Sunn 200s Q&A

[protoz]

By having both outputs at 8Ohm will not let you safely go down to 4Ohm. The lowest you can go is 8Ohm no matter what with how the amp is designed.

My Sorado goes down to 4Ohm. How it works is if you have two 8Ohm cabs it goes to 4Ohm automagically.

 

[Psycho Bass Guy]

Hmm. Maybe I ought to clarify what I meant: the 200s originally had 1 16ohm and 1 8ohm output, and I ignorantly ran both outputs into 8ohm cabs, blowing the fuse.

You can only run ONE output. Multiple jacks are not a mix'n'match propostition; you can one use ONE at a time. The different values are all separate taps off the amp's output transformer which is fed by the amp's output tubes. If you use more than one, even at their 'rated' values, you're drastically dropping your output impedance and making your tubes work way too hard to supply current, so you blow your fuse. You are also reducing your output power by doing this.

We then disconnected the polarity switch and modified the outputs to be 8ohms and 8ohms. I ran one of the outputs into an Ampeg 810 (4ohms) with the volume on 4 and it seemed to work perfectly fine.

Who is "we?" Also notice that when you use only one output, the amp works ok.

We then ran both outputs into the same two 8ohm cabs, and the fuse still blew after running the amp on 7 for about 3 minutes.

Again, the problem is that you're using multiple outputs- you can't do that! There may be nothing wrong with your amp at all. The fuse is doing exactly what it should: blowing because the tubes are drawing too much current. Chances are that you've probably taken a BIG chunk off your tubes' lives if nothing else is wrong. Try using only ONE output at the proper rating. If you need to use more than one cabinet, you'll have to use the cabinet's parallel jacks and make sure that you have the proper load

 

[Origami Kamikaz]

Alright, after all the advice I've taken from this (hijacked ) thread, I guess this is what I need to do to figure out if anything's wrong with the amp itself:

1. Run the amp at rehearsal volume through the Ampeg 810 (4ohms).
2. Run the amp at rehearsal volume through the 210 (8ohms), then back out through the 210's parallel jack into the 115 (8ohms).

Am I right?

And the "we" I kept saying was me and a friend of mine who's an electrical engineer...probably not the best thing I could've done, but I'm a poor college student, so eh well.

 

[protoz]

Do NOT run 4Ohm anything on that head. 8Ohm or higher or you will kill the tubes and fry the amp.

Your electrical engineer buddy should know Ohms Law and know you should put more load on the amp than what it is designed for. You can rewire the 2x10 to 16Ohm and get another 16Ohm cab and run them together to make 8Ohms and then you will be ok.