Yes, mostly single tone, with a few exceptions: VCO in pinpoint that varies frequency some as it approaches the target; and the Tejon can be run in VCO mode with very interesting audio feedback.
A Cibola is where I got very familiar with beep and dig. I had an older target ID detector that did not ID well at all and was not very deep. A friend who had been detecting for decades suggested trying a Cibola. Frustrating at first, since I dug pretty much every thing, as hours got added to the experience, the Cibola got more fun and more productive.
Techniques like: Thumbing the discriminator and learning to hear the differences between narrow and wide beeps, sharp and smooth edges on the beep and irregular modulations to the beeps (or scratchy beeps). With multiple beeps on a sweep, raising the coil slowly as the target area is swept (with a concentric coil) to help isolate and separate targets. Slowing down the sweep and walking around the target to see if it reacts differently or the same from different sweep approaches. It did not take long for the Cibola to pay for itself and then the finds got even better as I got more in tune with it.
I've since added several more detectors to the arsenal. The Cibola still gets hunt time. I have found that going back to the Cibola and sharpening up my listening with it helps me get better with the other detectors too.
My thoughts on best features are that the Tesoro beep and dig detectors are light weight, easy to swing, easy to use, productive and an education in learning observations and techniques that carry over well to more sophisticated and feature loaded detectors. And, as mentioned, I go back to a very familiar one to sharpen up the listening and observation of targets.
Cheers,
tvr
