How robust are G12 H speakers?

Cirrus

I've got an old Blackback G12H from the '70s.

I also have a 30 watt amp.

I'd happily run a cranked 15 watt amp into a 15 watt Celestion Blue all day and if ever blew just chalk it down to bad luck.

I'd be less happy to run a cranked 25 watt amp all day into a single G12-m25 Greenback.

Where do G12H 30 watters fall in this spectrum of robustness?

ICBM

My experience is that they're a bit more robust than the G12M-25 - it would normally be safe with a 30W amp - but with an old speaker like that I probably wouldn't risk pushing it too hard anyway.

Dr.Z thinks it's OK to fit a modern one in a 38W amp, but having seen one of those amps with a blown speaker, I disagree…

It also depends on the amp. Some 30W amps don't put out that much more than 30W even cranked, others do - a lot of it is down to the bias setup, cathode bias produces more compression and less peak power than fixed bias. You can put a pair of Blues in an AC30 and crank it all day long, but try that with a Marshall Bluesbreaker and you'll probably blow them.

Cirrus

That's fair. Well, the amp is a Genz Benz Black Pearl which has pretty much the same power section as an AC30. I was going to try it out in there just to give it a proper go, but there's no point putting a speaker in there I'm not comfortable diming the amp into.

Bygone_Tones

General rule of thumb I go by is that the  amp should be half the power rating of the speaker.

Im not sure what the deal is with the reissue vox blue, but I would be pretty sure it can handle a lot more power than an original. So the 15w rating is probably more about appearances and having it look authentic to the original rather than being its actual power rating. Same with the Heritage G12M at 20w.

breadfan

ICBM said:

You can put a pair of Blues in an AC30 and crank it all day long, but try that with a Marshall Bluesbreaker and you'll probably blow them.

@ICBM ;How much power would a cranked Bluesbreaker put out?

I'm running a Bluesbreaker style head into two Tayden Ace 25 speakers.

Am I risking damaging them by cranking the amp?

ICBM

breadfan said:

@ICBM ;How much power would a cranked Bluesbreaker put out?

I'm running a Bluesbreaker style head into two Tayden Ace 25 speakers.

Am I risking damaging them by cranking the amp?

Good questions…

I haven't measured one for a while, but from memory 45-50W. Whether your amp does depends on whether it uses the same spec transformers as Marshall do.

Whether the speakers will take it depends on how conservative Tayden are with their ratings - I have no experience of them. But different companies can be *very* different - Celestion are the most conservative, and their 25W speakers will basically take a cranked 25W amp. Other companies like Fane rate them for more like the actual electrical power input, which can be up to double the amp's clean power, so you would need 50W speaker for the same 25W amp.

My guess is that you're probably safe with that combination, since at worst it's likely to be 50W into 50W… but I can't be sure.