Arcam FMJA29 -Low audible Hum

Fraziel

Active Member
Just got a great deal on one of these brand new. Sounds excellent ( laid back my arse ) but it emits a low audible hum i can hear from my sitting position 9 feet away. It's not my mains as i have a conditioner and have plugged it in using various plugs in the flat as well as with every appliance turned off in the flat and even using different mains cables.

Now I am not bothered about the low hum as its inaudible playing music , even at low volume, or when the tv is on.

My question is this, is it normal? I appreciate this can happen with some amps ,and if it's normal then that's ok , but if its a sign of an issue with the amp then I will need to return it.

Any ideas?

thanks for your help
 

Hixs

Distinguished Member
My A38 has the typical analog hiss, but you gotta get pretty close to hear it.

What else is connected to the amp?
 

wokeye

Active Member
Yes there's a lot of sh*te talked about these amps being laid back. My A39 isn't, but it doesn't sound thin or overly bright like a lot of amps do.

Maybe you should try it without the power conditioner, just in-case this has developed a fault..
 

Fraziel

Active Member
Yes there's a lot of sh*te talked about these amps being laid back. My A39 isn't, but it doesn't sound thin or overly bright like a lot of amps do.

Maybe you should try it without the power conditioner, just in-case this has developed a fault..
I have. Low hum no matter where I plug it in. Doesn't affect sound. I've read on a couple of forums people saying they had similar issue. I e mailed Arcam so will wait to see what they say. Hopefully it's normal as I got a good deal and it sounds good. V similar to my old Nad but clearer.
 

Hixs

Distinguished Member
Using good quality speaker cable? Might be worth checking your plugs/wire are seated properly in the posts.

I've been through this myself with my Arcam. The cause for me is my AVR/subwoofer. If I remove the sub the whine lessens by half, if I remove the avr from the Arcam it stops completely. I've given up trying to fix it and recently bought a Beresford speaker amp/switch.
 

Fraziel

Active Member
Using good quality speaker cable? Might be worth checking your plugs/wire are seated properly in the posts.

I've been through this myself with my Arcam. The cause for me is my AVR/subwoofer. If I remove the sub the whine lessens by half, if I remove the avr from the Arcam it stops completely. I've given up trying to fix it and recently bought a Beresford speaker amp/switch.
Hi, yes I'm using good quality speaker cables, DNM resolution. The hum isnt from the speakers but directly from the amp. I have a separate AV amp with a sub connected to that. It's inaudible when playing music even at low volume. My concern is is it a sign of amp problem? If it's just normal for this amp then I'm ok with it as it's not bothersome in terms of noise.
 

dannnielll

Well-known Member
Hi, yes I'm using good quality speaker cables, DNM resolution. The hum isnt from the speakers but directly from the amp. I have a separate AV amp with a sub connected to that. It's inaudible when playing music even at low volume. My concern is is it a sign of amp problem? If it's just normal for this amp then I'm ok with it as it's not bothersome in terms of noise.
A hum is either an internal fault inside the amplifier or external hum due to external wiring forming a loop. The way to separate these possibilities is by . Removing all cables from the amplifier,except of course the loudspeakers,and running the amplifier very loud. Ideally there should be no hum and perhaps a little hiss. ... If this is occurs , there is no fault in the amplifier. If there is hum, then the amplifier is faulty. If the noise is coming directly from the amplifier, and not a speaker it is mechanical defect and should not exist in a quality product. ... However it will not likely impact the lifetime of the product.
Then add items one by one until the hum appears. Then check the earthing. The addition of say a TV via a usb or HDMI cable can provide an unintended earth connection.
 

Hixs

Distinguished Member
Hi, yes I'm using good quality speaker cables, DNM resolution. The hum isnt from the speakers but directly from the amp. I have a separate AV amp with a sub connected to that. It's inaudible when playing music even at low volume. My concern is is it a sign of amp problem? If it's just normal for this amp then I'm ok with it as it's not bothersome in terms of noise.
Ah that's likely the power supply. Stick your ear near the top vent and see if it's coming from the right-hand side.
 

Fraziel

Active Member
A hum is either an internal fault inside the amplifier or external hum due to external wiring forming a loop. The way to separate these possibilities is by . Removing all cables from the amplifier,except of course the loudspeakers,and running the amplifier very loud. Ideally there should be no hum and perhaps a little hiss. ... If this is occurs , there is no fault in the amplifier. If there is hum, then the amplifier is faulty. If the noise is coming directly from the amplifier, and not a speaker it is mechanical defect and should not exist in a quality product. ... However it will not likely impact the lifetime of the product.
Then add items one by one until the hum appears. Then check the earthing. The addition of say a TV via a usb or HDMI cable can provide an unintended earth connection.
You mean remove CD player and streamer so that when I crank the amp there is no music through the speakers? It hums when plugged in to any plug in the flat without anything else connected to it. I even turned off every appliance in flat except boiler. Still hums.
 

dannnielll

Well-known Member
You mean remove CD player and streamer so that when I crank the amp there is no music through the speakers? It hums when plugged in to any plug in the flat without anything else connected to it. I even turned off every appliance in flat except boiler. Still hums.
Yes I mean remove all external connections and not play music, but instead increase the volume up towards full.Obviously there is still a single power cable and the speaker cables. if there is an increasing hum volume,then the electronics , probably the power supply has a problem. If the hum is present, but not increasing and not from the speakers ,it is a mechanical vibration from the transformer not being well built.
 

Fraziel

Active Member
Yes I mean remove all external connections and not play music, but instead increase the volume up towards full.Obviously there is still a single power cable and the speaker cables. if there is an increasing hum volume,then the electronics , probably the power supply has a problem. If the hum is present, but not increasing and not from the speakers ,it is a mechanical vibration from the transformer not being well built.
I confident it's not the power supply but I'll try that anyway. If it's the amp should I be considering a return? It's brand new so no way I'm getting it repaired. Refund or exchange only. Discontinued though which is a pity.
 

stevelup

Distinguished Member
Anything with a transformer in it will hum to a greater or lesser degree. Some will be all but inaudible, others you'll hear from across the room. None are completely silent.

It's the windings / laminations in the transformer vibrating slightly in sympathy with the AC mains.

The surface you have the unit sat on can make a big difference as well - a hollow resonant unit will emphasise the sound. You could try putting something soft underneath it as a test.

That said, if you can hear it humming from across the room, I'd be inclined to exchange it - it could just be a particularly noisy transformer. It does happen.
 

Fraziel

Active Member
Anything with a transformer in it will hum to a greater or lesser degree. Some will be all but inaudible, others you'll hear from across the room. None are completely silent.

It's the windings / laminations in the transformer vibrating slightly in sympathy with the AC mains.

The surface you have the unit sat on can make a big difference as well - a hollow resonant unit will emphasise the sound. You could try putting something soft underneath it as a test.

That said, if you can hear it humming from across the room, I'd be inclined to exchange it - it could just be a particularly noisy transformer. It does happen.
t's the possibility it is a sign of a fault that concerns me. So if it's just one of these things that happen would you say it's ok to keep it if I'm ok with the low level noise?
 
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stevelup

Distinguished Member
It's not the sign of a fault, it's just manufacturing tolerances on the mains transformer.

Do try isolating it from the surface it's sat on - it might solve the problem for you.
 

dannnielll

Well-known Member
It's not the sign of a fault, it's just manufacturing tolerances on the mains transformer.

Do try isolating it from the surface it's sat on - it might solve the problem for you.

Whether it is or not a fault is arguable. The product is an expensive audio amplifier, and low noise an expected value. The full spec. sheet and acceptance data sheet for that transformer would have had acceptable levels for mechanical vibration noise as one of the measured parameters for transformers as components.
Now I would not expect it to affect the life of the unit. However it might be worth opening the unit and checking that There is no loose screws.
 

Leelo

Active Member
Whether it is or not a fault is arguable. The product is an expensive audio amplifier, and low noise an expected value. The full spec. sheet and acceptance data sheet for that transformer would have had acceptable levels for mechanical vibration noise as one of the measured parameters for transformers as components.
Now I would not expect it to affect the life of the unit. However it might be worth opening the unit and checking that There is no loose screws.
Agreed if it’s a toroidal transformer (doughnut shaped thing wound with lots of wire) these do have a reputation for generating hum in general they are normally clamped to the chassis via a metal plate on top with a bolt through the middle. I’d check that the bolt is nice and tight ( don’t over tighten it) see if that sorts it.
 

Fraziel

Active Member
ok, thanks folks. I have also e mailed Arcam to see what they say. If they get back to me and say its ok I will keep the amp ( hope they do as it looks and sounds superb and at £750 with a 6 year guarantee i got a bargain) . If they say it's an issue then sadly back it goes and as its discontinued I wont be able to get another.

I am not sure that I should have to take the amp apart and tighten screws and bolts either. I am reluctant to do that anyway in case I scratch it or something and the seller is awkward about a return.
 
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vinceledge

Standard Member
I don't know if it helps but I have an FMJ39 and it doeesn't hum audibly. However my Alpha 9 does have a hum, which I thought was loud previously, but on moving it to new house seems to have lessened considerably - it has never affected it in use though.
 

Fraziel

Active Member
Sounds like its something some units suffer from. Just read a forum article on it elsewhere . Had it on earlier tonight and could hear the hum over people speaking on the tv. Unacceptable really and it will annoy me. I understand a little hum close up might be reasonable but hum loud enough to be heard from 9 feet away with the TV on really isn't on. I have tried it in every room in house and hums. My previous amps dont so that says something too.
 
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Fraziel

Active Member
Decided to return it as it'll bug me and Richer sounds said it shouldn't hum like the way it is and that loudly. Bummer. For me and the seller.
 

dannnielll

Well-known Member
Decided to return it as it'll bug me and Richer sounds said it shouldn't hum like the way it is and that loudly. Bummer. For me and the seller.
I think that is a good call. That is a premium price product.. Once you hear it ,you can never unhear it,and it would just grow in irritation.
 
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Fraziel

Active Member
Thought you might want to know that Arcam said that some units of the A29 can have transformers where the windings are too tight which causes hum. They consider it a fault repairable under warranty. As I bought it new I'm not prepared to put it in for immediate repair and have returned it but interesting to know.
 

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