4 ohm speaker in place of an 8 ohm

[Bushbaby]

Hi
I've just bought an old 100 watt 12 speaker to fit an old HH amplifier (HH Performer) as one of the twin speakers was damaged. The speaker was sold as an 8 ohm speaker but on arrival its only a 4 ohm unit! Is it all possible to wire this with is sister 8 ohm speaker and still be of use at all?

Best Regards

[ppppenguin]

Is it marked 4 ohm, or did you measure it at 4 ohms? If the latter, it may well be an 8 ohm speaker. The resistance is always less than the impedance. The impedance varies over a wide range with frequency.

2 different speakers, even of the same nominal impedance, will sound different to each other and can differ quite a lot in sensitivity.

[Bushbaby]

Hi Jeffrey
Its marked as 4 ohms. It was sold as 8 but I wished I had a closer look at the sales photo.

[ppppenguin]

Were the original speakers conencted in series or parallel? If in series then it will probably be OK with the new speaker. If in parallel, there's a risk of overloading the amp.

[Bushbaby]

This was how they wired BUT I am not 100% sure that was how it was originally set up as previous work has been undertaken on it.

   

[skyclad]

No mate they need to be a pair. The amp will need a 4ohm minimum load (two 8ohm in parallel) anything less will damage the amp.

[Bushbaby]

Many thanks. Unfortunately one of the original speakers had a tear in the cone . I saw this one on ebay and thought it would be a useful replacement albeit I did think it was 8 Ohm.

[ppppenguin]

There is no doubt your 4 ohm speaker will work. But it will be a lot louder than the 8 ohm one next to it. And as @skyclad says, it will overload the amp. Whether the amp will mind is another question. A tough amp may well stand up to this kind of abuse, especially if you don't wind it up to 11.

[Murphyv310]

Hi
I've seen band lads fit two 4 ohm speakers to these to get more output. Never come across a failure.
As Jeffrey rightly says the original 8 ohm speaker will be quieter.
The amp is a tough cookie, normally sockets and physical damage were the only issues.
Surely you are not running it at 150 Watts? Again it'll be fine at lower volumes but band lads ran them with the wrong impedance speakers and flat out, relying on the amps protection circuitry.
Breath easily Rob.

[Bushbaby]

Hi Trevor
I bought the amp thinking that there might be a chance that I might do some stage playing again when I finally retired (I didn't see £33 as a massive loss on this basis).
Yes, as I recall HH amps are pretty robust but as you indicated I'm not going to playing anywhere near fully volume - even 4 watts is too loud at home.
Best regards