Product Review

Tributaries TX500 AC Line Conditioner

May, 2007

John E. Johnson, Jr.


Click on the photo to see a larger version.



● 1800 Watts

Three Sets of Independent Filtering on Five
   Pairs of AC Outlets

Surge Protection for Cable TV and Telephone

● Power On/Off Delay Adjustable

● Triggering Capable

Dimensions: 5.9" H x 17.2" W x 12.4" D

● Weight: 17 Pounds

● MSRP: $750 USA


Tributaries Cable


It is amazing that we get such good performance from our hi-fi equipment when the incoming AC is so dirty, meaning that it has noise up the kazoo from our refrigerators, air conditioners, light controllers, RF from the miles and miles of wiring to reach our house, and other things.

Topping that off is the fact that you don't get just a 60 Hz (50 Hz in other parts of the world) sine wave on your voltage. It is full of harmonics (about 4% THD+N).

In other words, your house AC power is garbage in relation to what it should be.

Enter the world of the AC Line Conditioner (Power Conditioner, Power Manager).

There are many types. Filters, balanced transformers (they act like a huge inductor that low-passes the 60 Hz), units that insert and subtract small voltages from the waveform to get it back to a sine wave, and units that convert the incoming AC to DC, then re-create the 60 Hz sine wave from scratch.

As they get more complex, they get more expensive.

The most basic type has a series of filters that remove some of the harmonics from the wall AC signal. Such is the design of the Tributaries TX500.

The Design

The TX500, priced at $750 retail, has three sets of filters, one set to two outlets, one set to one outlet, and the third set to the last two outlets. One filter is connected to each leg (+ and -).

Click on the photo above to see a larger version.

So, looking at the rear panel, you can see that there is one outlet assigned to "Analog", two to "Digital", and two to "Amplifiers". They are numbered 1 through 5, which corresponds to five LEDs on the front panel that light up when the unit is powered on. If your wall socket is wired incorrectly (hot and neutral reversed), a Polarity Fault LED on the panel will illuminate.

Outlets 1 and 2 are always on, when the unit is plugged in. When you press the On button, outlet 3 comes on immediately, then outlet 4 comes on 5 seconds later, and outlet 5 comes on 5 seconds after that. So, you get sequenced turn-on. This is useful when you have big power amplifiers that have current rush at power on. Otherwise, you may trip your circuit breakers.

When you push the On/Off button to turn it off, outlets 5, 4, and 3 turn off in reverse sequence, 5 seconds apart.

You can program the sequence to your preference with a series of dip switches seen in the upper left corner of the photo.

The only nit I have with the TX500 concerns the layout of the LED indicators on the front, in relation to the rear. I usually put such products on the rack, then plug components into them by reaching over the front. The outlets numbering on the rear is reversed from the front. In other words, LED 1 is on the left on the front panel, but outlet 1 is on the right on the rear panel, when leaning over the unit to plug something in. No big deal though, once you are aware of this.

Like all line conditioners, the TX500 has surge protection. In this case, the protection is provided not only for the hi-fi components, but your telephone system and cable TV system. There are phone jacks and cable TV jacks on the rear panel for this purpose. Protection is delivered via Silicon Avalanche Diodes (SAD), rather than Metal Oxide Varistors (MOV). SADs recover fully after a surge rather than deteriorating after each surge, as MOVs do.

Lastly, there are trigger jacks so you can turn the TX500 on simply by turning on your preamplifier or processor. The power on sequence would then turn on your power amplifiers.

There is a voltmeter on the front panel if you want to see what your incoming AC voltage is.


The TX500 is one of the nicer line conditioners I have used over the years. I used the trigger out from a Lexicon MC-12B SSP to turn on the TX500, which then turned on a McIntosh MC602 stereo power amplifier (600 watts per channel). I plugged the MCD201 into outlet 2 (always on) and the MC602 into outlet 4.

In my experience, line conditioners have more of a beneficial effect on mass market equipment, like receivers, than they do on high performance products. That is because mass market components tend not to have very robust power supplies.

That was the case here, as I could not discern any audible difference with the TX500. However, that does not diminish its surge protection value (a lightning strike would cook my expensive components just as much as it would any mass market receiver), nor its value in sequential power-on. However, this would be a very good product to use with any mass market setup, in that every bit of noise reduction will benefit the sound.

Speaking of noise reduction, here is a graph showing the harmonics present in my wall AC vs. the harmonics in the AC coming out of the TX500.

Notice that the second, sixth, and tenth harmonics are reduced, as well as some peaks between 1 kHz and 8 kHz. The reduction in some peaks is 10 dB, which is a lot. Like some other line conditioners I have tested, noise between 10 kHz and 50 kHz is actually increased. I have never figured out why that is, but it is there, for sure. Fortunately, power transformers in components down the line act like inductors, which low-pass and help filter out high frequency noise.


The Tributaries TX500 does its job. Harmonics from incoming 60 Hz AC are reduced, and reduction is always good. This product also has sequenced power-on, which I value highly, and surge protection for all of your expensive hi-fi components, as well as telephones and cable TV boxes.


- John E. Johnson, Jr. -

Copyright 2007 Secrets of Home Theater & High Fidelity

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