[71 dB]

I tend to "ignore" this thread because it is pinned always on the top. It doesn't "jump up" as a sign of activity.

 

[The Jester]

Probably a good idea …

 

[bigshot]

It’s the most important thread in the forum. That’s why it’s a target for thread crapping.

 

[bigshot]

My dad was a ham radio operator.. His stereo would play faintly when it wasn’t even turned on!

 

[The Jester]

Would there be regular standard revisions for consumer audio in regards to RFI rejection ?
The average home contains far more potential RFI sources than 20 or even 10 years ago, Mesh WiFi, automated “smart home” devices, even down to WiFi LED lightbulbs, plus every family member having a mobile phone or tablet etc …

 

[bigshot]

You know, since the demise of CB radios, I haven’t had any problems with RF. Twenty years ago, I used to hear truck drivers passing by. They probably use Wi-Fi hotspots now. Wi-Fi interference is more of a problem for me than RF.

 

[gregorio]

Would there be regular standard revisions for consumer audio in regards to RFI rejection ?

There are no standards for consumer (analogue) audio to revise. It’s down to individual manufacturers (and market forces) to decide how much RFI rejection their equipment provides. It would effectively be incompetent to design consumer equipment with so little RFI rejection that its audible performance is affected by the levels of RFI encountered in consumer environments, as competing products are not affected. This isn’t the case with digital audio transfer, where there are bodies which define standards (for example, for USB, Ethernet, etc.) and they do produce revisions. Although these tend to be for extensions or updates to the protocol to allow more functionality or higher transfer rates for instance.

In the case of old consumer equipment, from a time when RFI was significantly lower in consumer environments, it may well be more susceptible to modern levels of consumer RFI but equally, as there is no fixed/standard level of consumer RFI, modern levels of consumer RFI may well fall within the rejection tolerance allowed by a particular manufacturer at that time.

G

 

[cloudconnected]

I dont belive in Cable Sounds

 

[redrol]

wires sound like nothing

 

[jagwap]

There are no standards for consumer (analogue) audio to revise. It’s down to individual manufacturers (and market forces) to decide how much RFI rejection their equipment provides. It would effectively be incompetent to design consumer equipment with so little RFI rejection that its audible performance is affected by the levels of RFI encountered in consumer environments, as competing products are not affected. This isn’t the case with digital audio transfer, where there are bodies which define standards (for example, for USB, Ethernet, etc.) and they do produce revisions. Although these tend to be for extensions or updates to the protocol to allow more functionality or higher transfer rates for instance.

In the case of old consumer equipment, from a time when RFI was significantly lower in consumer environments, it may well be more susceptible to modern levels of consumer RFI but equally, as there is no fixed/standard level of consumer RFI, modern levels of consumer RFI may well fall within the rejection tolerance allowed by a particular manufacturer at that time.

G

This is not exactly true. All gear has RFI rejection standards: FCC in US, CE in Europe and CCC in China for example. However these standards are not enough to guarantee RFI does not affect the audio. I have seen plenty of examples where the standard is fully complied with with a good margin, yet interference, either conducted or radiated is measurable and audible. It often falls outside of the regulations' frequency requirements. This from very competent design teams, that learnt from the experience for next time, but did not necessarily share their in-house experience with professional bodies like the AES etc. It is getting rarer as experience increases, but never fully disappears as an issue, especially as the environment gets more saturated with faster and more powerful interference over more frequencies.

 

[bigshot]

The only time I've ever found RF interference is near radio broadcasting stations. Wifi is way more funky than RF. Crowded channels and interference there is a constant battle.

 

[castleofargh]

Op amps are really fond of singing along a nearby communicating cellphone. Some more than others but they all sing if not massively shielded. It's usually worse with portable products for various but kind of obvious reasons(space, grounding, high sensitivity transducers making all picked up crap louder).

 

[jagwap]

Op amps are really fond of singing along a nearby communicating cellphone. Some more than others but they all sing if not massively shielded. It's usually worse with portable products for various but kind of obvious reasons(space, grounding, high sensitivity transducers making all picked up crap louder).

Indeed. Particularly CDMA phones (Verizon is finally ending this horrible format).

Generally JFET and CMOS input opamps are more immune than the more common and lower noise bipolar types, as they do not present a PN junction directly on its input, like a "crystal radio" arrangement. However unwanted junk can get in through the other pins too. People always assume that PSRR (Power Supply Rejection Ratio) takes care of that. However that is around the audioband and a bit higher. Eventually at higher frequencies the rejection goes to zero and then becomes negative, i.e. it amplifies it!

Layout and decoupling is not a universal art.

 

[redrol]

HMMMM. Are you guys saying I should wrap my opamps in a shield?!

 

[Dogmatrix]

HMMMM. Are you guys saying I should wrap my opamps in a shield?!

More convenient to wear the tin foil hat that way you cover everything, just make sure it is properly grounded or the hum will get in