Unmatched speaker and amp impedance - will this break my amp?

[admin_exported]

Hi all

For the last 12 years I've had a Marantz amp and KEF Q35 speakers. For the last 5 years I've had nothing but problems with the amp. There have been a few "dry joints" which have needed resoldering ( I was told that this can happen with overheating) and fuses which keeps blowing <- this has been the main problem.

The amp is knackered now - it required constant "tapping" to make it work and the sound quality has rapidly degraded.

The amp is rated at 8-16 ohms, 50 watts per channel and the speakers are rated at 6 ohms, 100 watts max.

I read on a website recently that having speakers of lower impedance than your amp can cause it to "overwork" and so is not recommended.

So............ I have a few of questions which I'm really interested in reading your expert views on.

1) Is this imbalance in impedance likely to have broken my amp?

2) When I get a new amp which will be rated at 8 ohms will it also get broken in time if I drive the same speakers?

3) Am I better off getting a set of 8 ohm rated speakers aswell as the amp?

Best regards, Andrew

 

[Bodfish]

I would be surprised if the combination you describe could have broken the amp.

Your new amp will not be rated at 8 ohms - the thing you need to take notice of is the watts per channel figure. Generally speaking, amps are designed to deliver more power into lower ohm loads. The 'perfect' amp will double it's output for every halving of the speakers impedence. In reality it isn't that simple but most manufacturers will use similar methods and measures to get this information.

The other thing to be aware of is that speaker manufacturers will give a nominal (average) ohm figure for a speakers impedence curve through the frequency range - it is the minimum figure you should try and be aware of (B&W, Spendor and other I'm sure others quote the nominal load as well as a minimum figure in their spec sheets).

So, in summary, (and assuming you still like the sound when the amp is working 🙂) the Kefs should not present an unduly challenging or difficult load to the vast majority of solid state amplifiers in their likely price bracket (and I'm thinking NAD, Cambridge, Rotel etc etc).