Thursday, October 25, 2012

3840W Custom Power Resistor Bank for Testing Amplifier Power

Yes, I know, if you guys watch my YouTube videos, then you've probably seen my old resistor bank (aka "Fred Sanford" - Big Dummy). This resistor bank was comprised of (16) 50W resistors for a resulting load of 800W at either 2 ohms or 8 ohms. It was a great starter resistor bank, but in testing amps such as the Orion XTR-2250 and Rockford Fosgate Power 1000 Mosfet, I needed not only more power capability, but also configurations for 4 channel loads at 2 ohms.

Before I get too deep in the discussion of the new resistor bank, let me digress and explain my use of the resistor bank. In this case, I use the wirewound power resistors for testing audio amplifiers power output (in watts). Many people use speakers when attempting to calculate amplifier wattage output, but fail to account for the fact a speaker is a reactive load and other factors must be calculated to obtain wattage. When using resistors, the wattage calculation can be more easily obtained using Ohm's Law. We use a Velleman HPS-50 o'scope/True RMS Volt meter, Fluke 85III True RMS Volt meter, Steve Meade Designs/ D'Amore Engineering DD-1 (aka SMD DD-1) along with our resistor bank to calculate continuous (RMS) power output from the amplifiers we test. For more information on how I test my amplifiers, see this video (to be updated soon).

I recently invested in (32) 120W 16 ohm wirewound resistors so I could test a wider variety of amplifiers. See the result below:

Custom 3840W Resistor Bank made from PC Tower

The 3840W Power Resistor Bank has the following features:

- Custom PC Gaming Tower
- (8) Separate 480W 4 ohm loads
- Supports 8 channel amps down to 1 channel monoblocks
- (3) Internal 12V fans in push/pull configuration for maximum air flow
- 12VDC 600mA AC Adapter for powering the fans
- capable of testing 4 channel amps with all channels driven at 2 ohms (960W each)
- configurations for high-current amps at 1/2 ohm mono (3840W)
- multiple configurations for 1 ohm and 2 ohm loads (both stereo and mono)
- safely test amplifiers silently at various test tone frequencies
- Acrylic window showing off my lackluster wiring skills

Rear view of the 3840W Power Resistor Bank

Stay tuned for an upcoming video overview of the 3840W Air-Cooled Power Resistor bank.  We also have MANY amplifiers to test in the upcoming months, so stay tuned for updates, tests, overviews and more!

Make sure to Subscribe to my YouTube Channel to stay updated of my latest videos. You can also follow me on Twitter @oldschoolstereo.


Danny said...

Wow bro! Nice job with that resistor bank! Looks cool as hell! You might just be able to go into business for yourself making these resistor banks on the side. Be great to sell as test equipment!

dwillis said...

Thanks man. It took quite a bit of work to put this joker together, I'm not sure how many more I want to do. I do have another project I'll share soon and I may make those to sell. You'll see soon...

Mark said...

Jumper wire gauge, and hook up wire gauge?

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