Monster HTS 3500 Reference Power Center 
Home Theater AC Power AC Power
Written by Brian Kahn   
Friday, 01 October 1999

Before I start describing the unit itself and my experience with it, let’s talk about power, AC power. The vast majority of our audio components use AC power and look for that power coming in at a certain frequency, usually 60Hz. Unfortunately, in a less than perfect world, there is often a lot of "dirt" that comes in with our power, making that 60Hz sine wave less than perfect and also causing variations in voltage. This "dirty" power makes your power supplies in your equipment work harder and can also effect the sound and picture quality of what you hear and see.

Power pollution comes from many places before it gets into your home. Inside your home, many of your appliances generate noise, which travels into your power lines and into your equipment. You could do what I did and install dedicated circuits for your audio system, which helps, but you may need to do more. Most of the components in your system generate a lot of noise that is sent back out into the power lines for the next component to pick up.

Traditional power conditioners filter the noise out of the line coming from the wall, but do nothing to prevent noise coming from components plugged into the filter from entering other components.

The HTS3500 Power Reference Center ($399) addresses this issue with multiple filters. The unit contains four banks of outlets, each with its own filter, so that noise generated by a component on one outlet will not enter another. In addition to the filters, the HTS3500 also helps by increasing the power factor. The capacitance in the filters offsets the inductive load found on the AC line, pulling it towards a resistive load, making more current available to the amplifiers and other components.

As for the unit itself, the HTS3500 is pretty full-featured and should suffice for all but the most intricate systems. This well-designed, rack-mountable unit has several status LEDs, an expanded scale voltage meter reminiscent of the meters on Sunfire amplifiers, meter light controls and controls for turning switched outlets on and off. On the business side of the unit, there are 10 AC outlets, two switched, two switched with a delay and six unswitched. There are also filters for three coaxial RF lines, a phone line, a ground post and provisions to turn the switched outlets on remotely via an AC or DC trigger. If that is not enough, the HTS3500 also provides complete surge protection.

The AC outlets are divided into four blocks of filtration. The first two blocks have filters designed for audio components. Two high current outlets are provided for amplification. These outlets are switched, on a delay timer to prevent the thumps and bumps that can occur when turning systems on and off. The next two outlets are also switched but are do not have a timer and are designed for low-current audio devices such as tape decks, preamps and turntables. The next block has a filter designed for video components, is unswitched and has two outlets. The last block has a filter designed to work best with digital products, is unswitched and has four outlets. While you can hook up any of your gear to any of the outlets, the filters are designed differently. This means that the video outlets have a filter best designed not only to provide clean power going to those outlets, but to prevent noise typically generated by video components from getting back into the HTS3500. As video, audio and digital components all generate different types of noise, different filters are used for optimal results.

I first used the HTS3500 on my reference two-channel system. This system consists of Martin Logan Scenario speakers, Sunfire subwoofer, Rotel CD transport, Theta TLC and DAC, and Anthem preamp and amplifier. I also used a Bow Technology Wazoo in place of the Anthem electronics. The HTS3500 easily had room for all of my components. I was not expecting a huge difference in results, as this system had its own 20-amp circuit. I was surprised.

I played a multitude of discs while the system was hooked up to the power conditioner. There were several differences caused by the power conditioner that were heard consistently. The noise floor was lowered noticeably. This provided several benefits. There was a lot more detail evident with the conditioner in use. Imaging was improved and the soundstage expanded with most recordings. In the lower frequencies, I noticed much more detail. When listening to Holly Cole’s "Train Song" off of her album It Happened One Night (Metro Blue), the amount of detail in the bass was much greater with the conditioner. The different notes were clearly evident and the decay was much smoother. Eric Clapton’s Unplugged (Reprise) album came alive with the HTS3500. I have always enjoyed this album, but with the conditioner in use, Clapton’s voice became much more palpable, as did the instruments. The imaging and soundstage also became much more stable and clear, leading to a much more convincing experience.

I also used the HTS3500 in my theater system. This system currently consists of a B&K Ref 20, Anthem MCA5 amplifier, M&K MX200 subwoofer, Vandersteen speakers, Denon tape and CD decks, Toshiba DVD, Pioneer laser disc and RF decoder, Sony VCR, Toshiba television, a cable box, outboard comb filter and IR relay system. As this system has more components than the HTS3500 has outlets, I needed to compromise. The devices that had their own transformers (wall warts) were not plugged into the HTS3500. The remainder were plugged into their appropriate outlets, using an extension cord to get the necessary additional outlets onto the digital filter. If you need to use an extension cord, use it only with low-current devices to avoid overloading any of the outlets.

In addition to the sound benefits noted above, I also discovered that the video filters really did improve the picture on my system. I had previously had a problem with grounding in my cable system that caused noticeable horizontal bars to rise through the screen while watching cable. Rewiring and ground loop isolators helped a bit, but not much. The HTS3500 did not eliminate these annoying bars from cursing my screen, but they did reduce their intensity by a large degree. In addition to providing this much-needed improvement with cable TV, the HTS3500 also improved the picture with other sources. While watching many, many DVDs and laser discs, I noticed that the picture was cleaner. There was less video noise and the colors seemed to be a touch more vibrant.

The Downside
There is not much that is bad to say about this product. It held its own with my two-channel system when compared to other power conditioners. I had to step up to an Equi Tech power conditioner, which costs over three times as much as the HTS3500, to hear even slight improvements. With large home theater systems, the HTS3500 may fall short. With 10 outlets and a 15-amp capacity, the unit cannot handle large-scale, high-powered theaters. One simple solution to this problem would be to employ a second HTS3500. If two units are utilized, it is best to plug them into the same circuit and close to one another, which will minimize any grounding differences. Also, the HTS3500 lacks some of the versatility of more expensive units in regard to switched outlets. While this was not a problem in my system, it might prove an issue if more automation is desired.

The HTS3500 Reference Power Conditioner is an excellent bargain for a high-quality power conditioner and is highly recommended. The Monster Cable line of power conditioners is fairly new and growing. For simple audio-only systems, a smaller unit may suffice. For those with larger audio/video systems, the HTS3500 is a great piece and offers amazing bang for the buck value.

I strongly recommend a power conditioner. A good conditioner like the HTS3500 improves the performance of your whole system, as well as protecting it for a very reasonable price.
Manufacturer Monster
Model HTS 3500 Reference Power Center
Reviewer Brian Kahn

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