: My speaker outlets are labeled main out: 8ohm ext. out:
: 4ohm. My question is, will I have problems if I use
: speakers rated different ohms than the labeled outlets?
: I currently run a 1-15 8ohm cab and a 2-10 4ohm which is 2.67 ohm load. Will this amp run 2 ohms? Can I run just the 4 ohm cab from the 8 ohm outlet? Can I run it from the 4 ohm extension without running a speaker from the 8 ohm connection? This such a great amp, I dont want to fry it with an improper speaker setup. TIA
Rumblethump;
Yes, you can run into problems. The 2000S output transformer doesn't have a 2 ohm tap. The extension speaker jack is a switching jack....when you plug into it, it switches the transformer from the 8 ohm to the 4 ohm tap. Both output jacks are wired in parallel. When you plug in your 4 ohm and 8 ohm cabs you present a 2.67 ohm load (8x4/ 8+4 = 2.67) to the amp when it wants to see 4 ohms. Only a slight impedance mis-match. The larger problem is that due to the individual impedance of each cab, the 4 ohm cab will receive twice the power as the 8 ohm cab.
The 4 ohm cab from the 8 ohm ouput.....a big mis-match, but unless you play really loud, the huge output transformer shouldn't overheat (the big danger in mis-matched impedances).
Yes, better to run the 4 ohm cab from the extension jack, since it switches to the 4 ohm transformer tap ( you don't have to be plugged into the 8 ohm jack to do this).
Hope this helps!
Ryan
