It's still not clear to me what they mean by channels, in the
Sweetwater vid he says 148 channels (2:15 in vid).
There's only 12 channels in the 2.4G band...
I agree it would be nice to define what they mean by “channel” here. This is a subject I'd generally like to understand more and get a better hold of the history of developments, but it’s a deceptively complex topic, and digging into it often leads too deep into the weeds for me.
From my armchair, internet-based understanding, I think terminology surrounding the different techs can be conflated. This is just the jumping off point but one issue is that channel can be conflated (in what is meant) with frequency easily, and this is fair because the terms can be used interchangeably in some instances. But "channel" is an abstraction of division and arrangement, not something concrete and universal. In the context of 2.4 GHz band, channels refer to decided upon divisions of frequency ranges, not individual frequencies. In wireless audio systems, channel can refer to a preset that corresponds to a specific frequency sometimes within a group/channel matrix (there's the word channel again) one of a fixed number of presets. For instance, a system with a 10x10 group/channel configuration might be marketed as having “100 channels,” though in reality, the number of tunable frequencies could be much greater if the device allows direct selection at smaller intervals. I have a system where the specs say it has 96 frequencies (8x12 group/channel matrix), but it allows direct tuning in 25 kHz steps across a 24 MHz bandwidth, so there are actually 960 selectable frequencies.
But to users, this conception of channels and frequencies is more relevant with UHF analog systems, where frequency coordination and select actual operating frequencies are in play. 2.4 GHz systems are almost exclusively (or exclusively?) digital and use adaptive frequency selection schemes. The user might select a “channel,” but if current gear even requires this, it's probably just identifying predefined frequency hopping pattern or a virtual address in the system’s logic, not a specific or fixed frequency.
So I think, as here when a manufacturer advertises “40 channels” or “148 channels” referring to a 2.4 GHz digital system, it’s probably a simplification for marketing or just meeting the audience with more digestible concepts. These figures may represent the number of unique hopping sequences or logical pairings the system supports, not fixed or selectable RF channels/frequencies in the analog sense...but again, we don't know.
I think the lack of clarity stems from analog system terminology being repurposed in digital systems. Which it makes sense to do because that's what we're used to. And because the 2.4 GHz band is constantly being pointed to as "congested," the performance of digital systems is suspect because they're being viewed as operating under the same principles and constraints as analog systems...they are not. The performance of digital systems depends largely on the efficiency of their design and algorithmic implementation. Dependence on quality of components and construction obviously isn't unique. Just because two systems are the same in that they are both using the 2.4 GHz band does not mean that they are the same and will perform the same without regard to how well their frequency hopping schemes are engineered and how robust their error correction is. And bringing analog systems into things here creates more opportunity for conflation; auto-sensing in analog systems is not the same thing as frequency hopping. Automatic frequency management in analog systems isn't and can't be dynamic...two completely different things (auto-sensing and adaptive frequency hopping).
In my view, a lot of skepticism around 2.4 GHz audio gear comes from earlier implementations...but given how rapidly this tech evolves, impressions and criticisms from even just a year ago can be sorely outdated. Yes, the 2.4 GHz band is congested...okay fine, been said over and over...and that what is being addressed with design. Evaluating the latest designs and implementations of the tech and each piece of new gear on its own merits based on its real world performance (latency, noise, dropout resistance, use with # of other RF units) seems more sensible than dismissing all 2.4 GHz gear as unusable because the 2.4 GHz band is congested or because the number of "channels" listed on the box feels low.
I got Donner CV-2 wireless XLR adapters a few months back based partly on a review that highlighted that the reviewer was having ZERO RF issues in regular gigging in one of the busiest cities in the world he believed owing to a stellar frequency hopping implementation. They are 2.4 GHz yet there is a lot to like about them. I've been using them for our 4 vocal mics in the Baltimore/Washington and surrounding area. They have been absolutely flawless for us. The documentation says that 8 can be used together, although I've also seen it as 6...evolving revisions?
