I posted this as a follow-up to my SAC rig case build-out, but thought it might be useful as a standalone posting.
Furman ADA8000 Power Strip Modification
My initial thought was to add some fan cooling to the ADA8000 along with case ventilation. There have been a number of variations on this to lower the stress and heat on the voltage regulators. The mod shown from the German posting was rather silly, as adding a fan to a sealed case does almost nothing to improve heat dissipation, other than to distribute the heat throughout the inside of the case.
I figured I would add a case fan to the side and cross ventilate, or add ventilation holes in the case bottom and lid to allow for air flow. This idea rapidly passed, as there is insufficient space on the sides of the case to mount a fan or to allow for proper airflow.
Adding ventilation top and bottom was also problematic as the holes would need to line up perfectly top to bottom to allow multiple units to stack.
Instead I decided to go the "lower the mains voltage" route. Instead of creating a separate box for this, I built it into the Furman power strip. Isolating 4 of the strip plugs for ADA8000 use.
CLICK images for Larger View:
The transformer cost about $20 and is a 110/220 Primary to Dual 25V Secondary. I was going to get a dual 12V model, but they didn't have any in stock. The transformer is rated at 1.25A on the secondary, which translates to about 140 Watts, which is more than enough to handle 4 ADA8000 with room to spare.
What I discovered in the first pass however was the voltage dropped too much. With a 118V mains source, I was only getting about 89V to the ADA8000s which proved too low and the power supply fell out of regulation.
This created a slight 60Hz buzz in the audio path.
Since the transformer was a dual primary (110 or 220) I modified the circuit adding a switch to allow for full or reduced power, and a second switch to select the voltage reduction (-12.5v or -25V).
This worked out perfectly. See additional pictures below.
The end result was at -12.5v the ADA8000s are perfectly clean (no buzz) and definitely run much cooler. I may order a 20V transformer instead and switch it out as the -25V is probably overkill. (although would work where the mains voltage is 120V or higher).
The Transformer is available through Farnell. They have distributors worldwide through various different website names.
This is the one I purchased: (110/120 Pri / 2 x 25v Sec)
http://us.element-14.com/multicomp/m...78?Ntt=38K4878
For those interested... here is the schematic
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