Mixing different ohm speaker & amp

[ladyjan]

Hello,
I have a 150 watt amp 8ohm and got two 6ohm speakers, I connected at first on very short cable, as they had been cut before, then joined lonker speaker cable, then at first connected just one speaker to test while I finished the other cable, it started to smoke, I quickly turned all off and diconnected the speaker, it smelt burnt and guess it no good now, but am asking if you think it might have damaged the amp?? it turns on and the led lights but don't want to risk another speaker just in case it blows the amp..if it isn't already..
so my question is ..will it be just the speaker that's damaged or do you think it's the amp as well...???thx

 

[astrallite]

Well if the amp is smoking it seems to me it indicates the amp got owned, not the speakers...

 

[ladyjan]

I'm not sure if the smoke was coming from the back of the amp or the speaker as they were very close, and it was only on for about 15 secs and I did not power up much only about 5 % and the amp did not smell at the back at all, only the speaker..?¿?¿
if the amp was damaged wouldn't the amp smell burt as well?¿?¿
also if the amp is damaged, do you reckon it would be major damage?¿?
also would the amp still be able to start at all, as the clipping switch was on and wouldn't that burn the fuse first ?¿?¿?
sorry being a pain asking many questions, but I just really hope I haven't stuffed the amp..

and lastly..fingers crossed and the amp is fine..should I only use 8 ohm speakers with the amp or can I use different value and could it be because I only plugged only one speaker at first the reason for the damage...¿?¿?¿?

thankyou

 

[astrallite]

Amp damage is usually due to improper connections or stray wires touching each other. If the speakers are burning then the crossover network got cooked.

What speakers and what amp are you using?

 

[Guest]

The smoke you enjoyed was possibly poor wiring on your part and more likely to have damaged the amp than the speaker.

Test the amp with a pair of headphones (assuming it has a socket for them). If they work at least part of the amp is okay.

Test the apparently damaged speaker with a multimeter (every household should have one).

You set the the meter to Impedance (the Omega symbol) and in the low range . Put the two probes on the two speaker terminals and it should register around 8 ohms. If nothing or a short circuit (zero ohms) it's probably fried.

You can test the speaker cable in a similar manner.

 

[ladyjan]

okies found the multimeter after a noisy rumage on the balcony..! it's 4:18 am here.
zero on the speaker..but I'm not so worried about that as I got it 2nd hand and didn't cost a great deal it's the amp I'm more worried about..

and yes the wiring didn't help I suppose, as it was a different thickness cable..the speaker cable was finer than the connecting cable I used to extend it.

but on the amp at the terminal connectors for the speakers the both read 8 ohms..
I haven't got a large jack for the phones only mid so will have to wait for the morn to get adapter..
but do you reckon the amp should be ok as the reading is still 8 ohms.. (plz say yes).!

The amp is an NAD Stereo amplifier 3225PE power envelope, 150 watt with an impedance that I can adjust 8 ohm or 4 ohm
so which speakers would you reckomend best to use..??
and thanks for replying to me on this.

 

[astrallite]

To comply with FTC guidelines a lower ohm mode is included. All it does is roughly limit power output by half, nothing more than a brick wall filter. Stick to 8 ohm mode for full output. It has no actual relation to powering different types of speakers.

The NAD 3225PE is a 25Wx2 integrated amplifier.

If you turned up too high at some point, it would have cooked the speakers because the amplifier would be clipping and sending a highly distorted signal. If you managed to run it at a high volume level continuously then most likely the amp started cooking.

A bit earlier it was around 100F in my room and if I turn up the volume beyond 25% the my receiver's protection circuit kicked in and shuts down. After I turned on the air conditioner and it got down to around 90F the circuit breaker stopped kicking.

 

[ladyjan]

To comply with FTC guidelines a lower ohm mode is included. All it does is roughly limit power output by half, nothing more than a brick wall filter. Stick to 8 ohm mode for full output. It has no actual relation to powering different types of speakers.

The NAD 3225PE is a 25Wx2 integrated amplifier.

If you turned up too high at some point, it would have cooked the speakers because the amplifier would be clipping and sending a highly distorted signal. If you managed to run it at a high volume level continuously then most likely the amp started cooking.

A bit earlier it was around 100F in my room and if I turn up the volume beyond 25% the my receiver's protection circuit kicked in and shuts down. After I turned on the air conditioner and it got down to around 90F the circuit breaker stopped kicking.

But do you think it might be damaged as the ohm reading on the speaker conector points are all still reading 8 oms..??
I can get an adaptor plug when the shops open but am anxcious to know if I've buggered it..?¿?
on the model details it says it's 150 w or is that what 25W x 2 puts out in total power output or is it 50W total power output..??
also what speakers would you recommend I get..??

an yep we had it exreemly hot here during august, we had temps up to 46 degs in the shade..unbearable.and equipement was giving out all over the place...

 

[astrallite]

I recommend you get a pair of very efficient speakers that do not require much power to run. I would look at Klipsch speakers.

 

[Guest]

"But do you think it might be damaged as the ohm reading on the speaker conector points are all still reading 8 oms..??"

I didn't suggest you measure the amplifer, just the speakers.


As I suggested play some music and test that the headphone socket is delivering on both channels.

If all is well with the headphones maybe connect up the speaker you think is still working of the pair that may have been damaged. Connect to the speaker channel you think might have been affected -- and then to the other. Keep volume low. Turn off the power between tests.

If there's no more smoke and the thing sounds okay go ahead and buy some new speakers.

The NAD is a nice amplifier and deserves some decent hifi speakers so be prepared to spend some money. If you make it clear to the retailer that the amp is 25 watts per channel that's all they need to know, really. Most speakers are 8 ohms, sometimes 6 ohms.

My personal preference is for european designed speakers like KEF or Bowers & Wilkins, but really you should listen to what's on offer and let your ears decide -- then worry about the money!

 

[ladyjan]

Thanks guys, very kind for your help, I'll let you know how I get on, gonna get the adaptor for the headphones and fingers crossed..
I really hope it's gonna be ok..
thx Jan

 

[ladyjan]

oh dear bad news. was humming badly on left channel and started smoking with zero vol.
unplugged immediately and off to repair shop.

But what do you reckon it is, I know it's burnt *something* but what would that *something* be...?
any ideas and is it major or is it repairable?¿?¿?
and do you reckon it will be expensive...?
and should any good pro shop be able to do it with universal parts or would they have to come from NAD..?
coz I live in the Canary Islands Tenerife and suppose it may be hard to get original parts, dunno?¿?¿?

sorry so many questions..
Jan

 

[Guest]

Output transistor. Maybe just a resistor. Most parts like that are generic.

However a lot of amps use branded integrated circuits (often made by the big Japanese brands Hitachi, Sony etc) and that may be a little harder to source if the amp is as old as I suspect -- early 1990's ?

And you choose to live somewhere idyllic like the Canary Islands (dammit)!

No job like this is cheap because there's disassembly, diagnosis, procuring part, putting it in, testing etc. A good repair man will probably also replace some parts which age badly, like capacitors.

Make sure you get a quote, because it may be cheaper to replace the amp, especially as it could always fail again through sheer age.