The Dyson DC07 is a must for any collector as it was the first ever multi-cyclonic cleaner, and also the most powerful suction model Dyson have made, especially the carpet only non-clutched models. It is also by far the most noisy model Dyson have made and much of the noise is from the cyclone assembly, as well as a very shrill YDK screamer motor with very little sound deadening.
They were also the most popular model selling from 2001 until 2009. They pick up very well and require very little maintenance of the pre-motor filter, but the belts on the clutched models do stretch and start to slip on older models, and are difficult to replace compared to the single belted non-clutch models.
Older models are now very fragile with the cyclone assembly becoming very brittle almost like an eggshell, and other parts liable to snapping off. The Animal model was very prone to the purple plastic getting brittle and also faded in the sunlight.
They were much sturdier than the latest DC40 and 41 models and had metal poles instead of plastic ones.
I would highly recommend acquiring a good DC07 for any collection and also the DC15 as this was the first "Ball" cleaner, and the DC15 is not that common either due to its initial high price and heavy weight.
Here is one of my DC07's and also my DC15, along with a couple of other Early Dysons:
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