In a previous Adventures In AV article, I documented how buying second-hand helped me achieve my home cinema dream. However, as might be expected, by taking the DIY approach, not everything went to plan.
Don’t fall short
“Aaarrrrgghhh!”
Article continues belowNo, it’s not a precise technical term, but it’s an accurate description of the noise I made when I realised that some of the cables that I’d asked the builders to run through the walls of my rebuilt garage in preparation for my home cinema were too short.
Of the 15 cables (13 for speakers and two for ethernet), some had so much excess length I could have used them to strangle someone (probably a builder), but others had almost no slack at all.
It was doubly painful for me as this was the second time this had happened.
Years before, when we’d had a new floor down in the living room, I’d asked the handyman to place flat cables I especially purchased underneath the floor, enabling me to run a 5.1 set-up. However, one of the cables had come up frustratingly short, so adjustments were always stressful.
For it to have happened again in a dedicated room I’d spent months planning seemed unbelievable. Once again, it meant that cabling things up was hard work and it prevented me from arranging my kit on my stand in the order that would have made the most sense,
Eventually, I got around to extending the speaker cables using some leftover cable and connectors I bought from Amazon, but it’s not a particularly elegant fix.
Also, as the runs now have joins and can therefore come apart, it introduces another point of failure. However, it works, and once I added sliders under the feet stands, everything became significantly easier.
It should never have been an issue, though. My advice is don’t assume that something that seems obvious to you is obvious to others, and if you are relying on others, be as detailed as possible with your instructions – you’ll save yourself a lot of aggravation.
Know your ohms
As a What-Hi? reader, there’s a good chance you’re familiar with the fact that some speakers are run at 8 ohms and some at 4 ohms. Let’s quickly recap why.
Ohms is a measure of the impedance of a speaker. 4-ohm speakers are less resistive, which means they pull more power from your amplifier.
4-ohm speakers use that extra power to deliver lower distortion even at higher pressure levels, but the downside is that they are harder to drive.
It’s therefore important to know what your speakers demand, and if it’s 4 ohms, to be sure your receiver can handle it.
That sounds simple, but it isn’t always.
My Anthem MRX-720 receiver is nominally rated to handle 4 ohms, and I had it doing so for several years (with a Rotel RMB-1048 power amplifier handling the height channels). However, this was really pushing the Anthem to its limits, especially when you factor in that it’s also handling processing and HDMI.
In recent months, my Anthem has been suffering from shutdown issues, and it seems likely that this is due to years of being driven to the max.
Over time, the capacitors have likely become strained, causing the receiver’s protection circuits to kick in following a large power demand from a particularly exciting moment on a high-bit-rate 4K Blu-ray soundtrack.
No doubt this is where having a separate amp and processor pays dividends – though regular, large dividends are generally what you need to afford going this route.
At the very least, if you have a second power amplifier on hand, don’t do what I did and only use it to half its capacity. While the Rotel RMB-1048 can deliver 65W into 4-ohms with eight channels driven, I was only using it to power the four height channels.
Stupid.
In the end, I rewired everything so that the Rotel was powering the surrounds and backs as well as the heights, reducing the burden on the Anthem, which now just had to take care of just the front three channels.
Not only did this lighten the load, but with more power going to the front stage, the whole system sounded better, with clearer dynamics and greater detail.
The lesson here is to make sure your amplification is sufficient and balanced. Your ears and your receiver's internals will thank you.
Keep your cool
Socially, it might be gauche to focus on class, but when it comes to home cinema, it’s worth obsessing over for several reasons, including heat.
We have covered the differences in amplifier classes previously, but suffice to say that while Class A/B is loved for its generally fulsome, beefy sound, it runs hotter than alternatives.
This is worth being aware of, particularly if you're driving 4-ohm speakers, which add to the thermal load compared with 8-ohm designs.
With a total of 13 channels in my system potentially powered by Class A/B amplification, this was a concern I wish I’d thought about sooner.
Heat is the prime enemy of electronics, and while manufacturers take this into account, if you can give your gear extra help with cooling, it will repay you by running optimally for longer.
AC Infinity’s Aircom units are specifically designed to sit on top of AV receivers and amplifiers.
Three low-noise PWM 120mm fans kick in at a target temperature, drawing heat out from the unit and pushing it away. Depending on the model chosen, this warm air is expelled either upwards, to the front or to the rear, depending on your needs.
Fortunately, the company has good UK distribution, and mine were delivered promptly by UK supplier Hi-Fi Corner. It also sells Anthem receivers, which I took as a good sign.
In my system, the Aircom units were revelatory.
My amp used to consistently shut down when it reached 44 degrees, as read by an ‘el cheapo digital thermometer, but with the Aircom T10 in place, it never gets hotter than 32 degrees, and the problem has gone away.
After seeing it in action, my thought was simply: “where have you been all my life!?”
Yes, there is some fan noise, but it’s unintrusive and ceases when the fans stop as the temperature lowers rapidly. For the benefit and peace of mind they bring, it’s worth putting up with.
You only have to invest once, too, as they can be used with any future amplifier upgrade. For anyone running Class A/B amplification, I now consider these to be almost essential.
Do yourself a solid – don't forget the door
It’s not as if I hadn’t thought about soundproofing at all. I specifically requested that the builders use denser breeze blocks and reduce sound leakage when rebuilding the single garage, for example.
However, it turns out that to save cost, they used standard mineral wool cavity material. I should have specified Rockwool, which is denser and specifically designed to improve acoustic insulation in home theatres.
Fortunately, the room is at the other end of the house from the bedrooms, so a film can be played at volume even late at night without disturbing anyone, which is a win.
If you’re in the kitchen, though, it’s a different story.
Short-sightedly, I’d used the same semi-solid core door between the kitchen and cinema room as the rest of the house. As it happens, this means that sound is audible in the kitchen, but it’s ironically more of an issue for anyone inside the cinema room.
This is because virtually any noise, whether a conversation or a utensil being moved, can be heard when watching a movie, which is distracting to say the least.
The solution is simple: replace the door with a solid-core, FD30 fire-rated door. If your door frame can handle it, going up to FD-60 would reduce sound leakage even further.
So don’t do what I did: pay attention, 007, and don’t forget the door!
Sort your remotes
While most modern devices use Bluetooth remotes, the older devices in my room (namely the Anthem receiver and Oppo Blu-ray player) rely on ye-olde infra-red, which means that they need to have line of sight to work.
This is an issue, as in my room, the equipment rack is behind me, which means that if I wanted to access the receiver menu or control the Oppo, I would have to hold the remote aloft and point it backwards or contort myself in the chair, like Harry Potter awkwardly casting a spell.
As ever, the solution was straightforward: I bought a basic IR repeater along with an extension cable.
The Anthem has a port on the rear into which plugs the IR cable that goes into the extender, while for the Oppo, I run a cable that has to be dangled in front of the front-mounted IR receiver, kept in place with double-sided Velcro.
It’s surprising how much more civilised it is to face forward while operating the system. So, if your infrared gear is behind you, don’t skimp and get it sorted at the start.
A more sophisticated solution to the IR issue would, of course, be a universal remote. To this end, I dug out an old Logitech Harmony and spent much time setting it up. However, in operation, it proved to be unreliable and sluggish, and it was easier to ditch it.
I’ve since discovered that those looking to DIY rather than go for a custom install solution can use a Home Assistant to create a customised dashboard using a smartphone or a dedicated remote. It’s something I haven’t got to yet, but I’ll be investigating it in the future. Watch this space.
Tea, anyone?
Sometimes it’s the smaller things that matter.
While we were happy with the cinema-style recliners we found second-hand on Facebook Marketplace, they had an issue: while the cup holders are fine for a glass or can, they can’t accommodate that Great British essential – the mug of tea.
To solve this, we first considered tables that could slide under the chairs, but we weren’t keen on adding those to an already tight space.
I then researched whether I could add cinema-recliner-style swivelling tables that could be inserted into the cup holders – and it turns out these do not exist.
But there are close alternatives, all of which are designed for the cup holders in cars. While not as large as I would have wanted, and not hugely elegant, they do the job. There are many to choose from and the one I selected cost under £20.
And it’s fine. I put it in the middle cup holder so both seats can use it, and not only can you rest a mug on it, but you can also use it for snacks. Its design even retains the cup holder. Game-changer.
Clean power
OK, here we go. Power conditioners, or power cleaners, are a touchy subject for many. Some swear by them, while others swear at them, deeming them completely unnecessary.
It’s dangerous ground, then, but for the last couple of weeks, I’ve had the chance to test some entry-level gear from British brand Isotek, including a six-gang V5 Polaris power bar (an earlier version of which we reviewed back in 2015), a V5 Synchro Uni DC Blocker and four Initium cables.
For the uninitiated, power conditioners are designed to compensate for the unwanted noise present in mains electricity, which negatively distorts the performance of AV equipment.
According to IsoTek, the power bar removes differential mode noise, which emanates from anything plugged into wall sockets, such as appliances. It also apparently cleans up common mode noise, which is radio frequency interference (RFI) – the signals flying around the air from sources such as radio and wi-fi.
To highlight these issues, Isotek also lent me a noise analyser. When you plug this into a wall socket and a speaker, its display produces a number, up to 1000, to indicate how noisy the power ring is, while a speaker in the device broadcasts the noise so you can hear it.
When plugged into my standard surge-protecting plug, the display immediately went up to 420 and the speaker produced a cacophony of sound, with a radio station audible somewhere in the mix.
When plugging the analyser into the Polaris, however, the display number dropped to just 47 and all the noise disappeared, save that of the radio station, which I could now identify as TalkSport!
As I have now learned, the wires inside our power cables act as antennas, making them very good at picking up the radio signals floating by.
The DC Blocker is designed to do exactly what its name suggests: remove DC noise from your mains supply.
This type of interference can be introduced by devices such as dimmer switches and home EV chargers, which convert AC power into the DC required by electric vehicles. As an EV owner with a home charger, that makes me very much the target market.
The point of the exercise, though, is not electrical purity for its own sake, but the pursuit of better sound quality. So, did it make any difference there?
After several listening tests, my answer was… I think so. The difference was admittedly very subtle, but to my ears the sound was appreciably smoother, with a touch more clarity and definition.
Conscious of owner bias, I employed the help of two people with sharper ears than mine – my children – and conducted two blind A/B tests with music they knew well.
The results were a narrow victory for the power-cleaned cabling, with the Isotek-treated music preferred precisely 62.5 per cent of the time.
Far from a landslide victory then, but it’s enough to know that I’ll miss the gear when it goes back at the end of the loan period.
It also means I will have to find around £1600 if I want to get that smidgen of extra performance back.
Some will question the value of spending that much on a slight increase in quality, and I respect that. And, clearly, the more your setup costs in the first place, the more it makes sense.
While your mileage may vary, ultimately, it’s another thing that I personally wish I’d budgeted for at the start of the process.
Label up!
No matter how much you plan, there are always adjustments and additions to your system that must be made further down the line.
Even a relatively modest home cinema system will have myriad components, and the more ambitious your speaker layout, the more cables you’re going to have to contend with.
When I consider the complexity of my own system, it’s crazy to think how long it took me before I got around to spending a few quid on a labelling kit and an evening to sort it all.
A box of simple stickers sorted the plugs, while some nylon cable labels and a good pen sorted my speaker wiring. Now it’s done, I no longer have to spend ages tracing the path of every cable, making changes and troubleshooting far less stressful.
It might have taken a bit of time, but it’s another thing I can’t believe I didn’t do it at the start.
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