Linear Power 8002SW Amplifier Amplifier Dyno Test Old School AD-1

Early 90's Linear Power 8002SW 800W Mono Amplifier

The Linear Power 8002 was an 800 Watt single channel amplifier optimized for 8 and 4 ohm loads. It was available from 1991-1997 and sold at a MSRP of $1599. Unlike most of the mono amplifiers of today, this 8002 is capable of reproducing the entire 20Hz - 20kHz frequency range. 

We initially ran all of the tests using the 4 ohm power supply taps, which lowered rail voltage and increased current. Amp is less efficient in this mode and also produced less power. After a call with Linear Power, it was suggested I set the amp to the 8 ohm taps to run the 8 and 4 ohm Dyno tests. If you read the original Linear Power manual, they caution against running the amp in 8 ohm mode powering 4 ohm speakers. It is quite evident these amps are overbuilt and are more than capable of handling the additional load without breaking a sweat!

Linear Power 8002SW's Guts - TO-3 Transistors

Specifications according to the 1991 Car Stereo Review Directory (July/Aug 1991):

"1 channel. 800 W x 1. Features biwired output terminals for feedback loop, which keeps speaker wire DC resistance from reducing damping factor; defeatable subsonic filter; soft turn-on/off; fan cooling; metal shroud. FR 19-20,000 Hz. 17 x 3 x 9.5 in - $1,600" (CSR Jul/Aug 1991)

The Linear Power 8002 was also in a battle of "monster" amplifiers in the October 1991 Car Audio & Electronics magazine. Other challengers were the Rockford Fosgate Power 1000 Mosfet, Precision Power 2350DM, Orion GS500 and HiFonics Colossus VII...quite a group of large, powerful, Class AB amplifiers! Since the 8002SW is a mono amplifier, the tester used 2 of these amps in the comparison. It may or may not surprise you, but the Linear Power came out on top. Quite an impressive feat, considering the competition!

Watch the video and see the results obtained from this 20yr old car audio amplifier. Nothing short of spectacular!

Here are the results from my test with the SMD/D'Amore Engineering AD-1 Amp Dyno:

8 ohms mono - 8 ohms - Amp is rated at 800W at 12V
8 ohms - Certified 1% THD - 818W at 13.99V
8 ohms - Uncertified - 819W at 14.05V
8 ohms - Dynamic RMS - 1029W at 14.31V

4 ohms mono - 4 ohms - Amp is rated 800W at 12V
4 ohms - Certified 1% THD - 824W at 13.5V
4 ohms - Uncertified - 855W at 13.48V
4 ohms - Dynamic RMS - 1407W at 14.5V
4 ohms - Dynamic RMS - 1606W at 15.17V



All tests above were at 40Hz. As you can see by the results, this amp is well suited for subwoofers or mid-basses as it has a nice amount of dynamic headroom for those transient peaks. 

Watch the video in full 1080P HD Here >>

Or embedded below:


More Amp Dyno AD-1 tests coming!

Make sure you are subscribed to my channel so you'll receive notifications when I upload the next exciting video! Thanks for your support and remember to keep it Old School!


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Check out these other cool car audio channels:
http://www.youtube.com/CarAudioFabrication
http://www.youtube.com/meade916
http://www.youtube.com/SoundManCarAudio
http://www.youtube.com/DAmoreEngineering

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!



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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!***

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.




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

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 OldSchoolStereo.com. 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





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

-BigDWiz

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 OldSchoolStereo.com 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 rating....marketing 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!


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 HD or embedded below:

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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:

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"


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



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

The Vintage Rockford Fosgate Collection of OldSchoolStereo.com

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

We at OldSchoolStereo.com 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:

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Lepai LP-168HA Mini Amp Tested and Reviewed

Lepai LP-168HA "Super Bass" 2.1 Mini Power Amplifier

The Chinese mini amp invasion continues! This time we will show off the Lepai LP-168HA, a 2.1 channel mini amp. It is called a 2.1 amp, because it offers 2 stereo channels as well as a single "bass" channel. Sounds very promising at the rated 40x2, plus 68x1 power output. Now, as we've seen before, the manufacturer's ratings for these amps means nothing...Actual RMS output means everything!

The Lepai LP-168HA offers 3 inputs, all in parallel (non switchable). On the front, there is a 3.5mm stereo input jack, while the back offers left and right RCA input jacks as well as a USB port. The USB port will play back MP3 files on a compatible thumb drive, MP3 player, cell phone, etc. This feature wasn't tested other than for charging and it failed on 2 out of 3 devices tested. The 1st generation iPod Nano was the only device accepting a charge from the LP-168HA...neither the iPhone 3G nor the iPhone 4 would receive charge from the USB port.

Lepai LP-168HA's Rear Connections

The LP-168HA also offers a separate volume (and TINY knob) for the bass channel as well as the stereo channels. Unlike most amps offering a bass channel, there is no "master" volume controlling all outputs. You must adjust the bass channel and stereo channels independently. What a horrible design! Furthermore, the bass channel reaches full power at just a slight turn of the bass volume adjustment. There is no input gain control for the channels, just the volume knobs.

Speaking of input gain, there is a VERY important note here...I was unable to drive the front channels to clipping with an iPod Nano 1st gen or iPhone 4. It appears the LP-168HA wants an input of around 2-3V to reach max volume, and most portable devices don't have enough juice! I had to use my Yamaha home theater receiver with approx. 3V pre-outs to drive the LP-168HA to it's maximum volume. I didn't mention this in the video review, but feel it is a BIG deal.

Another area of interest is the crossover for the bass channel. I just verified my tests in the video using a 2nd example of this LP-168HA and both exhibit the same issue. The bass channel's crossover is cutting out some of the highs, but not fully until 2kHz or higher. I tested using a 1kHz test tone and was still able to hear it quite clear, even setting the crossover at 50Hz! Needless to say, you'll want to add a passive choke to keep your "subwoofer" from getting frequencies too high. Speaking of this, I'm not sure which "subwoofer" you'd use with this amp, but it better be a small and efficient one!

Lepai LP-168HA Controls

Watch as I verify RMS power output using the Velleman HPS50 and SMD DD-1 Distortion Detector. How close can we get to the manufacturers claim of 40x2 and 68x1? Well, you're gonna have to watch and see....

If you haven't seen the intro article to the "Chinese Mini Amp Invasion" check it out now. Also, I've made a video playlist of all the mini amps I've tested, see it HERE.

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

See the Lepai LP-168HA in HD on YouTube

or embedded below:

Alpine 7288 Cassette Radio/CD Changer Controller - Vintage, Old School!

Alpine 7288 Cassette Radio / CD Changer Controller - Pull Out, same Era as 7909

Take a journey back to 1989 with this Alpine 7288 Cassette Radio / CD Changer Controller with Pull Out functionality for security. This was not Alpine's top of the line unit, but at $500US MSRP, it was still a very pricey tape deck. The 7289 was Alpine's most expensive Cassette Radio at the time, $550 (with internal amplification), while the 7390 was the top end Cassette Tuner (no built-in amp) and would set you back a mere $600US. These high-end Alpine head units could control the 5952 and 5959 CD Changers.

So, why would one pay $500 for a Cassette Radio when the Alpine 7904 CD Tuner could be obtained for the same price? Well, you must recall, at the time (1989/1990), most people had cassette collections, but only a few CD's. Alpine was betting most people would opt for a nice cassette radio up front, then add a CD Changer when the funds became available. The 5952 CD Changer was a mere $650, so adding one was a big purchase for most folks. Now, if you had mad cash, you could just trash your cassettes, buy an Alpine 7909 CD Tuner for $1200, then add a 5952 CD Changer for many hours of listening pleasure!

Ok, sorry, back to reality. We are talking about the 7288 Cassette Radio, so I'll try to stay on topic. Let's see some of the technical specifications of the 7288:

• MSRP: $500US
• Pull-Out for security
• 4 RCA Pre-Amp Outputs for adding external amplifiers
• 16W + 16W Built-in amplifier
• GR Full Lock Tape Mechanism
• Auto Reverse
• Tape Frequency Response: 20Hz-20kHz
• Dolby B Noise Reduction
• CD Changer Controller
• 12FM and 6AM Radio Presets
• Dimensions: 7in x 2in x 6in

Click HERE to See FULL Size picture

I recently picked up a MINT Alpine 7288 and thought it was important to write an article and create a demo video showing off the unit. Click HERE to see the full specifications.

Although I was able to test the unit for functionality, I did not do a full test. The tape mechanism sounded rather loud to me, it may have always been this way, but I didn't want to stress it out. It most likely needs a new belt for the tape drive, but I don't know for sure. I was extremely impressed all features appeared to work properly and the FM tuner was working even without an antenna plugged in...now that's a sensitive tuner!! Unfortunately, I didn't have a 5952 or 5959 CD Changer to test out the controller functionality, but hopefully I'll come across one soon.

See more up close and personal pictures below:

Alpine 7288 Left Front Side

Alpine 7288 Front Right Side - Classic "chicklets"

As you can see in the pictures, the display is bright and clear. The buttons show very little wear, even less than my near mint Alpine 7903 CD Tuner. I used a soft brush to remove the dust, you may be able to see I missed some....dang those DSLR's!

One last picture I'll show before the video is the DIN plug and RCA Pre-Amp outputs. See below:

Alpine 7288's DIN Plug for CD Changer and RCA Output Jacks

Alright, so we all know a picture is worth 1000 words, so how much is a video worth? Well, for me, it all depends on the quality. The video below was captured in 1080/24P using my Canon 7D. I was planning on recording audio using an external device, but decided the internal mic would suffice for the tape sounds and output sounds. As I note in the video, I was using a small 4" dual-cone speaker, so don't expect any impressive sounds from the Tuner and Tape playback tests. Enjoy the video!


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



See the video on YouTube in 720p HD or embedded below:

Rockford Fosgate Power 650 Mosfet - True Old School Powerhouse

Late 80's Rockford Fosgate Power 650 Mosfet

Think old school power....think names like Orion, Precision Power and Rockford Fosgate. Up for review today is a late 80's Rockford Fosgate Power 650 Mosfet. This amp is an icon of the infamous Mosfet Power series by Rockford. People know the Power 300 as the "entry level" power series amp (MSRP $999*) and the "ultimate" power series as the Power 1000 Mosfet (MSRP $2650*). But why no respect for the big brother, Power 650? It's always tough to be the middle child! The Power 650 retailed for $1575* in 1990 and was available from approximately 1985-1993.

(*Pricing above was verified in an April 1990 Car Audio & Electronics Car Stereo Directory)

Here are the specs of the Power 650 Mosfet:

• Power Ratings: 4 Channel
• 4 Ohms: 125 watts per channel continuous power into 4 Ohms, 4 channels driven, from 20 to 20,000Hz, with less than 0.05% THD + N (Total Harmonic Distortion & Noise).
• 2 Ohms: 162.5 watts per channel continuous power into 2 Ohms, 4 channels driven, from 20 to 20,000Hz, with less than 0.1% THD + N.
• Power Ratings: 2 Channel (bridged) 4 Ohms: 325 watts per channel continuous power into 4 Ohms, 2 channels driven, from 20 to 20,000Hz, with less than 0.05% THD + N.
• Frequency Response: 20 to 20,000Hz, ± .5dB
• Bandwidth: 15 to 20,000Hz, ± 3dB.
• Damping Factor: greater than 200 at 50Hz.
• Slew Factor: greater than 2.5.
• Slew Rate: greater than 10 volts per microsecond.
• Protection: The Punch also employs thermal switches which protect the amplifier from overheating damage. Fuses are provided for speakers which are directly connected with no crossover components.
• Dimensions: 18 3/10” long x 8 1/10” wide x 2” high, exclusive of knobs and wiring. 19 3/10” long x 8 1/10” wide x 2%” high, minimum mounting requirements.

Disassembled Power 650 Mosfet - Fan Shroud, Amp "guts", bottom plate and fuse cover

You young kids out there don't know much about Class A/B subwoofer amps with the $300 1500-watt Class D amps you have today. The Power 650 and Power 1000 were classic subwoofer amps in their day. Instead of using DVC subs with "fat" surrounds, we had 15's, 18's and even 30" subs (See Wayne Harris' 1985 Terminator Hearse)!!! No mention these old school subs in many cases were 8 ohms, used in multiples and had an x-max of 10 or 12mm if you were lucky...We still appreciate the "Made in the USA" quality of these amps and the pride the workers put in each and every amp. Shoot, the Rockford amps were even smacked with a rubber mallet to ensure they could handle the "punch" as part of their QA process!

One feature lacking on the Power 650 you would find on the Power 300 was bass and treble controls. For the most part, if you could afford a Power 650, you could most likely also afford a matching "Z or ZX" preamp. These preamps had EQ adjustments and even fancy LED lights as a VU meter.

Bottom side of the Rockford Fosgate Power 650 Mosfet

In addition to being a powerful four-channel amplifier, the Power 650 is also a very flexible amp. In the mid to late 1980's there were only a handful of amplifiers with built in crossovers...the Power 650 being one. Unlike modern amps, the crossover settings are set at certain frequencies (instead of being fully-variable). Also, note the high crossover's cutoff begins at 140Hz, whereas the low pass could be set as low as 70Hz. It could be used in four, three or two channel operation. My initial RMS wattage tests have shown the Power 650 ratings to be conservative, more on this in an upcoming video and article.

Early Rockford Fosgate Power 650 Mosfet with DIN and RCA Inputs

Those familiar with the Power 650's know in addition to there being DIN/RCA and RCA only models, there was also a short run of the last Power 650's with a 4-inch fan as opposed to the 2-inch model available since the mid-1980's. From my research, the 4-inch models were the last production Power 650 mosfets and were produced in low numbers. See pictures and some more detail here: http://www.gamblin.net/power650.html



Stay tuned for the RMS wattage output demo of the Rockford Fosgate Power 650 Mosfet. Make sure to Subscribe to my YouTube Channel to stay updated of my latest videos. You can also follow me on Twitter @oldschoolstereo.


See the video on YouTube in 720p HD or embedded below:

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See the Old School Rockford Fosgate Power 650's in ACTION! Wayne Harris' "Terminator" Hearse Vintage 1985

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700 Watt Mini Amp? Lepai LP-V3 Tested and Reviewed

Lepai LP-V3 Mini Amp

The Chinese Mini Amp Invasion continues!! Next up is the Lepai LP-V3. This mini amp touts use of a BOSE power IC. In fact, the non-grammar corrected text "This Amplifier is use BOSE Power IC" is silk-screened on the amp. You'll also see "700 W Max Music Power" labeled on the amp. The LP-V3 uses the exact same enclosure as the LP-2020A+, I reviewed earlier.

See a size comparison w/ the LP-2020A+ below:

Lepai LP-2020A+ and LP-V3 Mini Amplifiers

In addition to touting a BOSE IC, the LP-V3 promises an RMS Power Output of 25 Watts. No clarification if this 25 Watts is per channel or total watts...

The next two pictures below show both ends of the amp...one for the controls, the other for the connections. Here again, the LP-V3 is a clone to the LP-2020A+:

Lepai LP-V3 Controls; Power, Tone/Direct, Bass, Treble & Volume

Lepai LP-V3 Connections; RCA, 1/8" inputs, Spring-Loaded Speaker Terminals and 12v5A DC  Power Input

Well, enough about the connections and controls, how does the LP-V3 sound? Well, in a nutshell, weak. I was expecting much more dynamic and punchy sound as delivered by the LP-2020A+. The LP-V3 appeared to run out of steam quickly and obviously didn't put out anywhere near the power of the 2020A+. In fact, the LP-V3, reminded me greatly of the tiny and unimpressive Kinter MA-150 I tested earlier. Very disappointing, especially considering the supposed "Real" RMS output of 25 watts. I was beginning to seriously doubt the validity of this claim. Fortunately, I have an easy way to determine the actual RMS output of this amp...

Results? Not impressive and not even close to the 700 Watt, or the 25 Watt RMS ratings. Using a 12V 35Ah Sealed Lead-Acid battery showing 13.0V of charge, I was able to obtain:

Output Test Results:

• 4.43V RMS of Unloaded Output at the speaker terminals
• 2.0 Watts RMS / channel at 8 ohms
• 3.6 Watts RMS / channel at 4 ohms
• 5.1 Watts RMS / channel at 2 ohms
• 11.9 Watts MAX / channel at 2 ohms

(tests above were conducted using a 1kHz 0dB Sine Wave Test Tone from the SMD DD-1 test disk and output was verified by the DD-1, which detects distortion at 1%. The resistive loads of 8, 4 and 2 were conducted with BOTH channels loaded)

Stay tuned for more tests of these mini amps and see which one (if any) you should buy. Check out my video review of the Lepai LP-V3 below. Make sure to Subscribe to my YouTube Channel to stay updated of my latest videos. You can also follow me on Twitter @oldschoolstereo.


See the video on YouTube in 720p HD or embedded below:

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500 Watts in Your Pocket? Kinter MA-150 Mini Amp

Kinter MA-150 vs. CD: Size Comparison

The promise of 500 Watts in a palm-sized amplifier is appealing to many people. The Kinter MA-150 is another contender in my Chinese Mini Amp Invasion shootout and is the smallest amp in the bunch. Although technology such as "Boosted Rail" has enabled Rockford Fosgate to make the PBR300x1 just slightly larger, it "only" promises 300 Watts of power at 1 ohm. Not to mention, the PBR300x1 costs around 10x as much as the Kinter MA-150...

I picked up the Kinter MA-150 from an eBay seller for around $15 US shipped from China. Now, logic will tell us we shouldn't expect much from an amp only costing a few dollars, right? Yes, this is a rational thought. "You get what you pay for" comes to mind. So, what does the $15 get you? Continue reading...

The Kinter MA-150 has a slightly different design than the other amps in this shootout as it requires molex-style plugs for the speakers and power. The other amps in this comparison have spring-loaded speaker terminals and a 5.5mm x 2.1mm center positive power plug.

Kinter MA-150 Speaker Output and Power Inputs

The opposite side of the MA-150 has a USB port for charging external devices, RCA L/R jacks, Volume knob and crossover switch. See picture below:

Kinter MA-150's USB, RCA, X-over and Volume adjustments

For more details on the technical specifications, please see the Chinese Mini Amp Invasion article for a spreadsheet comparing each amplifier in the shootout.

The Kinter MA-150 is heavily marketed on eBay as a motorcycle or scooter amplifier. Obviously, the main reason is the small size, low power consumption and "rated" high-power output. Now, logic and science will tell us, based on the MA-150's 12v 0.5A power requirement, you can use the equation Watts = Volts x Amps to get 12 x 0.5 = 6. Taking into account 100% efficiency, the amp should put out 6 watts, based on the power going in. Well, unfortunately, the amp is NOT 100% efficient, so even the 6 watts may be a stretch.

Power ratings vs. actual output aside, I decided to run the sound quality test first. I tested several tracks, including one of my favorite "Chelsea's Day" by Sam Cardon. It was readily appearant to me the MA-150 didn't have the power, clarity or dynamics of the Lepai LP-2020A+ . My reference speakers, the Athena Point 5 MKII bookshelf speakers are extremely transparent and it was obvious the MA-150 was struggling to push them to room-filling level. Again, based on the output I was expecting, this wasn't a surprise to me. After a few minutes demoing my reference tracks, I decided to put the MA-150 on the OldSchoolStereo.com test bench and get some actual numbers.

Results? Not impressive and not even close to the 500 Watt rating. Using a 12V 35Ah Sealed Lead-Acid battery showing 13.0V of charge, I was able to obtain:

Output Test Results:

• 4.56V RMS of Unloaded Output at the speaker terminals
• 2.1 Watts RMS / channel at 8 ohms
• 3.4 Watts RMS / channel at 4 ohms
• 5.3 Watts RMS / channel at 2 ohms
• 15.6 Watts MAX / channel at 2 ohms

(tests above were conducted using a 1kHz 0dB Sine Wave Test Tone from the SMD DD-1 test disk and output was verified by the DD-1, which detects distortion at 1%. The resistive loads of 8, 4 and 2 were conducted with BOTH channels loaded)

Stay tuned for more tests of these mini amps and see which one (if any) you should buy. Check out my video review of the Kinter MA-150 below. Make sure to Subscribe to my YouTube Channel to stay updated of my latest videos. You can also follow me on Twitter @oldschoolstereo.

See my video review / bench test of the Kinter MA-150 and decide for yourself if this is the amp for you...


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Chinese Mini Amp Invasion! Kinter, Lepai and More

Mini Amps Galore! 3 Models from Kinter, 3 from Lepai and 1 from TeLi

If you spend anytime on eBay looking at car audio amplifiers, then you've surely come across some of the amps I'm going to talk about here. Lepai and Kinter are just a few of the brands you'll see quite often. Some of these mini amps are small enough to fit in your pocket and promise 500 to 700W of power. So why spend several hundred dollars on a fancy name brand amplifier when you can pick up most of these for under $20 US shipped? In the near future, I'll test each amp for RMS Watt output and with some reference speakers and we may soon see why.

After receiving and testing my first mini amp, the Lepai LP-2020A+, I decided it may be interesting to pick up a few more of these mini amps and have a shootout! Here are the models I've obtained thus far:

Lepai Amps:

• LP-2020A+ - my first mini amp, rated at 550W MAX (20W RMS) output. Tripath design, TA-2020, 2-channel, RCA/3.5mm input, bass/treble/bypass, large volume knob w/ blue LED backlight. 4-8 ohm compatible, 9-13.2V 4A power requirement (per box, amp says 12V 2A?). S/N ratio >80dB
• LP-V3 - "This amp is use BOSE power IC" (my favorite amp quote). Rated at 700W MAX (25W RMS) output, identical in size to the LP-2020A+ (so why the 700W rating?). 2 channel, RCA/3.5mm input, bass/treble/bypass, large volume knob w/ blue LED backlight. 2-8 ohm compatible, 9-14.4V 5A power requirement (per box, amp says 12V 2A also). S/N ratio >80dB
• LP-168HA - 2.1 (3 channel) design with ratings of 40x2 and 68x1 watts. Has separate volume for bass, built-in x-over, bass/treble/volume (all same size). RCA/3.5mm inputs, USB port, spring-loaded speaker terminals for Front L/R and Sub. 14.4v 5A power requirement.

Kinter Amps:

• MA-150 - the smallest amp in the group, rated at 500W MAX. BTL desigh, filter for L/Off/H (x-over?), RCA L/R inputs, speaker/power connections by molex-style plug w/ attached wires. 12v 0.5A power requirement
• MA-170 - Similar design to the Lepai LP-2020A+, but smaller. BTL design, 2-channel. Large volume knob, bass/treble adjustments, sprint-loaded speaker terminals, RCA L/R inputs. 9-14.4V DC power requirement, no Amperage specified. Rated at 100W PMPO or 4W x2 RMS, S/N ratio >70dB
• MA-200 - largest amp in the group. 4-channel design using 2x TDA7377 IC's, rated at 41W x4 channels RMS at 1kHz. Has equal size knobs for treble/bass/volume. Includes display for function display; AUX or FM. Includes input for USB and SD/MMC card. 12V 5A power requirement.

TeLi Amp:

• A6 - identical in size to the Kinter MA-170. 2 channel, BTL design, RCA/3.5mm inputs, bass/treble range +/- 15dB. 8-15V DC power requirement (no amperage mentioned)

See the latest Spreadsheet below with specs comparison or download it if you prefer:

Stay tuned for upcoming tests of each mini amp and we'll see which one (if any) you should buy. Check out the 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.

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Big 'Ol Stack of Mini Amps!

Kinter MA-150 in Orion HCCA Red

SMD's DD-1 - New School Tool for Old School Amp Testing

SMD's DD-1 "Distortion Detector" vs. Velleman HPS50 Oscilloscope

Many of you who follow my blog and videos, know I've had a Velleman HPS50 oscilloscope for a while now and keep adding components to enhance the capabilities of my test bench. My primary focus now is testing amplifiers for maximum continuous RMS wattage output. We all know most of the ratings we see on amps today are not RMS, but MAX output. This is a marketing ploy, not useful at all in determining the actual output of an amplifier. I'll soon get one of these amps on the bench and show you actual RMS wattage output vs. the value claimed on the amp. You may be amazed and not laugh so much at the old school amps and their low wattage ratings...

I recently decided to pick up a SMD DD-1 "Distortion Detector". This device was developed by the brains at D'Amore Engineering in conjunction with the KING of car audio on the Internet, Steve Meade (www.stevemeadedesigns.com). Steve Meade (meade916 on YouTube) is famous for his 30,000 watt custom Chevy Tahoe and has several hundred videos. Steve is also the largest car audio channel on Youtube with over 100,000 subscribers and over 100 MILLION video views. Impressive to say the least, but this DD-1 is not hype, it is a truly powerful and affordable tool for everyone from electronics enthusiasts to car audio shop installers and many in between.

So, what's the deal with this DD-1 and why might you want one? The SMD DD-1 is marketed as an amplifier gain matching tool. Matching your car audio head unit and amplifier has been a black art for many years. Without an oscilloscope and test tone, setting gains was really just a guess for most folks. The DD-1 costs only a fraction of most oscilloscopes and offers simplicity in setting/matching gains for your car audio equipment.

Here's what's included in the package:

• The Distortion Detector (DD-1)
• Protective silicon rubber boot
• Calibrated Test Tone CD
• Harness
• Printed owner's manual

According to the manual, the DD-1 has the following specs:

• The DD-1's circuitry is 100% analog
• Distortion Detection trigger level > 1.0% Harmonic Distortion
• Guaranteed operating range of input signal is 1.2Vrms - 125Vrms (15,000 Watts at 1 ohm) Autoranging
• Signal Present LED trigger voltage 750mVrms
• Low Battery LED trigger battery voltage < 5.6Vdc
• Auto shut-off timer 8-10 minutes after on button is pressed

Now, I must be honest. The unit's ability to match gains is a great feature, but I've had this ability with my Velleman HPS50 portable o'scope for a while. A recent video on Steve's channel about the upcoming AD-1 "amp dyno" got the wheels spinning in my old school head. This DD-1 can be used for more than just matching gains...it can be used to assist in amplifier output testing! This feature in a sub $200 device is unheard of. A bench version of a THD analyzer can cost MANY thousands of dollars. I've been watching eBay for a year or more hoping to find a deal on one of these THD analyzers so I could verify distortion during my amplifier tests. After seeing the AD-1 demo, I was convinced to buy the DD-1 to use as a tool in my RMS output tests.

The DD-1 has proved to be an invaluable tool and will ensure accuracy in my amplifier tests. I have MANY old school amps I plan on testing in the upcoming months. The DD-1 will ensure < 1% distortion in my results which is great. As I mentioned above, not only do many manufacturers rate amps by "Max" output, they also sometimes use distortion numbers up to 10% for their ratings. I think it's important to keep the distortion less than 1%, which should be inaudible for most people.

I have done some initial tests with the DD-1 and have been impressed with it's ease of use and ability to detect low levels of distortion. See some videos below and be sure to subscribe to my YouTube channel to stay updated with the latest amplifier and car audio tests and demos.

Buy the DD-1 Direct at wccaraudio.com

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