X-Terra 70 - Swing Speed / Target Depth Question

[flysar]

I'm still learning my Xterra 70 and I'm confused about swing speed... I've read slow down, 3 seconds for full left - right - left swing, etc.

Sometimes when I get a promising high tone and ID and then slow down over the target I either loose it all together or the numbers get erratic so I chalk it up to falsing or some other anomaly and move on.

I buried a silver 1/2 at approximately 4", set up my system for my soil conditions and hearing; Grnd Bal 12, noise cancel 0, Vol 23, threshold 16, sens 15, tones 3. I was able to pick up the 1/2 at 4" regardless of how slow I went but at approx 6" I lost it at crawling speed but got a good tone/ID if I picked up the pace. I set up an air test, I know it's not the same as ground operation but I had to do it. My wife was watching the display while I moved the same silver 1/2 at approximately 6", the sound was erratic and the numbers were all over, 2-44. At the same distance I moved it quicker and the display was a solid 44/46. It didn't matter if I was in AM or FP Pattern #1.

Given the soil conditions/set up I described is it reasonable to think I get more depth with a quick (not speedy) vs slow swing speed, is it my soil conditions, or am I all messed up in my testing.

I'll be getting a 10.5" 7.5khz DD Coil hoping to increase my sensitivity, we'll see.

 

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[Longhair]

If your GB really is 12, then you're in some HOT ground! A DD is going to make a huge difference. You'll likely see an increase of about 10 on GB going to that 10.5" coil over a stock 9" concentric.

Besides that, get a set of good headphones w/volume adjustment, then turn the volume on the machine to 30 and use the adjustment on the phones to dial it down to an acceptable level. With good phones, your threshold should wind up between 1 and 4. And if you really want to appreciate the vocal capabilities of your Terra, go to multi (28) tones in AM. Then listen to the machine and pay little attention to the TID. Your swing speed should be however fast that allows you to isolate each hit. In AM, if it sounds like a kaliopie on meth you're swinging too fast. It's easy to swing too fast in C&T mode, because if you're not listening to and isolating the threshold breaks over disc'd objects then you have no idea that you're making a mistake. If isolating all hits seems impossible, then a smaller coil is called for. And turn your sensitivity up as far as you can with the coil still and properly Noise Canceled, then start your swing slowly. If it goes berserk and you're going slow, turn it down one step at a time until it stabilizes. Never turn down the Sens until you've slowed down to as slow as you can reasonably go.

JMO
HH!

 

[flysar]

The highest number on ground balance in my yard that I've gotten Auto GB is 15 and I get a lot of falsing if my sensitivity is much over 15; i guess my yard is hot or my system is bad.

I use a set of killer B Hornet headphones and set my vol at 30 and I think my threshold is around 8.

When I did the test I wasn't using my headphones.

I've read a lot of your posts on the xterra 70 and appreciate your feedback; I'm slowly moving towards using the 28 tones.

If your GB really is 12, then you're in some HOT ground! A DD is going to make a huge difference. You'll likely see an increase of about 10 on GB going to that 10.5" coil over a stock 9" concentric.

Besides that, get a set of good headphones w/volume adjustment, then turn the volume on the machine to 30 and use the adjustment on the phones to dial it down to an acceptable level. With good phones, your threshold should wind up between 1 and 4. And if you really want to appreciate the vocal capabilities of your Terra, go to multi (28) tones in AM. Then listen to the machine and pay little attention to the TID. Your swing speed should be however fast that allows you to isolate each hit. In AM, if it sounds like a kaliopie on meth you're swinging too fast. It's easy to swing too fast in C&T mode, because if you're not listening to and isolating the threshold breaks over disc'd objects then you have no idea that you're making a mistake. If isolating all hits seems impossible, then a smaller coil is called for. And turn your sensitivity up as far as you can with the coil still and properly Noise Canceled, then start your swing slowly. If it goes berserk and you're going slow, turn it down one step at a time until it stabilizes. Never turn down the Sens until you've slowed down to as slow as you can reasonably go.

JMO
HH!

 

[Longhair]

The difference with the DD coil is going to be huge to you. Your GB #'s will likely be closer to 25, and the added benefit of better separation is a bonus. It will see deeper, which means going slow enough for it to get a good look will be important.

Another thing that I wanted to mention about swing speed, is that how long it takes has a lot to do with how wide an arc you're covering. Fer example, if you are being extremely thorough and making short (2ft) overlapping swings, your left to right might be 1sec, but if you're trying to cover a lot of ground, your arc might travel over 8ft and your swing might need to be 4sec left to right.

Swing speed is governed by a combination of target density, coil size, and balance of relative sensitivity (the more the better) that allows stable operation. It should not be chatty. You need to be able to halt on a good tone, confirm it and pinpoint it. In heavier trash if you're moving too fast or have too big of a coil (or worse yet...both), then you'll halt late and take longer to confirm, and you may not even find it because falsing occurs often from going too fast or multiple targets under the coil at once, but not from going too slow or listening to each hit.