No Longer FS Celestion G12 Vintage 30 4 Ohm

dogload

I have a pair of these speakers that used to live in a Trace Elliot Super Tramp combo. The amp died and I had thought of using it as a cab for my Selmer head, but of course they are the wrong impedance. 

So as far as I can tell these are in full working condition, 12" Vintage 30s. I did a bit of a web search for info/ prices etc. but couldn't find out much apart from the fact that these aren't made anymore. 

photek

Does your Selmer not have an 8 ohm out?

dogload

It's got these:

:

ESchap

 

You could use them.  Just wire them in series giving an 8ohm load and go into the 7.5 ohm input on the Selmer.

dogload

Would 50 watts not pop the speakers in series? 

(I know nothing about such things!)

ESchap

Vintage 30's are actually 60 watt (RMS) each http://celestion.com/product/1/vintage_30/ .  You'll certainly be safe with a 50 watt T&B.  

Parallel or Series connection shouldn't make any difference to the combined power rating if the speakers are the same type.  The danger with series connection is that if one speaker goes down, the amp has no load ... i.e. bad for the output transformer, turn off immediately.  With parallel it has at least the load of the functioning speaker.

Nothing to lose by trying it, save you selling what might be for you the ideal speaker arrangement for that amp.

ICBM

The combined power rating is 120W either in parallel or in series, so there's no chance of the amp being a risk to them.

Probably better to keep them since 4-ohm speakers aren't really that useful usually, at least not individually, and hence might not fetch much.

[Technical aside] I have to disagree slightly with ESchap about the 'danger' with series connection - really, there's just as much danger, if not more so, with parallel. In parallel, if one speaker fails - which means that the amp must be supplying enough power to potentially blow either of them, if they're the same rating - then the remaining speaker will be taking even more power, and will fail even more quickly. Result: *two* dead speakers and no load on the amp...

The last three 2x12" combos I have replaced blown speakers in had both (parallel) drivers blown.

Series at least protects the unblown speaker, and you will notice *immediately*, as opposed to thrashing away even harder wondering why your amp isn't quite as loud as it was! [/Technical aside]

ESchap

ICBM said:

The combined power rating is 120W either in parallel or in series, so there's no chance of the amp being a risk to them.

Probably better to keep them since 4-ohm speakers aren't really that useful usually, at least not individually, and hence might not fetch much.

[Technical aside] I have to disagree slightly with ESchap about the 'danger' with series connection - really, there's just as much danger, if not more so, with parallel. In parallel, if one speaker fails - which means that the amp must be supplying enough power to potentially blow either of them, if they're the same rating - then the remaining speaker will be taking even more power, and will fail even more quickly. Result: *two* dead speakers and no load on the amp...

The last three 2x12" combos I have replaced blown speakers in had both (parallel) drivers blown.

Series at least protects the unblown speaker, and you will notice *immediately*, as opposed to thrashing away even harder wondering why your amp isn't quite as loud as it was! [/Technical aside]

I was on the side of the Output transformers, not the speakers! 

ICBM

ESchap said:

I was on the side of the Output transformers, not the speakers! 

In a well-designed and built amp, the valves are more at risk than the OT - and it should have an HT fuse too which will pop before anything bad happens to the amp... in theory!

Anyway, which is cheaper to fix if one of your speakers is a Blue or a Gold?!

dogload

Thanks for the info chaps. I'll try them in series then.

I guess I'd better un-for-sale them!

Yet again, I've learned something useful.

ESchap

Hope it works out for you. I shouldn't have been facetious re the serial / parallel. @ICBM is if course correct. The motto is if you lose all or a lot of volume suddenly ... Turn the amp off fast.