Speaker change

[knuckleberryfinn]

So I'll be getting a new speaker delivered tomorrow, but I am a bit concerned by talk of the necessity of draining caps. I won't get zapped unless I remove the chassis, but will removing the speaker load potentially damage the amp? Perplexed again by these infernal boxes...

[Cirrusband]

No. As long as you've turned the amp off you're in no danger at all from filter caps etc while changing the speaker. Just make sure you've got the right impedance speaker and that you wire it the right way round!

[ICBM]

As long as the amp is not powered up there is no risk from removing the speaker load. Usually, you have to have it fully on (standby switch to 'play') for there to be any danger even with it powered up. There's no risk from the filter caps unless you open the chassis, no.

Never be afraid to ask what with hindsight sounds like a foolish question, by the way. It's far more foolish to damage something (or yourself) because you were too embarassed to ask, and everyone has to start learning somewhere.

I started my learning about filter caps by giving myself a nasty shock while the amp was turned off and unplugged from the wall. I assumed it was safe... I was familiar with low-voltage solid-state circuits where the only dangerous part is the mains power side, so it was quite a shock in the other sense too.

[Dave_Mc]

Never be afraid to ask what with hindsight sounds like a foolish question, by the way. It's far more foolish to damage something (or yourself) because you were too embarassed to ask, and everyone has to start learning somewhere.

agreed

[ESBlonde]

Never be afraid to ask what with hindsight sounds like a foolish question, by the way. It's far more foolish to damage something (or yourself) because you were too embarassed to ask, and everyone has to start learning somewhere.

This in spades, they do say the only stupid queston is the one you didn't ask. We are all still learning and the only people not making mistakes are those not doing anything.

[ecc83]

This in spades, they do say the only stupid queston is the one you didn't ask. We are all still learning and the only people not making mistakes are those not doing anything.

Abso very lootley!

As one who spent 10 years or more teaching Joe Public (with varying degrees of success!) how to operate video recorders and then TVs when they got more complex, I have developed infinite patience.

I really do not mind answering the same basic questions, time after time, so never be afraid to ask!

Dave.

[knuckleberryfinn]

Okay, that's a relief to know. On the Watford Valves site there is a safety notice at the foot of every speaker page saying that all residual voltages should be drained, which implies that even disconnecting a speaker requires this. I suppose they are just covering themselves in case someone is tempted to open an amp up and poke about. I blew myself off stage with an AC30 during a soundcheck about 15 years ago (i had fixed a dry joint with a kit kat wrapper!) and have been cautious ever since.

I recently tried reading Valve Amplifiers by some ex-BBC engineer (I forget his name) to get my head round it, but the basic physics in the first chapter was too much for me. Damn my brain. But hopefully I'm getting somewhere. Thanks again for your help.

[mctoot]

I recently tried reading Valve Amplifiers by some ex-BBC engineer (I forget his name) to get my head round it, but the basic physics in the first chapter was too much for me. Damn my brain.

Not just you buddy. At the end of 3rd year (now year 9) I was begged not to choose to take physics O'Level... by my physics teacher... I'm not better now, 30 years later.

[p90fool]

I recently tried reading Valve Amplifiers by some ex-BBC engineer (I forget his name) to get my head round it, but the basic physics in the first chapter was too much for me.

Shame, the correct substitution of Polo wrappers for Kitkat foil is covered in chapter 4.

[bertie]

This in spades, they do say the only stupid queston is the one you didn't ask. We are all still learning and the only people not making mistakes are those not doing anything.

that in snow-shovels