Review: Araka’s Grunewald Bass Transformer

Review: Araka's Grunewald Bass Transformer: Just follow Steve Jobs' advice “Stay hungry. Stay foolish!” and try this unusual room acoustics accessory in your home

What seemed to begin like a pre-Christmas fairy tale actually began earlier, namely a few days after the North German HiFi Days 2022 . Unfortunately, I couldn’t be there myself, so I asked a friend who is a hi-fi enthusiast if he had heard anything interesting. His dry, typically North German answer: “Arakas Audio.” (Web: ) And then, less soberly, to add: “I was amazed by the overall setup … The bass energy from this cookie jar (note: by that meant he amazingly small speakers) was great. And I find the bass transformers especially exciting, but unfortunately I can’t put them on my own.” – “It’s a shame, I would have liked to hear that too!”, I thought to myself…

The fairaudio editorial team in Berlin obviously has telepathic abilities, but there is no other way I can explain why the phone rang just days later and I was offered the Grunewald Bass Transformer (price: 2,250 euros) from Arakas for testing! But maybe it was just because the editors remembered that I already use various bass absorbers from different manufacturers in my listening room (yes, I mean that literally) due to the challenging room acoustic conditions. So I know a little bit about absorbers. But what the hell is a bass transformer supposed to be? Curious? Me too.

The concept

Viewed from above, the walls inside the bass transformer follow a kind of snail shape. Its lateral opening is coupled to the room via the side wall of the room. According to Grunewald, the sound waves flow through the room into the bass transformer and then have to travel a longer distance through the spiral sound guide before they reach the top and bottom via two inserted funnels be deflected back into space. According to Grunewald, the funnels can be turned freely in any desired direction and thus allow the effect of the bass transformer to be sensitively adjusted to the room and personal preferences. In contrast to conventional bass absorbers – be it Helmholz resonators or porous absorbers – the sound energy in the bass transformer is not converted into heat, but, as Arakas calls it,

Consequently, there are no low-frequency absorbing materials to be found in the Grunewald bass transformer. The inner structure consists of a CNC-milled MDF spiral for the top and bottom. In between, a sound-conducting “chute” made of a thin, smooth material is firmly clamped, while the funnels mentioned are made of thick-walled plastic.

Can something like this work, I wonder? Well, what could be more obvious than to abuse this transformer with a few bass-heavy pieces of music to get to the bottom of its effect?

Transformed sound?

Mr. Grundwald brought his first demanding song with him: Canto At Gabelmeister’s Peak (Alexandre Desplat) from the Oscar-winning film music for The Grand Budapest Hotel (Original Soundtrack). I didn’t know the piece until now, but I immediately understood why Grundwald likes to play it at trade fairs: In addition to musical variety, this piece also makes a powerful (impressive) impression in the low frequency range below 50 Hertz with a large drum and an organ.

Even if both instruments play in the same frequency range , they make different demands on the bass competence of the playback chain – and on the room acoustics. First the almost tender, soft attack with the mallet, which is followed by a powerful, slow swinging out of the large orchestra drum, almost like a distant rumble of thunder. Here the listener can experience how the almost endlessly long swinging out of the head dies away in the silence. You can hear immediately that the bass transformer does not slow down the tones or rob them of energy, but rather lets them “fade out” completely in the room. Yes, I have the impression that the drum can now sustain longer than without a bass transformer, but with bass absorbers in the room. And at the same time, there are no disturbing room modeson. The two missing absorbers do not have a negative impact here. Class.

Only a little later Alexandre Desplat served the organ. Heralded by a brief moment of silence, my room fills with deep bass. Each new tone pushes new waves into the listening room. I am consciously writing in and not through, because now, at least when the volume control is above room volume, you notice that the bass energy “can no longer flow away” and a certain pressure builds up in the ears. Here the small volume and the solid construction of my basement room are noticeable. But to be honest: I would have expected that the absence of my two large absorbers would be announced much earlier by a swinging up of the room modes. But nothing like that. Were my two remaining absorbers in the room sufficient, or should the “Arakas bass slide” room modes also have something to counteract? I think there is something to both.

Contrasting program: After the rather soft, but abysmal and Oscar-winning basses, I prefer listening to Infected Mushrooms with Never Mind (Album: Army of Mushrooms) from my Qobuz playlist. The song is neither an award-winning song nor particularly high fidelity with a dynamic range value of 4, but the way the Israeli duo fires bass impulses through the booth – fast, hard and seamlessly – reminds you again that music consists of impulses. Here: from bass impulses. My Gauder Berlina RC7 BE then also fire ultra-precise, hard bass volleys into the room and the bass transformer doesn’t rob them of their speed one bit. However, they have a little more volume than I usually get presented with my absorbers and therefore appear a little rounder, less “angular”. It’s best if you listen to the song yourself and you’ll know what I mean.

While we’re in the fable world, let’s go straight from the infected mushrooms to the hippo’s space adventure by Béla Fleck & The Flecktones with the “Flight Of The Cosmic Hippo” from the album of the same name ( who actually comes up with these names…? ). Even if every audiophile knows this song – and after a good 30 years may not be able to hear it anymore – it still offers us one of the creakiest and most contoured basses that has been banned on round discs to date. If space doesn’t interfere. But neither he nor the Grunewald Bass-Transformer did that – the bass I praised so much grooved and growled in the lowest notes that it was pure joy.

The Arakas Transformer obviously masters fast bass impulses, which can also go deep into the frequency range. They’re not quite as bone-dry as with my absorbers, but they’re a bit fuller and more powerful. However, the position of the funnels, whether directed towards the listening position or in the direction of the front loudspeakers, had no audible influence on the bass reproduction. It is difficult to say whether this was due to the relatively short distance between the bass transformer and the listening position or to the peculiarities of my listening room.

Mirror Mirror …

But Mr. Grunewald had also brought a suitcase of his tried and tested acoustic mirrors for the all-round treatment of my room. After the bass transformer was set up, a total of seven acoustic mirrors were placed at precisely defined points in the room: one round mirror each on the loudspeakers, a square one with an edge length of 22 cm in the middle in between and another one behind the base level above the tweeters of the Speaker.

In order to open up the room acoustically to the rear as well, Mr. Grunewald set up two 22mm mirrors behind the listening position, at the level of the front loudspeakers. My new “mirror hall” was completed by a central acoustic mirror just below the ceiling. All mirrors were precisely aligned using the recommended and practical laser aiming device.

With ears just as meticulously trained on the speakers, I then listened to the first notes of Diana Krall’s classic “The Look of Love” (from the SACD Live in Paris). However, the pretensioned ears would not have been necessary, because the differences are almost noticeable in passing. Depending on the position and alignment of the mirrors, the spatial imaging can be very finely adjusted in all three dimensions. Every little change is immediately comprehensible, without it appearing artificial in any way. I am lastingly impressed by how sharply contoured voices and instruments are outlined in the tuned room – especially in the middle between the speakers. But sound bodies are even placed to the left and right of the speakers, depending on how far the round mirrors are turned outwards. I’m excited and fascinated.

Conclusion: Araka’s Grunewald bass transformer

What useful and nonsensical accessories there are in our hobby. I can count the real innovations of the last 20 years on two hands, if at all. The Grunewald bass transformer and the acoustic mirrors from Arakas have recently become part of it for me. Which of course doesn’t mean that the concept works everywhere or that everyone likes it in terms of sound or appearance. The topic of room acoustics is too dependent on the room (logically), the system and the listening taste.

I thought it was great how the acoustic mirrors opened up my listening room according to my mood and without any harmful side effects in terms of tonality. The bass transformer is just as exciting, because it understandably changes the quality of the bass reproduction without robbing it of energy. You may find the latter good or bad – some rooms have to be (massively) deprived of bass energy, for which the bass transformer is less suitable – but it is entirely in the spirit of the inventor and ultimately has to be tried out individually. My “listening room” didn’t offer the best conditions, and yet the effect of the bass transformer was clearly audible here as well. In larger rooms with less pronounced room modes, the bass transformer can certainly show off its concept even better.

So: Just follow Steve Jobs’ advice “Stay hungry. Stay foolish!” and try this unusual room acoustics accessory in your home. What did colleague Ralph Werner mean in his test back then ? “… I don’t really know anything comparable.” He’s right.


Araka’s Grunewald Bass Transformer:

  • Concept: Bass Transformer
  • Price: 2,250 euros
  • Colour: Black with white or black funnels
  • Dimensions: 160 x 50 x 70 cm (depth) (HxWxD)
  • Guarantee: 2 years

Araka’s Acoustic Mirrors:

  • Concept: acoustic mirror/reflector
  • Price: Box display 1,300 euros/piece, 22-piece mirror with base: 950 euros/piece
  • Colour: black and white
  • Guarantee: 2 years