2x 500w amplifier

[nitroboy]

i have found this amplifier on the net : BGR Blazer St Pro 2x 500W RMS Power Amplifier Kit DIY - eBay (item 160376004360 end time Mar-06-10 09:14:14 PST)

and i want to know if someone has any more detailed scheme or can tell me
where the three fuses are. or does someone have an other 2x 500w amplifier scheme.

thanks

[fotios]

2 X 500Wrms/8Ω? You can get so much power from this circuit only in your dreams. Unless the seller means 500Wrms from 1KHz and above.

Fotios

[bacon665]

the spec thingy says 700watt RMS into 4ohm. theres 8 chips on the heatsink. the two on the far sides are identical and the 4 in the middle are identical. The datasheet says 200 watt for the 2SA1494. Im guessing from the looks of it that this thing is push pull.
The power supply specs says +/- 70. thats 140 volts difference. If you calculate the watts thats 1120 per rail or 2240 watts total @ 16 amps.

So in my conclusion yes the power output is very possible because at 700 watts its running at 87% of its max capability. But if its drawing the 16 amps in class A its only 62% efficient. But keep in mind thats RMS not peak and thats per channel if it was designed right. Your gonna need ALOT of speakers, or very large enneficient car subs OR an ESL to use this. also this thing is gonna need a heatsink several several times larger than the board (probably the size of a cinder block)

[sumaudioguy]

BGR Mosfet 400w Amplifier KIT

[sumaudioguy]

The schematics are actually posted on the auctions. Have seen all these designs before and any one of these boards wound save a DIYer a lot of time and trouble. It is far easier to modify than to build from scratch!

What someone said about heat sinks is true. If free air cooled pretty much figure at least 1 square inch per watt of power. That is a big heat sink!

Looks pretty good to me really.

[multisync]

my new/old kenwood km-106 has +/- 68 volt rails and is spec'd at 125 watts @8 ohms. Maybe if there was a bridge kit and the outputs lasted more than a few milieseconds you might get 500 watts @4 ohms total for both channels

[bacon665]

from the looks of it it is bridged. 4 400 watt push pull amps bridged together per channel.
The only reason i specced the rail voltage is because it gave the amperage. watts = volts x amps. this means your kenwood should only be pulling 1.8 amps if thats 125 per channel rms

speaking of which if you do buy this good im wishing you good luck on finding the 140v ct transformer with 16 amp secondaries

[Minion]

I wouldn"t buy a BGR Kit EVER again , Total rip off , First I ordered a Kit but it came Pre built , Then the Schematic that comes with it isn"t even the circuit used on the Board , The schematic comes with a Partial Datasheet of the Mosfet output Transistors That has been Altered so it looks like the Mosfets are for audio when they are High voltage switching Transistors ......

Then to top it off I connect it to a Power supply and it doesn"t work ......

[sumaudioguy]

For all the amps this guy has this one:

2pcs of 100W Sanken Mono Power Amplifier PCB DIY - eBay (item 160399965992 end time Mar-01-10 19:47:36 PST)

would by my choice for favorite. Rather than have one giant amplifier I would instead have many smaller amplifiers with active crossovers. At least as the schematic goes this one matches closest to what I like to see in an amp.

[gearheaddruid]

From the schematic and rail voltages I would assume this might make 200 watts into 8 ohms without distortion. A lot of cheap amps rate their power at 10% distortion so it is feasible that it might do 250 watts/channel. A lot of cheap amps also rate power by total watts divided by channels. It is a deception but in honesty, 500w out of two channels is possible. I would not expect the output devices to survive sine wave loading into four ohms for very long, should be twice as many to handle that load.

Figure a 10 volt drop from rail to output: 70 - 10 = 60. Making sine wave would take that number times .707 to get 42.42 volts rms. 42 X 42 = 1764. To get the wattage: 1764/8 = 220.5. That is assuming you have a very stiff power supply.