I am not using a powered mixer as I prefer powered monitors. Some of the Mackie mixers, such as the CFX12 have built-in reverb, though it is not a powered mixer.
You might be able to peruse Musicians Friend or Ebay to find Powered Mixers with built-in effects.
Your options with a PA are:
Unpowered mixer --> Power Amplifier --> passive monitors
~ or ~
Powered mixer --> passive monitors
~ or ~
Unpowered mixer --> active (powered) monitors
Compared to self-contained keyboard or guitar amps, a PA is generally less portable -- as the amplifiers and speakers increase in size and quantity you need increased hauling capacity. Also, your setup/takedown time increases with a PA -- again, the more complicated the setup, the more time it takes.
If your system is for the theremin only the need for power is modest -- a theremin's tone carries very well. If you are playing other instruments through your PA along with the Theremin, then the size of the speakers and amplifiers will depend on the demands of the music.
In any case, you will get the best results with a seperate monitor for the theremin's dry tone -- this monitor should be within a couple feet of the thereminist at ear-level. The fx (reverb, etc) can be sent to the main pa speakers.
edit:
You may also want to take a look at the Bose Personal Amplification System (PAS). Theremins sound great through them as well as other instruments. The PAS is a good solution for a high-end PA system that is relatively portable -- though, admitedly, the PAS would not fall into the "good cheap amp" category.
You might be able to peruse Musicians Friend or Ebay to find Powered Mixers with built-in effects.
Your options with a PA are:
Unpowered mixer --> Power Amplifier --> passive monitors
~ or ~
Powered mixer --> passive monitors
~ or ~
Unpowered mixer --> active (powered) monitors
Compared to self-contained keyboard or guitar amps, a PA is generally less portable -- as the amplifiers and speakers increase in size and quantity you need increased hauling capacity. Also, your setup/takedown time increases with a PA -- again, the more complicated the setup, the more time it takes.
If your system is for the theremin only the need for power is modest -- a theremin's tone carries very well. If you are playing other instruments through your PA along with the Theremin, then the size of the speakers and amplifiers will depend on the demands of the music.
In any case, you will get the best results with a seperate monitor for the theremin's dry tone -- this monitor should be within a couple feet of the thereminist at ear-level. The fx (reverb, etc) can be sent to the main pa speakers.
edit:
You may also want to take a look at the Bose Personal Amplification System (PAS). Theremins sound great through them as well as other instruments. The PAS is a good solution for a high-end PA system that is relatively portable -- though, admitedly, the PAS would not fall into the "good cheap amp" category.