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4ohms into 8ohms?

#23
don't do it. i checked the manual: svt-cl can go into 4 or 2 ohms, not 8. I believe that tube amps are rather finicky about what sort of load you put on them.

SS amps have a minimum impedance, and you can run higher than that. Tubeamps are designed for specified loads on the transformer. You can run 2 8 ohm cabs at once, for a total load of 4 ohms, but running at a different impedance than the output transformer is designed to handle could be dangerous.

were it me, i would just find a smaller 4 ohm cab.
 
#26
Trent,

Running your svt at 4 ohms and your cab at 8 is totally fine. I have been doing this for years with not a single problem and have the exact same setup as you. I have used my svt with various smaller cabs rated 8 ohms as well.

Liam,

If heads _have_ to be perfectly matched, then why are SVT's wired for 4 ohm or 2 ohm, where 8x10's are 8 ohm cabs? That setup has been used by musicians for decades with no problem.

EDIT: I'm a.n idiot. I retract all of this
 
#28
snapple said:
Liam,
If heads _have_ to be perfectly matched, then why are SVT's wired for 4 ohm or 2 ohm, where 8x10's are 8 ohm cabs? That setup has been used by musicians for decades with no problem.
Click to expand...

The Ampeg 8 x 10's are 4 ohm cabs. Some (all?) have 8 ohm inputs to run only 4 of the drivers, but the full 810's are 4 ohm cabs.

Cheers,
Liam
 
#30
snapple said:
Trent,

Running your svt at 4 ohms and your cab at 8 is totally fine. I have been doing this for years with not a single problem and have the exact same setup as you. I have used my svt with various smaller cabs rated 8 ohms as well.

Liam,

If heads _have_ to be perfectly matched, then why are SVT's wired for 4 ohm or 2 ohm, where 8x10's are 8 ohm cabs? That setup has been used by musicians for decades with no problem.
Click to expand...

No one has said that the cab has to be perfectly matched. But you WILL be running with a 100% mis-match, which is more than just a 'little'. In doing so, you're pushing your amp to work in a range that its not intended to run in...and can cause problems. You notice that I didn't advocate gloom and doom, but eventual failure. It may equate to changing power tubes sooner than you might or it might mean wear to other, more difficult and expensive components. Or it might run for years...

In general, tube amps are no more finicky than SS amps, as long as you play within the wiggle room that's reasonable. For instance I wouldn't be concerned if we were talking about running a 2.67ohm load off of the 2 or 4 ohm taps.

Also, please note that 810's are generally 4 ohm cabs.
 
#31
I asked Dino at Ampeg about using my SVT with a 6 ohm cabinet and he said
"You should be okay though. The power section on those 2s and CLs are pretty tough. I ran an 8 ohm load with my CL for many years and never had any problems!


Best,
Dino"

I've run mine at 2, 4, 6 & 8 ohms and they always sound great. Of course, for 2 and 4 ohms I used the switch on the amp. for 6 & 8 ohms I leave the switch on 4 ohms.
 

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