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6 ohm Speakers into 8 ohm amp?

jonny round boy

Established Member
I've been looking at several options for new speakers to wall mount around my LCD tv, both seperates & all-in-one packages. Not being able to find exactly what I want (aesthetically), I'm thinking of going for the Tannoy EFX5.1 speaker set.

Trouble is, they're 6 ohm speakers, and my old Sherwood amp specifically states on the back 'use min 8 ohm speakers'. If I connect the EFX5.1's to it, will it damage the amp? If not, what other problems might it cause?

I also looked at the older FX5.1's (which are 8 ohm), but wanted the wider centre speaker.

As you have no doubt gathered, I'm a bit clueless on this kind of thing...:confused:

Thanks in advance.
 

alexs2

Distinguished Member
Have a read here for an explanation of Ohms. http://www.marktaw.com/recording/Electronics/OhmsAmpsandSpeakers.html you should be fine using 6ohm speakers as they should put less of a strain on the amp.

Whilst the amp will likely have no problems at all with 6 ohm speakers(given that many nominally 8ohm speakers drop well below that at certain points),the above statement is not true.

As you decrease the impedance of the load,the current demands placed on the amplifier increase,and thus actually increase the "strain" on the amp,and this is why many manufacturers will not rate their products for use with 4 ohm loads or lower,and most cannot double the power output as the impedance halves(as would be the case with an ideal current source).
 

jonny round boy

Established Member
OK, well I've done a bit of checking, and the amp is rated at 30W per channel (with an 8 ohm speaker). So would I be right in assuming that a 6 ohm speaker would be trying to draw 45W for the same volume? If so, does that mean that the amp would reach it's limit at 2/3rds of the volume it does now?

Does the above make sense (at least in theory)? Or am I completely misunderstanding the physics?
 

alexs2

Distinguished Member
OK, well I've done a bit of checking, and the amp is rated at 30W per channel (with an 8 ohm speaker). So would I be right in assuming that a 6 ohm speaker would be trying to draw 45W for the same volume? If so, does that mean that the amp would reach it's limit at 2/3rds of the volume it does now?

Does the above make sense (at least in theory)? Or am I completely misunderstanding the physics?

It makes sense up to a point,in that if the amp is seriously limited in terms of current delivery,it may not go much above 30-40W into a lower load.

I would think it will probably work fine,but it's best to ensure that it doesnt get hotter than normal when you try it out first.
 

jonny round boy

Established Member
Thanks for that. TBH I've not got a clue when it comes to audio - I'm tone deaf, and could happily listen to crackly MW radio all day....

I'm thinking I need a new amp now, too - all the gear I have came with the girlfriend :smashin: so I don't really know much about it. Since my original post I found a review for my amp, and I didn't realise what a cheapo POS it is!!! Her indoors reckoned it was fairly decent, but it could be better. She also insists the tannoy 632's are really good, but I think they're far too big & need replacing (as you can probably tell, I'm far more interested in how things look, rather than how they sound). Oh well. Never mind. :rolleyes:
 

jonny round boy

Established Member
Are you medically tone deaf ie unable to hear the relative difference between musical notes or even melodies

Err, no, I don't think so. I was just using 'tone deaf' in the non-medical sense, meaning that I really can't tell the difference between a cheap set-up & a decent one. I can tell the difference, for example, between having the sound through the TV and having the amp/speakers on, but not between my set-up and any other.
 

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