McGary Audio

Thursday, December 10, 2009

Home Theater Review!
Panamax M7500-Pro
Power Management Center

Smooth, Sequential Power-up, Courtesy of Pamamax

by John Gatski
Home theaters have made power cord/power conditioner/power distribution a big business. No longer can you just plug components into a cheap power strip, or God forbid, a 10-year old extension cord.
Today, components have differing power needs, plus some systems have so many plug-in devices that even eight-plug strips are not adequate. Couple the needs of the many components with the potential for AC-induced noise through irregular grounds, etc. and you need a power distribution gizmo such as the Panamax M7500-PRO.

The details
Priced at $1,999, the designed-in-USA/manufactured-in-China, the M7500-PRO features 11 outlets, voltage and current meters, status lights, programmable turn-on and turn-off, as well as phone and satellite/cable inputs/outputs. The heart of the unit is its noise filtration system and 720VA isolation transformer that provides “clean” power for digital source components, amplifiers and displays.
In addition, the ground isolation feature mechanically interrupts ground loops, making the M7500-PRO especially useful for applications with unstable power or ground problems. The M7500-PRO can be used for multi-zone audio/video whole-home automation and wherever remote diagnostics are needed. RS-232 communication comes standard with the unit and a TCP/IP card is optional. End users can configure each outlet bank individually to customize it for their home theater system.
The ruggedly-built, power-management unit sports 11 outlets (10 on the back panel, and an unswitched convenience outlet on the front). The outlets are divided into five “banks.” Banks 1 and 2 are rated at a combined 12 amps max and are equipped with EMI filters, making them ideal for AC-noise susceptible sources, such as preamps, VCRs, etc. Banks 3 and 4 are each rated at 6 amps max and are separated from the others via a separate ground isolated balanced power transfomer. Panamax recommends this bank for digital sources, such as Blu-ray/dvd players or flat-screen TVs. Bank 5 is rated at 15 amps max and designed for high current products, such as amplifiers, receivers. etc..
The back panel features include the satellite in/out and phone line in and out for completely protecting those products. The unit also has 12V triggers to allow control from other gear. The M7500-PRO can also be computer controlled via Ethernet; this feature also contains custom-setting parameters, such as variable delayed turn-on time for each bank or remote outlet bank rebooting.
My favorite feature is the delayed turn-on/turn-off function. Via the rear-panel delay/always on selector switches, you can select which bank of AC products to activate first, second and so on. This allows the components in a home theater to be turned on and shutdown in order to avoid nasty turn-on noises and potentially damaging voltage spike that can kill speaker drivers.

Front panel controls and status lights take up most of the front panel, which also has an accessory convenience front-panel outlet. The status lights includes outlet banks, unit on/off. The left meter indicates wall-outlet voltage; the right meter shows current draw and voltage output of the M7500-PRO. The rotary control adjusts meter brightness disableing the auto dimming feature, and a second front panel push button enables/disables ground isolation of Banks 3 and 4.

The audition
I set up the M7500-PRO in my home theater. My AC power system is actually quite good with heavy duty outlets, newly upgraded fuse panel and Essential Sound power cords for the amps, preamp, Blu-ray players and and I don’t have a noise problem. However, I love the idea of sequential turn-on to eliminate startup noise when the amps kick on before the preamp. **When you select delay via the rear -panel switches, the delayed startup begins by holding the main power switch for two seconds: Bank 1 activates first, then Bank 2, and so forth. Turn off just reveres the order for delayed turn-off.
I connected my Onkyo Pre-Pro preamp, two Blu-ray players, two Carver amplifiers, a Paradigm Servo-15 subwoofer and a Verizon Fios box to the Panamax. I used Essential Sound Products power cords for each component, except the Fios box. I then set the rear panel switches to “delay” to allow bank activation upon pushing the main front panel switch. I put the preamp in Bank 1. Then the two Blu-ray players and Fios box were plugged into Bank 3 and 4. The amps and subwoofer were plugged into Bank 5.

To start the start-up sequences you simply hold the main power button for two seconds. Banks 1-5 started up at 3-second intervals and worked without a hitch. I did find that the preamp needs to be plugged into Bank 1 and the amp in Bank 5 to give the preamp enough time to cycle through its startup before the amp goes live. Plug the preamp in bank 3, for example, and the amp cycles on before the preamp relay activates, causing audible ground buzz through the speakers.
Now of course, you can connect a computer to the RS-232 port and adjust the amount of delay in seconds for each bank. I would, however, would like to see a user-selectable delay adjustment on the front panel.

If you are going to have a plethora of electronic components in your system, you need a product like the Panamax M7500-PRO.
All the functions worked as advertised, and I like the current and voltage meter. But there was an irony in using the M7500-PRO, a device designed to reduce AC noise in an audio/video system. It generated its own mechanical noise through transformer vibration. In my Per Madsen wood component rack, the noise was clearly audible during quiet parts of a DVD or Blu-ray movie. I ended up placing the power center on the floor on heavy carpet with a rubber mat on top to dampen the noise. That reduced the noise to where it was not noticeable during movie playback.
Audio manufacturers should figure out a way to make transformer-based products quieter for home theater and hi-fi use. I also have used power amps and receivers that had noisy transformers. A picky listener does not like such noise intruding onto his favorite audio or video playback.

The verdict
The Panamax M7500-PRO is a high-quality power-distribution center with useful features, including the delayed turn-on/off, balanced power, watt/current meters and Ethernet control option. In the rack placement, it self-noise was slightly annoying in quiet passages during movies, but a move from the rack to a soft, sound absorbing surface remedied that malady.
Last, but not least, the M7500-PRO is really well made, a testament to Panamax’s selection of a top-notch Chinese factory for its assembly. Fit, finish, switch integrity, and outlet sturdiness are most apparent. If you are going to have a plethora of electronic components in your system, you need a product like the Panamax M7500-PRO.
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