What are the exact 20 frequencies on these units please. what is the mw output of the transmitters please.?

Frequency is 565 to 584 Power 10db/10MV

I have a sony srs xb20 speaker can i use your system if i use a 1/4 to 3/8 adapter to plug into the Sony unit? if not why not?

No, you can't. Because this receiver output is about the same level as a wired mic. It must be plugged into a 1/4'' speaker input designed for a mic connection. If your speaker has only 3.5mm line inputs which require a higher level signal than a mic provides, the mic will be not suitable to be used with it, even you add an adapter. The sound will be soft and hard to be heard.

Can I plug the receiver into my iPhone, audio mixer, or Mac to record the audio?

Sorry, it works with only audio mixer that has 1/4" mic jack. If you need a mic to use with Mac, we have the K031 (Asin: B074C125TN) USB wireless lav mic. But neither of them will work with iPhone.

can it be used for singing

It will be more suitable for speaking than singing. We would recommend the handheld mic K025(ASIN:B0795PNCBG) or K035(ASIN:B01MT6AAIC) for singing. All these mics need to work with speakers/amps that has 1/4'' mic input.

ASIN	B076F5W8Q5
Antenna Location	Speech, Video Conference
Audible Noise	58 Decibels
Audio Sensitivity	95 Decibels
Brand	FIFINE
Built-In Media	Headset microphone, Lavalier microphone,Transmitter, Receiver, Windscreens, 2 adapter-cables
Color	Black
Compatible Devices	Amplifier, Camera, Smartphone, Speaker
Connectivity Technology	TRS/TRRS
Connector Type	1/4" TRS
Customer Reviews	4.1 out of 5 stars 3,471 Reviews
Enclosure Material	Metal
Frequency Range	50 hz 16 khz
Frequency Response	50 KHz
Hardware Platform	Camera, Smartphone, Speaker
Importer Contact Information	Origin Marketing Pvt Ltd. Contact: 9870294946, [email protected]
Item Dimensions	6.8 x 16.2 x 20.2 centimeters
Item Type Name	Wireless Microphone
Item Weight	9.9 Ounces
Manufacturer	FIFINE
Manufacturer Contact Information	FIFINE - 9870294946
Mfr Part Number	ABCD170019
Microphone Form Factor	Headset
Model Name	wireless lapel microphone
Model Number	K037B
Number of Batteries	2 AAA batteries required. (included)
Number of Channels	1
Packer Contact Information	Origin Marketing Pvt Ltd. Contact: 9870294946, [email protected]
Polar Pattern	Unidirectional
Power Source	Battery Powered
Signal-to-Noise Ratio	58 dB
Special Feature	Wireless
UPC	728290254117
Unit Count	1 Count
Warranty Description	N/a.

FIFINE Wireless Microphone System,Fifine Wireless Microphone set with Headset/Lavalier Lapel Mics, Beltpack Transmitter/Receiver,Ideal for Teaching, Preaching and Public Speaking Applications.(K037B)

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