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.

Thursday, October 18, 2012

Amplifier Bench Tests Rare Amps and More

Once again, I've slacked off posting on the blog here. My apologies, I've been focusing on creating more content for my YouTube channel. Make sure you subscribe so you can stay updated and notified when I upload new content. My goal is to upload at least one video a week and for the past few weeks I've been doing 3 videos per week! See some of my recent video uploads below.

Wow, check a MINT copy of a mid-1970's Fosgate PR-235 amplifier. These amps are ULTRA-RARE and finding one in this condition is almost unheard of. Big thanks to Mike for sending this one my way!

Next up, a patiently awaited power output demo of a MINT Lanzar Opti Drive 50c ultra-cheater amplifier from the mid-1990's. Can it meet or beat it's 800w rating at 1/2 ohm mono? Watch the video to find out!

What about a purple beauty? Say what? The mid-1990's rare special edition Orion NT 200 arrives to the labs for testing. This amplifier is a dual-mono design and was built to the strictest standards to ensure the best sound quality possible. Watch me un-box and show off this beauty! 

Now, here's another very interesting power output demo. We test the Orion XTR-2250 "The Beast" amplifier to see if it can stand up to it's name. Well, do you think it can match or exceed it's rated 1000w output at 4 ohms bridged? No spoilers here, watch the video to find out! 

Orion XTR-2250 RMS Power Output Video

***Amp output tests coming soon. We also have lots of cool overviews of some fantastic Old School Car Audio Thanks for your patience!***