Most vacuum cleaner type vacuum pumps are brush type universal motors
and therefore can have their speed controlled by reducing the supply
voltage.  There are several types of motor speed controllers, most of
which are not suitable for this sort of motor.

A fan speed control for an induction motor will not work on this
motor and is likely to burn up, most likely without damage to anything
but the control.  A simple lamp dimmer will work if it is rated at a
high enough current.  If you use one of these, get one rated for at
least 500 watts, more if there is one that is affordable.  Better yet
is to use a router speed control.  Harbor Freight has one for about
$20 and it is rated for 20 amperes.

There is probably no reason to get a better controller but there are
several options.  Better controllers will be a little more efficient
but you can't just pick one willy-nilly as there can be important
details that are overlooked if you don't know what you are doing.

A major consideration is that these vacuum motors are really intended
to be run at full speed with unrestricted air flow.  They generate
a fair amount of heat and the air passing through them is used to cool
the motor.  If you block the air flow enough you will cause them to
burn up and this can happen fairly quickly if almost completely
blocked.  It is a good idea to provide a leak that insures enough
cooling air.

Really good turbine type vacuum pumps have a separate fan that provides
cooling air independent of the suction flow.  These are more expensive
and are not likely to be found in anything other than industrial
vacuums.

Unless you are good at working with motors it is probably a better
idea to buy one of the custom made player add-on pumps.  Eric
Bergstrom, who subscribes to this list, makes really good units.
I think the pumps are only a couple or few hundred dollars, a lot less
than replacing your house when it burns up.

Spencer Chase