AKG WMS 40 Mini Dual Instrument

I've been using this system on my accordion (both left and right side) for a year and have had absolutely no trouble with it. It was able to work through five or six walls in the opera house with ten other wireless transmitters competing with it.
Having said that, I found that the receiver was prone to local interference from my synthesiser (SM Pro VMachine) which was next to it on my pedalboard. Sometimes the signal light will come on even if the transmitter pack is not on. I moved it as far as possible from the synth and it has been working very well since.

The battery life is very good, even when using discount store batteries and the low battery level warning is good. Another nice function is that it will do it's best to stay on when there is very low battery but with an equally low battery it will refuse to turn on so there's no danger of starting a gig with a battery that's about to die.
The transmitters are very light and the clip is very adaptable so I can clip it onto my accordion straps easily.

Although it is not immediately obvious from the product description these transmitter packs CAN be used with electret/condenser microphones. They output phantom power on the mini XLR so I was able to simply plug in my existing Superlux condenser gooseneck microphones.

I bought these as an introduction to going wireless with the intention of upgrading to something more expensive in the long run but I haven't seen any reason to change yet. If there is a significant change in audio quality I am not able to detect it.

I bought this product with high hopes and initially gave a very negative review of the quality of sound of this product. I was very disapointed. I tried everything from grounded to non-grounded power, even changed the 1/4" cables. I thought nothing helped. The sound was bad and I couldn't use the product.

BUT then I got new cables from a friend and decided to give it a last go. It worked like a charm! No pops, no humm and no interference! I've been using it now for a while and the battery consumption is minimal and the range more than adequate for my needs. I use it for two bass guitars (fretted and frettless that I switch between songs) and it works very well.

It turned out that the 1/4" cables that came with the set were faulty, and the ones I initially replaced them (what are the chances of that!). So check the cables!

I was looking for a cheap wireless unit since I hadn't used one before and now...I don't really think I need another!

With this model you get 2 transmitters meaning 2 guitarists could share the unit or you could use 2 guitars and swap them over.

I get roughly 30 hours from a AA battery, a considerable amount more than other more expensive brands.

I also recently got myself a rack unit and after purchasing a 1U rack mount kit this fits seamlessly into my live rig!

Improvements on it - I worry about breaking the small antennas on the transmitters!

Comes with 2 transmitters, 2 cables, the unit and a universal plug/socket.

Highly recommend!

I was sceptical at first to buy this, because I was surprised by how much less it costs than most of the wireless units. However, as my first wireless system it was well worth the purchase.
I've been playing it for a week, and it sounds great. Definitely clear and crispy sound, doesn't seem that any frequency is cut out. The range is great, too: first thing that I did when I tested it was plug it in, hit record and walk around the flat. It only audibly cut out only once for a split second, and that was when I was ~20m away behind 2 solid walls. When I was behind one wall you could hear some hiss, but only when wearing headphones - didn't hear it on speakers. The transmitters connect to the receiver instantly: when you flick the switch, it's connected. The fact that the transmitters run on battery is also good and bad - means you can swap them out any time, but you might forget, as there is no battery indicator.
Of course, the build quality can be better, but I can't say it's "bad" in any way. The on switches can get stuck in places, and the transmitters are made out of plastic - but if you're careful, it shouldn't be a problem. There is some hiss when operating, of course - you can hear it very slightly when you pluck a note on clean setting and listen - but it's barely audible. The cable is a bit too long, but also manageable. A problem that I can see is that it's operating only on 2 frequencies that you can't switch - meaning if you play gigs at places with other wireless gear, you're going to have to check beforehand that there is no interference.
If you bought this and are getting bad sound - don't forget to play with the volume, as both the receiver and the transmitters have volume controls - which can be nice if you have hot pickups.
I found myself forgetting that I'm playing wireless when practicing - which is a good thing, since it means that the unit operates seamlessly for me. All in all, great gear for an even better price.