Wireless Microphones - New digital versions - Any effect on sound quality and why?

[OK1]

Assuming that all other factors are equal, e.g capsule, is there any benefit to sound quality from the recent trend in digital wireless microphones - such as the Sennheiser D1.

While I fully understand that the digital versions eliminate any licence requirements from uses, as they operate in "free" frequencies similar to those used in WiFi, how does the the overhead of AD/DA conversion compare to the compander technologies used in de-facto non-digital wireless, as it relates to the audio quality?

Are there any dis-benefits of the Digital Wireless Technology?

Thanks in advance for your comments and opinions

[seablade]

Assuming that all other factors are equal, e.g capsule, is there any benefit to sound quality from the recent trend in digital wireless microphones - such as the Sennheiser D1.

Compared to most wireless, the newer digital solutions often will be compander free. This can make a difference in quality by itself, not even touching on frequency response etc. But it is not a given, though I do not know of any currently using companders. However it wasn't a given that analog RF used companders, for instance the Lectrosonics Venue series, which is still my goto series, did not, and was even one of the few wireless solutions that Rational Acoustics sells to use with their Smaart measurement software as it was that good.

While I fully understand that the digital versions eliminate any licence requirements from uses, as they operate in "free" frequencies similar to those used in WiFi, how does the the overhead of AD/DA conversion compare to the compander technologies used in de-facto non-digital wireless, as it relates to the audio quality?

AD/DA is practically unnoticeable compared to companders on most analog wireless. The difference is that you will get latency added, typically <3mS but it is important to keep in mind.

Also, and this is IMPORTANT, do not assume that digital means license free. MANY digital RF solutions still operate in licensed TV bands.

Are there any dis-benefits of the Digital Wireless Technology?

Depending on the technology, if you are in fact in a license free band, you will be competing with existing broadcasts, and thus might have limited number of channels you can use reliably, compared to licensed analog RF in a wider spectrum with less interference. Also as mentioned latency, and I believe there are a few other factors that play into this that without finding some testing I won't go into yet.

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[Sam Spoons]

Wireless mics operating in the 2.4GHz WiFi band are much more susceptible to line of sight issues, I had serious problems with 4 x Line6 wireless mics (first time I had used them for real) because the stage safety barriers were between the transmitters and receivers, UHF kit would have been fine but the much higher carrier frequency is more easily disrupted by objects in it's path and, combined with 3000 people all with smartphones, it came and bit me on the bum at a big gig....... I'll know better next time

[OK1]

Wireless mics operating in the 2.4GHz WiFi band are much more susceptible to line of sight issues, I had serious problems with 4 x Line6 wireless mics (first time I had used them for real) because the stage safety barriers were between the transmitters and receivers, UHF kit would have been fine but the much higher carrier frequency is more easily disrupted by objects in it's path and, combined with 3000 people all with smartphones, it came and bit me on the bum at a big gig....... I'll know better next time

Am I glad I raised this enquiry, cos in the last month, I had recommended the acquisition of a Line6 X-Dv35 2.4 Ghz Digital wireless mic for a church where I am responsible for the PA. I don't think I'll change this recommendation, as I still think it will be an excellent sounding mic for the intended purpose, but I'll definitely give ample thought to the line of sight, interference and proximity related requirements, which you have highlighted.

With the de-facto analog wireless microphones, especially where there's a snake(multi-core) cable, to solve these types of issues, I would usually place the receiver somewhere close to the performers at or above head height where it is easier to maintain line of sight with the speaker/singer, then send the mic or line level output from the receiver[some receivers give you an option for either], to the mixer via the snake. This approach should also be applicable to resolving similar challenges with the digital wireless variant.

[seablade]

With the de-facto analog wireless microphones, especially where there's a snake(multi-core) cable, to solve these types of issues, I would usually place the receiver somewhere close to the performers at or above head height where it is easier to maintain line of sight with the speaker/singer, then send the mic or line level output from the receiver[some receivers give you an option for either], to the mixer via the snake. This approach should also be applicable to resolving similar challenges with the digital wireless variant.

The basic concepts of wireless antenna placement apply whether you are talking digital or analog. Always get the antenna as close to the transmitter as possible, avoid interference, etc.

Of course the same selection of antenna, directional, lpda, etc. might be a bit more restricted in the 2.4 range, not sure I have ever seen those remote mounted (Except in one case that I got called on where they did it very poorly assuming the same antenna would work just as well between a 500MHz signal and 2.4 GHz signal.)

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[Dave K]

On several occasions I've used 14 Line-6 V75's with ADUs and remote directional antennae mounted about 10ft in the air (line of sight to the stage) at the back of the Secombe Theatre auditorium with very good results.

[Sam Spoons]

My understanding is that the shorter wavelength of 2.4GHz radio is more likely to be disrupted by an obstruction. The wavelength of 2.4GHz is around 5" or 125mm, the diameter of a scaffolding pole (such as a safety barrier) is 2" so is close to half the wavelength, the wavelength of a CH 70 (865 MHz) wireless mic is nearer to 14" which is less likely to be disrupted by a 2" diameter obstruction. Either way get a good line of sight and keep your aerials a good half metre or more from anything which may get in the way.

IIRC, I read somewhere that problems can also occasionally arise where the transmitter and receiver are too close together, can anybody shed light?