I don't know. They should really be labelled as fun! But they are know way Timpani or Kettle Drums. All drums are adjustable pitch. It just so happens these are mechanised so the tuning is done by turning the drum on its stand.

Actually are they even drums? They don't have a shell. So they are just a rim, which isn't a drum per se. Unless the definition of a drum is the stretching of a membrane across an area as to be able to strike it with either hands, or some implements such as sticks or mallets.

Anyway check this link out. It answers your question in the first paragraph.

http://www.rototomdrums.com

Yes they are patented as adjustable pitch drums. Boom. Happy Roto-Tomming hackster.

I think some of the earliest "drums" we're a skin stretched over a pit or just taut in the process of harvesting and using animalskins.

Also cool roto tom site geckobeats

Your probably right. Although I was joking really but it got me thinking of what we refer to as a drum. Like an Oil drum. it's a kind of Barrel.

Well I just googled the definition on http://dictionary.reference.com/browse/drum and yes your right.

Thanks for responding to c the question ,this guy Colgrass first named these tymp-toms when designing these drums from the roto tom experts site and from reading the key tunes the tension rods for the drum head and the rotation changes the pitch of the roto tom unlike other drums it can achieve a Defined pitch and is used as an affordable alternative for schooling persons on pitch in place of a timpani .

Just wanted to pass a long some info pre remo roto tom 1956 search u-tube orff rotary timpani demonstration .think there still made today by sonor Germany using solid beech shells.Coffee Break2

Hacking must be a PA thing.....Cool1

Anywho, I have 6" -14" and they sound like drums to me! They came with foam muffler rings to put between the head and the edge and I took those all off. No use dialing down the volume on a freakin' drum kit!