On Mon, 10 Jan 2005 12:54:02 -0800 (PST), Stephen R Phillips wrote: > > > > Home stereo amps have some features you probably don't want. You might > want to buy a professional sound reinforcement grade amplifyer by > someone like Crown. Crown's D series, the D75A for example is an > excelent amp and not rated at enough wattage to kill you if you stand > next to the transducer. They are also a bit less expensive than there > other stuff. Alesis RA150 or RA300 might be just fine as well. I > suggest going to your local professional sound store and ask questions > explain what you need and get a suggestion from them. Nice thing is > it's all rack mountable and will be nice and neat in your lab. On the contrary, a home stereo amp is more than adequate to amplify a 1kHz tone to 85dB. With a moderate-effieciency loudspeaker, this is about one watt of output to aschieve 85 dB SPL at 1m. So forget about the gold-plated Crown idea. Besides, a Mark Levinson #33 power amplifier would be even nicer and neater in the lab, and can be used as a welder as well. > As for building your own amplifyer, well if the amps are FET based the > output shouldn't change at all. It really depends on the quality of the > amplifyer you have. This is why I suggested some professional gear like > the above. You can read pertinant information reguarding them and get > peoples experience. The most important thing is often a store can loan > you a unit to see if it does what you WANT, before you invest your > money into it. I would say that is worth the time and effort. If the gain of my op-amp circuit was varying by 10dB, would you tell me it is because I didn't use a JFET op amp? In any modern amp*, the gain is set by a feedback voltage divider. [*] I am aware of the no-overall-feedback triode amplifiers the extreme hifi folks use. Regards, Mark markrages@gmail -- "We act as though comfort and luxury were the chief requirements of life, when all that we need to make us happy is something to be enthusiastic about." - Einstein -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist