Optical Out Noise

[desmortum]

Hi, everyone.

I have an iMac 27'' Late 2013 and recently got Edifier Studio 7 (R2700) active acoustical speakers (two). The active speaker has Type-D digital amplifier. Thing is wired to Mac with Klotz FOPTM02 Optical Mini-jack to TOSLINK PVC cable of two meters.

The thing is that if speakers are connected to computer and there a signal from out, there is a static noise from every channel on each speaker. It is quite silent but you can heart it.

What can it be and how can I solve it if it's an issue?

 

[Chippy99]

Hi, everyone.

I have an iMac 27'' Late 2013 and recently got Edifier Studio 7 (R2700) active acoustical speakers (two). The active speaker has Type-D digital amplifier. Thing is wired to Mac with Klotz FOPTM02 Optical Mini-jack to TOSLINK PVC cable of two meters.

The thing is that if speakers are connected to computer and there a signal from out, there is a static noise from every channel on each speaker. It is quite silent but you can heart it.

What can it be and how can I solve it if it's an issue?

It's a fault with your speakers, possibly a design fault.

There's no way for a Mac to generate and introduce a digital noise signal down an optical cable.

 

[desmortum]

It's a fault with your speakers, possibly a design fault.

There's no way for a Mac to generate and introduce a digital noise signal down an optical cable.

Well, I don't point towards computer, just interesting if it is an actual fault. At service guy told me that there is sort of "okay" level of noise that can be potentialy generated by amplifier or DAC in there.
The speakers have signal-to-noise ratio = 85dB. Sorry, don't know if it has something to do with my issue. They cost below $200 so I'd like to know it that happebns to people whoe connect entry-level speakers to Macs via optics.

Oh, and they are 16/16/32 each in watts.

 

[MagicBoy]

Most speakers don't connect via optical cable, it tends to be used to connect to higher end audio equipment like AVRs.

As said above you can't generate noise down an optical cable. Barring a faulty Mac sound outputs, both digital and analogue outputs are some of the best you'll find in a computer.

 

[loekf]

Most speakers don't connect via optical cable, it tends to be used to connect to higher end audio equipment like AVRs.

As said above you can't generate noise down an optical cable. Barring a fault Mac sound outputs, both digital and analogue are some of the best you'll find in a computer.

Toslink output = SPDIF via optical = digital sound inside iMac is directly converted to an optical signal without being converted to analog at all. So the chance you pick something up in the iMac should be zero.

Maybe it's EMI (electromagnetic interference) from the iMac into the class D amp of your speakers. A class D amplifier uses pulse modulation, so maybe something is causing an disturbance. Could be poor shielding or grounding.

You didn't accidently put your mobile phone next to your speakers ?

 

[MagicBoy]

Toslink output = SPDIF via optical = digital sound inside iMac is directly converted to an optical signal without being converted to analog at all. So the chance you pick something up in the iMac should be zero.

Well aware of that, thanks.

 

[desmortum]

Toslink output = SPDIF via optical = digital sound inside iMac is directly converted to an optical signal without being converted to analog at all. So the chance you pick something up in the iMac should be zero.

Maybe it's EMI (electromagnetic interference) from the iMac into the class D amp of your speakers. A class D amplifier uses pulse modulation, so maybe something is causing an disturbance. Could be poor shielding or grounding.

You didn't accidently put your mobile phone next to your speakers ?

Well, it's my working room and there're electronics here and there, but I tried removing them from room completely with no luck. Can't remove iMac though and there's not too much space to place speakers elsewhere.

Do anyone have experience with speakers produing noise by themselves? I mean I read a lot about that speakers usually have sort of level of tolerated background noise they can produce with their amps or DAC. The really silent sizzling or something.
I'm talking about $200-400 price range including amp (active speakers). Or is that just impossible and it's straight faulty?

 

[jms969]

The problem is with the speakers not the iMac. Following are some specs for the speakers:

• Class D amplifier with DSP based electronic crossover and dynamic range control minimize system distortion
• Stand-alone bass signal output available for connection to external active subwoofer
• Multi-functional wireless remote control and side panel control on active speaker
• Universal 100V-240V power supply

The signal to noise ratio is only 85dBA...

So yup it is the speakers

 

[desmortum]

The problem is with the speakers not the iMac. Following are some specs for the speakers:

• Class D amplifier with DSP based electronic crossover and dynamic range control minimize system distortion
• Stand-alone bass signal output available for connection to external active subwoofer
• Multi-functional wireless remote control and side panel control on active speaker
• Universal 100V-240V power supply

The signal to noise ratio is only 85dBA...

So yup it is the speakers

So the SNR is what matters? What level is okay for $200-400 speakers?

 

[Chippy99]

Toslink output = SPDIF via optical = digital sound inside iMac is directly converted to an optical signal without being converted to analog at all. So the chance you pick something up in the iMac should be zero.

Well aware of that, thanks.

Well why didn't you say "there appears to be a fault with my speakers" then, instead of wasting peoples' time telling you something you already knew???

So the SNR is what matters? What level is okay for $200-400 speakers?

85dB is not terrible for cheap audio components. More likely it's just a poor design that hasn't been well tested with optical input and is performing well below spec.

 

[MagicBoy]

Well why didn't you say "there appears to be a fault with my speakers" then, instead of wasting peoples' time telling you something you already knew???.

I'm not the OP.