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Reviews For: Audio Authority 978-xxx

Category: Power Supplies

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Review Summary For : Audio Authority 978-xxx
Reviews: 2MSRP: $500+
60 to 100 amp at 13.8 volt modular powere supply
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
KC2URJ Rating: 2015-01-24
Excellent High Current Power Supply Time Owned: more than 12 months.
The Audio Authority 978 Series switching/switched-mode DC power supplies are indeed excellent heavy-duty high-quality "12V" (13.8VDC) power supplies. The 978-100 is indeed 13.8VDC and easily rated at 100-AMPS CONTINUOUS CURRENT!

These were originally (and still available as) 28VDC power supplies manufactured for the small aircraft aviation industry to power aircraft systems on the ground.

Audio Authority then contracted with the former consumer electronics giant retailer "Circuit City" to produce commercial quality 13.8VDC power supplies to power all of Circuit City's "car audio/stereo" (AM/FM/CD mobile radios & high-power stereo amplifiers) showrooms, supplying high-current DC power to those huge display banks of selectable stereos and amplifiers (you could just push various selector buttons in the showroom to hear any combination of car stereo and amplifier and speaker system, until you found the combination you liked best - they were very nice).

Though always available to the commercial sector, when Circuit City went bankrupt and closed, these power supplies were suddenly publicly available for a short time from various contractors & liquidation buyers via eBay & Craigslist etc.

I bought 6x of them from a local Circuit City store that was virtually brand new, the store having just been built less than 1 year before the it closed. The store had 3x 100-Amp "978-100" power supplies as well as 3x 60-Amp "978-60" power supplies.

They are engineered and constructed extremely well. N8RT (above review) purchased his 978's from me when I sold some locally on Craigslist. His review is mostly correct with the exception that the 978-xxx actually comes with a NEMA 5-20 20-Amp AC power cord plug (which is a common commercial and industrial receptacle plug found in most hospitals and businesses and even modern homes with higher current 20A electrical outlets).

Also a correction to above review - the 978 power supplies have a front panel LED/lamp display indicating the operating status of each internal 20A power supply (called "modules"). The manual states that the lamps can both flash or flicker AND stay lit continuously and either way it indicates normal operation. If a light actually stays out, that indicates a problem with it's corresponding module.

Amazingly, each module is independent of the others (a 978-100 contains 5x individual 20A power supplies!). On a 978 - if one of the internal module boards should ever fail - unlike most power supplies, the 978 will ignore that particular module and continue working normally, just at 20A lower continuous current).

Also, each board/module nicely contains a through-hole mounted glass fuse for individual protection. Plus the overall supply is also circuit-breaker protected with a heavy-duty Potter-Brumfield on/off switch.

The 978 Series supplies are constructed using a rigid metal chassis which is good for strength and RF shielding. But it is true that, for 2-way radio communication use, on some bands there is in fact an increase in background noise-floor signals. As said by N8RT, the addition of a handful inexpensive snap-on ferrite chokes (in most cases I prefer "TDK" brand ferrites) to the incoming AC cable & internal AC distribution wiring helps nicely quiet the 978. Additionally, common improvements always including good grounding and even adding a pair of AC capacitors to the AC cable where it enters the chassis could always also be easily installed and a fun little project improvement).

Also as indicated by the manual, 2x 978's can be connected (in parallel) for a truly powerful 200A continuous DC power supply - that's enough to power nearly any home rig/amplifier requiring a high-amp DC power supply.

The 978 works smooth and doesn't even break a sweat, even when run to maximum current. Yes the manufacturer also says that large audio "stiffening" capacitors can be added to the 978 (inline) if desired for redundancy with high-power stereo amplifier use.

Also unique is that the 978-100 comes with 5x 20A modules - but there is actually a 6th space/slot available (with harness connections already in place) to add a 6th 20A module for even more current handling power!

The 978 has large simple easy-to-connect -/+ terminal connection blocks located on the rear panel which simply fasten with large flathead set-screws. These terminals can easily handle large heavy-gauge battery cables and welding cables or any smaller gauge wiring of your choice - very versatile.

As described, these were originally made for 28V aircraft then factory-modified for 12V car audio/stereo showroom demonstration use. Many radio hobbyists have found these to be a excellent solution for using high-current DC radio equipment at home. The fact that these are high-current switching supplies means that they're very light versus a huge heavy linear supply of the same amperage.

If your home station has common 15A receptacles, Leviton 20A receptacles can be purchased at most hardware stores for only $3ea and the 20A outlets also accept common 15A 2&3-blade plugs too. Each station outlet circuit (in your shack) should have adequate wiring for 20A use (if you truly intend to run them continuously at full 100A load).

If you plan to parallel and connect 2x 978's together, please remember you should ALWAYS use identical length and thickness/gauge DC cables and you MUST connect both 978's with a common 3.5mm (1/8") jack patch cable (there is a 3.5mm jack on the rear panel of each 978).

Overall these are an excellent power supply and super heavy duty. These retailed (commercially) at approximately $1500 new and each 20A replacement module costs $250 + s&h from the factory (at those costs it's recommended and much cheaper to just buy a spare 978 for extra modules etc). I've never ever had one issue from any of mine and they've worked flawlessly and only required a routing blowing-out of internal dust perhaps once a year. I give them 5-stars as well-built, heavy-duty, high-power, well protected, and easily adapted for use with radio station equipment.

Certified RADAR & LIDAR operator, Police and Military, senior-level technician
N8RT Rating: 2009-10-14
A Light weight 978-100 Amp Power supply Time Owned: 3 to 6 months.
I have been using the 978-100 supply for about 4 Months now it is the 100 Amp version, using FIVE 20 amp individual Switching power supplies, and it runs my Complete station.
The Dc Output Measures 13.9vdc, with a 75 amp load from my Ameritron ALS-500 the PS drops only 100 Milli-volts!
When I first received the 978 I noticed that there are no Ferrite Cores to minimize RF Hash.
I installed 6 ferrite sleeve type cores over the incoming AC Mains that go to a terminal an internal AC Terminal block.
The power supply has an internal fan that runs all the time. If one supply fails the rest will still function! Two of the 978-100 may be connected together using a connection between the two on the rear of the units, for 200AMPS!
Each supply is is individually monitored for over voltage and overheating.
Like all switching Power supplies, it is a good idea to keep the PS away from the ANTENNA, to minimize any RF Hash!
The 978 comes in several versions 40.60,80, or 100 AMP. You just keep adding the 20 AMP Modules.
The main AC Plug is a 15 AMP type and will not fit into a normal 120 Volt outlet,as one of the ac prongs is Horizontal, instead of Vertical.
The front panel has 5 Indicator lights that, tell you each module is OK, if a module fails the lamp will flash OFF/ON, lastly there is a QOVERHEAT lamp that glows if a Module gets too hot.