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Rauna Freja Vintage 2-Way Loudspeaker Measurements

MAB

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Today I present measurements on a pair of Rauna Freja, aka affectionately as 'Swedish Tombstones';). They are a small 2-way in a concrete cabinet. I believe that Bo Hansson was involved with the design. I would appreciate any information members have regarding this nice little speaker.
1701555823279.png


These were made in the '80s, they are 100% original. Out of a discussion on another thread about the imagined virtues of avoiding measurements, I used the Rauna as an example of a speaker with weak bass but that still has a strong interaction with room modes and boundaries. Here I present a full set of measurements made in my shop using my simple loudspeaker testing rig; a stool with a plywood cutout graduated in 5 degree increments, a UMIK Microphone, REW, and VituixCAD. I will use the very good tutorial on how to roll-your-own spinroamas. I typically can get an acceptably close result as Amir or Erin when measuring the same speaker. You can too.

If you follow this post and the other thread on avoiding making measurements, I hope an appreciation will be for why even small speakers with limited bass output strongly interact with the room. In the case of measurements, I need to do some work to not have the room ruin the bass measurements below 300Hz. That same phenomena will cause the bass to vary by position in the room. And be really bad sounding in some places, and good in others.

I measured the woofer and port nearfield, and calculate an aligned sum to get in-room response free of the room boundaries as pictured below left. This is critical because we can't reliably measure bass frequencies as I just indicated above. I will later stitch the nearfield bass measures with 360 degree horizontal and vertical measurements as pictured below right, which need to be gated to filter out the room.
1701555764266.png


First the nearfield measurements of the woofer and port and the summed response:
1701559651383.png

The port is tuned super low, and is only 2.5 4.5cm diameter. It provides a small boost in output at 33Hz, but the port resonance at 780Hz and higher harmonics is larger, wow! I am not sure this is a good application of a port:rolleyes:. How audible the port resonance in far-field is unclear. These nearfield measurements show the resonance both in the direct woofer output and the summed woofer + port response. You can see that this speaker will not play much below 100Hz and the port barely helps, especially tuned so low. And the weak bass response it has will interact strongly with the room, as I show elsewhere.

I made a bunch of horizontal and vertical measurements at various angles, merging these in VituixCAD with the low frequency estimate, I obtain the following:
1701561836763.png

Aside from what I think is an odd port choice, the speaker has reasonably controlled directivity. Perhaps emphasized response in the 1.5-3kHz region. The notch at 780Hz caused by the port and its associated resonances at 1560Hz can be vaguely seen in the in-room response predictions. I am not sure if it is because of my method of stitching or if the port resonance shows up in the far-field.

Here is the estimated in room response based on the above measurements and my attempts to splice:
1701566776687.png


It's always been a pleasant speaker to listen to. I've called it congested in the past. I wonder if it's the port. Might be good to plug it and remeasure. That's in the future.

I use a DATS to measure the impedance:
1701567636961.png

Impedance trace shows two resonances at 350Hz and 450Hz, but not at the port resonance frequencies which makes me wonder if I am overemphasizing the effect of the port on the response. Not that it seems like a worthwhile port, but maybe it's effect is exaggerated, both in boosting bass and in generating issues at 780Hz and higher multiples.

1701563677136.png


The full spinoramas in horizontal and vertical:
1701567275991.png

1701567294964.png


Lastly, distortion at about as loud as I feel is safe.
1701568894921.png

I think you can see the port's resonance at 780Hz in the 5th and 7th HD peaks. Not that I am imagining that I can hear the distortion, rather the distortion indicates the resonance is there. No idea what the spike in even and odd distortion is at 300Hz, surround breakup? It is a 40+ year old speaker. I can't measure the woofer and tweeter separately, and can't demount the drivers to investigate further. I did measure both speakers to see if they match, here is an ungated on-axis measurement:
1701570988139.png

1701571016606.png


The output and distortion do match, including the HD peak at 300Hz. So they have aged equivalently, and don't appear broken.

That's the Rauna Freja. A bass-shy speaker that I measured. I welcome comments and input.
 
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GXAlan

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Nice work! I think for the 1980’s those are great measurements and gives validation to the idea that you always liked them subjectively.
 
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DanielT

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Very interesting, well done MAB.:D Interesting above all because the manufacturer of many Rauna models Bo Hansson was active in the same small town that I grew up in. In addition, Rauna's concrete speakers were something many young people (and older) in the 1980s in Sweden thought were cool.:cool:

Here is an article about Bo Hansson and Ranua. I translated it via Google Translate:

Cult speaker in concrete.

In the 1980s, the audio company Rauna of Sweden launched the concrete speaker. With its challenging shape and advanced technology, it was an immediate success both in Sweden and abroad. Today, the speaker has reached cult status.

The article was published in our journalCompany History 2017 No. 3.

The worst thing you can do with six wooden boards is a speaker!” exclaimed a trade fair visitor when he saw Rauna of Sweden's concrete speakers for the first time. His words were so accurate that they quickly turned into the manufacturer's advertising slogan. And the enthusiasm about the speaker was not strange - Rauna offered something completely new. The wooden speaker boxes suddenly appeared as pure frame fake constructions when you compared them to a speaker as heavy as an elementary school student and with a sound so clear that it felt like being in the middle of a concert hall.

reklam1-kopiera.jpg

An early advertising image. Olle Neckman was graphically knowledgeable and had the right contacts. Rauna of Sweden got off to a flying start in advertising. Photographer: Olle Neckman. Rauna of Sweden.

The story of the concrete speaker began in a hi-fi shop in Karlskoga. Here, music profiler and sound connoisseur Bo Hansson built speakers and produced acoustic music. He realized that something heavier than wood was needed to keep the sound from bouncing around in the speaker box and getting distorted on the way to the listener. At home in his villa, he tried to cast a bass horn in concrete that started in the basement and exited behind a grill in the living room. The sound was unique.

In 1982, he decided to, together with his colleague Lennart Bergstedt and the engineer Olle Neckman, invest in loudspeakers in concrete. The company was named Rauna of Sweden, after Hansson's Finnish family name Raunavaara. A logo in the form of a rune stone had to symbolize the heavy concrete. The models were given names such as Njord, Leira and Tyr.

In 1983, the first model, Leira, was launched. With a material new to the industry and a periscope-like shape, it grabbed attention. Despite the weight, the speakers were exported and approximately 80 percent ended up abroad. The concrete was painted white, but in Germany they were also sold in a raw concrete finish in exclusive interior design stores. For several years, Rauna was the market leader for high-quality loudspeakers in Sweden.

In the mid-1980s, Hansson chose to leave the company and instead began manufacturing concrete speakers under the same name as his record label - Opus3. They got a more angular shape and names like Chaconne, Chorus and Credo. Meanwhile, Rauna of Sweden launched new models – Freja, Balder and Ymer. The success of the concrete speakers soon led to more people wanting to ride the trend. At the end of the 80s, the construction company Skanska got into the game with Cheops, a pyramid-shaped loudspeaker in a concrete-like composite material.

During the early 1990s, problems began to pile up for the concrete speakers. Opus3 was crushed by the financial crisis and Rauna suffered financial problems as a result of a fateful switch to the wrong paint. A piece of hifi history went to the grave. Today, the concrete speaker is declared a cult and the designer Bo Hansson, who passed away in 2011, is hailed as one of the hi-fi world's greatest geniuses
(hmmm, that must stand for the author of that text. A wild free thinker and wild entrepreneur I would probably say). In 2011, Rauna's molds and equipment were bought by HiFi-punkten AB and speaker manufacturing resumed on a small scale.

spackling-rauna-kopiera (1).jpg

Loudspeaker elements are assembled at Rauna's factory in Åtorp. Photographer: Olle Neckman. Rauna of Sweden.


 

DanielT

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Interesting FR on those Rauna Freja. A bit wavy on the frequency lake (looks pretty bad), but in room response looks quite nice if you like such a sloping FR, so why not. :)

Then this with concrete as building material. For speakers as small as the Rauna Freja and also Ranua's larger models, I highly doubt whether the concrete in itself adds that much positive. It is probably unnecessary overkill. But it's fun in itself with concrete. :)
 
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MAB

MAB

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Very interesting, well done MAB.:D Interesting above all because the manufacturer of many Rauna models Bo Hansson was active in the same small town that I grew up in. In addition, Rauna's concrete speakers were something many young people (and older) in the 1980s in Sweden thought were cool.:cool:

Here is an article about Bo Hansson and Ranua. I translated it via Google Translate:

Cult speaker in concrete.

In the 1980s, the audio company Rauna of Sweden launched the concrete speaker. With its challenging shape and advanced technology, it was an immediate success both in Sweden and abroad. Today, the speaker has reached cult status.

The article was published in our journalCompany History 2017 No. 3.

The worst thing you can do with six wooden boards is a speaker!” exclaimed a trade fair visitor when he saw Rauna of Sweden's concrete speakers for the first time. His words were so accurate that they quickly turned into the manufacturer's advertising slogan. And the enthusiasm about the speaker was not strange - Rauna offered something completely new. The wooden speaker boxes suddenly appeared as pure frame fake constructions when you compared them to a speaker as heavy as an elementary school student and with a sound so clear that it felt like being in the middle of a concert hall.

View attachment 331491
An early advertising image. Olle Neckman was graphically knowledgeable and had the right contacts. Rauna of Sweden got off to a flying start in advertising. Photographer: Olle Neckman. Rauna of Sweden.

The story of the concrete speaker began in a hi-fi shop in Karlskoga. Here, music profiler and sound connoisseur Bo Hansson built speakers and produced acoustic music. He realized that something heavier than wood was needed to keep the sound from bouncing around in the speaker box and getting distorted on the way to the listener. At home in his villa, he tried to cast a bass horn in concrete that started in the basement and exited behind a grill in the living room. The sound was unique.

In 1982, he decided to, together with his colleague Lennart Bergstedt and the engineer Olle Neckman, invest in loudspeakers in concrete. The company was named Rauna of Sweden, after Hansson's Finnish family name Raunavaara. A logo in the form of a rune stone had to symbolize the heavy concrete. The models were given names such as Njord, Leira and Tyr.

In 1983, the first model, Leira, was launched. With a material new to the industry and a periscope-like shape, it grabbed attention. Despite the weight, the speakers were exported and approximately 80 percent ended up abroad. The concrete was painted white, but in Germany they were also sold in a raw concrete finish in exclusive interior design stores. For several years, Rauna was the market leader for high-quality loudspeakers in Sweden.

In the mid-1980s, Hansson chose to leave the company and instead began manufacturing concrete speakers under the same name as his record label - Opus3. They got a more angular shape and names like Chaconne, Chorus and Credo. Meanwhile, Rauna of Sweden launched new models – Freja, Balder and Ymer. The success of the concrete speakers soon led to more people wanting to ride the trend. At the end of the 80s, the construction company Skanska got into the game with Cheops, a pyramid-shaped loudspeaker in a concrete-like composite material.

During the early 1990s, problems began to pile up for the concrete speakers. Opus3 was crushed by the financial crisis and Rauna suffered financial problems as a result of a fateful switch to the wrong paint. A piece of hifi history went to the grave. Today, the concrete speaker is declared a cult and the designer Bo Hansson, who passed away in 2011, is hailed as one of the hi-fi world's greatest geniuses
(hmmm, that must stand for the author of that text. A wild free thinker and wild entrepreneur I would probably say). In 2011, Rauna's molds and equipment were bought by HiFi-punkten AB and speaker manufacturing resumed on a small scale.

View attachment 331492
Loudspeaker elements are assembled at Rauna's factory in Åtorp. Photographer: Olle Neckman. Rauna of Sweden.


Thanks DanielT!
This is incredibly useful. I find almost no information on Rauna.
Seems Bo left Rauna about the same time as these Freja were released.
I have heard various stories about the tweeter, not sure if I believe any of them.
As you have pointed out before, Bo Hansson was involved in many great and crazy projects.
I do like these speakers. The picture from the factory of the cabinet construction is great. The finish on mine reminds me of these guys.
 

mhardy6647

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BenB

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I propose plugging the problematic port to improve performance. The paucity of perceptible bass production paired with passband impurities compels us to dispose of the displeasure provided by the pesky port.
 

mhardy6647

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The paucity of perceptible bass production paired with passband impurities compels us to dispose of the displeasure provided by the pesky port.
Well done!
Be sure to use a pop filter (foam windscreen) on the mic if you record that sentence in a video review! ;)
 
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MAB

MAB

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offered strictly as is and FWIW, no guarantees about signal to noise ratio. ;)
Thanks for the link! Very useful.
I found the John Atkinson Stereophile review from 1989 with a couple measurements, I honestly forgot or didn't know about this.:)
The impedance measurement is here:
It's odd, if I scale Stereophile impedance measurement to what I see, it looks like a different woofer! DC resistance and the impedance peaks are entirely different frequency and magnitude. I have a hard time thinking this is just age, both of my speakers have matched impedance traces to each other.
1701644874020.png


Stereophile's measured spatially averaged frequency response is also different:
Stereophile's measurement shows really anemic bass, I see a much different tuning.
1701645767579.png

I note that my method for merging near and far-field response for the bass is not perfectly reliable, I need to think more if my estimate is accurate. But the impedance measurements seem to indicate that the drivers I have measure differently than Stereophile. I assume the drivers have both aged, or are not original, or Rauna changed the spec to a 6 Ohm driver between the review sample and my pair. Given how I got these, it's hard to imagine the drivers were replaced. Also, the drivers are glued to the concrete enclosure in a way it would be hard to demount without leaving noticeable marks. I see no evidence anything was replaced. A different driver would explain the bass increase (might actually be a good thing) and the odd port performance (not good).

John Atkinson commented on the bass in the Stereophile review:
The lightness of bass gave double basses too much of a nasal quality, though low-frequency control seemed good for a ported design. This midrange emphasis, while not associated with any fatiguing resonant effects, was persistently noticeable and had to be heard through for consistent musical enjoyment.
 

Curvature

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Thanks for the link! Very useful.
I found the John Atkinson Stereophile review from 1989 with a couple measurements, I honestly forgot or didn't know about this.:)
The impedance measurement is here:
It's odd, if I scale Stereophile impedance measurement to what I see, it looks like a different woofer! DC resistance and the impedance peaks are entirely different frequency and magnitude. I have a hard time thinking this is just age, both of my speakers have matched impedance traces to each other.
View attachment 331522

Stereophile's measured spatially averaged frequency response is also different:
Stereophile's measurement shows really anemic bass, I see a much different tuning.
View attachment 331526
I note that my method for merging near and far-field response for the bass is not perfectly reliable, I need to think more if my estimate is accurate. But the impedance measurements seem to indicate that the drivers I have measure differently than Stereophile. I assume the drivers have both aged, or are not original, or Rauna changed the spec to a 6 Ohm driver between the review sample and my pair. Given how I got these, it's hard to imagine the drivers were replaced. Also, the drivers are glued to the concrete enclosure in a way it would be hard to demount without leaving noticeable marks. I see no evidence anything was replaced. A different driver would explain the bass increase (might actually be a good thing) and the odd port performance (not good).

John Atkinson commented on the bass in the Stereophile review:
Please try https://automeris.io/WebPlotDigitizer/tutorial.html to compare graphs. It's accurate and easy to use.

I normally take a screenshot, upload it to WPD, extract the data, dump to a csv, then import into REW.
 
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DanielT

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Here more information about Ranua, in English. There is also contact information if you MAB want to email and ask, for example, which speaker elements are in Rauna Freya. Those who run that page will also probably find it really fun to take part in your tests, measurements::)


Speaking of port resonances, you can always plug it by using, heh heh:
gray-quikrete-concrete-mix-110190-64_1000.jpg

Incidentally, I think the shape of Rauna Freja seems appealing. The round shape of the speaker. Should be good for reducing baffle edge reflections. I also must say think that Rauna Freja looks like a modern speaker.:D

Edit:
I tipped and gave the link to this thread to: Technical questions: [email protected]
The test and measurements of Rauna Freja in this thread are very likely something he appreciates reading about.:)
(nop I don't know him, I just tipped him off about this thread)
 
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olieb

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I note that my method for merging near and far-field response for the bass is not perfectly reliable, I need to think more if my estimate is accurate.
From your pictures it looks like the center of rotation of your fixture is not the acoustical center of the speaker.
In the position on the right (180°) the speaker/woofer looks as if it is further from the microphone than it was at 0°.
That can easily account for a difference of 2-4dB in the levels of the measurements at the split point (≈300 Hz).
I would expect the graphs for on-axis, ER-Total and sound power to be much closer together at 300 Hz for a small speaker. And certainly so in the region below 100 Hz.

Very nice post!
 
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Schollaudio

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Can you pull the woofer and tweeter to see who built them. They look like off the shelf units of the time, SEAS or Vifa etc.

While the woofer is out you could try to fully stuff the box with polyfil to see if the resonant issue improves. Keeping the port area clear.
 
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MAB

MAB

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From your pictures it looks like the center of rotation of your fixture is not the acoustical center of the speaker.

In the position on the right (180°) the speaker/woofer looks as if it is further from the microphone than it was at 0°.
That can easily account for a difference of 2-4dB in the levels of the measurements at the split point (≈300 Hz).
I would expect the graphs for on-axis, ER-Total and sound power to be much closer together at 300 Hz for a small speaker. And certainly so in the region below 100 Hz.

Very nice post!
Thanks! The center of rotation is slightly off, I am limited by stability of the speaker on it's side. I was able to get the speaker's acoustic center closer to the center of rotation than in the pictures, but is is still slightly off-axis by ~5cm... the pictures are during setup up, so slightly misleading. To manage the woofer distance, I recorded with the mic at 1 meter, the rule of thumb being at least 3x the baffle dimension. The woofer does get nearer and further from the mic, but that compromise is supposedly mitigated by the 3x distance... Let me think more if the rule of thumb is good or not!

Also, below 300Hz, I am using close-field measurements of the woofer plus port, and those are crossed to the with the far-field measurements at ~300Hz. I am not confident I calculated everything correctly.

Thanks for the input, I will try a few more measurements later to see if I can reconcile...
 
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MAB

MAB

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Can you pull the woofer and tweeter to see who built them. They look like off the shelf units of the time, SEAS or Vifa etc.

While the woofer is out you could try to fully stuff the box with polyfil to see if the resonant issue improves. Keeping the port area clear.
Hi, fairly impossible to remove the drivers without damaging the speaker, they are glued in!

From the Stereophile review, a description of the drive units, they are allegedly Seas:
The tweeter is the 1" aluminum dome unit developed by SEAS for Monitor Audio and first seen in 1986 in that company's R652/MD model. The OEM version has appeared in models from Siefert as well as, with a shallow horn flare added, in Rauna's Balder design. The woofer appears to be a quite conventional polypropylene-cone unit, with an inverted-roll surround. No details on the crossover were forthcoming, but the frequency appears to lie around 2800Hz.

I speculate that Rauna changed from an 8 Ohm Seas woofer to a 6 Ohm. I say this because my speaker doesn't have the weak bass of the one reviewed by Stereophile (it isn't a bass-monster, bot not like we see in the old review!) The impedance measurement I made above compared to the Stereophile impedance trace seems to indicated 6 Ohm woofer in my version. The port is not well aligned with the woofer, perhaps extra fill will help a bit, but likely not much. I am thinking of doing a measurement with the port blocked.
 

olieb

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Also, below 300Hz, I am using close-field measurements of the woofer plus port, and those are crossed to the with the far-field measurements at ~300Hz. I am not confident I calculated everything correctly.
Sure, you explained your measurements very clearly.
But if you look up measurements of similarly sized BR-speakers (Genelec, Kef, Neumann,.... here at ASR or erinsaudiocorner.com) the directivity index at 100 Hz is practically zero. And at 300 Hz the power DI is typically about 2dB in those cases, whereas your result is close to 5 dB (that is what a cardioid pattern would give).
I guess by just shifting up the curves for power and early reflections (kind of a "recalibration") your result would better reflect the behaviour of the speakers although there might be other (smaller) issues in the measurement.
 
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