McIntosh Load Box ?

[AudioWizard]

Back in the early 70's I purchased a McIntosh dealer that was retiring. In the deal was two of these load boxes. I was told that they where made by McIntosh for their dealers to use in their service centers. Non-inductive, selectable 4,8,16 ohm, RCA's for O-scope monitoring, differently not home-brew , they are pretty neat. All the internal wiring is very nicely done. Any truth that they where made by McIntosh? Or who they where made by?

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[techguy0192]

I've run across some Mac built test equipment...but this one doesn't have the same look as the other stuff I have seen.

 

[c_dk]

McIntosh offered a kit to their service centers to build a variac and a loadbox in the early 80s....I do not doubt that a load box like you pictured could have been used by them in the 60s and 70s but most likely does not have the heat dissipation we needed as the amps got well over 300 watts.

 

[twiiii]

Mac sent us the parts and we constructed the load box and the box with the variac in it.

 

[dewickt]

Load box and variac were sold as sheet metal and parts list, You had to buy the parts to complete them.

 

[N8Nagel]

Certainly looks beefy. Can you see a watt rating on the resistors?

 

[AudioWizard]

Could it been made before the 70's ? I will take back the back off of one & get some more pictures. I am thinking that it might be because of the 16 ohm tap.

 

[CruzBay]

Certainly looks beefy. Can you see a watt rating on the resistors?

/derail on

Not the one you're asking about, but 500 watts on the one Terry posted.

We used to test the 2600's on them, but went quickly.

/Double Derail

Recently made a load box for an amplifier designer friend using 2000 watt water heater elements, and some ebay heat sinks and fan. I'll post a photo of it sometime.

/derail off

 

[dewickt]

The P487 uses 6 Dale 250W resistors and 2 thermostatically controlled fans, I have only gotten it hot enough to make the fans come on a couple of times in the past 20 years with a MC2600, causes my bench feed to sag below 110V and dim the lights....

 

[damacman]

I guess i’ll be keeping my MC2600s ...

 

[CruzBay]

The P487 uses 6 Dale 250W resistors and 2 thermostatically controlled fans, I have only gotten it hot enough to make the fans come on a couple of times in the past 20 years with a MC2600, causes my bench feed to sag below 110V and dim the lights....
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As I recall, the only time I've gotten a MC2600's fans to come on was on that load bench. And I had to turn the variac up to where it'd normally put out 127 volts to keep power to the '2600 near 115 volts. Blew a 20 amp fuse in the variac once.

Love seeing that circuit, thanks Terry!

 

[AudioWizard]

Ok, took off the back cage;

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Pretty good sized wires , no writing on resistors except for the taps, inside sure looks commercial.