Is this right?

[Benplaysbass]

I'm after some advice here folks. I've searched through the forum and found lots of info but thought I would just ask and see what replies I got.
My amp is a pretty cheap 'Indie guitars' 100 watt combo, nothing too grand but out here gigs are mostly in bars and bistro/cafe's. The speaker in the amp is what can only be described as RUBBISH. the amp just over powers it. I've taken it out and there is no make or ohms or anything on it, but can just make out that its 140watt. The amp itself says 100watt and where the jack for the speaker is says 4ohms min.
So would I be right in thinking that the speaker in it is likely to be an 8ohm speaker and the amp not running at full power?

I've found a Celestion speaker thats 150 watt at 8ohms, would this mean the amp is running at 75%? and if it was could I attach another small cab to bring it down to 4ohms and get the 100 watts? and what wattage speaker would be ok in a small cab? If it would work I'd make the cab myself. Can't afford a new amp at the moment so just trying to make the most of what I've got for now.

Ben.

[Mr. Foxen]

The watts don't mean much to anything. Better getting an extension cab in gear for sale, be cheaper, and work better unless you get serious with your cab making and follow designs.

[Benplaysbass]

So as long as the ohms are right its not really that important on the wattage for the extension cab? As long as its not too high.

[GarethFlatlands]

The speaker currently in your amp isn't necessarily 8 ohms, you could buy/borrow a multimeter and check it if you really wanted to know. It may well be 4 and just a terrible speaker which is why you're struggling to hear yourself. If it is a 4 ohm speaker and you add an 8 ohm cab, you'll be running at 2.66 ohms and risk damaging your amp (1/8 + 1/4 = .375, 1/.375 = 2.666).

Seems like the easiest solution to me would just be to replace the current speaker with an 8 ohm Celestion or other quality speaker with a high sensitivity if it's more volume you're after. This should help your sound cut through more and you can add the extra 8 ohm cab afterwards if you still need to push more air.

Edit:- You can mix and match speaker wattages, remember that the maximum you can push into them is the wattage of the lowest rated speaker * the number of speakers. My guitar cab runs 2 Celestions , a Hot 100 (100 watts) and a Vintage 30 (60 watts) so it can handle 120 watts total.

Edited February 16, 2011 by GarethFlatlands

[Mr. Foxen]

Sticking another speaker in the combo box might not help at all, the cab tuning could be all wrong for it, or if it is sealed, just totally choke the speaker.

You can't have too high watts. Sensitivity is sort of an important spec, tells you how much volume you get from your amp watts.

[Benplaysbass]

The cab does have a couple of ports in the back with a plastic tube thing in each hole.

[chris_b]

So you've got a 100 watt amp which had a socket for an extension speaker? That means your amp is 100 watts into 4 ohm or about 50 watts into the 8 ohm internal speaker.

If that's the case then I'm surprised that the speaker is 140 watts as it's only going to take 50-60 watts from the amp at 8 ohm. Cheap amp manufacturers are not normally generous enough to over spec anything! Is this the original speaker or has it been changed? Maybe your speaker has just blown?

The internal speaker should be 8 ohms so any replacement of the same size sounds like it will be an improvement, even if it isn't sonically matched with the cab.

[Benplaysbass]

It doesn't have a socket for an external cab...yet. was thinking that if the internal speaker was 8ohm and the amp says 4 minimum the I could potentially add another cab. Its never going to be that great but maybe the cheapest option for now. Going to pull the speaker out and test the ohms.

Edited February 17, 2011 by Benplaysbass