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:

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 wallah...my 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:

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!

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:

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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.



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Santa Visited OldSchoolStereo - More Old School Goodies!

Yes, it's true...Santa dropped off some Old School Car Audio for everyone to enjoy!


First up is the Rockford Fosgate PBR300x4 "boosted rail" amp to match the PBR300x1 I already have and have tested in a previous video. The 300x4 is a 4 channel amp rated at 75 watts for each of the 4 channels and is not bridgeable. It is the same TINY size as the 300x1 and will work great for a stealth install. More details coming soon on this...

Next up is a rare Infinity Nucleus KPX-2 tri-mode crossover system. This item also came with the optional FC-1 fader control for Front/Rear control. Take an old school 2 channel amp and power an entire system with mids/highs up front, mids/highs in the rear and a subwoofer. The Nucleus KPX-2 offers a 12dB low pass crossover slope at 75hz and a 6dB high pass filter at 150hz.

Last, but not least is a Soundstream Dealer's manual from the mid 90's called the "Heavyweight Boxing" Subwoofer Enclosure design installation manual. It is an extremely detailed with specs of the Soundstream subs of the time (SSR, Granite and SPL models). This extra large manual was for Soundstream dealers and had an original MSRP of $249 and even has a serial number!

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






See 3 of the latest items arriving at the OldSchoolStereo.com Labs. I show off two subwoofers and an ultra-rare NIB set of Boston Acoustics 767 coaxials.

First, you'll see an early 90's Rockford Fosgate PCH-812 "The Punch" Classic 12" 8 ohm subwoofer in MINT condition. Next up is an ultra-beefy 10" sub from Eclipse, the 8810.6. This is a single 6 ohm subwoofer made by TC Sounds. 600 watts RMS, 3" peak to peak excursion and an original retail price of $370 make this a desirable sub, especially in it's very good condition!

Last up is the unbelievable...a BNIB set of Boston Acoustics 767 6.5" coaxials. Per Boston's website, these were made between 1987 and 1993. So, these speakers have been sitting in the box, untouched for possibly over 20 years? Simply amazing!

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





See my latest amp arriving at the OldSchoolStereo.com labs....a MINT Rockford Fosgate Power 500m amplifier, in the box complete with birthsheet! According to an April 1995 Car Audio & Electronics Directory, the 500m retailed for $929 back in 1995. This amp and the 250m2 were Rockford's most expensive amps as the infamous 4 channel Power 300, 650 and 1000 had been retired from Rockford's lineup around 1993 or 1994.

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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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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