Black Ravioli Black Hole Signal Module Review

Posted on 21st September, 2020

Black Ravioli Black Hole Signal  Module Review

David Price untangles a web of audio intrigue with an interesting noise reduction system…

Black Ravioli

Black Hole Signal Module

£500 RRP

Black Ravioli Black Hole Signal  Module Review

In my four decades-long experience of upgrading, side-grading and down-grading – the latter two unintentional, by the way – I've learned that you generally get what you pay for. Sometimes though, clever set-up can really augment things, so your system sounds better than the sum of its parts. This includes careful control of noise; everything from the mechanical vibrations in your room to the radio frequency interference coming from the fridge, TV or anything else that's got a switching power supply inside. In short, if you've got decent hi-fi separates, then best not leave such things to chance.

We've seen lots of attention paid to interconnects and loudspeaker cables over recent years, and now, of course, some people are even taking their home network routers seriously. At the same time, others are turning to mains conditioners and/or filters and regenerators, especially those who live in cities and towns with lots of distortion on their AC supplies. Whilst yours truly was once a little sceptical, I'm now a believer and whenever I set-up a system then it gets the full treatment, right down to how I dress the cables at the back of the amplifier, to avoid feeding vibration into the casework of amps and source components.

This sort of attention to detail can be the difference between a good and a great system. Think of it as balancing your car wheels, setting the tyre pressures correctly and then getting the tracking done; suddenly something good-to-drive really becomes a pleasure – without having to upgrade your entire car. As far as hi-fi goes, this is where products such as the £500 Black Ravioli Black Hole Signal Module come in.

Black Ravioli Black Hole Signal  Module Review

Don't be put off by the name. To me, it almost sounds like a parody of a tweaky hi-fi wonder cure. I'm not too fond of it personally because it rather trivialises what's actually a serious product. Yet it's memorable, so there's method in Black Ravioli founder Derrick Ethell's madness – in a world not exactly starved of hi-fi accessories, this makes it stand out. Another problem is that its creator is – to put it kindly – something of a boffin who's over-qualified for much of what you see in the hi-fi world. He has a background in the Naval nuclear industry, but started life as a mechanical engineer; you don't get to work at this level without knowing your onions.


Derrick has a tendency to over intellectualise what he's doing – you can sense his passion and fascination with his products from a mile off. Yet, he's not good at boiling the processes down into pithy catchphrases for Joe Bloggs to understand. For this reason, his designs can seem rather esoteric – or even plain bonkers – yet I'm not so sure that they are. Black Hole is a passive noise-cancelling device, or to be more precise, noise reducing. It's been designed to draw what Derrick calls “parasitic energy” out of a system and sink it – moving it, if you will, to a metaphorical black hole. Though, I think the less flowery we are with our language here, the better. If not, some will start awarding me The Order of the Tinfoil Hat.

Put simply, it's an inert module that aims to dissipate mechanical and electrical [RFI, EMI] noise quickly and in real-time. This isn't such a wacky idea – for example, anyone who uses sand-filled speaker stands experiences a similar process in terms of mechanical noise reduction, with the spikes at the bottom of the stand grounding the energy.

Black Ravioli Black Hole Signal  Module Review

The Black Hole Signal Module is offered with a range of connections, from RCA phono to 6mm spade and 4mm plug to USB-A and HDMI. It plugs into whatever you can connect it to – you specify your desired termination when you order the unit – and you then just sit back and listen. Derrick says that you can add as many as you see fit to different parts of your system. “This parasitic energy is like a fog in the system, it doesn't have a direction, it just hangs around”, says Derrick. “The Black Hole effectively gets it out as soon as possible.”

Despite having worked in high-level engineering for much of his life, Derrick isn't obsessed with measurements in this context – although he claims that, “systems with these plugged use less energy, there's a measurable difference at the mains. Cumulatively its quite significant, in the whole context.”

Were you to try to reverse engineer a Black Hole, prizing open its casing or running it over with a tank – or something like that – you'd see what Derrick describes as “an engineered filter, a laminate of lots of component pieces – it's basically a massive multi-layer wafer.” He's not willing to go into any further detail, as obviously, it's his intellectual property, and he doesn't want to see foreign-made imported versions on eBay, next week. Suffice to say that it uses precise processes in its construction that reflect the research work he's put in over the years.

The Black Hole is exceptionally well finished, albeit in a functional way. The socketry and flying lead is top-bubble, and the anodised aluminium casing is a quality item and bereft of any fancy frills. Whether you think this constitutes good value at this price is your decision, but Derrick is willing to put his money where his mouth is by offering customers refunds if they're not satisfied with the difference it makes to their systems. You can't say fairer than that.


This product is not aimed at your average budget system, yet as the quality of the hi-fi increases, it becomes a more realistic proposition. I decided to jump in at the deep end and audition the Black Hole Signal Module with my current reference system – a Chord Hugo TT2, Sony TA-E86B preamplifier, Sony TA-N86B Class A power amp and Yamaha NS-1000M loudspeakers. This isn't at all forgiving; give it a poor recording and the sound is sharp enough to cut through Formica. However, it is highly revealing and tells you all about what it's playing, warts and all…

I connected up a Signal Module to the preamp ground terminal first and was surprised to hear the difference that I did. When my system is cold – especially the power amp and speakers, the latter thanks to the Beryllium midrange and treble drivers – it's a little edgy but always warms through to sound evenly balanced and three-dimensional. With this little widget attached, I found it to be slightly smoother while warming up; there was a lessening of the zing to female vocals for example. Suzanne Vega's Cracking didn't sound quite so brightly lit, her voice being less brittle. Interestingly though, it wasn't just about the tonality; there was a subtle improvement in dynamics. The contrast seemed to have been turned up a little, so the accenting on her guitar playing was more pronounced.

Black Ravioli Black Hole Signal  Module Review

With another module connected to one of my preamp's unused phono sockets, again there was a reduction in low-level noise. The Who's Who Are You had me less preoccupied with the middling CD transcription of an album I know very well via vinyl. Keith Moon's wondrous staccato snare drum work had better definition and articulation. There seemed to be more space between his ferocious hi-hat cymbal hits too as if the instrument was able to decay faster. Some active mains power conditioners I've tried produce a cleaner sound that seems more 'sat upon' like it's lost its get-up-and-go – yet the reverse was the case here. The music flowed more naturally, with a more propulsive feel.

Owner of a Lonely Heart by Yes showed me that it wasn't adversely affecting dynamics – quite the reverse. The music was fast, punchy and engaging, yet sounded a little less processed and mushy. It was a subtle effect, but the improvements were there all the same. Again I kept coming back to the sense that I was listening deeper into the recording, being less distracted by what was happening superficially. Bass notes seemed slightly louder and better articulated, as well as being more chewy – the track's big walking bassline come over as more expressive and engaging.


I always feel cautious about recommending products such as these; we're into cable territory here where what works in one system may not do so in another. Yet in my fussy and explicit sounding system, the Black Hole(s) did something positive. The improvements were 'bankable' as they say, akin to a successful cable upgrade where you wouldn't want to go back. I'm not going to embarrass myself by attempting any sort of explanation of why; that's for Derrick. Yet those with serious systems should consider auditioning it for themselves. Whether the Signal Module is good value depends on whether you think similarly priced cable upgrades and other such tweaks are worth it. It made a subtle but clear and consistent improvement to my system's sound – and if you don't hear a difference in yours, then you can always return it. Don't let the zany name fool you, listen without prejudice and see what you think.

More Information at Black Ravioli


David Price's avatar

David Price

David started his career in 1993 writing for Hi-Fi World and went on to edit the magazine for nearly a decade. He was then made Editor of Hi-Fi Choice and continued to freelance for it and Hi-Fi News until becoming StereoNET’s Editor-in-Chief.

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Posted in: Hi-Fi Accessories Isolation Applause Awards 2020
Tags: black ravioli  mcru