There seems to be a lot of postings about the audio level coming out of the Ace 250 from Garrett, with good reason. Unless you've been listening to Led Zeppelin at full volume for the past 20 years, you have probably come to the conclusion that a level control is a must for this MD. This is my experience with toning down the dings from this machine. BTW, I'm a tech.
I removed the case from my 250 in the hopes of installing a volume control on the unit itself. It's very crowded inside and a control of standard size just won't fit (most are the size of 6 or 7 dimes stacked together). Also, the jack is mounted directly on the circuit board, making a mod that much more difficult. An external control would look like a 4-year-old did the work.
So, a change to an existing pair of headphones is the answer. I had been using a pair of Sony headphones that have an impedance of 32 ohms that I had already shortened the cable on and changed the 1/4 inch plug; adding resistance will bring the volume down. I experimented and found that a resistor value of about 1000 ohms works well. Yes, this a lot of additional resistance, but it was necessary for a comfortable listening level.
It should be noted at this point that MDs don't have stereo output; it is 2 channel from a mono source. On a pair of headphones the 1/4 inch plug in often referred to as 'ring, tip, sleave'--the right channel is connected to the tip of the plug, the left channel is the ring (center contact) and both channels are common grounded to the sleave. The Ace 250 DOES NOT use this arrangement; it uses ouput to the ring and tip (left and right) only--this means the headphone speakers are in series. It also means they are out of phase, but considering the frequencies used, it doesn't matter.
I added the resistor (1/2 watt) between the 2 shield wires of the headphone, and put it inside the new 1/4 inch plug. BTW, I used a right angle plug as this will take a little of the tension off the cable. Now, this pair of phones is dedicated to the Ace 250, as they probably won't work correctly on other MDs that use a standard common ground. Most headphones will use a molded plug; don't bother cutting these apart to repair or re-use them--just replace the plug (make sure you get a stereo plug, not mono). There seems to be no standard for the impedance of headphones; I've seen as low as 8 ohms, and higher than 2500 ohms--this will make a difference in the volume level when a series resistance is added, so experimenting will be necessary. It would be nicer to have a true volume control, but the output of the 250 is fairly constant and the mod I tried worked well for me on my last hunt.
I removed the case from my 250 in the hopes of installing a volume control on the unit itself. It's very crowded inside and a control of standard size just won't fit (most are the size of 6 or 7 dimes stacked together). Also, the jack is mounted directly on the circuit board, making a mod that much more difficult. An external control would look like a 4-year-old did the work.
So, a change to an existing pair of headphones is the answer. I had been using a pair of Sony headphones that have an impedance of 32 ohms that I had already shortened the cable on and changed the 1/4 inch plug; adding resistance will bring the volume down. I experimented and found that a resistor value of about 1000 ohms works well. Yes, this a lot of additional resistance, but it was necessary for a comfortable listening level.
It should be noted at this point that MDs don't have stereo output; it is 2 channel from a mono source. On a pair of headphones the 1/4 inch plug in often referred to as 'ring, tip, sleave'--the right channel is connected to the tip of the plug, the left channel is the ring (center contact) and both channels are common grounded to the sleave. The Ace 250 DOES NOT use this arrangement; it uses ouput to the ring and tip (left and right) only--this means the headphone speakers are in series. It also means they are out of phase, but considering the frequencies used, it doesn't matter.
I added the resistor (1/2 watt) between the 2 shield wires of the headphone, and put it inside the new 1/4 inch plug. BTW, I used a right angle plug as this will take a little of the tension off the cable. Now, this pair of phones is dedicated to the Ace 250, as they probably won't work correctly on other MDs that use a standard common ground. Most headphones will use a molded plug; don't bother cutting these apart to repair or re-use them--just replace the plug (make sure you get a stereo plug, not mono). There seems to be no standard for the impedance of headphones; I've seen as low as 8 ohms, and higher than 2500 ohms--this will make a difference in the volume level when a series resistance is added, so experimenting will be necessary. It would be nicer to have a true volume control, but the output of the 250 is fairly constant and the mod I tried worked well for me on my last hunt.
? Love the trigger mod.... Thanks, Tom
