Or120 too much for 120W cab?

[vitja]

Hi there!

I finally got my hand on proper Celestion G12H Blacbacks from 70's.
So this speakers are 30W Each, that makes 120W in 4x12 configuration.

How safe is to run my OR120 near max power? It this a potential risk for blowing my new celestions?
I have a Master volume mod, but I rely like the amp on max, no master volume at all.
I know that Or120 is like 120Watts of clean power. This is something that my amp tech told me. So if I run Drive to max and no master volume attenuation… how much power does OR puts out?

I really like the sound of this blackbacks!

Thanx for any help!

[fiveightandten]

There is a risk. You aren't guaranteed to blow the speakers, but the 70's amps are strong and put out a lot of low end. I run speakers at their limit all the time, but I personally wouldn't run old speakers that hard.

You can run the amp on two EL34's. There's not that much of a decrease on volume, but it will ensure your speakers are safe. You sacrifice a bit of fullness or girth in the sound, and a bit of headroom. But the amp still sounds fantastic running on 2 tubes. This is EXACTLY what an OR-80 is. It's just an OR-120 without the extra 2 tube sockets.

-Nick

[jontheid]

My 70s Orange can chuck out 165 Watts clean with a fresh set of EL34s in it . . .

[Gladmarr]

Yeah, full tilt an Orange OR120 can put out more than 120 watts for sure. I run a quad of G12-H30s in my favorite 4x12 cab, but that's because I can always buy another set of these speakers if I blow them. I've never had any problems with this setup, but I'd be a lot more nervous about it if my speakers were irreplaceable.

[vitja]

Yeah, I was thinking to pull two tubes out and rebias it and Ohm compensation…

How do I know that speakers are working too hard???

And I if I blow a speaker is there a chance to blow the amp to, if I'm on a concert rocking hard and I have no idea that this is happening???

Is it maybe a better idea to play some more durable speakers for live shows?

[fiveightandten]

Yeah, I was thinking to pull two tubes out and rebias it and Ohm compensation…

How do I know that speakers are working too hard???

And I if I blow a speaker is there a chance to blow the amp to, if I'm on a concert rocking hard and I have no idea that this is happening???

Is it maybe a better idea to play some more durable speakers for live shows?

You could potentially damage the output transformer, but in practice it would likely be ok. Those are good speakers, and you will be completely safe running the amp with 2 tubes. I would do that. Enjoy the speakers and the amp.

You can try it out without rebiasing. It won't creep up much. It's a good idea to check the bias after pulling two tubes, but it makes very little difference. The bigger reason to do it is to pick which 2 tubes you want to run.

As an added benefit, the amp is cheaper to use, and you also have a backup tube set that you can replace without the need to rebias the amp. I used to do this with my 50W amps. I'd buy a matched quad of power tubes, and keep the unused pair as a backup set at gigs. If a tube goes down, you can throw them right in.