Old School MTX Thunder Bandpass Subwoofer Box - Sold at Circuit City

In this article, we will be taking a closer look at an old school MTX Thunder bandpass subwoofer box. This particular speaker box was sold at Circuit City back in the day and features two 10-inch drivers inside. We will examine the construction of the box, clean the interior, and explore the woofers. Additionally, we will discuss the specifications of the MTX Thunder subwoofer box and its compatibility with the MTX Blue Thunder Pro amplifier.

Introduction to the MTX Thunder Bandpass Subwoofer Box

I recently had the opportunity to acquire a unique speaker box, the MTX Thunder bandpass subwoofer box. A generous individual contacted me and offered this cool speaker box, and I couldn't resist. So, let's dive in and take a closer look at this vintage piece of audio equipment.

The MTX Thunder Bandpass Subwoofer Box

The MTX Thunder bandpass subwoofer box is a single reflex bandpass box that houses two 10-inch drivers. The box features ports on both sides and has a single terminal. Upon initial inspection, the box appears to be a little dirty on the inside, so I decided to remove the Plexi panel to get a better look at its construction.

Inside the MTX Thunder Bandpass Subwoofer Box

After removing the screws, I lifted the Plexi panel and was pleasantly surprised by its thickness. The panel is approximately a third of an inch thick and has a gasket seal all the way around, ensuring a snug fit. However, the inside of the box did require some cleaning, as it was a bit dirty.

Examining the Woofers

Next, I proceeded to take a closer look at the woofers inside the MTX Thunder bandpass subwoofer box. I carefully pulled out one of the 10-inch drivers and noticed that the wires connecting it were surprisingly small. The woofer itself appeared to be a standard model from that era, with a foam surround that had not deteriorated. However, the wiring was inefficient and insufficient, with wires that seemed to be around 20 or 22 gauge.

Upon further inspection, I disconnected the driver and observed some bugs and spiders on the back. It's a good thing there wasn't any spider activity inside the box. The wiring definitely needed an upgrade, so I decided to replace it with larger gauge wire for better performance.

Cleaning the Box and Reassembling

Before vacuuming out the box, I took a moment to examine the inside and noticed a date stamped on the interior. The box also had two and a half inch ports and a terminal cut with small speaker wires. After vacuuming out the box to remove dirt and dust, I reassembled it, using the original small gauge wires to keep it as close to its original design as possible.

Cleaning the Acrylic Panel

The Plexi panel of the MTX Thunder bandpass subwoo fer box had some scratches and dirt on it. To clean it, I used a product called Novus Plastic Clean and a microfiber towel. I applied the cleaner to the panel and gently wiped away the dirt and scratches. While some of the deeper scratches remained, the panel looked much shinier and cleaner than before.

Shop for Novus Plastic Clean on Amazon*: https://amzn.to/3Fy9P2t

Testing the Speakers and Amplifier

With the box cleaned and reassembled, it was time to test the speakers and amplifier. I used an MTX Blue Thunder Pro 1502 amplifier to match the vintage style of the subwoofer box. The amplifier was wired up with eight gauge wire and bridged for optimal performance. I used 16 gauge wire to connect the amplifier to the subwoofer box.

The sound produced by the MTX Thunder bandpass subwoofer box was impressive. The deep bass tones were best experienced with headphones or quality speakers, as computer or iPad speakers may not do justice to the audio quality.

Conclusion

In this article, we explored the MTX Thunder bandpass subwoofer box, a vintage audio equipment sold at Circuit City. We examined the construction of the box, cleaned the interior, and discussed the woofers. Additionally, we tested the subwoofer box with the MTX Blue Thunder Pro amplifier, resulting in a satisfying audio experience.

If you're interested in learning more about the MTX Blue Thunder Pro amplifier, be sure to check out willistonaudio.com, where a full video of the amplifier's dyno will be released. Thank you for reading, and until next time, keep enjoying the music!

Sources:

• 1999 Car Audio and Electronics Directory
• *Amazon - Novus Plastic Polish is an affiliate link
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Old School Rockford Fosgate Punch Pro SPP-184 18" Subwoofers

What's up guys? I know there are some of you die hard Rockford Fosgate collectors out there and I'm hoping someone has a pair of the infamous "Punch Pro 18's" from the late 80's /early 90's. The model was SPP-184 and at the time, they were some of the biggest and baddest subs money could buy. I have a friend who's working on an old school install and these subs are essential pieces he's missing. 

Please contact me via Facebook if you have a MINT/NIB/VGC set of these subs. I'll make sure to get you some OldSchoolStereo.com stickers for your trouble and hopefully we can work out a reasonable price. 

Here are the specs of the SPP-184 as provided by Rockford Fosgate:

• 18" Pro Subwoofer
• 159oz Magnet
• 3" Vented Voice Coil
• Power Handling 200W continuous average
• 4 ohms (SPP-184) single voice coil
• Mounting Depth: 7 3/4"
• Sensitivity: 94.5dB 1W/1M
• Approx. years of mfg: 1987-1992

Rockford Fosgate Punch Pro SPP-124 12" subwoofers - same style as the needed SPP-184's

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-BigDWiz

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





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-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!


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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:

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: