Stage amp for keyboards?

[Rob Sherratt]

Hello dtscape,

What size venue (floor area and height) do you want to cater for, how many people, what sort of music, what other band members will be using your equipment, and what sound level do you want? 110 dB is equivalent to standing next to a pneumatic road hammer without ear protectors, and this level always causes hearing injury. 55 dB is equivalent to a normal conversation with someone 3 metres away. 90 dB is the average sound level at major rock concerts. Also, what is your budget?

Placing only two cabinets at the front operating at full volume with power as low as 150 W can be dangerous for anyone coming within 3 meters of the speakers. It can lead to sound levels of 120 dB or more, so be careful if you want to avoid injury claims!!

If you have a large venue then you need to distribute cabinets throughout the auditorium, preferably suspended so they are at least 3 meters above people. Ideally you need many cabinets each rated at about 200 to 300 W, with adjustable delay lines to get the sound in phase, and you need active feedback suppression for all Mics. To provide safe and adequate volume for all people in a large venue is a major undertaking best left to professional PA companies. It is very expensive to do it safely and adequately, we are talking about PA equipment costing $50,000 or more for very large open air concerts.

Until you can be clearer about your venue requirements and budget, you will receive advice that ranges from the use of of 40 W studio monitor speakers right through to using multiple stacked cabinets with separate 2000 W bass, 1000 W midrange and 500 W horns. These higher power systems are completely unsuitable for small venues, as the frequency response is crap if operated at less that 30% rated power. You will get much better sound (frequency response etc) by using the correctly rated sound system for the size of venue you will perform in most of the time.

Best regards,
Rob