No Minelab Detector to date transmits more than two primary frequencies. All the publicity about 28 or any other number of frequencies notwithstanding. Any competent electronics engineer can easily demonstrate the accuracy of this statement.
If you count all the harmonics of the two primary frequencies and then add in the fact that the noise cancellation system shifts both the upper and lower frequency SLIGHTLY to seek the quietest operation, then you can pick any number you want to describe how many frequencies it “uses”. If you are confused, join the club - it has been a major effort of ML over the years to make the whole thing as mysterious as possible.
My opinion, of course, but based on solid analysis I have read elsewhere. Forum rules prohibit my furnishing a link, but if you are interested, google “geotec fbs/bbs carl” and read the whole thread.
None of the above is intended to say that the Equinox 600 or 800 will not be popular and extremely capable Detectors. ML’s engineers are tops. Their Marketing department is even smarter.