Just a follow-up on a thread I posted last month; I was setting up a retro-gaming office that includes a CRT TV sensitive to magnetic fields, and I was asking for recommendations for magnetically shielded subwoofers.
Recap:
Here's the
original post but I'll summarise it super quick:
https://forums.audioholics.com/forums/threads/recommendations-for-a-magnetically-shielded-subwoofer.126703/
* The goal was to have retro-gaming setup inspired by the below picture, where the older CRT television is living in a recessed back-box (at the perfect standing height for Time Crisis style light gun games
), and the modern TV mounted in front of it, via an overhead barn door slider. I altered the idea slightly by having my version of the setup be symmetrically laid out, so I could have surround sound in the room. The AVR I chose was a
Yamaha Aventage RX-A2040 from 2015, as it can decode Pro Logic 2 (for the backwards compatibility with Pro Logic 1 and OG Dolby Surround, for early-mid 90s consoles like the Super Nintendo and the original PlayStation), and is also Atmos-capable so it has a nice range of formats. The speakers I chose are decent for the cost, but magnetic shielding was the most important factor, to avoid damaging the CRT so I went for the
Ascend Acoustics CBM-170SE BOOKSHELF MONITOR PAIR for the front left and right, and
Ascend Acoustics CMT-340SE2 for the centre.
The project has actually been coming along really well; the back box is drywalled out, most of the cabling has been run, and I'm just planning to install an extractor fan in the side, so the CRT doesn't cook itself for lack of ventilation
* In the original thread, some folks said there were no need for magnetically shielded subwoofers at all (just keep the subs 2-3 feet away from the CRT)
* Others suggested models of shielded subs or DIY solutions for shielding existing subs.
* Others shared their personal experiences with using unshielded speakers and subwoofers near CRT TVs with no issues, so there was a broad range of opinions.
The Problem:
In the end, I decided to hunt down a
Yamaha YST-SW315 - these subwoofers were released around the mid-2000s and are confirmed to actually be magnetically shielded. The problem was that it was VERY difficult to track down, and I ended up settling for the U.S. 110V version of the subwoofer (I'm based in Ireland where the standard voltage is 230 Volts AC), so I will be using this sub with a step-down transformer, and I'm concerned that the step-down might introduce distortion on the audio.
My solution:
In this video,
Paul McGowan (PS Audio) advises that using a step down transformer to power U.S. 110V products (in a region with 220V input voltage) can definitely end up degrading the sound. And to avoid this, he says to make sure to choose a transformer that is much larger than what you strictly need. Paul recommends a transformer that is at least ten times the size required, to avoid audible hum or similar problems.
Paul's advice is meant to apply to amplifiers, but I would assume that this would also apply to importing U.S. 110V powered subwoofers and using them with step-down transformers? Subwoofers are probably also sensitive to voltage fluctuations and using a step-down that is "too big for the job" may be a reliable way to avoid downgrading audio quality?
So on that basis.... to use the Yamaha YST-SW315 in Ireland, where the input voltage is 220V, I'd need a step-down transformer that can convert the 220V input voltage to the 110V required by the subwoofer. As the Yamaha YST-SW315 has a maximum power consumption of 250 watts, a good-quality transformer with a minimum rating of 10 times that (2500 watts) would be enough to handle any power spikes or fluctuations without impacting the audio. One option I found was the
ST-2500 Step Down Transformer from Goldsource - this has a 2500W maximum capacity, and it has a sturdy design with multiple safety features, and is priced around $120 on Amazon.
Based on the above, this setup should power the subwoofer without ever running near its full capacity, and as a result, it should not get too hot. This means that the transformer should work reliably and not overheat, which could damage neighbouring equipment. It also probably shouldn't introduce buzzing or distortion on the audio..
Just wondering if anyone has any thoughts or feedback on this plan? Are the assumptions I've made correct, or is there anything that I've overlooked? (The subwoofer has its own dedicated circuit in the room. Also the AVR and all the other speakers have been sourced locally from Irish distributors, so it's only the subwoofer that I'm concerned about)
Thanks!
