>-----Original Message----- >From: Ted Rook [mailto:[email protected]] >Sent: Friday, July 19, 2002 1:01 PM >To: < >Subject: Re: suggestion for >100W audio amp > > > >There are hundreds of audio amplifier brands out there but >most are designed for audio applications which means two >things so far as your application is concerned: > >the ratings are for continuous operation with speech and music >which have a high average to peak signal voltage ratio > >as a result, if you operate them continuously with sine wave >signals you should de-rate by a factor between four and eight >otherwise the amp will go into thermal protection mode or fail >from overheating if the ventilation is not fan assisted. > > >secondly the bandwidth will be limited to exclude frequencies >below about 20Hz and above about 20kHz > >If you need a response down to DC or up to 50kHz an audio amp >is not suitable. Even if it passes the signal it will not meet >the full power rating which is typically 1kHz or 20 to 20K on >better brands. > >You don't mention output impedance or load impedance. > >Many audio amps are unhappy below four Ohms unless you include >2 ohm rating in your search requirement. > >My employer has twenty years experience with high power audio >amps for installation and sound rental company touring applications. > >Our models include 2 ohm and 1 ohm ratings, and a variety of >different power levels and construction standards. There are >light weight models with switching power supplies which are >easy to move around and we have at the other extreme 200 pound >behemoths with linear toroidal power supplies. > >You can research our range at www.crestaudio.com > >If you have specific questions please feel free to contact me >off-line at [email protected] or 201 475 4659. > >Ted Rook >Audio Engineer
The original poster said that the intended use was DO160 & Method CS101. For these tests, the lower frequency limit is 30 Hz. The output impedance of the Solar amp is about 2 ohms, and it is usually used with a 6220-1 injection transformer. Since the 6220-1 has a 2:1 turns ratio, the output impedance of the amplifier / transformer pair is about 0.5 ohms. Method CS101 defines an injection power limit by limiting the amplifier drive to that level which produces an 80 Watt dissipation into a 0.5 ohm calibration load. So, if your amplifier is putting out its rated 100 Watts, you should not have any trouble injecting enough audio frequency power to create the required CS101 voltage across the impedance of the EUT. (If the EUT input impedance is less than 0.5 ohms, then you will hit the power drive limit before reaching the required applied voltage.) Before buying another amplifier, do the calibration sequence of CS101. Does your Solar amp deliver 80 to 100 Watts to your 0.5 ohm resistive load? Another thing to remember about audio power amps is that current flowing in the EUT powerline will induce a stepped-up voltage to the amplifier output stage. The amplifier must not only be designed to deliver power into a passive load, it also needs to be tolerant of power induced from the load. Solar has designed protective sensing into its amplifiers. Long ago, I used McIntosh MC-60 tube amplifiers, which were very tolerant of load noise. After the 80 Watt requirement was imposed, I began using McIntosh MC-100 solid state amplifiers. I now use the Solar 6552-1A 100 Watt Amplifier or the Solar 8850-1 100 Watt Sweep Generator, and can do the CS101 test with no problems. OTOH, I do wish that I had about 200 Watts available, since I don't like to push test equipment to near its maximum ratings on a regular basis. Regards, Ed Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
