Understand & clone Larsen 8

A few of you know that I have a strong interest in developing a modest cost speaker system that sounds good placed against the wall. Coming from successfully cloned Linkwitz LX521 & also original spec Linkwitz Orions, this might be a tall order, as full-bandwidth dipole imaging is difficult to replicate. I started a thread/project to combine quarter sphere (pi) bass with dipole mid/highs a while ago. That effort morphed after an acceptance of defeat, into an examination of the Linkwitz LXmini -- which I made a variant of using different drivers & construction. The resulting pentagon tower is actually a good sounding inexpensive speaker (not including the cost of 4-ch amp and 2x4 HD) but still needs the 3-4' distance from the front wall to achieve ideal performance.

I'm still trying to figure out how to get the consistent bass response of a near-wall floor stander with excellent imaging.

Yesterday, I came across the Larsen speakers.

This is a loudspeaker line that comes from the Ortho Acoustic concepts of Stig Carlsson & John Larsen. Larsen's about page provides a summary.

Larsen02.jpg


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The Larsen 4, 6, 8 & 9 are all smallish floor-standing mirror-image pairs designed for close-wall placement. Each features a mid/treble panel atop the tower that's angled up and inward. It looks like 45 degree in both planes. The large 8 & 9 models feature an additional side firing woofer close to the intersection of floor and wall, like the NHT 2.9 I once owned & inspired me. This config is certain to increase the perceived bass output in most rooms.

A collection of reviews applauds their ability to reproduce music well, predictably, consistently. These are keywords for me!
I haven't gone through them all but these reviews stand out:

Joe N Tell on Larsen 4
Absolute Sound on model 8
Absolute Sound on model 9
Positive Feedback on model 8

The best detailed pics on fairaudio.de

At first glance, it seems eminently feasible to replicate the basic design of the Larsen speaker in a pentagon tower -- a shape I have come to quite appreciate having built LXmini-ish pentagon towers. But before I embark on another project, I must ask --

1. Does anyone here have hands on (ears on?) experience with any of the Larsen speakers? Surely some of the Scandinavians here. I doubt I will find any here in Western Canada. Can you please share your experience?
2. Has someone already tried to replicate any of the Larsen speakers? Again, please share.

Thanks for your attention!
 
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frugal-phile™
Joined 2001
Paid Member
Pretty good. Right up against a wall they need more damping in the line or you have excessive bass. Many have been done with angled tops to further tune the room response.

The castle was specifically to be placed closer or even against a wall, the original has drivers front 7 back like the original EPI microTower.
dave
 
From what I can gather, the Castle microTowers are interesting but don't really address directivity for the higher frequencies the way the Larsens do. That angle baffle pictured in my first post is common to all the Larsens & this is what makes them unique, imo. I'll wait to hear from anyone who has heard or owned the Larsens.
 
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I have an interest in having a secondary system that emphasises spaciousness at the expense of some imaging and likely some tonal balance. I have heard Sonab speakers in the 70s and MBLs a decade or two ago that achieve this. I have looked, though not hard, and failed to find (comprehensible to me) design principles on which Carlsson speakers are based. I have heard a pair of Larssen speakers at an audio show a few years ago and they didn't provide enhanced spaciousness. However, they were in a very large room with a very high ceiling which appeared unsuitable to me. Given I have heard "working" Sonabs I am reluctant to wholly dismiss them. The marketing waffle is not encouraging. This comment is encouraging. Does anyone have the 3rd version of his book mine is the 1st?
 
frugal-phile™
Joined 2001
Paid Member
The angled midbass means more HF reflections. The 2 upward tweeters give sufficient energy off the ceiling and wall to give sufficient HF energy. The wave-guidish thing over the 3rd tweeter is different, there is an explanation of how it is supposed to work in the Stereophile review.

Imaging will be dispersed, the room you have will play a big role.

The microTower is an idea to leverage off of. You can angle the top, there is a a section in the planset.

Castle MTM-10-top3.JPG
CHN-microTowers.jpg


There is a US made loudspeaker that does similar things, the company name eludes me, upfiring drivers, PR loaded TLs (next post someone will chime in with the brand, happens every time). And the Canadian made Morrison. The original Hegeman thatthe Morrison grew out of liked to be against the wall.

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Which reminds us of the Dueval Planets.

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There 360° horns are a bit different but invoke Radialstrahlers, evolutions of the Ohm Walsh driver. You will also find some “radial” loudspeakers here.

Mirage has a number of products based on this concept.

545049-1bc9050e-brand_new_mirage_omni_150_bookshelf_speakers-3646301700.jpeg


And i mentioned the loudspeakers that the Larsen evolved from, Sonabs.

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dave
 
Imaging and bass response are almost independent goals. Perhaps that's what you meant. Near wall has the potential to smooth lower midrange. For bass you may want to consider something with capabilities like a multi-sub system.
Perhaps this is so. I should clarify: I'm less interested in a precise illusion of musicians in a 3D space & more interested in a generally spacious believable depiction. The former generally isn't what I hear in live music, and doesn't seem realistically achievable in more than a single spot for one person. For me this is not acceptable; I might as well wear headphones. Call it philosophical, if you like: music is meant to be shared.

Most non-audiophiles don't plant themselves in a sweet spot chair to listen solely to the music. They -- and I -- want great sound in a general area, feeling free to move about and engage in other things while still paying attention to the music. If the music, recording & the system's reproduction is good enough, I stop and pay exclusive attention.
 

Thanks for the second link which I think gives me enough hints about the principles involved to consider designs to optimise. It also seems to confirm that the poor performance of the Larsen speaker w.r.t. expected spatial information that I heard at the audio show was because of an inappropriate room. Whether the Larsen speakers work well in more appropriate rooms I don't know but my poor experience with them in an inappropriate room is perhaps best ignored (unless you listen in a very large room with high ceilings!).
 
I think one secret of Larsen and Sonab speakers is they act efficiently due to reinforcement by two walls, i.e. floor and back wall.

My design with measurements

https://www.diyaudio.com/community/...oupled-up-firing-speakers.121385/post-6707993

I like the sound
Thanks for the links, gents. Looks like I've stirred up discussions that go back many years. Decades, even. 😅 All good, it's educational about designs I've never studied closely.

The use of multiple tweeters runs counter to current thinking, in most ways, but the proof is in the listening, I guess.

The most puzzling part of the current Larsen 8 & 9 designs is the metal plate that divides the primary dome tweeter in half. It's not clear whether the hidden half is exposed to the back... or blocked with damping material? If the former, that energy would bounce off the back and side walls. All this, presumably, ends up in a linear power response curve in room.

I have Peerless 10" SLS drivers that could serve as woofers. 6.5" aluminum Seas drivers, also used in my pentagon tower Lxmini copies, would be suitable for the mid. For the primary tweeter, I'm considering a Wavecore waveguide 30mm that could be crossed quite low (maybe 1.5khz) with somewhat narrow directivity, or if wide dispersion is important here, any of several 25mm domes on hand. These mostly have to cross 2khz or higher, though the FR of the Seas 6.5" droops >1.5khz. Compromises. As for the other up firing tweeters, I guess I would have to try them, but would prefer to avoid them if possible. Instinctive bias, possibly unwarranted.

So reasonably suitable drivers are on hand to try a Larsen-ish clone.

Still want to hear from at least one user of the current Larsen models.
 
frugal-phile™
Joined 2001
Paid Member
The most puzzling part of the current Larsen 8 & 9 designs is the metal plate that divides the primary dome tweeter in half.

617larson.3.jpg


https://www.stereophile.com/content/larsen-hifi-8-loudspeaker-measurements

Fastened to the upper corner of the angled baffle is a stainless-steel plate, made with a round opening just large enough for half of the tweeter's dome to show through, and folded at an angle of about 135°. It seems that this plate both prevents waves propagated by half of the dome from reaching the listener and reflects at least some of the output of the unoccluded half; according to the Larsen HiFi website, this arrangement helps the Larsen 8 to reproduce upper octaves "with more body" and contributes to "a more linear frequency response."

Really ugly impedance curve.

317Lar8fig1.jpg


dave
 
I note that you are on Salt-Spring.

When you come to Victoria you could come borrow thw towers i first posted to just see what they do, and don’t do, wrt your goal.

I might have some bits in the free pile you could leverage in your experiments.

dave
Thanks for your generous offer. 👍 I'll get in touch next time I head over!

I saw that mention about the metal tweeter divider in TAS review; still not that clear. I'd love to meet Larsen and/or his engineers for a detailed discussion!
 
Seems to be an acoustic lense. Similar to the Karlsson design with big drivers you get better dispersion. The "main" tweeter gets better dispersion. The other ones are for more reflections from the walls due to being pointed to other directions.

Mr Pfleiderer who made his Pfleid loudspeakers has put indirect reflecting tweeters on top and sides of his FRS loudspeakers.

First one is a bookshelf design the other a floorstander, all with indirect reflecting tweeters (loudspeaker history, long out of production)

aktiv-lautsprecher-pfleid-foto-bild-112448491.jpg


FRS20SKirsche.jpg
 
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The use of multiple tweeters runs counter to current thinking, in most ways, but the proof is in the listening, I guess.

They can have advantages w.r.t. spaciousness staggered and working with the side walls as mentioned in the forum discussion linked earlier (mentioning relevant physics not marketing). Working with the ceiling is unlikely to have a similar effect because of the absence of a time delay between what the ears hear.

The most puzzling part of the current Larsen 8 & 9 designs is the metal plate that divides the primary dome tweeter in half. It's not clear whether the hidden half is exposed to the back... or blocked with damping material? If the former, that energy would bounce off the back and side walls. All this, presumably, ends up in a linear power response curve in room.

The plate acts like a waveguide to shape the high frequency radiation pattern as does the felt/foam. My guess (and it is only a guess) is that the present form was adopted because after splitting with SSC as their manufacturer (if I understand the situation correctly) the new Larsen design would have to be clearly different to the OA52. I doubt there is an opening at the back because these speakers are meant to be placed against a wall which would block it.

The Larsen speaker stereophile reviewed has what look like addressable engineering issues. The response from the manufacturer and the marketing material do not seem to be that of an engineer or at least not an acoustical one. Carlsson on the other hand did appear to reason like an engineer and the OA52 for example does not seem to have similar issues even using drivers from the 80s. It is a speaker I would like to hear but I have some doubts about the degree of spaciousness it may be able to provide which is my primary objective (others likely have different objectives as do I in the main system). The stereo imaging is likely noticeably better than the Sonab's from the 70s which I suspect may have been been a significant factor in the design. There's always trade-offs when it comes to the physics and engineering (not necessarily reflected in the marketing and myth building!) which is part of the fun.

If you do have a go at a speaker along these lines please keep the forum informed.
 

andy19191 --​


Thanks for your comments.

Some of the multiple tweeter setups in both Carlsson & Larsen speakers over the years seem a bit haphazard, but they must be based on at least some degree of empirical experimentation. It seems, btw, that Larsen "inherited" Carlsson's patents and designs. They appear to have worked together for quite a while.

I also noted the mid freq hump (650Hz iirc & dip above) measured by Stereophile for the Larsen 8, which may have been affected or exacerbated by the test room. This is not a serious hurdle, imo, since I will use full active amplification & DSP at least in the development phase if I embark on this project.