Most guitar wireless will work fine. Some tint the sound with a bit of compresson that can be good or bad denpending on what you play. My favorite is Telex.
HUH??? I have gone through the entire Internet and all the shops in Sweden, and I found one (1) wireless set that would cope with frequences below 40 Hz. Namely Shure T. OTOH, a 34" scale is said unable to reproduce any fundamentals below 40Hz (which I find hard to fully believe), so perhaps it doesn't matter? I'd go with a Shure T (UT in the US?). It is also fairly affordable.
Here is telex's unit. Claims 20hz. I have never sent a spectrum analyzer signal across it but I have have also never had a problem. Telex Wireless
A frequency range of e.g. 40-20000 doesn't mean that it doesn't handle anything below 40 Hz, it's just not as loud - same as with speakers. @ Bruce, it's probably gonads
That gets a little tricky with wireless. A wireless device may cut frequencies that it feels it "doesn't need" to make a clearer transmission for the used frequencies. You can plug just about all guitar wirelesses into a bass but on some things will sound different. Thats why I fell in love with that telex. Someone took the time to design for bass. I have to respect that.
There's a fair amount of misinformation in these responses. Most wireless units do NOT go down to 20 hz or below. Most go down to about 50 hz or 100 hz, which is completely unsatisfactory for bass guitar, either 4-string or 5-string. Use one of these units, and your sound will blow. The frequency range of the transmitter and receiver (not always the same) is one of the most important considerations. Get a unit that goes down to 20 hz. Several Shure UHF units do this, and are relatively inexpensive (about $300 - $350). Be SURE to read the specs for the frequency range. If you're paying less than $300 for a new unit, it's probably going to disappoint you. Finally, do a search of TalkBass on this topic. It has been discussed widely.
[In general, single frequency, crystal controlled wireless systems work best for bass guitar. The only system that we have that is crystal and rack-mountable is the LX system. The LX is a professional VHF system that does work well for bass guitar. However, if you do a good deal of extensive travel, you may choose a frequency agile system such as the UC series. Frequency agile wireless systems generally have a fairly steep low frequency roll-off at about 50 Hz. This may cause some reduction of low-frequency output with 5-string bass guitars, but generally doesn't affect a four string.]// C&pasted from Shure website// This may be of some interest to the subject. Pkr2