Power Extension Blocks – Serial or Star-wired?
Basics of normal (serial) and star-wired power extension blocks
Most normal (serial) power extension blocks have two or three internal brass strips that connect the inlet to all the outlets in a single run. This means that all outputs are in normal, series connection. This does not have to be a bad thing, though; it can actually have its advantages.
Above: a simple and affordable (~30 euro) serial Apsa block. The inlet or the main cable connects to the clamps of the first socket, and from that point on the power is carried across by brass (or another metal allow) strips. Although the strips look like copper, the block itself sounds comparatively harsh.
Above: one step up from the Apsa block above, a 60-euro serial Popp block with aluminum housing. I don’t know what kind of conductor material is used for the conductors or the clamps, but it is definitely no copper. Yet, compared to the Apsa block above, this block sounds airier as well as more refined and fluid.
Above: a CP-Audio star-wired extension block
A star-wired power extension block has individual connections from the inlet to each individual socket. These connections could still be made with brass strips but that is very uncommon. More often the internal connections are comprised of solid-core or stranded wire, and it is not uncommon to use audio-grade wire such as OCC copper, silver or a combination of metals for this application. The length of the wire should be the same for every connector. I found this out after assembling the block as pictured above, where the connectors closest to the entry with the shorter wires sounded more articulate than the others. The next block I made (see below) utilized same-length cables for all outlets.
Advantages and disadvantages of Standard serial power extension blocks
Because the sockets are serial, only the first appliance in line has the most direct power supply. In this position, the connected audio component will sound most rich and powerful, with most attack and most liveliness. For every position you move back from the first position, the sound will be increasingly less full and lively. Importantly, this is not only true when connecting a device on its own which is caused by the length of the conductors, but when connecting multiple components, they all interact with each other. So when moving backward in the extension block, the other appliances and the capacitance of their power cords that are plugged in ahead of the component in question also have a large effect on the resultant overall sound.
This disadvantage can however actually be a surprise advantage! You will be able to tune your audio equipment as you wish; an appliance that needs a richer and more powerful sound can be placed in the first position, “in front of” an appliance which you want to tame slightly. Each successive component loses a little in terms of a powerful delivery, becoming ever thinner. This can be a bad thing, or a good thing, depending on your taste, the sound of the setup and the desired result.
Please note that it is not a rule that a power amp needs the most power and therefore must be placed in the first position of the extension block. This could very well work under some circumstances but the amplifier’s great capacitance might also mellow the following components’ sound to a very noticeable extent.
Advantages and disadvantages of star-wired extension blocks
There are three distinct advantages to the star-wired power strips. First: the wiring; more often than not, much better quality conductors are used. Most wire sounds more natural and relaxed than the brass or undefined alloy power strips inside normal extension blocks. Second: the star-wiring principle, particularly its ground wiring, allows the system to achieve better soundstage focus. Third: all positions in a star-wired extension block are equal and this means that you do not have to worry about where to plug in your appliances.
There is only one disadvantage you cannot tune your set-up by changing the order of connections. But it probably saves you a big headache!
It’s boring to state, but as is often the case in audio, there is no real right or wrong. There are however large differences among extension blocks of the same type, and even more so when comparing normal (serial) extension blocks with star wired extension blocks. It is important to know the mechanisms behind them and the way that they influence the sound of the system. Also, it is important to be aware that every power cable connected to the extension block, whether connected to a device or not, influences the overall sound of the system. By carefully choosing how to connect your system’s components you’ll be able to very accurately fine-tune your system.