The Sovereign is different than the Explorers and E-Trac as far as audio which some like and some don't, I like the Sovereign audio my self and in the higher tones it don't make a difference if it is copper or silver. When you get to know the Sovereign well from experience you will soon see the way the signal act along with the numbers of a good 180 ID meter you will be able to tell a quarter signal from a penny/dime signal, even sometimes if it is silver or not all by the way the signal sounds like and how the meter will read the 180. Is it 100% accurate?? NO but it give a idea and if it is deeper in a old area chance are you want to dig it as it is a wheat penny IH or silver. I found that on a copper penny or dime it seems like I could get 179-180 bounce back and forth while if it was a quarter it seem to lock more on 180, now for silver it seems like this is mostly deeper, so I can tell the depth by the audio if it is not disturbed ground, deeper is a little weaker signals and many times you will be swinging slower or miss the signal as it may be weaker and thus smaller signals too. Now if it is a 179-180 bounce I figure it is a older penny like a wheatie if it seems to favor the 180 number there is a good possibility it is a silver while a more solid 180 is a quarter and if deeper it is silver. This is when I have my meter calibrated to 179-180 on a new dime. On a zinc penny or a IH and some early wheats I get a 176-177 on my meter while a 177-178 for me is normally a screw cap. Nickles always have a sound all to themselves and if not deep a 143-144 and some war nickles as high as 151, but has that nice sound to it, maybe it is just the round sound of it, but I think many will tell you they can hear the difference in the tone on a nickle. Now a deeper V or some Buffalo's I have seen the meter read as low as 139-140, but has the nickle sound to it unlike the beaver tail that reads 140-142.
Now while hunting I like to dig all the 179-180 readings and picking up it all, but if I only wanted to dig older pennies or silver I dig the ones that are deeper I will go for the weaker signals and swing slower, but the only time I do this is when the zinc pennies are real bad and it too is not 100% accurate, but helps.
On the Explorers the silver read a little higher in numbers and audio than clad, but it too wasn't 100% accurate either as many have seen when they expected a penny or dime and see it was a half dollar they dug and some with bad hearing such as me missed a lot of the weaker signals because the audio was so quick and back to normal threshold you may miss it while the Sovereign kept the tone of the last target so we could tell if the detector seen a different target. The Sovereign to me is quicker in responding to the targets also and didn't have to wait for the threshold to return to get a visual ID where the Sovereign showed a number as soon as the audio changed which to me may it so much easier to ID and more accurate too.
The meter on the Sovereign is basically a voltage meter and can be why the ID is more accurate more than what you can with your ears and why I have always recommend a 180 meter for those that are serious about digging more coins and less trash when out detecting.
With the Sovereign audio and the 180 meter I like those deep and weaker signals and many close to iron trash as I can get a signal close to what I want to hear, then work the signal looking for the good numbers of 179-180 area and find a coin beside a nail or other trash over the Explorers. The Explorers like the Sovereign are great detectors and does have some better features for some and I have a few around here that really do well with the Explorer and have hunted with them too and got coins they missed and they have got some I missed too, so it all comes down to how well you know the detector you are using and how the features help you find the finds you do, you just got to use the detector and understand it.
I been using the Makro Racer this year so far and haven't seen anything the Sovereign couldn't do better with, but got to use use it more and get to know it better and maybe see something it can do as good or better.
Rick