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Sunn Musical Equipment => Q & A => Topic started by: gray on September 17, 2006, 05:03:26 pm

Title: running Model T @ 2 ohms
Post by: gray on September 17, 2006, 05:03:26 pm

I'm going to pick up my Model T (seventies) from my service guy tomorrow, and I'm going to be running it at 2 ohms. Is it okay to run it at this consistently? Also, does running at 4, 8 or 16 ohms decrease the wattage? I was always under the impression that it did, but I've heard both yes and no to that question and I trust the input I get on this site. I'm sorry if this sounds like a stupid question but this is my first amp of this magnitude, and until lately I've only used either combos or cheap stuff that only ran 4 ohms because it was designed to marketed for use with a certain cabinet. I guess I'm just trying to get the skinny on this thing before I go do something ignorant and blow it to pieces or whatever.

Title: Re: running Model T @ 2 ohms
Post by: JoeArthur on September 17, 2006, 05:24:31 pm

For most efficient power transfer, what you set the selector switch for the model T needs to match the total load of your speaker cabinets.

It will run at 2 ohms fine into a 2 ohm load.

A tube amp needs to be matched to its load - unlike a solid state amp which can put out more or less wattage depending on the load, a tube amp can destroy itself (at least it's fairly expensive output transformer) by running mismatched.

Now with that said as an official disclaimer... If you are NOT running the model T full out all the time, it does have ample output transformer capability to withstand a 100% mismatch (e.g. 2, 4 or 8 can be used with a 4 ohm load).  Lesser mismatches at 50% are even more commonplace - such as either 4 or 8 ohm amp selector into a 6 ohm cabinet.

Title: Re: running Model T @ 2 ohms
Post by: gray on September 17, 2006, 05:48:42 pm

I see, thank you. Now, since the Model T is switchable for the ohm ratings, and as I understand it, if I switch the head down to 4 ohms and use a 4 ohm load, I'm only running at half the output as 2 ohms.

Title: Re: running Model T @ 2 ohms
Post by: JoeArthur on September 17, 2006, 06:08:58 pm

Quote from: gray on September 17, 2006, 05:48:42 pm

I see, thank you. Now, since the Model T is switchable for the ohm ratings, and as I understand it, if I switch the head down to 4 ohms and use a 4 ohm load, I'm only running at half the output as 2 ohms.

NO!!!

Switching the head to 4 ohms and using a 4 ohm load will result in full power transfer!

Title: Re: running Model T @ 2 ohms
Post by: gray on September 17, 2006, 06:30:53 pm

Ah, I see! Well that's even better, actually. Thank you for your help, Joe.