I went out today with my new HO900 wireless headphones I ordered from Wal-Mart.com. They only cost $19.98 plus .97 cents shipping and $1.99 sales tax for a grand total of $22.94. I made a mount so I could snap it on my GTI1500 or my ACE250. Today I was using the GTI 1500 and I couldn't hardly tell the difference between them and my wired headphones. I am not too sure about the battery life of the transmitter. It uses just one 9 volt battery. I was out a couple of hrs today and they were still working. They operate on a frequency of 49.85Mhz, have a transmit range of approximately 100 ft., and an audio input level of 500mV max. If you use these on a metal detector that doesn't have a volume control, like the Ace 250, you need to use an inline volume control such as a radio shack 42-136. I found that when I used them on the Ace 250 the volume was really low even with the headphones turned all the way up until I installed the inline volume control and adusted it to about midrange. On the GTI1500 I adjusted the volume of the detector, using my wired headphones with their volume controls turned all the way up, to were the audio was just audible. That setting worked well with these headphones and I had to turn the volume control on them about midway.
The mount I made cost about .50 cents. It is made from a piece of 1" black roll plastic water line attached to two pieces of a paint stirrer stick. You can make one in about 5 minutes using a pvc pipe cutter. The snap clamp you make is attached to the stirrer sticks, one stick the length of the transmitter and the other shorter, with two #8 1/2 inch screws. The transmitter is held to the stirrer sticks with pony soxs, those little stretchy thing used for pony tails. I wrapped some electrical tape around the metal detector shaft to make it fit snug.