Amps that Rumble...Earthquake PA-2040c and PA-2300

Earthquake PA-2040c and PA-2300 Amplifiers from 1995. Photo (c) OldSchoolStereo.com

One of the "sleeper" Car Audio brands back in the mid-90's was Earthquake. Competing against established brands such as Rockford Fosgate, Orion, Precision Power, Soundstream, etc. proved to be a difficult task. Everyone had a favorite brand, but how did the lesser known brands survive? Well, building quality products was one way and another was to test well in the Car Audio magazines. Earthquake accomplished both of these tasks and although never became as popular as the brands listed above, they did create a place for themselves in old school car audio history!

I recently acquired two Earthquake amplifiers and will briefly overview them below.

First up is the Earthquake PA-2040c. The PA-2040c is a two-channel amplifier with a built-in crossover. The crossover is non-adjustable and either 80Hz low-pass or 200Hz high-pass at 12dB/octave. You could also bypass the crossover to use the amp full range. In addition, the amp also included rotary bass and treble controls at 45Hz and 12kHz. Going by the model number, one might assume the amp is rated at 40w x 2, however specs in the included manual state 52w x 2 @ 4 ohms. I'm still unsure of the "250 watts at 2 ohms" silk-screened on the amp. I don't see any specs referring to this power at 2 ohms? Maybe Earthquake was following lesser brands with "max" output claims? Well, only the bench test for RMS output power will tell us....

Earthquake PA-2040c Amplifier Controls

Earthquake PA-2040c Amplifier Top View

Earthquake PA-2040c Amplifier Speaker Outputs and Power Connections

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Earthquake also produced larger amplifiers, such as the PA-2300. Again, going by the model number, one might assume 2 x 300 watts, right? According to the manual, 2 x 380 watts RMS at 4 ohms and a mind-boggling 1150 watts RMS at 4 ohms bridged. In the mid-90's there were few car audio amplifiers claiming 1000 watts plus. The PA-2300 had no internal crossover, but had a counterpart, the PA-2300c, which did. A rather unusual feature of the PA-2300 was the dual bass controls. One centered at 30Hz and the other at 45Hz. Why two bass controls? I'm not certain, but maybe a tuning choice for those using sealed vs. ported subwoofer enclosures?

Earthquake PA-2300 Amplifier

Earthquake PA-2300 Bass Controls and Inputs

Although these amplifiers look very similar to amps made by Zed Audio (HiFonics VII, VII, Autotek BTS series, Crunch CR series, etc.), Earthquake amps were NOT made by Zed Audio. Although this is the case, rest assured the Earthquake PA series amps were built like a tank. The amps you see above were originally purchased in 1995 and variants of the PA series went back to the early 1990's.

Stay tuned for upcoming power output tests of these amps. Make sure to SUBSCRIBE to my YouTube Channel to stay notified of my latest video uploads.

See the mystery "unboxing" of these Old School Gems below:

Video in 720p HD

or embedded below:



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Orion 275 SX - Old School 75x2 Powerhouse!

Old School Early to Mid-1990's 75x2 (150 watt) RMS Amps from Rockford, Phoenix Gold, Soundstream and Orion

So, you may have already seen some of my earlier amp output tests on the Rockford Fosgate Punch 150HD vs. Phoenix Gold MS-275 and the Soundstream Reference 300....but what about the Orion 275 SX? Well, wait no longer, my friends. I finally got the Orion 275 SX on the OldSchoolStereo.com test bench for some RMS watt output tests. How do you think it compared to the others? Well, keep reading to find out.

Now, first of all, I think it is important to mention a comparison of the 275 SX....in many ways, it is very similar to the 225 HCCA. Both share the same sized heatsink and require a 35A fuse. I've done some preliminary tests with Orion's 225 HCCA "digital reference" amp a while back and I must say the amp was VERY impressive! The 275 SX is only rated to handle 4 ohm mono or 2 ohm stereo loads. As with many of the old school amps, it can handle lower ohm loads, but not designed to handle the 1/2 ohm loads as the 225 HCCA does without a sweat!

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Orion 275 SX vs. 225 HCCA vs. Messy Test Bench!

Instead of spending so much time comparing the 275 SX to the 225 HCCA, let's move on to the comparison against the other 150 watt amps I've mentioned before. Here are the specs of the 275 SX:

Specs: rated @ 12.5 volts*
2 x 75W @ 4 ohms
2 x 150W @ 2 ohms
1 x 300W @ 4 ohms bridged
THD: 0.03%
S/N: 110dB
Freq. Response: 6Hz 20kHz (±0.5dB)
Fuse: 35A
Dimensions: 11" x 8.5" x 2.25" (28cm x 21.6cm x 5.7cm)

*note: The Orion 275 SX uses an unregulated power supply, so more volts = more power! Also, my power supply is non-adjustable at 13.8v, nearly a volt and a half more than Orion's 12.5v rating, so take this into consideration.

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Orion's 2nd Gen HCCA and SX Spec Sheet / Manual

Ok, enough specs and talk about the amp, let's see how it performed.

Watch the video in 1080p HD

or embedded below:

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Make sure you subscribe to my YouTube channel to stay notified of the latest "old school" car audio videos. Much more exciting tests, demos and information coming up soon...

-BigD

Soundstream Reference 300 Power Output Test

Soundstream Reference 300 on the OldSchoolStereo.com Test Bench

I recall back in the early 90's patiently awaiting my monthly Car Audio magazines so I could see amp tests. It was very rare to come across a test I actually cared about, but maybe once a year or so. I drooled over the Phoenix Gold MS series, Rockford Fosgate HD series, Soundstream Reference series, just to mention a few. Well, these days, I spend some of my free time bench testing some of these amps I always wanted back in the day.

I recently picked up a Soundstream Reference 300 and couldn't wait to add it to my old school 150 watt (75x2 RMS) amp tests. If you've missed it, I've already done an overview and RMS watt output test of the Phoenix Gold MS-275 and Rockford Fosgate Punch 150HD.

The Reference 300 is a no-frills old school amp. It has no internal crossover and as with earlier Soundstream amps, all connections are made on one side. There are also two openings on the bottom of the amp with switches. One switch controls high power or high current mode, while the other allows switching between mono / coherent stereo / mixed-mono modes. The Reference 300 is rated to handle 1/2 ohm loads in stereo or 1ohm modes in mono, while in the high-current mode. High power modes are designed for loads down to 1 ohm stereo or 2 ohms mono.

See power output specs from the manual below:

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Soundstream Reference 200/300/500 Power Ratings at 12v

Also, here are some of the design specs of the Soundstream Reference Series amplifiers:

Soundstream Reference Series Design Features

The ability to drive 1/2 ohm loads was a rarity back in the early 90's. Only a handful of amps were rated to handle these loads. Orion HCCA models come to mind, but there were others from US Amps and Phoenix Gold, to mention a few.

As for the power output test, I was anticipating Soundstream to rate the Reference 300 conservatively. As you may have seen already, the Rockford Fosgate Punch 150HD was rated at the same 75x2 at 4 ohms and delivered nearly 120x2 at 4 ohms on the OldSchoolStereo.com test bench. Many manufacturers during this time rated their amps based on 12v, not the 14.4v you see today.

150 Watt Old School Amps from Phoenix Gold, Rockford Fosgate, Orion & Soundstream

So, enough talk already, how did the Soundstream Reference 300 perform on the bench? Well, now that you asked, here are the measurements (All taken based on 100Hz test tone and 13.8v input).

Continuous RMS Wattage Output: 

• 4 ohms Stereo - 105.6 watts/ch (both channels driven)
• 2 ohms Stereo - 134.1 watts/ch (both channels driven)
• 4 ohms Mono - 267.3* watts (in high-power mode)
• 2 ohms Mono - 224.7 watts (in high-current mode**)

*See the update video below for the updated 4 ohm mono test
**The Reference 300 popped it's 30A fuse when I attempted 2 ohm mono testing in the high-power mode.

See the power output test in in 720p HD or embedded below:



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UPDATE: One more demo to see if the 4 ohm bridged mono mode would yield the rated 300 watts:


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Keep watching and subscribe to my YouTube channel to stay updated with my latest Old School Car Audio tests and demos.

-BigD

Unboxing Old School Car Audio Gear

I will be the first to admit, unboxing videos do not appeal to me. Why? Mainly because people do unboxings for things like cameras, camcorders, computers, etc. and there is no excitement factor there. Now, take a plain brown box (with unknown goodies inside), open this up on camera and share your excitement with the world! This is how BigDWiz does unboxings at the OldSchoolStereo labs!


First off, I must say not all of the unboxings I do on my YouTube channel are from purchases. Many are from trades and barters for other gear. This is a part-time gig for me and I don't have unlimited funds to buy all of this cool, old school equipment. Well, since I know opening these packages is exciting for me, I thought you guys might enjoy the experience?

OldSchoolStereo.com Mystery Box!

Finding nice, old school car stereo gear is exciting in itself, but opening a package with unknown contents (well, unknown to you) is fun for all. Those of us who enjoy the old school gear also love to see "timeless classics"...the amps, speakers, head units, etc. that have either been babied or unused all of these years. I still find it amazing to see the condition of some of my 25+ year old equipment.


Most of these videos will just show the unboxing process, but in some cases, I may hook up and test the contents. Honestly, it just depends on how I'm feeling at the current time (and how much space is remaining on my iPhone's internal storage!). This brings up another interesting point....some of you may wonder what equipment I use to record and produce these short videos. Well, I have two words for you; iPhone and iMovie (we won't count "and" as a word!).


Recently, I've discovered making videos with the iPhone 4, is not only a simple process, but also gives a pretty good output video for viewing online. I also ensure use of the included ear buds / mic combination to get better audio, while still leaving both hands free to tear open the boxes. Once I capture the segments on my iPhone 4, basic editing is handled by the iMovie app for the iPhone. This $5 app turns your iPhone into a VERY powerful hand-held editing machine. If there is any interest, I may show the process I use to capture, edit and upload my videos to YouTube. You guys just let me know by making comments here or on my YouTube Channel.


While you are visiting, please Subscribe to my channel so you can get notification when I upload a new video. My intentions are to upload a new video every few days. As I've mentioned before, the more subscribers, comments, likes, etc. I have, the more videos I'll put up. I appreciate your enthusiasm as being an "old school nut" is addictive!


Unboxing Old School Car Stereo Gear
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Unboxing Old School Car Stereo Gear #2
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Unboxing Old School Car Stereo Gear #3
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Unboxing Old School Car Stereo Gear #4


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Old School PPI Pro Mos Amps - Precision Power!

Most of you old school car audio fans know the early 1990's was a time when aftermarket car audio was getting extremely popular. At this time, it was rare to find a factory CD player and the factory speakers were weak at best in most cases. Manufacturers such as Rockford Fosgate, Linear Power, Precision Power (PPI), Autotek, Orion and Soundstream (to name a few) were some of the very popular aftermarket car audio brands at the time.

The competition between the manufacturers was intense and each one was trying to best the other. Orion's HCCA series amps, released in the late 1980's were extremely popular and had an edge power wise on most other amps with their rating and ability to handle extremely low ohm loads. These low-wattage rated / low ohm handling amps came to be known as "cheater amps". The cheater amps could put out as much as 8x their rated 4 ohm power rating at lower loads. PPI hit the "cheater" market in 1990 with the Pro Mos 2050. Pro Mos was short for Professional Mosfet. This first gen Pro Mos amp was rated to handle loads down to 1ohm and would provide 4x it's rated 4ohm power at 1ohm. Cough up around $800 for a 50x2 amp, and get a 400x1 monster when loaded down. Interestingly enough, Orion's 25x2 "cheater", the 225 HCCA was stable down to 1/2 (some even say 1/4) ohm loads and would put out in excess of 400 watts and cost less than $600.

I've shown a comparison of the Orion 225 HCCA and the PPI Pro Mos 25 in a previous posting and video. You can see my preliminary power output results HERE.

PPI Pro Mos 2050 (top), Pro Mos 12 & Pro Mos 25 - Image (C) OldSchoolStereo.com

These Pro Mos amps were available up until around 1995, adding additional models including the Pro Mos 12, 24 and 50 (replacing the 2050) beginning in 1991. They also released 4 channel models; the Pro Mos 425 and 450. These Pro Mos amps were no frills, offering no internal crossovers or bass/treble controls. They offered a DIN connection for powering a PPI pre-amp or crossover in addition to the standard RCA input jacks. The Power and Ground connections were made via 8 or 10 awg leads and the speaker/remote connection was made by an infamous molex connector. I say infamous because this connector has been a huge failure throughout the years. The wires don't stay inside the connector and the molex connector itself breaks very easily. Many people created terminal strips or soldered the leads to the circuit board.

The Pro Mos amps you see in the photo above are the "art series", finished in white including a unique design by an artist. These amps were also available in black with red lettering.

See the video demo below:

Also, visit YouTube and subscribe to my channel for more exciting OLD SCHOOL car audio gear!

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Vintage Fosgate Car Amps - PR 220 & PR-250 Pre-Rockford

Fosgate PR-250II and PR 220 Vintage Car Audio Amplifiers

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I decided to dig out some real dinosaurs in the car audio world....the Fosgate "The Punch" PR 220 and PR-250 Type II amplifiers. These amps were produced by Fosgate Electronics, Inc. in the late 1970's before Rockford joined Fosgate. I believe the PR-250 was 1978 or 1979 and this model was also produced in 1980 as a Rockford Fosgate PR-250II (logo was different than the one pictured above). The PR 220 was also late 1970's, found in the 1978 and 1979 Car Stereo Directory issues of Audio magazine, but not in the 1976 issue. I don't have the 1977 issue to see if they are listed there...

These amplifiers were state of the art at the time they were produced. Just think, in the late 1970's, many people were still rocking 8 tracks and a cassette player was "high-end". I don't believe there were many (if any) head units with pre-outs at the time. You definitely were lucky to have one of these back then. Don't forget, 3-way 6x9's were considered high-end at this time! Take your PR-250, power up the Sony tape deck and Jensen or Sparkomatic 6x9's and you were rockin'!!

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Another view of the Fosgate "The Punch" PR-250 Type II / PreAmp & PR 220 Amplifiers

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The Fosgate PR-250 Type II had a matching Pre-Amp, which controlled the unit's volume, bass and treble controls. The volume knob was a smooth rotating potentiometer, while the bass and treble controls had a "clicking" type potentiometer (meaning you had only a certain number of positions, by turning these knobs, it would click into position). The PR-250's pre-amp had only two connections, both DIN style plugs. One DIN cable would be integrated in with your head unit and the other would carry the signal from the pre-amp to the PR-250 amp. Then, you would need some speakers capable of handling 50 watts RMS per channel, not the easiest task in the late 70's...The PR-250 was also bridgeable or capable of handling loads more demanding than 4 ohms.

The Fosgate PR 220 was much simpler and less powerful than the 250. It was rated at 20 watts x 2 channels into 4 ohms, no options for bridging or lower ohm loads. It also came without a pre-amp, all controls (bass and treble) were on the amp itself by 3-way sliders. Your options were low/mid/high for bass and treble adjustments. Again, speaker level inputs were the only signal source allowed into the amp and since most head units were only good for a couple of watts, the 20 watt PR 220 was a decent upgrade and would drive efficient speakers to loud (at the time) levels, around 110dB. Fosgate had a warning in the manual, "Sound levels of 110 dB have been recorded inside a car using the PR-220 and High Efficiency speakers. This is loud enough to lead to permanent loss of hearing after long periods of exposure. So use common sense.."

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Photo (c) 2011 - Dereck Willis - OldSchoolStereo.com

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So, you know me, I'm good for putting up video demo's right? Well yes, I have posted an overview of the amps below. That said, don't get too excited about seeing these amps in action as I'm a little hesitant to power them up. The PR 220 at least needed to pull power from the head unit for the remote turn on.

Quote by tomtomjr, one of if not the US's largest Fosgate/Rockford Fosgate collector and radio/amp technician:

" ...ALSO, on the turn on remote wire (red) , you will need to draw power from it to turn on the amp. We used to use a 12V light bulb and a switch. Put the remote wire (red) to the positive of the bulb, then the switch between the 12V ground and the 12V ground of the bulb. Flip the switch, and it will come on. These have the power-draw on the remote wire rather than the power input like modern amps... Hope this info helps........Tom"


See the video demo in 720p HD or embedded below:

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Video Overview of the Rockford Fosgate Punch Power 360

I recently created a video overview of the Rockford Fosgate Punch Power 360 I wrote about before. Enjoy the video demo below:


View in 720p HD or watch embedded below:


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The World's Most Powerful iPod Dock? Athena iVoice

Athena iVoice iPod Dock

What is the world's most powerful iPod dock? Is it the Athena iVoice? Well, not likely, but I decided to test one of these iVoice docks on the oldschoolstereo test bench. I have one of these units with a bad speaker, so I decided to pull it apart and test the amplifier using my resistor load.


The Athena iVoice is an amazingly good sounding iPod dock. I've been VERY impressed with these docks since I first purchased one on closeout a few years ago. The unit also has a 1/8" input so you can also use it with other portable music devices, computers, cell phones, etc...any device with a 1/8" output. Trust me, you won't believe the sound coming out of dual 3.5" speakers! The bass is very punchy, mids extremely transparent and even the highs will surprise you. Another useful feature of the Athena iVoice is the built-in power supply. No external power brick needed with this dock! (just a light-weight 6 foot power cable) Probably the only real downside is the lack of an internal battery for portable usage. The dock also includes a USB port for iTunes syncing and a RCA video output for passing signals from an iPod Photo or iPod Video 5G (not sure about 5.5G or iPod "Classic"?). My iPhone 4 fits on the dock, but will not charge and gives me a "not compatible" warning. That said, it will pass audio from the iPhone.

Athena iVoice with Metal Speaker Grill Removed

Athena iVoice Rear Connections

Here are the iVoice specs from Athena:

Design:	Direct Radiating iPod Dock Sound System
Features:	Wall mountable - Provides Greater Installation Flexibility USB Connectivity - Allows the iPod to Sync with iTunes on your Computer IR Remote Control - Remotely Controls your iPod and the iVoice Charges iPod While Docked
Frequency Response:	65 Hz — 17 kHz
System Power:	25 Watts RMS / Channel
Input:	3.5mm Audio Input - Can be Used with Any Portable Audio Device (with an Audio Output) or Computer
Output:	Composite Video Output - Allows an iPod Photo / Video to Output Video Content to an External Display Device
Dimensions — Standard: (Height x Depth x Width)	5" x 15-½" x 6-½"
Dimensions — Metric: (Height x Depth x Width)	140cm x 393cm x 170cm
Weight:	4.7 lbs / 2.1 kgs
Finishes:	Polished High Gloss Black

Well, enough talk about the sound and specs of the iVoice, what about the output power? Athena says 25 watts RMS per channel, which honestly, is a LOT of power for 3.5" speakers. My test involved sacrificing one of my iVoice docks, so see the internals below:

Athena iVoice Internal Components

As you can tell by the pictures, the 3.5" speakers appear to have neodymium magnets and a dual-cone design for enhanced highs. A quick measurement of each speaker show a load of approx. 6.8 ohms. Since my resistor loads are setup for 8, 4 and 2 ohm configurations, these are the loads I decided to use for my testing.  I honestly wasn't sure the tiny "BASH" Class D amp could handle the 2 ohm tests, but decided to do it anyway...why not?


So, did Athena accurately rate the internal amplifier? Well, I guess it depends on the testing parameters they used. For my 1000 Hz tone resistive load test, the amp seems to be somewhat overrated. See the video for the detailed test results, but the approximate measured RMS wattage was 10, 20 & 32 (at 8, 4 and 2 ohms, respectively). 


Although the Athena iVoice may not be the world's most powerful iPod dock, it is the most powerful iPod dock measured on the oldschoolstereo test bench! (as of August 2011)


Watch the demo in 1080p HD or embedded below:


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RF Punch 150HD vs PG MS-275 - Part 2 - Power Output Tests

As promised, here is the update of the comparison between the Rockford Fosgate Punch 150HD and Phoenix Gold MS-275....I call it "Part 2 - Power Output Test"


Before I get started, I wanted to stress the importance of changing out the capacitors if you have a Phoenix Gold MS or MPS series amp. My MS-275 is in MINT condition and appears to have little use, however the caps still showed signs of leaking. In order to prevent a blown up amp and possibly starting a fire, I sent the amp to Envision Electronics (www.envisionelec.net) for the capacitor replacement. Although they make no mention of amplifier repair, the owner, Aaron Hammet has an extensive background in designing, building and repairing amplifiers. I was extremely pleased with his work and professionalism and highly recommend contacting envisionelec.net for your Phoenix Gold capacitor replacements!


The 2nd part to my shootout between the 150HD and MS-275 involves resistive power output tests using 100hz test tones. This may not be the most accurate method for obtaining maximum RMS output power, however it is the method I used for this comparison. If you've not seen my bench setup before, see my previous posting about the components used.


Being a huge old school amp fan, I've always wanted to see the power output of the 150HD. Back in the early 90's, there were a few magazine tests of the Phoenix Gold amps (MS-250 and MS-275), but none of the 150HD. I had an idea of the expected power output of the MS-275 based on these magazine tests, but the infamous Punch 150HD had only sample birth sheets and I had never seen an example of the 4ohmsstereo and mono output. I've always heard these RF amps were "very" underrated, but what is the true RMS output? Read more to find out...


The Punch 150HD was a BEAST on the test bench. Rated at 75x2 4ohms stereo, it put out an effortless 119.2 watts x 2! The MS-275 was much less powerful at 80.9 x 2 into 4ohms stereo. It has been mentioned before the MS-275 has more "reserve" power for transient peaks, such as those in music. I didn't have a way to test true music output power, so you'll have to consider this when comparing the raw resistive output numbers. I appreciate any and all comments of my testing methods and those who disagree are more than welcomed to perform their own tests!


The Punch 150HD out powered the MS-275 in all of my resistive output tests. Here are the results in order of 4ohms stereo, 2ohms stereo, 4ohms mono and 2ohms mono:


RMS Watt Resistive Output:

1) Rockford Fosgate Punch 150HD - 119.2, 191.8, 299.2 and 330.2
2) Phoenix Gold MS-275 - 80.9, 134.1, 217.5 and 224.7    


See the video below or visit YouTube for the 720 and 1080P High-Definition versions.


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Phoenix Gold MS-275 Update and More

I have had many comments on the Phoenix Gold MS-275 vs. Rockford Fosgate Punch 150HD and many want to know the results of my test. Well, I may actually be able to get those results online sooner than expected. The MS-275 is in the hands of an expert technician right now and should be back in action within a couple of weeks. I had originally planned on testing the amps with subs only, but now I think I'll use the Phoenix Gold XV4 tri-mode crossover to fully test the amp's capabilities with the full music spectrum. Are you excited to see the results? I know I am...


Also, please check the comments posted on YouTube as I've had some well though out responses to my overview, including some technical corrections. The comments about music power versus test tones made me reconsider using the output tests as my main deciding factor on the winner. Even Zed Audio warns test tones are not a good indicator of an amp's true musical output and actually put severe stress on the amp. See the 2011 Zed Audio amp lineup's manual for an extremely well written technical description of amp operation.


Please send all comments, questions and suggestions to oldschoolstereo at gmail. I hope to have a submission form shortly....


-D