well discover that the new 8Ω box adds very little to your overall sound.

[Bill Fitzmaurice]

Assuming the Silverado Special is a 2x12 I'd get a 4 ohm 2x12 extension.

[triggerthehorizon]

  On 31/03/2025 at 18:27, Bill Fitzmaurice said:

Assuming the Silverado Special is a 2x12 I'd get a 4 ohm 2x12 extension.

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Yes it is a 2x12

 

But what are the downsides of the 8ohm? The expansion cab speakers are 10 inch so I'm guesing they will add more high end and presence to the sound. Also there won't be any risk of damage at 2.7 Ohms since the amp can handle 2.

IT would still be an upgrade over running only the built in cab no?

[Bill Fitzmaurice]

The difference between tens and twelves is slight. Just having the combo up on top of the extension will make the high end more obvious. For that matter putting it on a stand would.

[BassmanPaul]

Depending on the sensitivity and frequency response of the added cabinet it possibly could be a downgrade!!

 

[triggerthehorizon]

Thank you for the input gentlemen 

[Bill Fitzmaurice]

  On 31/03/2025 at 21:02, BassmanPaul said:

Depending on the sensitivity and frequency response of the added cabinet it possibly could be a downgrade!!

 

Expand  

True. Just like a box of chocolates when you mix drivers you never know what you're going to get.

[BassBod]

SWR used to say their amps would run down to 2 ohms, but (having used a lot of them over the years) I wouldn't recommend it.  They run fairly hot anyway and going that low will only get them hotter quicker.  The extra output will be marginal, but put more stress on the amp.  

 

Maybe look out for a cheap Workingman's head and use that as a power amp for an additional cab?  

[triggerthehorizon]

  On 03/04/2025 at 09:23, BassBod said:

SWR used to say their amps would run down to 2 ohms, but (having used a lot of them over the years) I wouldn't recommend it.  They run fairly hot anyway and going that low will only get them hotter quicker.  The extra output will be marginal, but put more stress on the amp.  

 

Maybe look out for a cheap Workingman's head and use that as a power amp for an additional cab?  

Expand  

So are you saying running at 2,7 Ohms would be preferable?

[BassBod]

I wouldn’t want to run lower than 4ohms, which is probably the internal load of the combo’s own speakers.  For expansion options I would find another SWR head (Bass 350, or any of the Workingmans series) and drive that from the preamp of the combo (patched into effects return).