There's a couple of things I did to my Golden that added a little more depth in my mild ground, but they resulted in a little more noise. Setting the ground balance slightly negative instead of slightly positive added about an inch, but it made some hot rocks respond that won't respond with a neutral or slightly positive balance. Easy to tell them though as they gave an odd sounding high tone on both sides of the rock, and the Golden nulls on them in all metal mode. Setting the threshold to maximum doesn't actually add any depth, but it makes the almost inaudible signals a lot louder and, in most cases, results in more deep targets being recovered. Aggravating when going to all metal mode, but in the past I added a small on/off toggle switch to a couple of detectors (not the Golden) that allowed maxing the threshold in disc mode and toggling back back to normal before pinpointing. I can also hear deeper targets using my Timberwolf Lobo headphones with the limiter switched on. The limiter attenuates loud signals, and reduces the modulation, but amplifies weak signals. They allow me to hear "whispers" that I wouldn't hear without them, but I don't hear as well as I once did so the headphones might not help anyone with good hearing. Another thing that you probably already know, the Golden disc mode reads downscale on deeper targets. By reading downscale a deep coin can drop a tone or more down from the tone it would normally give, so a deep coin can give a response that's a mix of it's normal tone and the next lower tone or drop to the next lower tone or maybe even lower.
As for another detector with tones, I checked one out about this time last year that I actually like better than the Golden. It has the option of nine, two or one tones, more depth than the Golden and is only a few ounces heavier, but I couldn't justify buying one as I wouldn't use it any more than I do the Golden. As far as I know Mr Bill is the only dealer who has them in stock, if he still has any. Read about it
HERE. As much as I like the Golden I don't use it enough to justify keeping, but my wife and daughter make me keep it because it's the only detector I have my 9 year old grandson can use. By the way, I don't like the 9X8 standard coil either, that's why I have a "Super 7" X2 coil on mine
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