Amplifier causing severe interference to FM radio....
Gary Brenton
Posts: 642
Forum Member
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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.
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.
0
Comments
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.
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.
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.
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.
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.
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.
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.
http://www.ybw.com/expert-advice/vhf/news/509220/warning-don-t-get-confused-between-the-ce-mark-and-the-china-export-mark
Doesn't really matter - they will stick a 'proper' CE sticker on for nothing more than the cost of the sticker
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.
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.
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.
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.