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9th April 2003, 05:50 PM  #1 
diyAudio Member
Join Date: Mar 2003
Location: Locked Up In The Amp Rack

Can This Amp Be Modified???????
Greetings
Let be the first to say, I Know Nothing On DIY Amplifiers. I will send this back to the manufacter, if its possible. This amplifier consist of; Two 2KVA Transformers Four 17500 MFD 100V Capacitors 28 x 200 watt, 20MHZ output Transistors. This amp is currently 350 @ 8 ohms per channel I'm looking for 700  800 watts per channel. (8 ohms) Can the Power supply handle my desired wattage? Thanks!
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OMNIFEX 
9th April 2003, 06:22 PM  #2 
diyAudio Member
Join Date: Apr 2002
Location: California

OMNIFEX,
The dominant (but not only) factor in derterminig "how much power this can amp put out" is the value of the rail voltages. The voltage level of the rails are determinded by the ratio of the primary to secondary windings of the main transformer. Your first resonse might be, OK, I will replace the transformer with a "higher power" one. With that change you will (probably) need new diodes and filter caps. Then you need to know if the driver portion of the amplifier can work (or even survive) on higher rail voltages. I simple trick to find out how much an amplifier can put out, take your AC voltage (US 110v, Europe 220v etc) and multiply that by the value of the mains fuse. Example, a 7 amp fuse times 110 Volts = 770 watt amplifier AT BEST. If it is a stereo amp, divide by 2 for watts per channel, in this example 385 watts per channel. Some on this forum will disagree with me on the issue above, but it is a very good indicator about what an amp is capable of, and no amp can put out more power than goes into it. In short, if you want a a 700  800 watt amplifier, buy a 700  800 watt amplifier. Now the question might be, Why do you want/need an amplifier with that much power? Aud_Mot 
9th April 2003, 06:39 PM  #3 
diyAudio Member
Join Date: Mar 2003
Location: Locked Up In The Amp Rack

Aud_Mot, Thank You.
So, what your saying 120 volts times two 15 amp Breakers (No fuse) = 3600 watts at best? So what would be the average? As for why I want a 700  800 watt amp............. This amp is the lowest wattage amp I'm using, but the of the biggest in terms of rack spaces. (4 Rack Space) I do alot of gigs, so, I generally Bridge it. I figured why Bridge it, if it can get modified. Thanks!
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OMNIFEX 
10th April 2003, 06:40 AM  #4 
diyAudio Member
Join Date: Apr 2002
Location: California

OMNIFEX,
The math I presented was mainly so that you can get an idea about true RMS power. Audio amplifier manufacturers are famous for stretching the truth, or even lying and fraudulently representing their products. The AC power and fuse example gives you an idea the maximum output POSSIBLE. No, in theory, you can get a maximum 1800 watts out of a US wall socket. You have to share the 15 amps between the 2 sockets. Plus it is common to have 2 or 3 dual sockets on the same breaker. That lamp is eating into your available 1800 watts of power. I believe you can get a maximum 10 or 12 amps, 24 hours a day/7 days a week from a "15 amp circuit". As I recall 15 amps RMS for over an hour will trip the 15 amp circuit breaker. Plus the AC power sags during the day, call it 110 volts. Now you are down to a real world 1320 watts per circuit breaker. The good news: Those 700 watt amplifers (assuming they are a real 700 watts) consume (on average) about 10% (maybe 20%) of that 700 watt figure. I am talking about RMS power over a period of 10 seconds to 1 minute. But now you are getting into the can of worms how much power "is a lot of power" and how much more power do you need to have "a whole lot more power." If I can find something on the web, I will give you a link to explain the Power Vs Loudness Vs dB's Vs Perceived Loudness. Hint: In order for 10 watts to sound twice as loud, you need 100 watts. Yes, a factor of 10 times the power to sound 2 times as loud. Twice the power, sounds just a little louder. Aud_Mot 
11th April 2003, 03:37 AM  #5 
diyAudio Member
Join Date: Mar 2003
Location: Locked Up In The Amp Rack

Thank You For Your Insight On Things!
Best Regards,
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OMNIFEX 
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