FS: Sony Mobile ES 7547 AKA "Big Red"

Shipping alone will cost me $40 I bet. Thing is HUGE. I will post demensions up later

Bump

$220 shipped

200$ shipped! BUMP

I'm only commenting because you asked me to...

The amplifier is rated at 75W x 4 at 4 ohms and 0.04%THD. The amplifier is 0.5 ohm stable, but only for channels C/D. It accomplishes this by paralleling the output devices via relays. So rather than being "bridged", the channels are paralleled in mono mode.

The outputs are interesting devices. They're MosFets rated at 100V and 70A; a great combination. The rails are +/- 28V in "high voltage" mode. This gives you ~150W into 4 ohms.

You can see where this is going.

At 2 ohms and in "high voltage" mode, you're still at 28V rails so ~250W per channel (that's 250W x 4) is not unrealistic when playing music (as opposed to test tones).

At 0.5 or 1 ohm, the amplifier should be switched into high current mode, because you will almost certainly reach an overcurrent situation quickly at 28V rails. When switched into high current mode, the amplifier halves its rails to 14V so as not to trigger an overcurrent situation. So you're limited to the same amount of power.

So what's the point of having the 0.5 and 1 ohm capability if you don't gain anything? It's partly marketing. People see that and think "superior amplifier" when it's more "bait and switch" and "LOL..." to us engineers. You aren't gaining anything but flexibility, which is valuable in its own right - but don't go changing your woofers just because it can drive 'em.

The other part is stability. The output transistors can't drive sub 1 ohm loads without blowing up, so Sony implements some extensive overcurrent circuitry to force you to switch into another, lower voltage mode.

"High current" sounds better than "low voltage", but it's the same thing in power supply engineering-land.

Another thing - there is a sh*tload of SMD circuitry under that "sparse" board. It always kills me when some chucklehead opens a Japanese amplifier on AmpGuts.com and comments on the low parts count.

It's a solid amp. If it wasn't so huge, I'd have no problem owning one. I bet it sounds divine.

Still available.......130$ plus shipping!!!!