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How a sound engineer designs his sauna sound system

Music in the sauna need not be a yes or no proposition. Like at a spa or while deep into a massage, a little ambient auditory-ness may just be the thing to enhance your sauna experience. But what sauna sound system design should you go with? Those walk around blue tooth speakers are ok until the charge runs out. And what a buzz kill when your phone rings right in the middle of Kengo Tokusashi’s Music for Sauna Quiet Night. I’ve always been a big fan of hard wiring saunas for really good sound. And I’m pleased to introduce Michael, who is a professional sound engineer. Michael has curated installations for Walker Art Center in Minneapolis. He has a keen sense and ear to “acousmatic sound” and we are grateful for his contributions to Saunatimes. Welcome Michael:

My favorite thing about a sauna is its simplicity.

I love how the straightforward act of heating up a small space has the potential to excite transformational experiences. It can also be an element of a routine—whether focused on relaxation, community, or some combination—that demands no explanation.

What you see and hear depends a good deal on where you are standing. 

– C.S. Lewis. The Magician’s Nephew, 1955

Listening inside the sauna

A few weeks ago, Glenn let me try out his personal sauna. Standing there, I experienced so many small but significant sounds: evaporating water, a humming lightbulb, the crackling of burning wood, the low rumbling of heat. Even internal sounds like my own perspiration became more present as I stood there heating up. I was reminded how the organization of space, how it’s orientated and how the facilitation of sound in space—or lack thereof—can drastically influence our experience.

For a long time, humans have been designing concert halls and various structures in which to better appreciate the sound that travels through them. In the mid 1950’s, Pierre Schaeffer and Luc Ferrari, along with several others, began experimenting with a notion called acousmatic sound. The defining feature of acousmatic sound was that the source of the sound was hidden from the listener. In other words, this was sound that could really only be transmitted and played via a set of loudspeakers. Not seeing the source of a sound was a revolutionary idea when it was first conceived and is still a very relevant idea—one that influences our experience of a vast number of public and communal spaces.

Much of my work has been about discovery through amplification. I find great satisfaction and insight in amplifying a seemingly invisible object and bringing it into a perceivable range. It’s interesting to me the new perspective you find when amplifying latent qualities of everyday life. On YouTube, the trend of ASMR (autonomous sensory meridian response) videos, which highlight a broader human fascination with “quiet being loud”, illustrate there is a specific kind of power in the intangible, the tranquil, and the unseen.

considering sauna sound system design

Glenn asked me to come up with a simple sound system that can be used in a sauna environment. Diagram A shows this “sound installation” that can be easily assembled via the various parts I’ve selected, all of which are hyperlinked at the end of this article.

Sauna Sound Installation, integrating with ventilation in hot room

In 1974, Swedish designer Stig Carlsson​ introduced a speaker that could sit on the floor and disperse sound upward and into the room. This approach works well for a sauna context where it’s ideal to have speakers sitting on the floor. Speakers down low protect the electrical components from heat and humidity. Floor speakers also allow the sound to diffuse into the sauna more evenly, regardless of where you are in the room. Placing speakers on the walls or ceiling put them too close to actual “ear level” and actually detract from a nice sauna experience since most saunas are designed for people to sit about halfway between the floor and ceiling.

Why to include a subwoofer within your sauna sound system design

The box to the lower-left in the diagram is the subwoofer. Sharing an exterior wall with the sauna allows low frequencies from the subwoofer to be perceivable from both inside and outside the hot room. (This design is for a sauna that shares a wall with a changing room that has its own set of loudspeakers). The sound from the subwoofer acts as a source of low frequency content for both rooms. Low frequency sounds are less directional than high frequency sounds, meaning that the subwoofer does not have to directly face the listener. So, the subwoofer can be outside, while still being appreciated inside, and visa versa.

Sauna sound diagram (not valid for Beasty Boys).

In diagram B (above) you can see that the subwoofer and the two speakers inside the sauna can be connected through a passive attenuator “T”. An attenuator is a small knob that can be mounted on a wall to control the volume of the sound inside the sauna. It’s completely optional. You can add the attenuator between the subwoofer and amplifier as shown in the diagram, or you can bypass it and connect the amplifier directly to the subwoofer if you don’t want the added control.

Amps

The amplifier I selected for this project has a Bluetooth antenna that you can use to adjust the level of sound. Having a physical knob is nice if you don’t want to bring your phone with you into the sauna (assuming you use your phone to control Bluetooth). I should also note that this installation is wired in series. In series, the total load impedance is distributed between the speakers, putting less stress on the amplifier and allowing for this specific configuration of loudspeakers to function properly.

Recommended sauna sound system design

Above are hyperlinks to the parts I selected for this project. I also really like these loudspeakers from Gallo Acoustics and this subwoofer. You can find them for sale here. The subwoofer from Gallo Acoustics works a little differently from the one I linked to from Polk Audio. It connects to the amplifier’s “bridge” port that’s designed specifically for subwoofers. In that case, the other loudspeakers connect through the amplifier and are not routed through the subwoofer like diagram B suggests.

There are many other possible approaches to this. I believe that the organization of a space and the objects and sounds inside it have the potential to facilitate seemingly transformative experiences. I hope these suggestions spark some helpful ideas. I’m excited to be a part of this community and look forward to being a part of more exciting collaborations still to come.

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9 thoughts on “How a sound engineer designs his sauna sound system”

  1. Great article Michael. Speaker placement can be crucial as well. In our sauna having a couple of bookshelf speakers like the Sony’s you spec’d placed together in the room center, about 6″ above the floor and aiming towards the outer walls works well. Some high end is lost (unavoidable with all of the benches?) but overall works well. It’s difficult to know the point source of the sound as it sounds like the entire wall is the speaker (it sort of is now but that’s a longer discussion) and yet some L+R imaging is preserved quite well. This works for lower gain levels. Louder would likely require something different.
    Some foam on the floor between the speakers and the outer walls and maybe some in the lower corners might help a bit.

  2. Yes, foam on the floor between the speakers is a great idea.

    Regarding speakers in the hot room, my backyard sauna still has the original patio speakers from 2003, and they still sound great. They sit in the corners along the floor under the upper benches.. I built a cedar box around them to protect from guests above, who sometimes dump water over their heads on the upper bench.

  3. Hi Glenn,
    The sauna we are building this week is designed to be taken apart and moved in some distant future.
    Each wall is a separate panel, the roof and floor disassemble into smaller pieces too.

    I’ve worked out moisture issues with most of the seams, but some would work most easily with foam tape or caulking.

    🔥 Is that possible? Are there any caulks that don’t off-gas, etc.?
    There are silicone Foam rubber Tapes that can take extreme heat, but maybe they off-gas, I’m not sure.

    Any recommendations?
    Thanks!

  4. All that water dumping isn’t hurting your benches?

    So this discussion distracted me for a bit from more important things (like deadlines)… What I found worked somewhat well is foam on the floor extending about 2′ out from the speakers and then I also placed a bit above the speakers extending about 3′ out. The top piece helped to eliminate the speaker as a source point and cleaned the sound up a bit as it eliminated a time domain reflection problem (sound directly from the speaker arrives at your ears a few ms ahead of sound bouncing off the walls). I was surprised by the time based echo in such a small space.

  5. I’m happy you liked the article Walker 🙂

    You’ve made some good observations! Regarding your high frequency roll-off situation, you’re right that you lose some of that information with the sound having to travel through/around a wooden bench. It sounds like you’ve discovered some interesting solutions with the reflections activating the wall—I would love to hear more about your wall speaker dilemma…

    I would imagine that since you have your speakers so close to the wall, all of the sounds you’re hearing in the room are ones that have been reflected off of the wood, which naturally will add an interesting effect to the delays that you mention you’re dealing with too. Those are also accentuated by the fact that every surface in the room is a hard material (wood) and is highly reflective! I forgot to mention this in the post, but because there are so many reflections happening in a sauna environment, you often run into phase issues. Phase refers to the alignment of the polarities of sound waves. When you have a multi-speaker array and a highly reflective room, you usually run into some amount of phasing because the sound from each speaker is reaching your ear at a slightly different time. The closer you have the speakers together (and the less stereo information you have playing) the less you’ll experience the phasing effect—that can sometimes be challenging to listen to. A lot of this can be mitigated by the stuff you mentioned that you’re already doing, like adding foam or other materials to absorb or redirect the sound waves so you have less “out of phase” material in the room…

  6. Where do I want to put the subwoofer? The picture shows outside of the sauna, and the diagram shows inside the sauna. Also, wouldn’t I want the “T” attenuator inside the sauna to control the volume as opposed to inside the changing room? Can the attenuator handle the heat and moisture, is that why it is in the changing room?

  7. Todd:

    My subwoofer is in the changing room under one of my benches. I especially like tuning the volume down in the hot room down to a level such that i can feel the bass permeating from the other room blending with the speakers in the hot room as the perfect mix of auditory lämpömassa (in my bones).

    Attenuator inside the hot room:
    I hear you there. I’ve been using this exact component here installed in the hot room, just above the lower bench, right about where ones outside ankle bone could adjust it, if we were challenged to do such a thing. It’s $20. I’ve bought probably 10 of these through my sauna building carrier.

    With each installation, I foil tape the blue electrical box. The attenuator cover does a nice job of keeping moisture out. I installed this unit in my backyard sauna hot room in 2003 and it’s performed flawlessly since, especially lately, during Sauna music in the time of corona when i’ve found myself turning up the volume on Wim Hof’s playlist rising up from super cool body temp. after extended cold plunge in nature.

  8. Sorry for the confusion! The first diagram (Diagram A) is correct in terms of placement. The schematic (Diagram B) illustrates the wiring and signal flow. I shouldn’t have made that blue line differentiating the sauna/changing room—just ignore that 🙂

  9. Michael, I hope it is not too late to ask another question. I like the idea of having speakers in both the changing room and hot room. I would also like to add a third pair outside under my covered porch area, preferably with a little bass so that I don’t need to get the subwoofer out there.

    Can I put a third set of speakers in series with this amp? My familiarity with power settings is limited so I have no idea how to calculate how to best match load between speaker and amp.

    Would you have a recommendation on outdoor speakers?

    Thanks!

    –Matt

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