Aktimate mini speakers buzzing, hissing and playing fm radio. Sound engineers?

[wespelarno]

I recently purchased a set of aktimate mini speakers and they are behaving strangely. They emit a static hiss (more than normal amplifier hiss), a medium frequency buzzing sound and are picking up and quietly playing fm radio, specifically fm 102.3 (In canberra, ABC radio). I have tried the following things with minimal success:

Rewired all electrical items in my room-no change

Used a powerboard that trims excess frequencies in AC current-no change

Using shielded wire to connect the master and slave speaker-buzzing and hiss reduced marginally

Checked all power sockets in house for correct wiring-all sockets correct

Unplugged all power appliances in house simultaneously to check they aren't emitting radio interference-no change


There is little pattern or consitency regarding speaker position and buzz. I've moved the speakers all around my room and house and get varied results with no apparent logic. Often being placed in the same location at different times gives different results.

I disconnected the slave speaker from the master speaker and removed the input cables. Connected to a frequency trimming powerboard the master speaker still picks up and quietly plays fm radio.

I wrapped the speakers in alumium foil (home made faraday cage), and achieved blissful interference free music. Obviously this isn't a long term solution. I have been unable to recreate the situation in the store I purchased the speakers from and they assure me the system is functional.

The system consists of a master speakers with a built in digital amp, connected to a slave speaker.

So, who has suggestions as to what next?

 

[niftydog]

Used a powerboard that trims excess frequencies in AC current-no change

These things are a waste of money - the electricity supply company already goes to great lengths to ensure AC power is clean and free from interference. Your appliances filter the AC and turn it into DC almost immediately after it enters the appliance - they also have means of reducing radio interference getting into the circuits. Radio interference comes via the air in most cases anyway, not the mains power cable or any other attached cable.

Anywho... just to clarify - with nothing plugged into the master speaker except for the power cable, it still picks up the radio?
Sounds like a case of budget engineering. Some circuits are just prone to this kind of behaviour, others are poorly designed and fail to filter unwanted interference. It's kinda rare to have a circuit fault that causes something like this - it's usually a case of bad design.

If it cost you a decent amount then I'd suggest it's not fit for sale and I'd be asking for my money back - implied warranty covers more than just the "works/doesn't work" scenario. If it was cheap and nasty then you got what you paid for.

 

[harmonix1234]

The medium hum you describe is called 60 cycle hum and is unavoidable in some cases.
Light dimmers, flouro lights, wall mounted fan switches all contribute to 60 cycle hum, as do powerlines nearby and nighbours (in apartment buildings) using hair dryers and coffee grinders etc.

Also, I had the same problem in my studio with radio frequency being amplified through the speaker of a guitar amp.
It turns out that it had a bad earth and was easily fixed.

You can make a faraday cage by lining the inside of the speaker cabinet with Dimarzio copper tape or brass mesh and reassembling it but it's more trouble than it's worth in some cases.

My tips would be

- Change your globes from powersaver to old school 'pollute the planet' style globes (I know I know)
- Turn off all flouro globes (kitchen / laundry etc)
- Turn off all lights that use dimmers
- Place your speakers at least a metre away from any other electrical device
- Place the speaker facing true north if you can

By placing it true north (Like when playing an electric guitar) the polarity of the magnets are affected differently and 60 cycle hum has less of an effect.

*edit*
The best way to check if it's the earth is to turn it on and play some music, as the music is playing, with your bare finger touch the negative (black) terminal of the speaker cable plug (if it is external).
If your hum goes away when you do this it is an earth problem. Possibly in your new unit, possibly in the house wiring itself.

 

[niftydog]

Hopefully it's 50 hertz hum given he appears to be in Canberra!
You usually hear the 1st harmonic (100hz) due to the power supply's rectifier.

harmonix1234 has a good point about a bad earth - how exactly is the system powered? A mains lead or a power adapter?

 

[wespelarno]

Yep, it still picks up radio frequency with only power attached to it.

The medium hum you describe is called 60 cycle hum and is unavoidable in some cases.
Light dimmers, flouro lights, wall mounted fan switches all contribute to 60 cycle hum, as do powerlines nearby and nighbours (in apartment buildings) using hair dryers and coffee grinders etc.

Also, I had the same problem in my studio with radio frequency being amplified through the speaker of a guitar amp.
It turns out that it had a bad earth and was easily fixed.

You can make a faraday cage by lining the inside of the speaker cabinet with Dimarzio copper tape or brass mesh and reassembling it but it's more trouble than it's worth in some cases.

My tips would be

- Change your globes from powersaver to old school 'pollute the planet' style globes (I know I know)
- Turn off all flouro globes (kitchen / laundry etc)
- Turn off all lights that use dimmers
- Place your speakers at least a metre away from any other electrical device
- Place the speaker facing true north if you can

By placing it true north (Like when playing an electric guitar) the polarity of the magnets are affected differently and 60 cycle hum has less of an effect.

*edit*
The best way to check if it's the earth is to turn it on and play some music, as the music is playing, with your bare finger touch the negative (black) terminal of the speaker cable plug (if it is external).
If your hum goes away when you do this it is an earth problem. Possibly in your new unit, possibly in the house wiring itself.

There are no flouro globes
Dimmer lights were off
True north made little to no difference
I've tried moving speakers from electrical devices, little noticeable difference.
The earthing tip made no difference.

The system is powered off a powerboard which digitally trims frequencies that don't coincide with the 50hz of the power. It has an earthing connection in the powerboard.

Would creating a faraday cage void warranty? I tried a farady cage around the speakers made of aluminium foil and that fixed everything.

I think the issue is that amplifier is really badly shielded, or not at all. Apparently it has a built in digital amplifier, and digital amps are particularly prone to interference.

They aren't cheap and nasty, it was 600 bucks for the speakers with built in amp. Apart from the pain in the ass buzzing they sound fantastic. Aktimate are a combination of Epoz and Creek, both of which have a good reputation as far as I know.

Any more advice, should I return them and try for something else, or continue my quest to sort them out? If I return them, what should I buy instead? I'm not keen on fucking around with all this a second time.

 

[harmonix1234]

You may void the warranty, but where's the fun in giving in eh?

If the speakers are easily deconstructed you could easily insulate it yourself.
The best way is to buy conductive paint. It's used for lining/insulating the electric guitars wiring cavities and is a thick paint with suspended metal particles in it. Instant liquid faraday cage!
Just paint the inside of the cabinet and allow to dry.

Just watch our for glued up speaker boxes. They are not designed to come apart easy and pulling apart glued chipboard speakers is like trying to pull apart two superglued weetbix's.

I get all my stuff from stewmac.com but you could prob get some cheaper through your local music shop or jaycar.

http://www.stewmac.com/shop/Electronics,_pickups/Supplies:_Shielding/Conductive_Shielding_Paint.html

 

[wespelarno]

That certainly has me thinking. Aluminium foil certainly worked well, so this should fix it totally. I'm just not real keen to void warranty yet. I might use that as a last resort if I can't get the speakers changed or warrantied or just make the bastards work.

 

[niftydog]

Yeah, my feeling is that any fix is going to be a mod which will void warranty. Try having them exchanged or refunded first on the basis that they do not meet your expectations of quality - google 'statutory warranty' before you make contact so you know your rights.

 

[Damienp]

What model are they?

A mate got the basic model and found no issues like that at all. Bloody great speakers though.

The dearer model has a tuner and all sorts of guff in it that could cause interference under the right conditions.

I would try calling aktimate in the first instance and see if they have heard of the issue. If not i would imagine being a local product they would be more than inquisitive to find the solution. It may be as simple as them implementing shielding as has already been mentioned.

I would be further investigating the ground loop issue as well.


http://www.aktimate.com/

 

[CP]

Did you end up with a resolution to your issue? I'm an online audio retailer and just took on Aktimate as a product....so want to ensure they're up to their otherwise good reputation. Interested in hearing if you got a resolution with this.

Cheers.

 

[Damienp]

What models are you selling?

I would be interested in grabbing a pair around tax time.

 

[wespelarno]

Yeah, I eventually got them warranted-problem is basically resolved. Occasionally pick up strange things like German radio at about 1am, but it is very rare and very faint. And buzzing only occurs when cables are badly routed. Currently speakers are on my desk which has a rather fast computer, dual screens, loads of wireless stuff and a printer so if anywhere is going to cause static it would be there, and static is rare. Overall happy with them, they sound awesome and look great. I haven't heard a system without a dedicated amp that sounds better.

 

[CP]

Hey Wes, great to hear mate, sounds like there shouldn't be any issues. Thanks for taking the time to let me know.

Damien, I'm stocking both the Mini and Maxi versions. I've only spent a short time auditioning them, tossing up between the two for my own use in the next week or so. Probably the Maxis as some of my musical tastes involve some high impact bass (eg electronica).

This is where I'm retailing them, when the time's right feel free to PM or email me and being a fellow rider I should be able to work out a deal