[Gary Brenton]

Not sure if this is posted in the correct place...but here goes.

I recently purchased a replacement amplifier - just a bog-standard cheap model until I purchase something better.

The amplifier is an 'Eltax acura-70' of which has several inputs...unfortunately I have noticed that when using this amp, my FM tuner suffers badly on interference.

This issue has taken two weeks to realise what was causing the problem - of which was the amplifier.

I have plugged in my Sansui amplifier at the moment and the FM radio reception is fine...but as soon as the Eltax is plugged in, the FM reception is very poor.

I am racking my brains as to understand why?

The only logical explanation (and I may be wrong here) but I have noticed that the Sansui amplifier has a live, neutral and an earth....whereas the 'Eltax' only has a live and neutral, so I am wondering if the interference is caused by the amp not being earthed?

This is the very first time I have used an amplifier of which has caused interference to an FM tuner.

[David Waine]

I am no electronics expert, but I suspect you have hit the nail on the head. In hi-fi, it is normal to earth everything through the amplifier, but if it has no earth, how can you?

Can you describe the interference? If it is a low-pitched hum, it is most likely an earth loop and you would need advice from someone much better qualified than me. If it is crackling static, you are picking up interference from nearby electrical devices. Fit them with suppressors if you can. If it a twittering sound in the background, you have the birdies, which means that the signal is too strong for your amp. Fit an attenuator to the input. That should sort it out.

Sansui was a highly-respected hi-fi maker in the '70s and '80s, but then they disappeared. By coincidence, I read last week that they have just returned. Eltax has always been a bit of a budget brand. If your Sansui amp is still in full working order, I doubt whether the Eltax will outperform it.

[Andy2]

Maybe the new amp has a switch-mode power supply instead of the traditional linear type. SMPS's are known for causing radio interference, although it is usually worse on AM.

[Chris Frost]

^^^ wot he said

I have the same problem with a PC and clock radio at home. Stick the Eltax back on Ebay and buy something like an old Rotel/NAD/Creek - a traditional Hi-Fi amp with a proper transformer power supply.

[Winston_1]

Don't put it on eBay. It is not fit for purpose so take it back as faulty for a refund. Your neighbours could be suffering interference as well.

[Nigel Goodwin]

Quote:

Originally Posted by Winston_1

Don't put it on eBay. It is not fit for purpose so take it back as faulty for a refund. Your neighbours could be suffering interference as well.

As you don't know the circumstances you've no way of knowing if it's 'not fit for purpose' or not, or indeed even if he bought it new or second hand. Presumably this is another example of your paranoia normally directed at 'homeplugs'?.

The 'fault' could just as easily be insufficient and poor signal on the FM tuner, and the amp could just as easily be operating perfectly within specification and regulations.

For those that suggested it 'could' be a switch-mode PSU, it could just as easily be a class-D amplifier as well.

[Chris Frost]

Quote:

Originally Posted by Winston_1

Don't put it on eBay. It is not fit for purpose so take it back as faulty for a refund. Your neighbours could be suffering interference as well.

Unless the OP has a Tardis then what you suggest might me a tad tricky.

I checked before posting my original reply. Could find none new for sale; only used ones. Maybe you know different? Post us a link if you do. The other thing is that the OP never said it was bought new.... Just cheap.

[Andy2]

Quote:

Originally Posted by Nigel Goodwin

As you don't know the circumstances you've no way of knowing if it's 'not fit for purpose' or not, or indeed even if he bought it new or second hand. Presumably this is another example of your paranoia normally directed at 'homeplugs'?.

The 'fault' could just as easily be insufficient and poor signal on the FM tuner, and the amp could just as easily be operating perfectly within specification and regulations.
For those that suggested it 'could' be a switch-mode PSU, it could just as easily be a class-D amplifier as well.

If the problem is poor signal, why does the OP only get the interference with the new amp in service? It's obviously generating some kind of hash, so it is unsuitable, either by poor design or through a fault.
As for the class-D amp idea, that is entirely possible but a switching amplifier should not radiate hash either.

[Nigel Goodwin]

Quote:

Originally Posted by Andy2

If the problem is poor signal, why does the OP only get the interference with the new amp in service? It's obviously generating some kind of hash, so it is unsuitable, either by poor design or through a fault.
As for the class-D amp idea, that is entirely possible but a switching amplifier should not radiate hash either.

Switch-mode PSU's, class-D amplifiers (and everything else for that matter) have to meet specific regulations about generated interference.

The issue of poor signal could easily cause interference even if the amplifier met the regulations, as the receiver (and signal strength) also have to meet specific targets.

This is why we can't say for certain what or where the problem is.

[Andy2]

Quote:

Originally Posted by Nigel Goodwin

Switch-mode PSU's, class-D amplifiers (and everything else for that matter) have to meet specific regulations about generated interference.The issue of poor signal could easily cause interference even if the amplifier met the regulations, as the receiver (and signal strength) also have to meet specific targets.

This is why we can't say for certain what or where the problem is.

They are supposed to meet specific regulations. In real life, many don't come anywhere near. So it could easily be that the new amp is radiating stuff it shouldn't. We don't know.
My PC psu wipes out everything from 2 MHz to about 7 MHz plus several frequencies on MW, because the makers thoughtfully omitted the chokes and capacitors on the mains input (I looked). I had to make my own filter to stop the racket escaping. And guess what - the PSU carries a CE mark. What a crock it all is.

[Nigel Goodwin]

Quote:

Originally Posted by Andy2

And guess what - the PSU carries a CE mark. What a crock it all is.

The CE mark is self certifying

And from personal knowledge Chinese manufacturers will happily apply CE stickers to any product for the cost of the sticker, no tests needed or done

However, this doesn't mean the item in this case doesn't comply, none of us have any way of knowing.

[jackpot lewis]

I always thought that the interferance would have been caused by poorly screened wiring?

[Dino]

Quote:

Originally Posted by Nigel Goodwin

And from personal knowledge Chinese manufacturers will happily apply CE stickers to any product for the cost of the sticker, no tests needed or done

Chinese manufacturers have been known to stick on a China Export mark which looks very similar.

http://www.ybw.com/expert-advice/vhf/news/509220/warning-don-t-get-confused-between-the-ce-mark-and-the-china-export-mark

[chrisbartley]

Quote:

which looks very similar.

Sheer co-incidence I'm sure

[Nigel Goodwin]

Quote:

Originally Posted by Dino

Chinese manufacturers have been known to stick on a China Export mark which looks very similar.

Doesn't really matter - they will stick a 'proper' CE sticker on for nothing more than the cost of the sticker

[Orbitalzone]

Yeah those Crafty Chinese (and others) have no qualms about putting certification on things that have never been tested....same with quoting specifications on products where they've hacked a cpu/memory or whatnot and made it appear faster/bigger than it really is.

[davidseven]

Quote:

Originally Posted by Nigel Goodwin

The CE mark is self certifying

And from personal knowledge Chinese manufacturers will happily apply CE stickers to any product for the cost of the sticker, no tests needed or done

However, this doesn't mean the item in this case doesn't comply, none of us have any way of knowing.

CE = China Exempt.

[jjne]

Quote:

Originally Posted by Orbitalzone

Yeah those Crafty Chinese (and others) have no qualms about putting certification on things that have never been tested....same with quoting specifications on products where they've hacked a cpu/memory or whatnot and made it appear faster/bigger than it really is.

Bit of a difference between eBay fraud and a bit of dodgy self-certification though.

Eltax is a reputable-enough manufacturer. It is unlikely that they'd be deliberately importing items that don't meet the required regulations.

[Nigel Goodwin]

Quote:

Originally Posted by jjne

Eltax is a reputable-enough manufacturer. It is unlikely that they'd be deliberately importing items that don't meet the required regulations.

It's only supposition that the unit under discussion doesn't meet the regulations - it 'may' be perfectly fine.

[Winston_1]

Quote:

Originally Posted by Nigel Goodwin

As you don't know the circumstances you've no way of knowing if it's 'not fit for purpose' or not, or indeed even if he bought it new or second hand. Presumably this is another example of your paranoia normally directed at 'homeplugs'?.

The 'fault' could just as easily be insufficient and poor signal on the FM tuner, and the amp could just as easily be operating perfectly within specification and regulations.

For those that suggested it 'could' be a switch-mode PSU, it could just as easily be a class-D amplifier as well.

The sale of goods act also applies to second hand goods if not bought from a private individual. I do not have a paranoia about home plugs, they are a proven source of interference, though they are off topic for this thread. As for poor FM signal note that the interference only happens with the new amp so it must be radiating interference, however small.

[jjne]

Quote:

Originally Posted by Nigel Goodwin

It's only supposition that the unit under discussion doesn't meet the regulations - it 'may' be perfectly fine.

Absolutely -- all I was saying was that if this particular unit is in breach of interference regulations, then it's more likely (IMO) that the OP simply bought a daft one, rather than Eltax themselves importing stuff that's improperly designed or has a load of components missing.

That's possible if you're talking about something imported by a small distributor, but I can't see it happening from a fairly large Europe-wide manufacturer/designer with a reputation to maintain.

But yes, this is all assuming there's actually something wrong with the amp in the first place.

[Nigel Goodwin]

Quote:

Originally Posted by Winston_1

The sale of goods act also applies to second hand goods if not bought from a private individual. I do not have a paranoia about home plugs, they are a proven source of interference, though they are off topic for this thread. As for poor FM signal note that the interference only happens with the new amp so it must be radiating interference, however small.

But quite possibly within specification, and regulations - assuming of course it's not faulty?, failure of the main reservoir capacitor in SMPSU's (assuming this even is a SMPSU?) causes the unit to generate masses of interference.

[Orbitalzone]

Quote:

Originally Posted by jjne

Bit of a difference between eBay fraud and a bit of dodgy self-certification though.

Eltax is a reputable-enough manufacturer. It is unlikely that they'd be deliberately importing items that don't meet the required regulations.

I suspect often the manufacturers are not aware of what the component manufacturers might do.... just look how even the biggest makers like IBM, Dell etc have all suffered over the years from things like bad caps...not sure if that counts as fraud but severe cost cutting by someone in the supply chain.

[Chris Frost]

Quote:

Originally Posted by Orbitalzone

I suspect often the manufacturers are not aware of what the component manufacturers might do.... just look how even the biggest makers like IBM, Dell etc have all suffered over the years from things like bad caps...not sure if that counts as fraud but severe cost cutting by someone in the supply chain.

Chinese contract manufacturing comes to mind.
[LIST=1][*]Produce a sample using the best quality components[*]Under-price to win the order[*]Make progressively bigger margins by cutting corners and substituting ever cheaper components until the client complains[*]Improve quality just long enough for the client to become complacent. Then drop the quality again[/LIST]