There are plenty of other specs to compare and I'll soon have a blog post with those specs, but when it comes to wireless transmitters, one of the most significant is looking at the amount of power a transmitter can output while sending a signal to the receiver. Let's compare a few tiers of common wireless units in the sound field: Comtek m-216 IFBs send an audio signal outputting 10mW (milliwatts) of power. Sennheiser G2s use 20mW, G3s: 30mW. Zaxcom QIFB option of QRX100 (older version) along with some older Lectrosonics units send signals at 50mW. Some of the older and even newer Lectrosonics send signals at 100mW. The most common Lectrosonics transmitters these days are the SMV series. "V" meaning "variable" as in a variable power. The SMQV can send signals at 50mW, or 100mW or even 250mW, which is pretty much only necessary for very long distance in crowds such as the national anthem on the center of a football field at a stadium with tens of thousands of fans with their phones, coaches with their headsets, security with their walkies and officials with their wireless mics. For the record, the Zaxcom TRXLA2 can output variable power of 25, 50, or 125mW.
Why the lower output power on newer digital wireless transmitters?
Of course, the more power it outputs, the quicker it drains batteries. With all of this said, now, with digital wireless becoming popular, we often find manufacturers trading output power and wireless range for battery draining features, which is 1 of 2 or 3 reasons why the newer transmitters are lower in output power.
1: To save battery life to keep the transmitter working long enough to be serviceable
2: To prevent intermod when there's too many transmitters outputting too much power too close to the receivers or other RF reflective surfaces
3: Also possibly because for a few reasons, lithium has become far more expensive as of Jan 2023, so now we're encouraged to use weaker batteries such as rechargeable NimH or even some rechargeable lithiums.
IFB Transmitters
Comtek M-216, Comtek M-216 Option P7: 10mW
Sennheiser EW 300 IEM: 10, 30mW
Shure PSM 300: 10, 20, 30mW (selectable)
Comtek M-175: 40mW
Zaxcom ZaxNet IFB200, IFB300: 75mW
Comtek BST-25/216, Comtek BST-75/216 : 100mW
Zaxcom TRX900, Shure PSM 900, Shure PSM 1000: 10, 50, 100mW (selectable)
Comtek BST-75: 120mW
Lectrosonics IFBT4: 250mW
Body Transmitters (Legacy)
Shure QLXD14-93: 1, 10mW
Shure ULXD Series: 1, 10, 20mW
Sennheiser EW 100 G2: 20mW
Shure SLX: 30mW
Shure FP Series: 10-30mW (varies by region)
Zaxcom TRXLT2, Lectrosonics LMb, LMa, Shure LX Series: 50mW
WisyCom MTP41, MTP40, MTP40 Lite: 10, 50mW (selectable)
Audio LTD TXP: 20, 50mW (selectable)
Lectrosonics SSM: 25, 50mW (selectable)
Audio LTD A10 US: 10, 20, 50mW (selectable)
Lectrosonics UM400a, UM200, SMd or SMDa, MM: 100mW
Lectrosonics LT: 50, 100mW (selectable)
WisyCom MTP40S: 10, 50, 100mW (selectable)
Zaxcom TRXLA2: 25, 50, 125mW (selectable)
Lectrosonics SMQa: 250mW
Body Transmitters (Newer as of 2024)
Plug-On (Boom) Transmitters
Shure FP Series: 10-30mW (varies by region)
Sennheiser SKP300: 10, 30mW (selectable)
Sony UTX-P03: 10 (Asia), 30 (Europe), 40mW (Americas)
Audio LTD PTX: 25, 50mW
Lectrosonics HM, UH400a: 100mW
Zaxcom TRX742: 25, 50, 125 mW (selectable)
Brett Ainslie is a NYC based freelance non-union Production Sound Mixer owner/operator.
He has been mixing sound on location for Film & TV since 2010 for narrative feature films, TV commercials, corporate videos, musical and corporate event live streams and broadcasts, digital content, documentaries and network reality shows. Brett has mixed sound for TBS, HBO, Showtime, Bravo, Disney ABC, Discovery, Food Network, Fox, VH1, A&E, ESPN, MTV, National Geographic, Bloomberg, Vice and more.