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Linn Isobariks

Loudspeakers
#1

I’m very interested in how these famous current-munchers fare up today. I have the required amplification for them (I guess…) and I want that world-class bass without subs (who doesn’t), but…
In terms of imaging, how diffuse are they really, both in the good and bad? They’re a very basic approach towards omni-directionality with their upwards facing mid and tweeter meant to be complemented by the back wall reflections… Since they’re by this principle bound close to the wall, I’m wondering how spacious they manage to sound (and how much there is trade-off in terms of accuracy of placement of cues and “macroscale phase”, etc… forgive my lack of exact audio vocabulary, I know you know what I mean though)

If you’ve heard Isobariks (and enough other speakers) in an acoustically proper config, would you mind commenting on some of these:

  1. What are some common enough
    *(meaning not super-niche a product, a bit broad since high-end speakers are a very niche group but you know… something that’s owned by more than a handful of people)
    speakers that you’d most relate their sound to? Divide this comparison into how many aspects you like, I mean even if you find a very piquant and relatively “small” describable detail in the Isobariks’ sound that reminds you of some other speakers, do describe.
    What about speakers that sound even opposing compared to Isobariks?
    (I need maximum referential info on these because they’re still expensive and I can’t audition any)

  2. How would I theoretically (though if you or someone you know has perfected this, describe…) find the optimal room volume and proportions for a pair of Isobariks given their quantified properties (or let’s say quantifiable without a need for lab-grade measurements)? I know this might not be exactly possible, and of course this might require an expensive simulation/optimization software, and more, so let’s keep this mainly about what kind of configs have been found optimal just by ear, right.
    This is also a general question about analytic optimization, I guess. If I was designing a crossover (for a given setup only) I’d like to account for as many quantifiable non-electric attributes translateable to circuit design as possible. Obviously manufacturers can only optimize products using sufficiently broad margins of analytic data, I’d like to get access to the margins and pinch and shift them to fit specific conditions (dunno the start of it though), isn’t this basically something like… the end-user minimizing the set of compromises that a marketable product intrinsically has to have? Sorry, off topic.

  3. What would you list as a handful of their most pleasing sonic characteristics, and what handful of records or artists have clicked with the Isobariks especially synergistically for you?
    (Never having actually heard them, I somehow have a feeling Autechre would shine through them… If you have Isobariks, play “st epreo” and “Zeiss Contarex” and report back, (please))

  4. What do you dislike about the Isobariks?

  5. Would I actually do well with my amplification?
    Electrocompaniet ECI-1 dual-mono Class-A, peak current 80A, starting at 100W into 8ohms and maximum output of 500W. The manufacturer specs these to handle down to 1/2 ohms, I recall this being their official statement. The transformers are 650VA toroids. Has a high-current cord. …has a well-designed output protection circuit as well!

  6. Should I favour a batch from some period and or avoid others? They were in production for quite a while…

7.Do you think they’re well worth at least 1500$ in working condition?

8…How exactly do I hook them to a stereo amp’s terminals with the stock crossovers? The images seem confusing, haha.

9.About modding them.
Any sense to make my own crossover with premium parts if and when I have money and skill? I would be changing something anyway, but is there point in redoing the whole filters? I guess I’m asking if they have generally well-constructed crossovers. I’d go all silver, Mundorff, what have you, but obviously I won’t if that costs as much or more as the speakers and with (too) diminishing returns.

  1. Why don’t I see subwoofers utilizing isobaric loading?

  2. Anything else?

  3. Everything else.

Thanks.

#2

I once was the owner of a Van Medevoort line arry with isobaric low towers https://www.vanmedevoortaudio.nl/brochures/RDQN.pdf. It’s impressive to say the least. However the same can be accomplished and maybe even better with a well designed open baffle http://aespeakers.com/ronald-wanders-open-baffle-with-dipole12s-and-diy-ribbons/ which is the complete opposite. I don’t know the Linn Isobarik but reading about it gives me the impression that we’re talking about a subwoofer with an additional tweeter.

About modding: My experience is ABSOLUTE control over the woofers. They are by definition high mass, high transient and speed, motors that need lots and lots of energy to keep 'm in check. That means a very, very low impedant pathway between the VERY STRONG, VERY LOW IMPEDANCE output amplifier, preferably with multiple MOSFET’s https://www.amb.org/audio/beta24/ and the actual driver. In my DIY build line arry described in the article above I implemented the “zero ohm” coils https://www.lautsprechershop.de/hifi/mundorf-transformer-core-coils_en.htm in a LR2 low pass filter and high quality, very thick silver coated copper litz wire https://en.wikipedia.org/wiki/Litz_wire between the amp as well as in the speaker enclosure.

Hope this helps in your quest for perfection… :slight_smile:

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#3

Sure it helps, all help needed and appreciated.

Since you mention how a minimal impedance pathway leading to a woofer gives it all the better control, I assume control covers the terms “speed” and “grip”, right?
In a high-end application, why not have the woofer(s) hooked up with pure silver heavy gauge wire? Is a thinner pure silver wire pretty much the same as a correspondingly thicker gauge copper wire, as the woofer sees it? (This is not how I’ve understood)
Since the wires connecting to a woofer don’t have such big issue with skin-effect, are they silver-plated for reasons other than that? How much benefit does (presumably fairly thin?) silver plating offer in a woofer wire? I assume the benefit for impedance grows very rapidly with relatively small increases to silver-plate thickness, with the wire “resembling” a pure silver one more and more, am I wrong? Then again I thought this was more the case with higher frequency transfer due to none other than skin effect? I must be missing something crucial…

Why not use pure silver to truly have the lowest impedance pathway to the woofer? All sources seem to consistently praise silver for its overall “speed” and “controlled attack/decay” factor, which is expected since it offers least resistance among metals. Aren’t those the main attributes a woofer just loves to see to remain in control?
When I switched from standard quality twisted copper speaker cables to hollow core, braided silver-plated copper, I paid close attention to the change in both ends of the frequency range, and yes, the silver made the bass a lot more responsive, the very low end keeps up better in tight passages. And that’s with a mere plating.

#4

Well, that is not my experience, but heck… since you already tried and if it works for you… Great…! My take on copper is that it is by far the most musical conductor. But silver is a better conductor, also when it’s oxidized. Hence… the silver coated copper…

#5

Doesn’t anyone here have any experience of the Linn Isobariks? They’re quite famous…

#6

It is a very old speaker, long discontinued.

You will find some information searching the Web, but I doubt answers to your very specific questions.

Good luck.

#7

I’ve heard them a few times over the years and never been very impressed… To be honest, I wouldn’t spend $1500 on them… they’re quite old (and more than likely will need to be restored, which I don’t know how doable that is any more) and technology has moved forward.

For $1500, I think you can find better (and newer) speakers.

Just my 2c

#8

I’d like suggestions on what to spend that kind of money on if I want a pretty much full-range speaker with a wide sweet spot.

#9

Audio Physic Virgo II. Easily obtainable for your budget and has enough low end slam despite smaller drivers. Will completely disappear!

#10

Or Thiel CS2.4

#11

Hi Arenith, Isobarik loading for a woofer can work well but it is one of many solutions to the problem of putting a woofer in a box. It can provide a “solution” to the problem of back pressure on the primary woofer (forward facing) and can decrease the enclosure volume compared to just one woofer performing that task (frequency extension is lower, power handling is doubled, impedance is halved, driver cost doubled). As far as optimal room volume goes, it’s a woofer in a box in a room. I can recommend Sigfreid Linkwitz’s (R.I.P) site as a starting point, lot’s of useful scientific information there. One interesting option I have never heard about or tried is using a passive radiator as the the “rear woofer” in such a box. (Mr. Brunhaver, are you reading this?) But it’s still a box, manufacturers have gone through heroic lengths to make box speaker enclosures non resonant which raises the cost, weight, etc. I have heard a few Isobarik incarnations over the years (Eggleston, Dynaudio, Linn and others) and they all sounded great, I have never owned one though. I do own open baffle speakers sourced from Acoustic Elegance woofers (Dipole 12"), I use 3 per channel and have 3 channels for stereo use, they provide the best bass reproduction I have ever heard in my listening room. They have a requirements that should be met (at least 3’ to the back wall) but they can be placed near a parallel side wall. Those AE woofers are specifically designed for open baffle use and are somewhat unique, designed with modern techniques (low mass, low inductance, under hung voice coil, linear BL curve, low flux modulation of the magnetic field, etc) For a box solution, Mr. Brunhaver’s concept of using the walls of the box enclosure as a passive radiator is genius and I look forward to hearing it, seems to solve many problems. I use Bohlender Graebner Neo 10’s and Neo3’s in a line source array and was going to use a “servo solution” at first. When I found out about the AE woofers, I had to try them and they are superior. I was more interested in a “badass” mid-bass coupler / woofer than a subwoofer solution, I have not been disappointed. I don’t use passive crossovers in my system and don’t really care for them, I understand their purpose in inexpensive applications. I use 2 DBX Venue 360 DSP crossovers and for the supposed “sin” of an additional A/D , D/A conversion, I get an impressive toolkit of options that can’t be replicated with passive devices. I can also configure and adjust the DSP with an application on any device with a Ethernet connection. If you can find a used Linn in good condition for a favorable price and don’t have the room for open baffle stuff, go for it. I would stay away from modding the passive crossover unless you have measurement tools (Clio, Dayton Audio) then again you could purchase a DBX 360, remove the passive crossover and “roll your own”. Best of luck with your endeavors. Just my 2c worth.

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