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Yea, right, and Lee never suffered from that.

A 30 watt amplifier can damage speakers just as bad as a 700W. The under powered amplifier becomes distorted at high volumes and dumps high frequency, high power signals in the speakers, and can damage high frequency drivers such as expensive tweeters

A penalty must be inflicted as a result of stupidity. In this case the penalty was a minor burn on a couple fingers.

Attached are photos of a 7.2 ohm load bank using water heaters. Here is a Home Depot link. 120 volt-2000 watt heater Note that the elements must be submerged in a full bucket of water. At $10 each, It's reliable, as long as the bucket is full of water, and cheap. Without water, the plastic...

700 is in the front followed by 700B

Marantz used vellum lens covers. The 700 has LEDs. Shouldn't have any temperature rise.

The calculation Joe did determined the impedance of the cap at 20 Khz. The formula is 1 / (2 × π × f × C). π= 3.14, f = 20Khz, c= 0.1 uf. That works out to .001256. 1/.001256 = 79.6 ohms. To determine the impedance of the R/C network, add the cap impedance 79.6 ohms + 5 ohms from...

I set up 2 meters and a signal generator to indirectly measure the impedance of the zobels at several frequencies. I measured the current through the input of each channel. The following settings were used: Frequency: 20, 100, 1k, 10k, 20k. Source Voltage 2.0 volts Measured A Current (AC...

Test equipment ground loops! Amp input and output can not both be grounded. Been there. Done it.

The only need for soft start is to protect the power switch. The triac board I use for 700's easily handles the 120-150 amp inrush currents on the first cycle. I wouldn't use a soft without an output relay. There's a stability/race condition that will damage speakers.

Well the bulb is going to flash if you're playing music. The problem would seem to be with the sockets of the two outputs that you pulled to make it work. 1. What's the waveform look like at 100 Hz, 1khz and then around 10 Khz. 2. Do the load share test with only 1,2 & 4 installed and then...

The 4 ohm resistor limits the current to about 30 amps (Ohms law says 120V divided by 4 ohms = 30 amps) . I recorded peak currents in the 150 amp range when developing the triac board so limiting the current to 30 amps likely a good compromise. When using this type of of start, It is...

To test the meters, a person could take any 1.5v battery, and a series 100K pot or so, and adjust the pot for full scale on the meter. It will be important to make sure the pot is at maximum resistance before making the connection. Otherwise the battery will turn the unobtanium meter into a one...

I have the original rotary power switch used in the 700B and I assume that was what was in the 700. The switch was prone to failure as it was misapplied. Adding a soft start would be nearly impossible due to space constraints. I have a solid-state switch.(trriac) that mounts on a small board...

FWIW, I'm AKA brewstraveler on EBAY

As for Phoenix connectors, yes. I can't fathom a reason not to get them.

One of the long term So. Cal. shops (All Electronics?) recently went under and I bought a pile of the I/O jacks the 4000 uses. I don't know why as I swore I'd never touch a 4000 again for the exact same reason Lee mentioned.

That's a pretty good job on the boards. Even if I had the time to build them I'd still probably buy 'em assembled from Mark Lucitt. I've got all of the lead benders and board holders and crap like that. Building them is still a work of art.

I misinterpreted Joes original post. One of the leads from the transformer secondary is tapped off at the bridge rectifier AC terminal and fed to the relay board. It is half wave rectified on the board and lightly filtered so that when AC fails the relay drops out quickly. A person could wire...

I bought an OWON to show real time power line waveforms along with a Power Point. When connecting a scope to a computer and projector it's highly recommended to buy isolation probes to avoid ground loops.