Faster than you can chop an onion or a bushel of parsley, the prices for the Cuisinart food processor have dropped. Large advertisements in the last two weeks have told readers of a price "plummet" or "break" or a "sale". Some have offered a kitchen scale as well, as an incentive to purchase the top-of-the-line Cuisinart at $200 instead of $225 or the other model at $140 instead of $160.

What's the explanation? Has the competitions brought the first and - most experts agree - the best of these mechanical kitchen choppers and churners, to its knees?

Evidently not. According to retail dealers and a spokesman for the Cuisinart organization, which distributes the French-made processor in the United States, sales have held up very well. So much so, the Cuisinart man said, that the firm and the manufacturer have decided to pass on the economies of volume production to consumers.

While the violins are playing, the sharp-eyed consumer shouldn't ignore a small box with a black cloth over it just beyond the spotlighted sale items. It won't be opened until sometime this fall, but it contains - surprise - a new and improved model of the Cuisinart Food Processor.

The new model, the DCL-7, will offer: a bowl with about 50 percent more capacity than the present model's, a stronger motor, a two-bottom off-on system for either pulse or continuous operations, a top that may be positioned with the feed tube at the rear of the front of the bowl, and a stop time after shut-off of no more than 2.5 seconds. Other features that are judged less significant are reduced size, operating noise , a 30-year warranty on the motor and an extra safety switch.

The company promises it will chop up to two pounds of meal at one time or make as much as six cups of flour into dough. A new blade, designed for kneading, has been developed for use with the DLC-7.

This model will retail for about $250.

Selling for only $25 less, could the present top-of-the-line Cuisiart, the CFP-5, compete? Obviously the decision in the executive suite kitchen was no. (To further complicate the situation, the new Cuisinart will be manufactured in Japan. The two models currently offered are produced by Robot Coupe, a French firm.) Therefore the new price structure and the mid-summer sales hype.

The trade learned of the newest Cuisinart product at the National Housewears Exposition in Chicago earlier this month. Preliminary speculation is that the DLC-7, at $250, will cut sharply into sales of the $200 CFP-5.

What effect the $140, plastic-base CFP-9 will have on the myriad of middle price and economy competitors remains to be seen. Local stores reported impressive increase in Cuisinart sales during the first week after the price cut.

For those to whom more is less, there is yet another alternative in the food processor galary. Cuisinart also is marketing an outsized model called the Triomphe. Its intended mostly for restaurant use, but there is only one restriction on purchase by an individual - the price. It sells for $600.