Dunlap Clarke 500 Power Supply Info

[Raymond]

Hello to all
Does anyone know what the secondary voltage is on The Dunlap Clarke Dreadnaught 500 Power Amplifiers Transformer?

Kind Regards

Ray

 

[Mooly]

These are old aren't they ? I remember the name from old magazines of the late 70's ??

Do you know the DC rail voltage for starters, to work back from that.

 

[Raymond]

Hi Mooly
I have a few bits of info on this power amp but no mention of the voltage of the secondaries........The smoothing caps are 75Volt 17,000uf . Info on the power supply is almost zero! Wish i'd have taken measurments before the traffo went down! but nevermind!!

 

[AndrewT]

what are the output powers into 8r0 and 4r0?
These will give us a very good clue to what they fitted as standard.

 

[Raymond]

Hi Andrew
The output power of the amp are 150watts into 8ohms,300 into 4ohms and 600 into 2ohms rms rated.

Regards

Ray

 

[AndrewT]

use a 230:0-40, 0-40Vac dual secondary transformer.
If you plan to use only 8ohm speakers then 2channels will need 300 to 500VA.
if you may use it 4ohm speakers the channels will need 600 to 1000VA.

I don't expect it is properly designed and built to drive 2ohm speakers. I would expect it to drive a 2r0 load for a short while, i.e. until it gets too hot.

With your 240Vac supply you should have about 58 to 59Vdc on each supply rail, but this will vary a lot depending on the demand at the time (day/night).

 

[Raymond]

Hi Andrew
I've ordered a 400VA 42 0 42v toroidal and i'm hoping that will do the trick! You can view the amp here: The schematic is for the Dunlap Clarke 1000 but they both share the same boards. I've replaced the electrolytics with 100volt 22,000uf in the power supply. Pictures by isobarik - Photobucket

Thanks for your input...Brilliant

 

[Krisfr]

I posted before the rails where plus and minus 60 volts