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 OldSchoolStereo.com 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.

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 OldSchoolStereo.com 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!***

Donations to OldSchoolStereo.com

I recently accidentally deleted several emails from my phone and found they were not put in the deleted folder, but deleted entirely. I had a couple of people inquire about donating items to OldSchoolStereo. I'm hoping you read the website and see this post and send me another email.

You can feel free to use the donate section of this website or contact me if you have amps, speakers, head units or other old school gear you want to donate. I will most likely sell many of the donated items to help pay for the website and test equipment. 

Thank you for your support!

-Dereck

Video Updates - Lanzar, Fosgate, Alpine and More!

I've uploaded several videos since the last blog post here on OldSchoolStereo.com. There are three videos about the Fosgate "Frequency Energizer" Model 201 processor. If anyone has any further details about these units, please contact me at oldschoolstereo[at] gmail dot com.

First up, see the Alpine 3342 11-band EQ / Sound Field Processor. Just a quick overview of the EQ and showing it in action!





Next up, see baby Lanzar Opti Drive Plus 50 amplifier. I've had several people request I show off how I test amplifiers for operation when they arrive at OldSchoolStereo's labs. This is not a power output test, rather a simple speaker test of each channel and bridged operation.






Next up, see the BIG Lanzar Opti Drive 50c "Ultra-High Current" amplifiers. You'll see an early 1994 blue model and a later 1996-1998 black model. I overview the connections and check the amplifier "guts" for differences between the models. In a future video, we'll also bench test each of these amps for power output. Do you think there will be a difference in the output at 1/2 ohm mono? It will be interesting to see...

Now, here's some vintage gear from Fosgate Electronics. Yes, I said Fosgate, not Rockford Fosgate. This means pre-1980, folks. The Frequency Energizer you'll see is from around 1973 and is the foundation for the Punch EQ circuit used in Fosgate and later Rockford Fosgate car audio amplifiers. 

Fosgate Frequency Energizer "Teaser" Video

Fosgate Frequency Energizer Overview Video




Fosgate Frequency Energizer Demo Video
See the vintage sound processors in action!





***Amp output tests coming soon...I've done tests on the Lanzar 50c and Orion XTR-2250. As soon as I get a chance to edit the videos, I'll have them online. Thanks for your patience!***

Navigation of the Website

Make sure to check out the links near the top of the site...we've added links to our Forums, Videos, Donations and most recently, Installs. If you have an old school install you'd like to share, let me know about it in the forums. 

More info and what you've all been waiting for....Amp Tests coming soon!

Old School Soundstream MC500 Car Audio Amplifier

You guys know I like the old school "monster" amps, and I recently came across a rare beast indeed...a Soundstream MC500 from the late 1980's. The MC500 was part of the original "monster amp test" held by Car Stereo Review back in 1989. Here are the specs of the MC500:

• Four Channel Amp rated at 125 watts x 4 channels
• Bridgeable for 2 or 3 channel operation delivering up to 250 watts x 2 channels
• LSE - Linear Subwoofer Extension with adjustable frequency for added low end impact
• No built-in crossovers
• 2 ohm stereo / 4 ohm mono stable
• Dual 30A fuses for power
• Up to 70A current draw at maximum output

1989 Soundstream MC500 Amplifier

The MC500 was one of the few amps in 1989 to have integrated terminal connectors. The power, ground and speaker terminals can accept up to 8GA wire. The RCA jacks are gold plated and very high quality. The dual 30A fuses are inserted just beside the power terminals.

Soundstream MC500 Amplifier - Power Connectors

The Soundstream MC500 was available for a short period of time around the 1989/1990 time frame. From what I've been told by Soundstream experts, this amp was one of the few Soundstream powder coated. Most of their other amps at this time (D series and Class A) were anodized aluminum. Many of the first batch of MC500's had extreme paint flaking issues and had to be recalled. The next run of amps had a better coating, but based on the U.S. MSRP of $1295, not many of these amps were sold. 

Unlike many of the other Soundstream high-end amps at the time, this one was not touted as "Class A". That said, the MC series (MC500, MC300, MC245 and MC140) were well regarded for their sound quality and flexibility. Yes, at the time, 500 watts was considered BIG power! 

Soundstream MC500 guts - Nice!

Amp output tests coming soon...just waiting for the NC weather to cool a little. Maybe one day my labs will be climate controlled! Enjoy the video overview below. Output test coming in the future.


See my video overview of the Soundstream MC500 below.


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

Watch the video on YouTube in 1080P or embedded below:

Possibly the Ultimate 50 Watt Cheater Amp from the 90's?

Yes, I know, if you guys watch my YouTube videos, then you've probably seen the Lanzar Opti 50c. But wait, is it possible another "50 watt" amp may give the Lanzar a challenge for king of the 25x2 amps? Well, yes, specifically the U.S. Amps VLX-50. I recently came across a near MINT 1996 model in the "Mirror Polish" finish which looks nearly chrome. See the pics below:

1996-1998 U.S. Amps VLX-50 Ultra-High Current Cheater Amp

The VLX-50 has the following ratings:


2 x 25W at 4 ohms (12V)
2 x 31W at 4 ohms (14.4V)
2 x 62W at 2 ohms (14.4V)
2 x 125W at 1 ohm (14.4V)
2 x 250W at 0.5ohm (14.4V)
2 x 500W at 0.25ohm (14.4V)
1 x 1000W at 0.5 ohm bridged (14.4V)
THD: less than 0.006%
External 120A Fuse Required

VLX-50 Inputs and "Vari-Loud" controls

The U.S. Amps logo is laser etched on the heatsink and it surprisingly took me several days to prove this was actually a VLX-50. For some reason, U.S. Amps didn't put any markings on the end plates or even on the circuit board indicating the model of some of their amps (this one included). I was able to get confirmation from U.S. Amps this was indeed a VLX-50, based on the serial number. I even posted a thread over on DIYMA to get some info and got some great info in the archaeological dig.


So, the best part about having an amp rated at 50 watts total put out 1000 watts is the "cheater" factor. Back in the 90's, you could have two of these and still compete in the 100 watt and under competition class (as they rated amps by their 4 ohm output power). Thus the "cheater" status as you could have up to 2000 watts if these amps were properly loaded down. Orion really started the cheater amp category with the 225 HCCA, which was introduced in the late 1980's. Also, as a response to ultra-cheater amps like the VLX-25 and VLX-50, Orion developed the "1-watt" Concept 97.3 back around 1997. The cheater amp era basically ended around the early 2000's as most manufacturers were competing to see how high they could rate their amps (by using MAX power) instead of underrating amps. Another reason why I prefer the car amplifiers from the 80's and 90's...

VLX-50 Power / Ground / Speaker Terminals

Get ready for the long awaited 25x2 cheater amp shootout. As soon as the temps cool and I complete my additional resistor loads, we'll see how the VLX-50 competes against the monster Lanzar 50c. I don't believe the Orion 225 HCCA, Rockford Power 50x2, MTA 225HO or Audio Art 50HC have a chance against the VLX-50 or 50c, but who knows? We all may be surprised!




See my video overview of the U.S. Amps VLX-50 below.




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


Watch the video on YouTube in 1080P or embedded below:

BigDWiz on The Tech Guy Radio Show!

Wow, today was my lucky day!! I was able to get on the caller list to talk to Leo Laporte on his nationally syndicated radio show "The Tech Guy". Leo runs twit.tv, an Internet broadcast network delivering dozens of audio and video podcasts weekly.


My question was regarding YouTube and how to download a list of my subscribers so I can do a giveaway. Leo mentioned YouTube probably doesn't make this easy for a reason...to keep spam down. My reasons for wanting the list are totally legit; I just want a way to get a text listing of all the subscribers so I can put them in Random.org to choose a lucky winner for whatever Old School car audio item I plan on giving away.


See show 887 on TechGuyLabs for more info. See the embedded YouTube Video at the bottom of this article. My favorite quote from the twit.tv chat room during the show by username Howard: 

"Leo 80ties & 90ties old school? I must be ancient school."

By the way, Leo got a kick out of my "Chinese mini Amp Invasion" videos! Thanks for the recommendation Leo, I'll try it out and let you know how it works.


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


Dereck
aka "BigDWiz"


See my segment embedded below or See it on YouTube

Old School Car Audio Tribute Video - Submitted

Here we have a great video put together by "MrRubenEsp" on YouTube. The video is a dedication to the old school car audio gear and installs. He mentions finding most of the pictures on the Internet, and I think he did a great job putting together the slideshow. Enjoy the video below!


I've asked before and will continue to remind OldSchoolStereo.com fans...please submit your photos/videos/installs/etc! You can reach me at oldschoolstereo at gmail dot com or via message on YouTube via username BigDWiz

BigDWiz - OldSchoolStereo.com

Old School Monster Car Audio Amplifiers

Some Old School Monster Amps from the OldSchoolStereo Collection...no Class D here!

Anyone who was in the car audio scene during the 90's probably recognizes names like "The Beast" and "Power 1000c". Old school monster amps were unlike the big mono block amps of today...they were Class A/B, much less efficient and some would say, much better sounding than the amps of today. I'm not getting in a battle of what's better, just confirming there are two sides here. Since you are visiting OldSchoolStereo.com, you are more than likely a fan of the older amps. Many of the amps you see in the picture above are almost legendary in the history of car audio. Let's talk a little about each amp and it's impact on car audio.


First off, you'll notice a trio of Orion amps, all bearing the same heatsink design. The "big red" Orion 2100 HCCA is well known to be a monster cheater amp. The "Digital Reference" model displayed above was rated to handle 2 ohm mono or 1 ohm stereo loads and put out in excess of 800 watts loaded down. Efficiency? Well, not so much. All of these big Orion's require a 2nd battery and an electrical upgrade on most vehicles. Why, might you ask? Well, these amps can pull over 100A of current and most stock electrical systems would not be able to handle this massive load. Speaking of massive, the XTR-2250 was so well known as "The Beast", Orion even engraved this saying on the amp. It is rated at 250 watts per channel at 4 ohms stereo, 500 watts per channel at 2 ohms stereo or 1000 watts bridged at 4 ohms. What you say? No one ohm bridged like a Sundown? No sir, this amp would and will fry if pushed too hard.

Orion Monster Amp Art by BigDWiz

Speaking of being pushed too hard, the Orion Concept 97.3 is an amp of almost legendary status. A quick search on the Internet will give you dozens upon dozens of different pages attempting to explain this amp. Orion introduced the amp in 1997 as a bold statement to IASCA and dBDrag for the wattage classes. The 97.3 was rated at 0.5 watts per channel at 4 ohms...yes, I said 1/2 watt per channel! What's up with that? Well, Orion was trying to show the "cheater amp" had gone too far when companies such as US Amps and their VLX-25 had ratings of 12.5 watts per channel at 4 ohms but put out over 1000 watts loaded down to 1/2 ohm. Orion, an originator of cheater amps with the 225 HCCA back in the 1980's, decided it was time for this to stop. What did they accomplish in their effort to change the rules? Well, they ticked off many competitors who attempted to use these amps at low ohm loads (and fried the amps) and even got the amp banned by IASCA in 1998 (source - Orion dealer). Why would the amp cause this much controversy? Check out these ridiculous ratings, it may help (ratings pulled from the Concept 97.3 manual):




STEREO (watts @ ohm load)


0.5x2 @4
1x2 @2
2x2 @1
4x2 @0.5
8x2 @0.25
16x2 @0.125
32x2 @0.0625
64x2 @0.03125
128x2 @0.015625
256x2 @0.0078125
512x2 @0.00390625


 MONO (watts @ ohm load)


2Wx1 @4
4wx1 @2
8WX1 @1
16WX1 @0.5
32WX1 @.25
64WX1 @.125
128WX1 @.0625
256WX1 @.03125
512WX1 @.015625
1024WX1 @.0078125




Next we'll talk about the monster Rockford Fosgate amps, the Power 1000c Mosfet "Terminator Edition" and Power 650 Mosfet. Back in the early 90's the 1000c sold for $2650, while the 650 was around $1800. Again, these amps were WAY out of the reach of most car audio fanatics including me. These Power Series amps all had model numbers based on their output at 2 ohms stereo or 4 ohms bridged. For example, the 1000c was rated at 150x4 at 4 ohms, 250x4 at 2 ohms or 500x2 at 4 ohms. Similarly, the Power 650 Mosfet was rated at 125x2 at 4 ohms, 167.5x2 at 2 ohms or 325x2 at 4 ohms bridged. Unlike the Punch series amps at the time, these Power series are not known to be underrated more than 10-15%. Both amps have a temperature controlled cooling fan and the 1000c includes an ultra cool LED meter for each channel.

1991-1993 Rockford Fosgate Power 1000c Mosfet Amplifier

Next up, we'll discuss the Precision Power ProMOS 450. This amp preceded PPI's "Power Class" line and the models in the ProMOS family were made from the late 80's until the mid 90's. The 450 was the most expensive ProMOS amp and incorporated two separate ProMOS 50's into one chassis. When the first ProMOS amp, the PPI ProMOS 2050 hit the market in 1989, it went for around $800. By the early/mid 90's, the four channel 450 could be picked up for around $900 US. All of the ProMOS amps were rated to handle 1 ohm stereo or 2 ohm bridged loads. The 450 had the following ratings; 50x4 at 4 ohms, 100x4 at 2 ohms, 200x4 at 1 ohm, 200x2 at 4 ohms or 400x2 at 2 ohms. The heat sink used by these older PPI amps are in my opinion, some of the most classy designs of all time. Very simple, yet elegant and powerful. Too bad PPI used the hateful proprietary Molex plug for speaker connections and straight 8ga wiring for the positive and ground connections. As you can see from the picture below, the ProMOS 450 is even longer than the Orion 2100 HCCA!

PPI ProMOS 450 "Art Series" vs. Orion 2100 HCCA "Digital Reference"

The Earthquake PA-2300 is another very powerful Class A/B amp from the 90's. It is rated at 380x2 at 4 ohms, 575x2 at 2 ohms or 1150x1 at 4 ohms. Based on ratings alone, this is the most powerful old school amp in the bunch. The newer Dragster DH-1804 edges out the PA-2300 in power ratings, but just slightly. The Dragster is another four channel amp rated at 180x4 at 4 ohms, 300x4 at 2 ohms or 600x2 bridged at 4 ohms. Although I haven't confirmed by testing, I believe the Earthquake PA-2300 may be the most powerful amp in this group. What do you think?


See my video overview of each amp below.




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


Watch the video on YouTube in 1080P or embedded below: