Is this correct? Peavey Bandit extension query..

usedtobe

https://www.ebay.co.uk/itm/peavey-bandit-112-transtube-with-marshall-speaker/382473133033?hash=item590d2cdbe9:g:rIcAAOSwj-BbCTsw
Says upgraded to 100w speaker (fair enough) but says you can no longer run an extension cab off the back as it is already running at full load. 
Just out of curiosity, is this correct? And, in layman terms, if so, why..?

Cheers, m' dears..

ICBM

Yes, if the replacement speaker is 4-ohm - which it might be - then you can no longer connect an extension cab.

The amp normally has an 8-ohm speaker, and is rated for 80W into 8 ohms and 100W into 4 ohms - which is the minimum. So normally, adding a 8 ohm extension speaker takes the load down to 4 ohms and increases the power to 100W.

If the replacement speaker is 4 ohm, then the amp is running at 4 ohms already, so adding an extension speaker would take the load below 4 ohms (the minimum impedance) which may damage it.

Personally, I think this is a bad idea. Unless the extension speaker jack is removed or disconnected it’s still possible to plug a cab into it, which someone could do without realising - and although Peaveys are very tough and the worst that’s likely to happen is that the thermal cutout would trip, I wouldn’t risk it. The volume difference between 80 and 100W is negligible anyway, so there’s really no advantage in doing this.

I would also want to see inside the back panel, and how the DIY power socket conversion has been done.

At £40 it’s still a bargain though, you could easily fit a better speaker if necessary.

usedtobe

Thanks @ICBM ;

Funkfingers

ICBM said:

At £40 it’s still a bargain 

Think of the auction as being for a Marshall/Celestion loudspeaker with a free Peavey amplifier attached.

Out with the 4 Ohm 'speaker. In with an 8 Ohm 'speaker to suit your tastes and wallet. Possibly, sell the Marshall/Celestion to finance its replacement.

ICBM said:

I would also want to see inside the back panel and how the DIY power socket conversion has been done.

It would be nice to have the original semi-closed rear panel sections. Ideally, the mains socket should be fastened through something firmer than hardboard. e.g. The metal chassis of the amp.

ICBM

Funkfingers said:

It would be nice to have the original semi-closed rear panel sections.

This version doesn't have an upper panel as standard - or even any battens up the sides of the cabinet to hold one, so those must be additions too.

Funkfingers said:

Ideally, the mains socket should be fastened through something firmer than hardboard. e.g. The metal chassis of the amp.

Exactly. And not with the back of the socket probably left exposed so if the panel is pulled off, you could touch the live terminals...

thomasw88

Thought I'd revive this thread..

Bought a red  stripe (china) bandit last night for not much money.  Had the volume dropping thing so sprayed some contact cleaner in all the jacks and voila it works and sounds really good.

It has the no label speaker in it. I do have  4 ohm speaker which I was wanting to try.  From reading this and other stuff I'm fine swapping the two speakers over and then just not using the extension socket ie tape it off?

Is that correct @ICBM ;?

ICBM

Yes. The extension speaker jack is in parallel with the speaker on these, minimum total load is 4 ohms.

(On the Studio Pro it disconnects the internal speaker so you can’t use a 4-ohm speaker.)

thomasw88

ICBM said:

Yes. The extension speaker jack is in parallel with the speaker on these, minimum total load is 4 ohms.

(On the Studio Pro it disconnects the internal speaker so you can’t use a 4-ohm speaker.)

Thank you.

Yorkie

Interesting! What about speakers with lower power rating (40-60w for instance) but higher impedance (16 ohm)? Would those be suitable?

ICBM

Yorkie said:

Interesting! What about speakers with lower power rating (40-60w for instance) but higher impedance (16 ohm)? Would those be suitable?

Yes - 50W or more at 16 ohms would be safe.

With the usual caveat about some manufacturers' ratings being less conservative than others, anyway.

Yorkie

Must be the first time physics has been on my side. I could get used to this.