Saturday, December 8, 2012

Amazing Car Audio Museum in Germany

It has sort of been a dream of mine to put my old school equipment into a showcase, sort of a museum. Unfortunately, I don't currently have a good room to showcase my gear, but maybe one day. In the meantime, check out this guy "Danny" in Germany and his awesome collection of old school car audio and an incredible display of it all. I'd call this the ultimate man cave! Although some of the text is in German, all of the pictures are in English ;-)

Keep it old school, more goodies on the horizon!


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!***

Wednesday, September 19, 2012

Donations to

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!


Tuesday, September 18, 2012

Video Updates - Lanzar, Fosgate, Alpine and More!

I've uploaded several videos since the last blog post here on 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!***

Sunday, September 2, 2012

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!

Saturday, August 11, 2012

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
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
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:

Saturday, July 21, 2012

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:

Saturday, June 30, 2012

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, 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 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 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 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.

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 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 -

Tuesday, June 19, 2012

Old School Monster Car Audio Amplifiers

Some Old School Monster Amps from the OldSchoolStereo 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, 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:

Saturday, June 2, 2012

Rare Old School Rockford Fosgate Power 1000 Mosfet Terminator Edition Amplifier

est. 1990 Rockford Fosgate Power 1000 Mosfet "Terminator Edition" Amplifier designed by Wayne Harris

Let us take a journey back to the year 1989...Car audio had been around for a while, but with amplifiers such as the HiFonics Colossus, Linear Power 8002 and Rockford Fosgate Power 1000, things were really getting serious. Wayne Harris, one of the pioneers of modern car stereos, was hired by Rockford Corporation and was given the task of swapping out his amps in the "Terminator Hearse" with the Power 1000 Mosfets. Wayne was kind enough to send an email describing the beginnings of the 1000C:

"If I recall correctly, I went to work for Rockford in July of 1989. One of my first tasks was to upgrade the equipment I was using in the Terminator. Rockford gave me 6 each Power 1000 amplifiers. Unfortunately, they were too long to fit in my car. I took the sheet metal for each amp to a machine shop and had them cut off the “caboose”. This made the amp about 6 inches shorter. (Now the amps would fit in my amp rack.) I then designed an LED bargraph meter display and installed these displays within the MAIN housing of the amplifiers. The final step was to chrome plate the amp shroud and then apply custom silkscreen.

The VP of marketing (Jerry Cave) saw the amps in my car prior to the 1990 CES show in Las Vegas. He like the amps in my car so much that he decided to make all Power 1000 amps look the same."

As many of you old schooler's know, Wayne Harris' Terminator Hearse is a legend in car audio. If you haven't seen it, take the time to view the video of this beast from 1985 from dBDragUSA's YouTube channel...can you say 30" subwoofer?

Sorry for the side track, I'll try to stay on subject here. The Rockford Fosgate Power 1000 Mosfet "Terminator Edition" (from now on we'll refer to as the 1000C) was a step forward in design from the original Power 1000 Mosfet, which was introduced around 1987. The internals were identical except for the LED meter and removal of the "caboose". The 1000C's chrome appearance and $2650 US MSRP meant this amp was not for your average 16 year old getting a new was for serious competitors and those who got had the means to buy such an expensive amplifier. Many Rockford dealers had one or more of these amps in their demo vehicles and most of us could only dream of owning such an amp.

RF T1000 vs. Orion Concept 97.3

The 1000C is a four-channel, class A/B amplifier with no internal crossovers. See detailed specs below:

  • Power Ratings 2 Channels (Bridged): 500 watts x 2 channels from 20-20,000Hz with less than 0.1% THD
  • Power Ratings 4 Channels4 Ohms: 150 watts x 4 channels from 20-20,000Hz with less than 0.05% THD; 2 Ohms: 250 watts x 4 channels from 20-20,000Hz with less than 0.1% THD
  • Frequency Response: 20-100,000Hz +0.5dB, -3.0dB
  • Damping Factor: At circuit board: Over 200 (referred to 4 ohms); At speaker fuse: Over 50 (referred to 4 ohms)
  • Signal to Noise Ratio: Over 80dB Unweighted
  • Instantaneous Peak Output Current: Over 100 Amperers 
  • Protection: The Power 1000 is protected by analog computer output protection circuitry and a 100A fuse. A thermal sensor shuts down the amplifier in case of overheating
  • Dimensions: 22.75" L x 7.4" W x 3.75" H
  • Weight: 21lbs
  • MSRP: $2650 US (1991)

Here is an informational email I received directly from Rockford Fosgate when I inquired about the 1000c Terminator Edition amp:

“The T1000’s went from the black painted and silkscreened ones with the caboose (that covered the 6ga B+ & Gnd terminal block), then to the black painted and silkscreened ones that no longer had the caboose and just had the one B+ and two GND cables hanging out of it.  Then it migrated into a chrome fan shroud.  That’s about the time that Wayne Harris came on board with designing the LED output meter for the T1000’s.  Then probably in ’92-’93* is when the Terminator Edition hit the market with the special screening and LED display.  It was a very limited run….I think maybe only 100pcs or so.  I think Wayne had 10 of them for himself.”

(* I think the year range was '90-91 - BigDWiz)

See the unboxing and overview video below. More information coming as soon as I get the amp repaired and fully functional...

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:

Sunday, May 13, 2012 Updates - May 2012

Thanks to everyone who visits the website, leaves comments, sends emails and subscribes to my YouTube Channel! The past several months have been extremely busy in my personal life and I haven't had the time to dedicate to the website. I hope you understand this is still a passion of mine, just had to take the back burner for a while. I'm hoping to be back in full force in the upcoming months and have TONS of planned videos, demos, tutorials and other goodies. In the meantime, anyone who has pictures of old school installs (they have taken or have rights to) or do any videos on old school car audio, please let me know and I'll be glad to link to them from here. You can reach me at oldschoolstereo (at] gmail dot com. It may take me a few days to get back with you, so please be patient.

As many of you know, I've been talking about the 1990's 25x2 cheater amps for almost a year now. Well, I recently came across two new additions for the shootout and will hopefully have time to test them soon. I actually have an unboxing video and will post below for one of the amps...MTX Thunder 225 HO. It is rated at 25x2 at 4ohms, but has 90A, yes 90A worth of fusing!!! The epitome of cheater amp status! It may be the amp to beat in the group, we'll see...

MTX Thunder 2300 (left) and MTX Thunder 225 HO (right)

See the video of me unboxing the MTX Thunder 225 HO and comparing it physically to the earlier generation Thunder 2300:

I also recently found a really neat Rockford Fosgate LED sign for the OldSchoolStereo labs. You can see it in the background of the MTX amps above, but also below in an unboxing video:

Thanks as always for visiting and please bookmark this page and sign up on the right side of the page for email alerts when a new article is posted. I look forward to your participation in the forums and keep it Old School!


Sunday, April 15, 2012

Old School 1990's 50 Watt Cheater Amps Tested

This post will be a work in progress until I complete my round of tests on the 25x2 Watt "cheater amps" from the 90's. I'll include a spreadsheet showing the results and links to the videos I create for each amplifier. Thus far, the test will include:

1) Rockford Fosgate Punch 45HD - from approx. 1991, not a true high-current amp like many of the other's, but well known to be underrated and able to handle almost any speaker load

2) Orion 225 HCCA - from the early 90's, test will include the "Digital Reference" and maybe the "Competition Amp/X-over" models. One of the most feared cheater amps of the early through mid 90's.

3) Precision Power ProMOS 25 - also an early 90's cheater amp rated to handle 1 ohm loads and promises the warm, smooth SQ of an early PPI amp

4) Phoenix Gold MPS-2240 - part of Phoenix Gold's "Mobile Professional Series" the MPS-2240 is identical in size to the MS-275 and is a high-current amp rated at 24x2 and designed to handle loads down to 1 ohm

5) Phoenix Gold M25 - the "M" series from Phoenix Gold were known for superb SQ and are very popular among collectors and those building old school systems as well.

6) US Amps 50HCA - an early version of a 25x2 cheater from US Amps. No crossovers, no terminal strips, just raw power and old school flair

7) US Amps USA-50 - a late 90's 25x2 amp designed to handle loads down to 1 ohm

8) Zapco Z50C2 - mid-90's amp, small in footprint, big in SQ

Bookmark this page as it will be continually updated with more information on each of these amps!


Tuesday, April 3, 2012

Some Really Powerful Mini Amps? The Rockford Fosgate Punch Boosted Rail Amplifiers PBR300x1 PBR300x2 PBR300x4

Rockford Fosgate Punch "Boosted Rail Amps" - From left to right; PBR300x1, PBR300x2 and PBR300x4

I get questioned all the time as to why I do tests and reviews of new amps on Isn't this website for stereo gear from the 80's and 90's? Well, yes, but I also like to test new products that stand out from the rest. As you may have seen on my YouTube channel, I like to make portable boomboxes and tiny amps such as the Rockford Fosgate PBR series intrigue me. Also, let me make it clear...these Punch PBR series amps pack a big power "punch" and are not to be confused with the other Chinese Mini Amps I've tested in the past. Those amps from Lepai, Kinter and others will brag about "500 Watts" or more and must have misplaced the decimal point when converting from Chinese to English or something...

The Rockford PBR series I'm talking about here are the 300 watt versions; Specifically the monoblock PBR300x1, stereo PBR300x2 and four-channel PBR300x4. Each amp is identical in size, but vastly different in output configuration.

  • The Punch PBR300x1 is a mono block amp, designed for subwoofer duty only. It is rated at 75x1 at 4 ohms, 150x1 at 2 ohms and 300x1 at 1 ohm. The PBR300x1 is also unique in that it relies on the three 15,000uf 25V caps to keep the rail boosted during high power operation. The PBR300x1 has no switching power supply toroid, whereas both the PBR300x2 and PBR300x4 do
  • The Punch PBR300x2 is the most flexible amp in this series as it is suitable for stereo, mono or tri-mode operation and has built in low-pass and high-pass crossovers. The PBR300x2 is rated at 100x2 at 4 ohms, 150x2 at 2 ohms or 300x1 at 4 ohms bridged mono. Before I purchased the amp, I contacted Rockford Fosgate to find out if the amp could be used in "tri-mode" operation (stereo and mono simultaneously) and the answer was yes. This intrigued me as it would allow me to test the amp using an old school tri-mode crossover, and possibly a good candidate for a boombox project.
  • Lastly, the Punch PBR300x4 is a four channel model rated only to handle 4 ohm loads at 75x4. You can choose Low Pass, High Pass or bypass for crossover duties. Unfortunately, no Punch Bass port is provided and the PBR300x4 is not bridgeable. This amp seems well suited for powering front and rear full range speakers.
  • All of the PBR300 series measure  6-15/16"W x 1-9/16"H x 4-5/16"D
  • Street price for the PBR300 series is around $250 US each
Not mentioned above is the recently introduced Punch PBR500x1. The 500x1 is not only larger in size, but also much larger in power output delivering 500 watts at 1 ohm. We may get one of these amps soon to run through the test bench, so stay tuned.

PBR300 series internal components, left to right; PBR300x1, PBR300x2 & PBR300x4

Over the past few months, we've had a chance to put two of the PBR300 amps on the OldSchoolStereo test bench and also run through some real world tests with speakers and subwoofers.

First to test was the original "Boosted Rail" amp offered by Rockford Fosgate, the PBR300x1. After seeing Steve Meade's video about this amp at the 2011 Consumer Electronics Show, I was eager to get my hands on one. PASNATION also has an excellent video explaining the technology in these amps. I also created a couple of videos showing off the PBR300x1. See them below:

Part 1: Unboxing and Overview - See on YouTube in 1080P HD or embedded below

Part 2: RMS Power Output Test - See on YouTube in 1080P HD or embedded below

After the apparent success of the PBR300x1, Rockford expanded the line of "boosted rail" amps with the PBR300x4 and most recently the PBR300x2. I purchased both amps, most recently the PBR300x2. With this amp's ability to work in stereo, mono, or both (using passive crossovers), I decided this might be the perfect amp for a high powered portable boombox. Also, to add some flair of old school, I decided to test the amp using a Phoenix Gold XVR4 tri-mode crossover network. The XVR4 provides 80Hz low-pass filtering at 12dB/octave and 120Hz high-pass at 6dB/octave. I thought this would be a perfect match for my recently created Rockford Fosgate AUDIOphile Bookshelf Speakers and a trio of old school JL Audio 8W6 subwoofers. It turned out to be a great combination indeed! See the full test and demo below:

Rockford Fosgate PBR300x2 Bench Tested and Demo'd - on YouTube in 1080P HD or embedded below

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Saturday, March 17, 2012

1990 MTX Terminator MTA 250 Amplifier - PPI Built Cheater

MTX Terminator MTA 250 100 Watt Car Audio Amplifier

Following the theme of the recent posting of the Dragster DH 1804, I guess I have a thing for bright red amplifiers. The MTX Terminator MTA 250 is the most recent addition to the collection and an impressive one indeed. The MTA 250 is one of MTX's first car audio amplifiers and was actually made by PPI (Precision Power). The MTA 250 closely resembles the PPI ProMOS 2050 and even uses the hated and nearly impossible to find replacement PPI speaker harness.

The MTA series of amps from MTX included two models; the MTA 225 and the MTA 250. Both models were stable down to 1 ohm and followed suit to the Orion HCCA's as "cheater" amplifiers for competition use. The 225 retailed for $500 US while the 250 was going for $650. In addition to the stunning red heat sink, MTX offered both models in white.

MTX MTA 250 Gain, Inputs, Max Thump, and LED's for Power and R/L clip

During the late 80's and early 90's, having a cheater amp was very important for competition purposes. There were several classes including under 50, 100, 150 and 250 watts. The higher wattage classes were ultra competitive, so those new to the scene and/or those on a budget would steer to the lower wattage classes. Cheater amps like the Orion HCCA's, PPI ProMOS, Phoenix Gold MPS and others were popular among competitors. The cheater amps could produce four times (or more) their rated 4 ohm power into lower ohm loads.

At the time MTX released the MTA series amps, they also introduced a Terminator line of subwoofers. They had a red cone and touted "2 ohm" resistance for maximum power output from your amp. A perfect match to the MTA series amps and their high-current, low-ohm output genius!

Here are the specs of the MTA 250 from MTX:

RMS Output:

  • 4ohms Stereo: 50 W per channel
  • 2ohms Stereo: 100 W per channel
  • 1ohm Stereo: 200 W per channel
  • 4ohms Mono: 200 W
  • 2ohms Stereo: 400 W
Total Harmonic Distortion (THD): 0.02%
Frequency Response (+/- 1dB): 15-40kHz
Signal to Noise Ratio: 102dB A weighted
Slew Rate: 15V/us
Damping Factor @ 100Hz 4ohm load: >500
Damping Factor @ 100Hz 2ohm load: >250
Stereo Separation: 72dB
Input Sensitivity: 100mv - 2V
Input Impedance: 10k Ohms
Supply Voltage: 10.5-16V
Fuse Rating: 30 Amp
Shipping Weight: 12 Pounds
Dimensions: 14" L x 8.5" W x 2.3" H

Internal Bridging for Mono or Mixed-Mono Applications
MOSFET Power Supply and complementary discrete output circuitry
Two-layer glass epoxy computer grade circuit board
Low-Noise, sealed conductive plastic potentiometer
Designed and built in the USA

MTX MTA 250 "Gut" shot - Circuit Board

See video demo below!

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



Friday, March 9, 2012

Dragster DH 1804 1.2kW Car Audio Amplifier

Dragster DH 1804 1.2kW Amp vs. Orion XTR 2250 "The Beast"

I recently picked up an Italian made amplifier from Dragster, called the "DH 1804" or "1.2kW" amplifier. This amp is a 4 channel model rated at 180 watts x 4 channels at 4 ohms and 300 watts x 4 channels at 2 ohms or bridged at 600 watts x 2 (giving you the 1,200 or 1.2kW of power). Dragster also offered a 2 channel version of the amp, called the DH 1802. Ratings are 360 watts x 2 at 4 ohms, 600 x 2 at 2 ohms or 1200 watts bridged at 4 ohms.

As you can see by the comparison above, the DH 1804 makes the Orion "Beast" look not so beastly...The Dragster is about 5 inches longer and 3 inches wider than the Orion. All connections are made via terminal strips and there are dual connections for power/ground. The DH 1804 is beautifully constructed of aluminum and partly chrome plated and partly powder-coated a bright, candy red.

Unfortunately for me, the seller I purchased the amp from shipped it with virtually NO packing material. The amp took a beating during transit, had the mounting tabs and a few fins bent. Needless to say, I was NOT a happy camper! Anyone who sells a car amp listen....pack an amp VERY carefully when shipping. If you haven't worked at UPS or FedEx (or any other shipping/receiving company) unloading and loading trucks, you have no idea how much the package goes through before it's delivered to the destination.

Continuing with the amp itself, there is very little information available online about this 1.2kW amp. A quick "all language" search with Google helps as this amp appears to be very popular outside of the USA. Since it was made in Italy, I can only think of well-made exotic cars such as Ferrari and Lamborghini. Thanks to Google Translate, I was able to retrieve the following specifications:

The Dragster brand from Italy is known for very good sounding amps. Excellent workmanship combined with a stylish design are just a figurehead of this high-end manufacturer, this power comes in all walks of life up to the top model DH 1804, with impressive values.

PWM MOSFET power supplies
Variable Crossovers
RedRubin aluminum heat sink
High-quality epoxy circuit boards
2 ohm stable stereo
Sealed potentiometers
Teflon-plated RCA connectors
High Speed ​​HEXFET audio outputs

4 x 180 / 300 watts RMS at 4 / 2 Ohms
2 x 600 watts RMS into 4 ohms
variable 50-500Hz HP / LP filter for Front & Rear
Distortion 0.05% Signal-to> 103 dB

Dimensions: 740 x 55 x 245 mm

Dragster DH 1804 vs. HiFonics Zeus VII

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Dragster Demo Vehicle equipped with DH 1804 Amplifier

See the video on YouTube in 1080p HD or embedded below:

Sunday, February 19, 2012

Old School Polk Audio C4 Subwoofer - Fourth Order Bandpass Enclosure

Polk Audio C4 Subwoofer - Fourth Order Bandpass Enclosure with Four 6x9 Subwoofers in Isobaric Configuration

Wow, a true survivor here! An early 90's Polk Audio C4 subwoofer. This enclosure is one of the most unique factory car audio subwoofers of all time. It uses four 6x9 subwoofers mounted in a compound isobaric configuration. The center chamber is sealed, while both outer chambers are vented with a 3" x 5" port. Dual binding posts offer either 4 ohm stereo, 8 ohm mono or 2 ohm mono configuration.

Here are the technical specs provided by Polk:

Driver complement - Four 6x9 drivers monted in a isobaric push pull configuration
Enclosure type - 4th order bandpass
Frequency response - 25 to 150 Hertz
Sensitivity - 94 db @ 1 Watt @ 1 Meter
Recommended amplification - 25 to 200 Watts per channel
Impedance - 4 Ohm stereo, 2 or 8 Ohm mono
Dimensions - 8" H x 26.25" W x 17.125 D
Weight - 26 pounds

Bottom Panel of C4 Removed

Now, looking cool is nice, but sound quality and bass output is what's really important. After reviewing some  of the magazines in the OldSchoolStereo library, I found a test of this subwoofer by Car Stereo Review (March/April 1992). Since I don't have the equipment to compile technical measurements of speakers, I was intrigued to see the reviewer was able to get 119dB out of this unit. I've been using a JL Audio 12w6v2 for the past few weeks and although I haven't had my system measured, I feel pretty confident I'm pushing 125dB with only 300w. I guess what I'm alluding to is right off the bat, I wasn't expecting to obtain the output I'd become accustomed to over the past few weeks. However, I have been using a single Kicker Solobaric s10c the past year or so and it has been sufficient for my tastes so the C4 may be enough for my needs.

Now, I've only tested out the C4 for an hour or so total, so I won't leave my final impression until I've been able to give it a few weeks in my car. For now, I'll just say my initial impression is the C4 is quite impressive. It won't flex your windows or take your breathe away, but it will provide clean, hard-hitting, dynamic bass good enough for those looking to add some low end to their modest systems. I'll update the article in a few weeks with my overall impression. I've posted the video overview including demo below. Enjoy!

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See the video on YouTube in 1080p HD or embedded below:

Thursday, February 16, 2012

Old School Car Audio Bookshelf Speakers? DIY Audiophile Project

Custom Rockford Fosgate AUDIOphile Bookshelf Speakers

Ok, I admit it....I'm an old school car audio junkie! Much of my equipment is in mint condition and actually using this gear is really cool. You guys may recall my Rockford Fosgate AUDIOphile RFA-414 component system from the Old School Boombox article. I was going to need the 4" mids in enclosures anyway, so why not use some small bookshelf cabinets? Exactly! I just needed some patience, a few tools and first set of car audio based bookshelf speakers.

The donor bookshelf speaker cabinets were taken from an early 90's surround sound system by a company called Universal. The particular cabinets I used for this project had a 4" speaker, but no tweeter. No problem. A quick trip to the hardware store to get a 2 1/8" hole saw (per Rockford's RFA manual) and the mounting hole for the tweeter was done. It is interesting Rockford recommends a 2 1/8" hole as I found it slightly large....oh well, I digress.

In addition to cutting holes for the tweeters, I also had to line the interior of the cabinets with sound deadening material. The metal enclosures without the dampening material would cause some unwanted coloration (is that a word?). Anyway, I think you know what I mean. After adding the deadening material, the enclosures had a "thud" instead of a "ting". Still not as dead sounding an MDF based enclosure, but much lighter and smaller.

As with many inexpensive speakers, the donor Universal's had tiny 22ga internal speaker wire. This was easily remedied by de-soldering the factory wire and upgrading to some 16ga Phoenix Gold OFC speaker wire. I also used hook and loop tape to mount the AUDIOphile crossovers. The flush mount tweeter pods were mounted using silicon sealant and some custom brackets. Everything came together very well and I'm happy with the results.

Now, I can write all day about the process, how they sound, etc., but if a picture is worth 1000 words, then a video is worth 10,000. I created a video build log of this project and also give a sound demo of the speakers. They are very transparent, but as expected, somewhat weak on the bass output. This component system was designed to be used with a subwoofer and maybe even a midbass. My plans are to cross them over at 150Hz and other plans TBD...

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See the video on YouTube in 1080p HD or embedded below:

Tuesday, January 31, 2012

Boombox Using Old School Rockford Fosgate AUDIOPhile Speakers

Custom Old School Boombox using Rockford Fosgate AUDIOphile Speakers (est. 1995)

Now, here's a project I've thought about putting together for around 20 years...a portable stereo (aka "Boombox") made from car stereo gear. In this instance, I'm using all Rockford Fosgate gear from 1995 or earlier. A single Punch 45 amplifier will power the entire system, including 4" AUDIOphile component speakers with a 1" silk-dome tweeter and bass notes will be handled by an 8" AUDIOphile subwoofer. This subwoofer should work quite nice as it is designed for a very small 0.33cu/ft sealed enclosure. The "brain" of the system will be another Rockford piece, the PA-1 pre-amp. This unit will control 2 different inputs and provide overall volume, bass, mid and treble controls.

Here is the proposed gear (subject to change):

  1. Military-Style Waterproof ABS Plastic Case
  2. Rockford Fosgate PA-1 Pre-Amp (est. 1987)
  3. Rockford Fosgate Punch 45 Amplifier (est. 1989)
  4. Rockford Fosgate RFA-414 4" AUDIOphile component system (est. 1995)
  5. Rockford Fosgate RFA-408 8" AUDIOphile subwoofer (est. 1995)
  6. (2) 8Ah Sealed Lead Acid Batteries
  7. Integrated iPod dock / AUX jack / USB port
  8. 12V Battery Gauge
  9. 12V Trickle Charger
  10. 12V 25A Lighted Switch
  11. ....more to come

I've worked on the boombox since the video below and found the case is going to be very limited in size for all of the proposed components. I may need to substitute a Punch 30 and use only one battery. Once I get the subwoofer enclosure completed (making sure to hit the optimal 0.33cu/ft internal air space), I'll have a better idea how much space I'll have for the other components. I could also use a PA-1HD or PA-2 as they are 1/2 DIN as compared to the PA-1's full DIN size, but the PA-1 just looks cooler to me!

I show off the power source(s), dual 8Ah sealed lead-acid batteries in the video. These batteries are around 4lbs each and should give us 2-3 hours of very loud playback. I'll test the playback time in an upcoming video. Again, due to space limitations, I may need to scale down to one battery.

Stay tuned for upcoming updates, the build process and the final result of my "OldSchool Boombox"

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See the video on YouTube in 1080p HD or embedded below:

Tuesday, January 24, 2012

The Vintage Rockford Fosgate Collection of

Some of the Older Fosgate and Rockford Fosgate Amps in the OldSchoolStereo collection

We at are Rockford Fosgate fanatics! I myself, started off with a late 80's Punch 45 and still have the amp to this day (and it still works great!). I decided to put together a video slideshow of much of our old school collection of Fosgate and Rockford Fosgate gear.

The slideshow was put together to show off models ranging from a 1978 PR-250 to the 2005 "25 To Life" Anniversary models of the Punch 45, 75 and 150. Enjoy the slideshow showing off models such as:

  • Fosgate (Pre-Rockford) Amps including the PR-220 and PR-250
  • 1st Generation Punch 45, 75, 150 and several Perfect Interface chrome and gold amp shrouds
  • 2nd Generation and HD series Punch 45, 75 and 150
  • Old School Power series amps including the Power 100HD, Power 300, Power 360, Power 650 and Power 1000 Mosfet model
  • A MASSIVE collection of the 1992-1996 DSM series amps including; Punch 40, 60, 100, 200 (plus the ix models) and a few of the 4 channel models; 4020, 160x4 and 400x4. I also show off a MINT Punch Power 500M in the original box!
  • Speakers including the "Punch Classic" subwoofers and AUDIOphile mids/tweets and subs from the mid-1990's
  • And MUCH more! Enjoy the 5 minute video!
I also created both music tracks on my iPad using GarageBand. I'm no expert making music, but have fun doing it. Let me know what you think of my beats and such.

Rockford Fosgate DSM Heaven!

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See the video on YouTube in 1080p HD or embedded below: