Old School US Amps 50HCA vs. USA-50

I recently put a couple of US Amps amplifiers (1992'ish US-50HCA and 1999'ish USA-50) on the OldSchoolStereo.com test bench. The outcome was not quite what I expected. Both amplifiers are rated at 25 watts x 2 into 4ohms.

First up is the 1992'ish US-50HCA, which is finished in a beautiful blue color and is in AMAZING condition to be a nearly 20 year old amp. As with most of the late 80's and early 90's car amplifiers, the 50HCA has direct wiring, no terminal strips for the wiring connections. The 50HCA requires a 30A fuse and is stable to 1ohm mono or 0.5ohms stereo, according to the manual. Later models of this amp, known as the USA-50HC, require a 75A fuse, and are likely to be MUCH more underrated than this model. US Amps denoted their "competition" amps as either HCA,  HC or VLX series.

Proceed forward a few years to approximately 1999 and you could pick up a US Amps USA-50 in your choice of several colors. My sample is purple in color and has terminal strip connections for speakers and power. It also has a clear acrylic cover on the bottom of the amp to show off the "guts". The standard USA model amplifiers were rated for 1ohm stability in contrast to the HCA, HC or VLX series' 0.5ohm stability. The USA-50 requires a 25A fuse and also includes a 100Hz high pass or low pass crossover.

I was expecting the US-50HCA to be a beast, but not so much. Here are the results (RMS unless otherwise stated):

4ohms stereo - 33.4w/ch
2ohms stereo - 59.6w/ch
4ohms bridged - 126.3w
2ohms bridged - 198.2w
Max Output at 2ohms mono - 282.5w (hard clipping)

(The US-50HCA, like the Orion 225HCCA is rated to handle 1ohm mono and 0.5ohms stereo and I don't have the resistor bank loads to test these configurations yet.)

And the USA-50:

4ohms stereo - 38w/ch
2ohms stereo - 65w/ch
4ohms bridged - 133.7w
2ohms bridged - 167.6w
Max Output at 2ohms mono - 274.9w (hard clipping)

Surprised with the test results? I was. I guess the real test will be the 1 ohm mono test for the US-50HCA to see how much power it's really capable of. Now, let's see if I can sell a few amps to fund the needed resistors for the additional 800W 2ohm load.

Stay tuned, more coming soon...



See both amps pictured below; 50HCA in blue and USA-50 in purple...

US Amps US-50HCA on top and USA-50 on bottom

US Amps US-50HCA on top and USA-50 on bottom

US Amps US-50HCA Guts

Testing Power Output from Old School Amps - Part 2 - Video Demo

I recently did a video review showing the details on how I measure output power on my old school amps. I've had a ton of questions with people wanting me to explain further the process. If you want to do this yourself, you'll most likely need to invest some money in the tools. At a minimum, you'll need the following:

• 12v Automotive starter or Marine Deep Cycle battery or 12-14.4v Power Supply with enough output to handle your amp's load
• True RMS Volt Meter
• Oscilloscope (My Velleman HPS-50 has a built-in RMS Volt Meter)
• Speakers or Resistors for "loading" the amp

Watch the video to see the components I use for my tests. 


Click the link if you prefer to see the video in HD (720 or 1080p):

Old School Amp Output Test Demo in 1080p HD!

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More 90's Cheater Amps Coming Soon...

What's up old school fans? Sorry, it's been too long since my last post. I have acquired a few more "cheater" amps from the 90's I'll be testing soon. I've decided to stick with the "50 watt" (25x2) cheater amps as these are more affordable and easier to come by.

Here's a 1992'ish US-Amps US-50HCA, high-current, competition 25x2 amp:

US Amps US-50HCA - 1992 Model in 9.5/10 Condition

Another popular 25x2 cheater amp from the 90's was the HiFonics Ulysses. This mode is the Ulysses VIII, which has the Utilink connectors for speaker and power. Unfortunately, my amp was missing these connectors and since Zed stated these connectors are no longer made (the power connectors were specifically tooled for these amps and no longer manufactured). The speaker connectors are easier to come by. You can either spend $15-20US on eBay or search the Digi-Key catalog for a suitable replacement. I chose the latter.

Fully Polished 1996 HiFonics Ulysses VIII

More details on these cheater amps and maybe I'll be able to come across a few more to include in my shootout. I'm looking for 1) MTX 225HO 2) MTX MTA 225 (clone to the PPI Pro Mos 25) 3) Autotek 9050BTS and a few more I can't think of right now.


Here is the list of 90's cheater amps thus far for my shootout:

1) Rockford Fosgate Punch 45HD
2) Precision Power Pro Mos 25
3) Phoenix Gold MPS-2240
4) Orion 225HCCA (Gen2 and Gen3)

5) US Amps US-50HCA

6) HiFonics Ulysses VIII

So, how will I perform the shootout? Well, I'm thinking a true power output test using my dummy loads and oscilloscope as the first test. I plan to have the means of testing loads from 4ohms down to 1/2 ohm. Obviously, I'm not going to load amps, such as the Punch 45HD lower than 1ohm as it was not intended to handle extremely low impedance loads as some of the others were. Many people may argue the Punch 45HD should not even be considered as a cheater amp, but those people can do their own shootouts!

In addition to the power output tests, I'll also demo each amp powering one or more subwoofers. It will be interesting to see if the most powerful amp also controls the subwoofer(s) best. We'll find out soon enough...

-BigD

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Update: 6/27/11

Many of you have contacted me asking why am I taking so long to post the shootout between the cheater amps I have listed above. Honestly, I was hoping to get the HiFonics Ulysses VIII amps repaired as they were both dead. My repair tech said it would be about $100/ea to have them fixed and since I needed some other amps repaired, I decided to trade in the Ulysses amps. That said, I won't be getting them back, so I'll have to remove them from the test. I've seen a few Autotek 9050BTS's lately, so maybe I'll be able to pick up one of those for the shootout.


In addition, the Phoenix Gold MPS-2240 is experiencing the same issue as many 90's Phoenix Gold amps....leaky output capacitors. These capacitors will need to be swapped prior to any further testing with this amp. Too bad as it may be several months before I'm able to get around to having it repaired. 


Stay tuned for updates....

Old School Cheater Amps - RMS Power Output Test Results

I'm sure many of you have been eager to see my test results from my previous posting on early 90's "cheater amps". Well, I've finally assembled the pieces needed to test RMS power output from the amps. See my previous post for details on my testing methods.

Did I have any favorites? I must say, I thought the Orion 225HCCA would take top honors, but envisioned the Phoenix Gold MPS-2240 would be close behind. Although the Rockford Fosgate Punch 40i DSM was not included in my original "cheater amps" posting or the video I created, I felt it was a worthy opponent to the similar amp models. I put together a separate video on the Punch 40i DSM a while back and it nearly blew me away with it's power and clarity....I guess I was unaware of just how underrated this little amp is!

The Precision Power Pro Mos 25 was no slouch either. It wouldn't win the price/performance ratio, but it outputted 1.5x or greater it's rated output at all test loads. Since this is not a sound quality test, the only comparisons were RMS output power. The PPI Pro Mos 25 would probably gain points to some people for it's "Art" design, but I was always a bigger fan of the black series PPI amps. Also, in the old school, lacking bass and/or treble controls would be another minus for me.

The venerable Punch 45HD was a favorite back in the early 90's and for good reasons. It was reasonably priced ($279 US) and put out at least 2x it's rated power at 2 and 4 ohms. As I've stated in the past, Rockford didn't rate this amp to handle 1 ohm stereo or 2 ohm mono loads; however I've had a Punch 45HD since December 1991 and used it for several years in the 2 ohm mono configuration with no issues whatsoever. It was interesting to see the power output lower in the 2 ohm mono test than the 4 ohm mono test with the Punch 45HD. The limiting circuitry must have come into play to protect the amp from overload.

The Orion 225HCCA and Phoenix Gold MPS-2240 were the only two amps in my test rated to handle 1 ohm mono or 0.5 ohms stereo loads. Unfortunately my current setup provides loads down to 2 ohms and no 1 ohm or 0.5 ohm configuration. I'll add more resistors in the future and test these amps again to find out their full output potential. I have little doubt the Orion 225HCCA will output over 500 watts but have less optimism in the Phoenix Gold MPS-2240...especially when comparing the 4 ohm mono vs. 2 ohm mono loads with this amp.

I hear ya, enough with the jibber-jabber, on with the results! See the embedded spreadsheet below or Click HERE to see the full size image:

Testing Power Output from Old School Amps

Old School friends, have you ever wondered how underrated your treasured amps are? Well, I must say I've always wanted the ability to measure actual output from my amps to show we did actually get what we paid for.

My wishes have come true with the latest 2 items I've added to my test bench....an Oscilloscope and a "dummy load" (aka "Fred Sanford") resistor bank. The o'scope is a portable model by Velleman (HPS50) and the resistor bank is one I put together based on another project I found online. See the detailed layout here:

400W Dummy Load Project

I essentially took his design and doubled it. This gives me (2) 400W loads at 4ohms or (1) 800W load at 2ohms. These resistors can handle up to 3x their rated power for short periods of time. I had originally planned on using 32 instead of 16 resistors, but then decided I could add more in another enclosure as needed. Here is a pic of my creation:

So some of you may be wondering what the resistors are used for. Basically, they are designed to handle the output power from the amps without producing any sound. This allows you to reach max output without damaging your hearing. After I did a simple test with an old Realistic speaker, there was no doubt I needed to build a Fred Sanford. Not to mention, I can safely test many different frequencies, including 1000Hz, which is not pleasing to hear at high volumes!


Next, I needed an oscilloscope to monitor the waveform from the amp. I considered many models, including desktop and portable designs. I finally settled on the Velleman HPS50 portable oscilloscope. I purchased from Kitsusa.net and it was around $230US shipped. I also considered the HPS10SE, but it did not have USB output for monitoring / capturing via PC, which I thought may be important. Another selling point for me of the Velleman o'scopes is the built-in audio measurement tools. They essentially have a built-in True RMS Volt meter and taking the AC Volts x AC Volts and dividing by the ohm load you get max output power (The Velleman does the math for you and just shows power output). The HPS50 will also let you decide between MAX power and RMS power. I decided to perform all of my tests using the RMS power measurement.

Components used in my testing include:

• 100A Audio Authority 978 13.8V Power Supply
• iPod Nano (1st Gen) with test tones - 100Hz and 1000Hz
• 1/8" to stereo RCA adapter
• 12ga Speaker Wire to Connect Amp to Dummy Load
• Windows XP laptop to monitor/capture live waveform from HPS50
• Velleman HPS50 Portable Oscilloscope
• 800W Dummy Load Resistor bank (AKA "Fred Sanford")
  

So, I bet you are curious about some of my findings....stay tuned as I'll post results very soon....

-BigD

Velleman HPS50 Portable Oscilloscope for Testing Amp Output Power

I finally got a chance to test the Velleman HPS50 today. It was pretty simple to setup, even for the o'scope novice like myself.

I don't have my dummy load resistor bank yet, but I do have a 6.5" Realistic Dual Cone car speaker I was willing to donate to the cause. I measured it's resistance to be 4.2 ohms.

I used a 100Hz test tone for my tests and calibrated the HPS50 per the instructions. First, ensure the switch on the probe is set to 10x, also check the display to ensure 10x. Then use the tip of the probe to touch the calibration point on the side of the scope. Lastly, view the waveform, and adjust the small screw on the probe until the wave form has even square waves. (I was wondering what the small, plastic screwdriver was for in the box, now I know!)

You have a few choices for measuring power output. I initially tested Peak watts, then decided RMS was a better test. In the HPS50, it is displayed as W^4Ω. You can also set the ohms (Ω) to 2, 4, 8, 16 or 32. Since my speaker measured 4Ω, I set the meter to "W^4Ω" for RMS wattage at 4 ohms. I'll eventually put together a demo video of the unit, with setting up the unit for power output being the main objective.

I already had a Rockford Fosgate Punch 4020DSM on my test bench, so I decided it would be a good first test. The "old school" amp is rated at 20 watts x 4 @ 4 ohms. My test signal was a 100Hz tone and my power source was my Audio Authority Model 978 100A 13.8V power supply.

Here are my results:

76.65 watts RMS per channel (only 1 of the 4 channels driven) @ 4ohms, 100Hz @ 13.8v. Not bad for an amp rated at 20 watts per channel! The main difference to note is I can't measure THD, so Rockford's measurement (although still way underrated) was tested at 0.1% or less THD while mine could be up to 10%. They also usually test at 1000Hz, my test was limited to 100Hz (mainly to save my eardrums!). Once I get my resistors, I'll be able to test at various frequencies.

I also had a Rockford Fosgate Punch 30HD close by and knew it would be a good test. The amp is rated at 15 watts x 2 @ 4 ohms. I measured 24.75 watts RMS (from 1 channel) @ 4ohms, 100Hz @ 13.8v.

The HPS50 will connect to a PC via USB and capture real-time data as well. I attempted to test with my Windows 7 32-bit laptop and was unable to get the o'scope to communicate with the Velleman software. From reading the forms about this unit, many others are experiencing issues as well with Windows Vista. I'll attempt to install the software on a Windows XP computer to see if I can get the device communicating for real-time capture.

So far, the Velleman HPS50 is a fun tool! More tests coming soon...I'll have my dummy load setup complete and will begin testing the output power of my old school amps. Stay tuned in...

Not Really Old School - Orion HCCA 275g4 "Cheater Amp"

See my recent video review of the Orion HCCA 275g4 below. It is the last of the "Made In the USA" Orion amps, circa 1999-2000. This amp is a BEAST with 180A of fusing with output exceeding 2000w at 1ohm mono loads. 









Here are the published ratings at 12v:

• 4 ohms stereo = 75w/ch
• 2 ohms stereo = 150w/ch
• 1 ohm stereo = 300w/ch
• 1/2 ohm stereo = 600w/ch
• 4 ohms mono = 300w
• 2 ohms mono = 600w
• 1 ohm mono = 1200w

See the video below for more details about this monster amp:

Click the link if you prefer to see the video in HD (720 or 1080p):

http://www.youtube.com/watch?v=71UbM7N2VNU&hd=1

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Here are some images of Orion HCCA 275g4 (actually a 275R in a g4 shroud):

(Guts of a Monster!)

(Size vs. Iphone)

(Input Connectors / Gain Adjustments / X-Over Settings)

Excellent "Old School Showoff" Thread at DIYMA

One of my favorite forums for mobile audio, DIYMobileAudio.com has an excellent thread in their forums about Old School Gear. Grab your popcorn and soda and get ready for some interesting gear and reading:

http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/36261-old-school-showoff-thread.html

Enjoy!

Old School Car Audio Magazines - Help!

I'm on an all out hunt for 1988-2005 Car Audio & Electronics and Car Stereo Review magazines. I had most of the issues back to the beginning of CA&E (1988), but tossed them during a move around 10 years ago. I know there must be some folks out there who have not made the mistake I did and still have these mags....right? 

I'm attempting to digitally archive all of these magazines for historical purposes. I've contacted CA&E and they are planning on archiving the issues themselves, but they also said this would take quite a while and was not a priority. I fully understand their stance as they must review and promote the current products to keep advertisers happy and such. As for me, I'm an old school car audio NUT and think it is VERY important to get these mags archived ASAP!

Anyone out there with some or all of these old mags want to be the first to donate their mags for a few months so I can get them scanned? Contact me at oldschoolstereo at gmail (.com) so we can work out the details. 

Let's keep the Old School alive!

Update 4/29/11:
I've received some feedback, even had some VERY generous people offer up their magazines (thank you!). I'm going to keep an ongoing list of the magazines I'm still missing to fill my collection. See the list below and let me know if you can help.




Here are the CA&E's I know I'm missing:

1988 - July (premiere issue), Aug, Sept, Nov
1989 - Mar, Apr, Sept
1990 - May, July, Sept
1992 - Dec
2003 - Jan, Apr, May, June
2004 - Jan, May, June
2006 - Feb, Mar, Nov
2007 - July
2008 - Dec (final issue)


Auto Sound & Security Magazines Needed:

1990 - Nov (I have Nov, but my issue is in BAD shape), Dec
1991 - Feb - Nov
1992 - Feb, Oct
1993 - Jan, May, June, July-Nov
1994 - All 12 issues
1995 - Jan-July, Aug-Oct
1996 - May
1997 - May
1998 - Sept, Dec
1999 - Mar, May
2000 - Sept, Nov
2001 - Oct
2002 - Mar, June, Aug-Dec (final issue = 12/02)

-BigD

New Site Design Coming Soon....

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