Through the years In have owned and/or handled dozens of Compadres, most with a 7" Concentric coil in the earlier days. They were not all the same.
I had one, at a time, and as a Tesoro Dealer I checked out those that came in before then went to the consumer. Often I would make sure things worked OK, but I'd also compare them against my own unit or one on display and, like many of the earlier-era Tesoro's, they could vary.
There can be variables due to:
1.. The internal components used and how tight a tolerance they used
2.. The calibrations that were performance at the factory.
3.. How tight the search coil performance is.
I think in the much more recent years Tesoro might have built their detectors with a little tighter control so there was less variation from specimen to specimen, but I know that early-on I would check out all the models that came it. I prefer a manually GB'ed detectors, so if a Bandido, for example, was a bit hotter than the Bandido I was using, the 'hot' model became mine and my former Bandido was sold as a used unit. Sometimes in a batch of models ordered, there would also be one or two weak, wimpy, poor performing units.
Since mid-'83 I used a 7" Concentric search coil on virtually every detector I owned, and I had very good results and success in the ghost towns and other places I searched, but .... I was also picky on the 7" coil I kept in my personal arsenal. I would try out every 7" coil I could, on my manual GB models and one or two preset units I also kept on-hand. Some coils were a little better than others.ost of the time very close, but I can get selective at times.
I always prefer to have and usually use a smaller-than-stock search coil. When they came out with their labeled 5.75 coil I got one to try. In measures 6" across, so I call it a 6" coil. Currently I have two of the 6" Concentric coils and one 7" Concentric coils. Working each of them on a Bandido II µMAX or an Outlaw, making sure the GB is proper with each coil mounted and with the Discrimination at minimum, I prefer both of the 6" coils to the 7". Not my much, but perhaps a half-inch improvement over the 7" I have.
Just too many slight differences in the detectors and coils alone to be certain, but I know I would personally prefer to use a Compadre with a 6" Concentric or a 7" Concentric than the 8" donut Concentric coil.
Monte