marshall avt 50 connecting to 4x12 cab

Megadeth45 · Groupie Joined: 06 Feb 2005 Posts: 34

hey i have a marshall avt 50 and they'res a headphone out jack--is this what i would use to connect it to a marshall 1960B cab?

1bassleft · Posted: Fri Feb 17, 2006 12:39 am Post subject:

Only if you're planning on a very quiet gig. The headphone jack cuts the power amp to the combo's internal speaker and will feed all of 1 Watt to your 1960 (which is not a powered cab). If you think about it, you wouldn't want headphones pumping 50W directly into your ear'oles.

Have a look at the back panel of the amp section of your combo. Next to the cooling fan vents, before the DI out and FX s/r, is an extension speaker jack. It's coloured red and has the charming advice, "WARNING, risk of hazardous energy." This is the socket you'd plug the lead into from your 1960 and everything will work nicely.

The reason for the shock-horror warning is straightforward enough. The jack lead from your guitar to the amp is carrying a minute thimble of current from the pups, so you can touch it all you like. Once amplified to 50W, it's packing a fair old current; enough to turn all those driver magnets over. If you pull the lead out of your extension cab and stick your thumb over the lead tip, you'll get very unpleasant confirmation. I was stupid enough to do exactly that back in my teens.

Just make sure that you have connected up the speaker to the amp before switching on, and switch off before unplugging the lead. This is good policy for valve or SS amps and a habit worth getting into. Because the overall impedance of your combined speakers will be reduced (I'm assuming the internal speaker will still be receiving) the output will be louder.

1bassleft · Posted: Fri Feb 17, 2006 12:47 am Post subject:

ps, don't use an ordinary instrument cable to connect your 1960B to the combo's speaker out. You want to get (if you don't have one) a jack lead specifically for amp to speaker cabinet. It should be unshielded and of a thicker grade to cope with the extra horses galloping along it. Any guitar store worth its salt will have some. Make a note of which is your cab lead, and only use it for that. There's no risk to yourself from using cab lead to connect your guitar to the amp but, being unshielded, you will hum like Paula Radcliffe's running knickers if you do.

lee_UK · Posted: Fri Feb 17, 2006 9:59 pm Post subject:

Have you ever heard 1 watt at full tilt? it can be pretty hair raising.

Megadeth45 · Groupie Joined: 06 Feb 2005 Posts: 34

hey thanks guys, i thought thats what the red plug in the back was for, only thing is the speaker cable is so short (running from the speker in teh combo) that to unplug it i think i might have to unscrew the back of the amp.

1bassleft · Posted: Sun Feb 19, 2006 4:14 am Post subject:

Quote:

only thing is the speaker cable is so short (running from the speker in teh combo) that to unplug it i think i might have to unscrew the back of the amp

No, no no, mate Exclamation

Leave that one as is. What you need to do is pop along to the guitar shop and buy yourself an amp-speaker cab lead with 1/4" jacks on each end. Just in case they don't understand, tell them you want an unshielded, heavy duty lead. Try not to get it overlong as this will have an effect on quality; 10ft should be ample really.

Leave your cable running from the combo connected and certainly don't start unscrewing the back of the amp. Warranty and death issues abound and there's just no need. By leaving your combo speaker connected, you will get an increase in output and you can use the combo driver as a monitor and point the 1960 at the audience. I don't think the problem of the amp struggling to drive all the speakers is too much of an issue. Marshall's site reckoned that any of their extension cabs could be used.

Lee, I know that 1W full-tilt is still 1/10th of a 100W amp on full bore but c'mon, where do you do your gigs? The Women's Institute? Razz

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