The Linn Isobarik DIY-Mods Bible
Posted by: Alan Ball
Date: 5/6/2003 11:17:00

I'm starting this topic so people can post all their DIY Isobarik modifications in one place. I recently aquired a nice 1989 pair which need a little work. I've already started doing the XO's but surely there is a lot that can be done to these speakers which will bring them more up-to-date against the modern competition.

The thing that sparked this was that my demo Shahinian Obelisks arrived and to be honest, I prefer the Briks !!. Ok, the Obs have a cleaner top-end and a little more detail but I believe the Briks can be tweaked and tampered with to produce a modern speaker destroyer for very little money. When you think the Obs are 4k new and the Briks cost me 400 s/h then you can see why I'd rather spend a little on the Briks getting them updated rather than forking loads out for the Obs. I also don't mind taking a soldering iron or drill etc to a pair of 400 speakers..

So - What upgrades are available to the Briks ? If you have one then post it here. Try and indicate what it will achieve and if it applies to all incarnations of Isobarik or specific models. General, useful information is also welcome. As the information builds up I'll extract it out and try and get Tony to host it all somewhere on the PFM site.

Now, I'm not up on electronics so don't know much about that side of things yet but a few ideas I have had are -

1. Building A New Passive XO.

The Briks I have come with the XO's in the base of the stand. The PCB is screwed into a piece of MDF which just sits inside the stand. Surely we can better this !?

The passive XO's could be re-located into seperate boxes which could then be located away from the speaker. I'm sure the XO itself could also be improved upon ! It is a 15 year+ old design after all !

Are semi-active XO's a possibility ? Still have the single speaker wire coming in but have the XO powered by a DIY-Hicap for example. I have no idea but someone might !

2. Supporting The Cabinet.

I have never liked the arrangement on any speaker where the spikes penetrate the speaker cabinet rather than have the spikes as part of the cabinet and face them downwards. Some Brik variations I have seen don't have any spikes at all and use rubber 'feet'.

There is a lot of room for experimentation here.

3. The Cabinet And Its Internal Structure.

Cross-bracing ? Dampening materials ? Can we improve upon the structure of the cabinet itself ?

4. The Drivers.

Since the B110 midrange and B139 bass-units are no longer made then what are the options for driver replacement ? I have some info here which I will post below but what have other people done ? Has anyone been crazy enough to actually add more drive units ?

5. Cosmetics.

I know.. Most people think Briks are ugly and have zero WAF... How can we resolve this and keep the better half happy ?

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The Linn Isobarik is an all-time classic loudspeaker and still sits in some of the best ever systems I have heard. It might not be to everyones taste but for the money, they are truly the great speaker buy of today. They are loads of fun and allow you to get your hands dirty.. What more can a hi-fi nerd ask for !!? [:lol]


Isobarik Driver Units
Posted by: Alan Ball
Date: 5/6/2003 11:18:00

Tweeter

Original units are either Scan-speak or Hiquphon.

Suggested Replacement unit - Scan-speak D2008

Mid-Range

B110 Mid-range Driver no longer available

Suggested Replacement Unit - Monacor SPH135/AD

Bass

B139 Bass Driver no longer available

No replacement unit available !!

Replacement Drivers / Repairs

Replacement drivers available from www.wilmslow-audio.co.uk/ - 01455 286 603

Existing B139 drivers can be repaired by DK Loudspeakers - 01708 447344






Re: Isobarik Driver Units
Posted by: John and my dog Jake
Date: 5/6/2003 11:46:00

hi,
your aspirations are very laudible,but if you start modifying the Bariks in some of the ways you suggest they will not be Bariks.
I presumed you bought them because of their sound. Why on earth then would you wish to change it.
The cabinet is very well braced and impossible to get into without virtually destroying them.
The rear panel on the early ones was glued into place with a threaded rod bolting it to the midrange pipe.
I presume the later ones whilst being screwed also have this rod behind the makers rear label.

Replacement drivers other than the above Scanspeaks must alter the nature of the beast not always for the better.
Spiking could indeed be improved but I can't see how you could put an adjustable spike in the bottom and still marry up with the stand. Better to harden the seating of the spike in the Barik.
Bass drivers would have to come out and that is not a straightforward job. I have a tip for this which I will post below.

Taking xovers away from the speaker mean more cables running in between any gain may be lost.

A better plan than some of the mods would be to spend time returning them to the condition in which they left Glasgow, I have and the sound quality improves every time I look at them.

john & Jake


Re: The Linn Isobarik DIY-Mods Bible
Posted by: PatrickD
Date: 5/6/2003 11:56:00

"The passive XO's could be re-located into seperate boxes which could then be located away from the speaker. I'm sure the XO itself could also be improved upon ! It is a 15 year+ old design after all !"

- If you locate the x/o away from the cabinet you have to run longer cables between the x/o outputs and the drivers. This doesn't sound like it would improve the sound to me.
- Passive x/o (filter) design probably hasn't progressed that much in the last 15 years, best to replace it with an active x/o if you want to improve it.

"Are semi-active XO's a possibility ? Still have the single speaker wire coming in but have the XO powered by a DIY-Hicap for example. I have no idea but someone might !"

- Not really practical since active x/os use low power components and therefore require the power amplifiers between x/o and driver ie. the conventional active configuration.

You could try the Falcon type x/os in the base of the cabinet; some people seem to think it's better.

Sorry to be a killjoy.



Re: B139 removal
Posted by: John and my dog Jake
Date: 5/6/2003 11:59:00

hi,
To remove the B139's in the Barik you need to be a little brave ( I don't mean a small red Indian).

If the front one is proving difficult to prise out with a wide wood chisel, with the veneer protected.

Measure from the very front bottom edge of the wood back to the baffle.
From underneath drill a 1/4 inch hole through the base up towards the front of the speaker at the measured distance from the front.
A screw driver can then be pushed through the hole from underneath and pushed behind the chassis front, a push backwards and the driver will lever out.

The inner one is done exactly the same, the measurement being taken from the front edge again back to the inner baffle.

When all work is completed a dowel is glued back in the hole and cut off flush.

john & Jake


Changing Briks
Posted by: Alan Ball
Date: 5/6/2003 12:16:00

John,

The same could be said of modifying anything, including Naim equipment. [;)] You are right though. I am talking about changing the Briks into a different, hopefully better speaker. Compared against the Obelisks which share some of the same fundamental sound qualities they won hands down on warmth and scale but lost out on detail, grip and control. I want to incorporate Obelisk-like qualities into my Briks.

The XO's for mine are actually a problem because I want to move to Mana stands but that means nowhere to put the XO itself. As Mana stands are topped with glass then the Briks will need to be spiked at the base to get the best results. I have seen Fox's and they have small rubber feet on them. I personally think spikes will perform better but experimentation is needed.

As for the XO - Vibration in any circuitry we know is bad. If it is unavoidable then yes, try and couple it directly to the speaker to reduce any time smear and delay effects but I still think it is better to eliminate it instead. Locating the XO in a seperate box will help achieve this. Agreed, it will mean longer cable lengths between the XO and speaker but I think the trade off would be worth it.

I followed some of your posts about your Brik restoration project and hats off to you. It looked like you did a sterling job on them. But I'm taking about a different angle. Looking at the Brik and saying.. That is basically a 30 year old design. How can we make this better ? Can we impart some of the more desirable qualities of a modern speaker into it ?

I bought my Briks on impulse. Partially because I wanted a speaker I get my hands dirty with and because I like my music to sound big ! Where else could I get that for 400 ? But they don't do some of the things that even my Allaes can do. I think there is a place in this world for a bastard-hybrid Brik.

Anyway - A post with your knowledge of the cabinets and how to get the drivers in and out etc would surely be useful.

Ta.

-A-


Re: Changing Briks
Posted by: John and my dog Jake
Date: 5/6/2003 13:11:00

hi Alan,
right see where you are coming from now.
I, in your shoes, would be tempted to go for extremely modern drivers.
Carbon fibre cones. metal dome tweeters, bring them into the 21'st century.
If you are going to drag them kicking and screaming you may as well go the whole hog.
If you are ready for a lot of experimentation, what was in the Obelisks? then I wish you well and keep us posted.

john & Jake


A drastic change ?
Posted by: Alan Ball
Date: 5/6/2003 13:43:00

John -

Excellent. Now we are on the same wave-length. [:D] - For me, going active is not an option. I have no desire to buy another 4 x Nap135's !

The current B110 midrange in the Briks is superb and forms the basis for why I love them. Vocals are frighteningly realistic. Acoustic instruments like guitars likewise. I've never heard another speaker achieve this so well.

At the top I feel there could be more presence and head-room. This could be down to the fact that two of the current tweeters have been victimised by children and have had the domes poked in. They still work and the sound seems to compare to the none-damaged tweeters but there is a general lack of 'sparkle' when compared to a modern speaker. I have considered the addition of a super-tweeter to each but that would mean a custom 4-way XO but it could be done. I will try and get the specs for the current drivers and find out what the XO's are set at and see what the options are.

Replaceing the bass-drivers are going to be the tricky ones. Personally, I'd rather leave these alone as I have heard Briks do incredible bass. Mine kind-of get there but there is still a wooliness which I would like to tighten up. Mana stands may help achieve this so replacement bass-drivers are low priority for now. Plus there will be a difficulty finding oval units that both fit and out-perform the existing units.

One great desire I have is to work out a way to get the Briks to function about 3' away from a back wall.. Have you tried much experimentation with placement of yours ?

Cheers

-A-


Re: A drastic change ?
Posted by: John and my dog Jake
Date: 5/6/2003 02:29:00

hi Alan,
regarding your pushed in tweeters are they still in or have you tried/managed to get them out.

If they are still in there are a couple of ways.

Double up some sellotape sticky side out and carefully attach it to the dome and ease it out repeatedly as the tape will come off, use fresh tape and repeat.
If that fails try the same with bluetac. as a last resort and probably the only one that will work use a needle and puncture the dome at the bottom of the childmade crease and angle the needle and push the crease out carefully from inside with the side of the needle.
The crease should unfold if you are careful.
A tiny spot of pva will repair the needle hole.

If the signal is right feeding the Bariks then distance from the wall is room related.
Their present position in my girlfriends house is 4 3/4's from the wall as the bass is emphasised any closer whereas in my house right back to the wall is right.

john & Jake


pulling out pushed in tweeters.
Posted by: Jiiim
Date: 5/6/2003 02:44:00

Another method of pulling out pushed-in tweeters:

Cover tweeter with mouth. Suck.
Works surprisingly well.

Jim.



Pushed in tweeters.
Posted by: Alan Ball
Date: 5/6/2003 02:48:00

I tried the sellotape. Not having it at all. The creases have hardened on one and it isn't budging. The other didn't fair much better.

I may try the needle as the only other option was to buy a new pair. One does rattle slightly at high vols so I'll try and rectify that one as a priority.

-A-


Split isobariks.
Posted by: Jiiim
Date: 5/6/2003 02:50:00

My favourite mod for briks is what I call the 'split-isobarik' mod.

If you look at the crossover, you will see that each isobarik is in fact wired as two 3-way speakers, joined at the crossover. (most briks in fact use two crossovers - so it's very easy indeed to see what is happening)
Simply split them at the crossover, and use an individual power amp for 'each' 3 way speaker.

This mod yields, quite frankly, enormous benefits. I wont use the phrase 'jaw dropping' because I hate it, but this really has to be heard to be believed.
It also enables quite low powered amps to drive them easily.
For instance, a nap90 driving a 'split-brik' sounds better than a nap135 driving a non-split brik. I can only imagine how good 4off nap135's driving split-briks would sound. [:)]


Jim.



Oiled finish
Posted by: Mick Parry
Date: 5/6/2003 02:52:00

Chaps

Has anyone actually removed the varnish and oil finished the cabinets. I have the Teak finish and keep toying with the idea.

If you did it, how did you get on.

Regards

Mick


Re: Oiled finish
Posted by: Jiiim
Date: 5/6/2003 02:54:00

Mick,

I havent done that, but it does indeed sound lovely.
Jim.



Re: Changing Briks
Posted by: PatrickD
Date: 5/6/2003 03:04:00

Alan

I started a thread about home-brew brik stands a while back. Fox (I think) said that you can bolt the mana glass directly to the bottom of the cabinets. I don't know who has actually tried this, but it might be better than fitting downward spikes to the bottom of the cabinets as I'm not sure if the glass would take the pressure.

Someone, somewhere has the external x/os on a sound-somethingorother within the mana brik stand (you might have to be on phase greaterthanone to do this), someone else has fitted the falcon x/os in the bottom of the base instead.

(Sorry I find the whole mana thing a bit inaccessable, although I would like to try some mana brik stands.)

Interesting that you want to stick with the brik midrange as from what I've read, this is where modern designs score most heavily over the briks. You could try the neodyme (ninka) tweeter which gets a (mostly) good press.

As for improving the WAF, I've come to the conculsion that you need to marry a blind woman (in my case she'd have to be anyway - according to my brother); after a while you do get sort-of used to them though.


Oil Finish
Posted by: Alan Ball
Date: 5/6/2003 03:08:00

Mick -

I am going to have to take some wire wool to mine to get rid of the perished glue from the back of the velcro strips which I have now removed. I suspect I will end up cleaning up the whole cabinet while I'm at it.

Re-finishing them is a different matter though. I have no idea if the varnish is an integral part of the sound and what effect oil would have.

Whenever I have used MDF for Isoplats it has always performed better when primed/sprayed/lacquered. The coating seems to help the board resonate and gives it some life. Whether the varnish on the Briks has this effect I don't know.

I wonder if Alex S has any ideas on this ?

On the looks front though I personally like naked Briks over the foam grills.. they are just horrible ! The cloth grills are better and look quite easy to make. Fox has done a nice set for his which are secured with sticky sponge pads.

-A-


Split/Active Briks?
Posted by: mcai7et2
Date: 5/6/2003 03:16:00

On the subject of splitting briks, has anyone heard of anyone driving Briks with a 12 pack (one amp per drive unit)?

I always thought it would be a cool thing to try.


Oiling Briks
Posted by: Mick Parry
Date: 5/6/2003 03:19:00

Jim

Was it difficult to do.

How long did it take to rub it down.

How many coats of oil did you give it.

How do you know when the varnish is off or did you use a stripper.

Does it look better than the varnish finish.

Regards

Mick
Regards

Mick


Re: Oil Finish
Posted by: John and my dog Jake
Date: 5/6/2003 03:25:00

hi Alan,
Are the foam covers on yours original and do you like naked Bariks enough to sell me the grills. Mine are flat foam at the moment.

Wire wool, coarse, is the best to remove varnish rubbed always with the grain.
Then several coats of an oil of your choice and a final buffing.
All oils darken the finish after wire wooling but the grain really stands out.
I can't see different finishes altering the sound the finish is only skin deep.

Mick,
the varnish is off when you are covered in brown dust and the wood is lighter and dull with no traces of shine.
john & Jake


My Grills
Posted by: Alan Ball
Date: 5/6/2003 03:31:00

John -

They are original and in quite good condition.. albeit a bit musty.

If you want them you can have them for free ! Where are you ?

-A-


Splitting Briks
Posted by: Alan Ball
Date: 5/6/2003 03:44:00

When I got mine the XO's were split. During the resoldering process I tried a few bi-amp combinations.

1. Bi-amped : Bass 2 x 135's - Mid/Treble 1 x 180

Ok. Good depth of bass but top end was a bit thin. Got 'edgy' at higher volumes.

2. Bi-amped : Mid/Treble 2 x 135's - Bass 1 x 180

Far better top end but bass became sluggish. Could really push the limits of the volume though.

In the end I resoldered them completely using the core of NACA5 and that was by far the best option. I think if I had 4 x 135's then things would of been a lot more coherant but I didn't.. [:(]

-A-


Re: My Grills
Posted by: John and my dog Jake
Date: 5/6/2003 05:05:00

hi Alan,
thanks, thats very generous of you, I'll pay the postage of course.
could you please email me your address and I'l get the cash off to you.
I'm at Stockton on tees in the north east john.baldam@ntlworld.com


john & Jake



Biamping
Posted by: Paul Ranson
Date: 5/6/2003 22:18:00

Alan,

The biamping that works (reputedly) with Briks is front and back rather than top and bottom. This option is only available to users of the older crossovers where the speaker is literally constructed as two three ways, each with its own crossover, and then the amp has to drive both. Using an amp per crossover means each amp is seeing a complete 8 Ohm speaker.

The Falcon 8 Ohm Isobarik crossovers are cheap enough to make this worth considering. I believe that all Briks that came with the 'in stand' crossover still have the cavity in the base where the wiring terminates and where you can fit the old style crossovers.

But active is way better.

FWIW I believe '12 packs' aren't that rare. If you use 6 stereo amps then the number of boxes is reasonably containable. I would expect (but I don't really know....) 6 NAP250s to outperform 6 NAP135s for example.

Paul


Re: A drastic change ?
Posted by: James Jong
Date: 5/6/2003 23:39:00

John/Alan,

Quote:
I, in your shoes, would be tempted to go for extremely modern drivers.


IMHO, the only reason why the 'Brik is as popular today as it was when first introduced is due solely to the absolute dearth of large sealed box loudspeakers that doesn't cost an arm and a leg. The populist bass reflex design has a lot to answer for when it has been fashionable to squeeze a gallon of bass out of a pint jar. Frankly, it is ludicrous that so many people (myself included, but I have now seen the light) have been had by this scam.

With all due respect to 'Brik fan(atic)s, there is nothing special or magical about the design of the system. The results it produces might give you goose-bumps, but it ain't black magic. The prodigous bass capability of the 'Brik is all about moving air, and plenty of it. All it takes is a suitable 10-inch or bigger bass driver, properly loaded by a sealed enclosure of a healthy volume, and you're the biz.

Oh wait, that's what I have cooking in the garage. Shhhhhhhhhhhhhh !!!

James

P/S: Before Ron jumps down my throat again, I have not made a qualitative comment about the 'Brik being good or bad.


Re: Isobarik Driver Units
Posted by: Martin
Date: 6/6/2003 01:22:00

Quote:
Bass

B139 Bass Driver no longer available

No replacement unit available !!



I once queried this with Linn, and was told that the Keltik bass drivers should go in, but were very expensive!!

cheers, Martin


Re: Split isobariks.
Posted by: Martin
Date: 6/6/2003 01:25:00

Quote:
I can only imagine how good 4off nap135's driving split-briks would sound.



It's a damn big upgrade from 2x135s. You get a lot more headroom and speed.

cheers, Martin


Re: isobariks.
Posted by: Arthur Bye
Date: 6/6/2003 04:33:00

James Jong wrote:

"With all due respect to 'Brik fan(atic)s, there is nothing special or magical about the design of the system. The results it produces might give you goose-bumps, but it ain't black magic"

James:

I used to think this, but I'm not so confident anymore. After all Linn tried a 2nd time with the Keltik and failed. There's not too many others out there after the Keltik and Isobarik. I think it must be harder to do that it appears. Even Linn has now resorted to ports with their Melodik (isobarik config). Speaker design is as much art as it is science, but I think there's a bit of luck there too.

Arthur Bye




Fixed the tweeters !
Posted by: Alan Ball
Date: 6/6/2003 08:01:00

Well actually, my dealer did it for me and he got ever so forceful with the electrical tape and got the buggers out again. I was obviously being over cautious trying to get the tape to stick. Sticking fingers in tweeters.. like things near my eyes.. Freaks me out ! But has that made a difference !? Some of that sparkle I missed with the Naim speakers has returned !

Hoorah ! [:D]

I know what John means when he says they get better every time he listens to them.

-A-




Re: Fixed the tweeters !
Posted by: John and my dog Jake
Date: 6/6/2003 09:15:00

hi Alan,
good to hear you've had a result (didn't you find it awkward getting the Bariks down to your dealers?)


john & Jake


Moving Briks
Posted by: Alan Ball
Date: 6/6/2003 09:26:00

Nah.. Sod that !

He came round to have a listen to mine. I think he's been pining for another set since he sold his a few months ago.

Awwww.. [:rollin]

He has found another set albeit a very old pair (1977 we think). I'm on listening duty next week to see how they compare against mine.

Good, he keeps them.

Bad, they become spare parts or the victim of my evil intentions. [:evil]

Now mine are sounding a lot healthier I've suddenly become all reluctant to get medieval on their ass.

-A-




Re: Fixed the tweeters !
Posted by: PatrickD
Date: 7/6/2003 11:39:00

"I know what John means when he says they get better every time he listens to them."

I think briks need to settle down each time you move them (I seem to remember Fox saying this too), maybe it's something to do with their imense weight. It makes them quite difficult to set up though, because each time you move them you have to wait for a day or two for them to sound any better, and by then you're not sure if they really are better ... or not.



Free to anyone who wants them -
Posted by: Alan Ball
Date: 10/6/2003 13:14:00

A pair of 1989 Isobarik stands -

I've replaced them with Mana stands.. After hearing the difference then I'd feel guilty if I tried to charge for these. [:rollin]

They are not worth posting but if anyone wants them they are in Chester.

-A-


Re: My Grills
Posted by: John and my dog Jake
Date: 13/6/2003 08:05:00

hi Alan,
tried to reach you at work but you had probably left already.

The postie tried to deliver the grills at 12:10 but I wasn't there so he took them to the depot which shuts at 1:30.
The depot is just over the road from me, so near, yet so far.

Opens at 7 in the morning, guess who'll be up early in the morning.
Thanks for the grills and your help.

a very grateful john & Jake





Re: My Grills
Posted by: Alan Ball
Date: 14/6/2003 00:04:00

John -

I scooted off to the pub at lunchtime enjoying the weather and then went home and monged out with some tunes for the afternoon.

It's midnight.. I'm still here. [:smokin]

I've not had this much fun listening to music for such a long time.. Been like this since for a few weeks now. Oh yeah.. Ever since I got these antique bargain-bucket speakers home. [;)]

Hope the grills have arrived ok.

-A-


Re: My Grills
Posted by: John and my dog Jake
Date: 14/6/2003 09:23:00

hi Alan,
yes, the grills were waiting for me this morning perfectly packaged.
The've had a shower and are now relaxing prior to fitting to the Bariks.
The've finished them off a treat.
You're a gent. Thanks

john &


Time to do the XO's.
Posted by: Alan Ball
Date: 18/6/2003 02:34:00

I started looking around for the components which will let me build a replacement set of Brik XO's for my late-model pair.

I supplied Falcon with the details but they cannot help me !. The XO's they supply are for pre-1989 models whereas mine are 1989 (s/n 7xxx).

I think the stumbling block here is that my speakers are 4-ohm whereas the previous versions are all 8-ohm.

Can someone give me a brief rundown of what this means. Are the drive-units themselves rated at 4-ohm or is it because the 8-ohm drive-units are in parallel forcing it down to 4-ohm ? The back of my Briks has 3 pairs of banana's. +/- for bass,mid and treble. These appear to be wired internally direct to the relevant drive units.

Anyone have any words of wisdom that will set me off in the right direction ?

Will a standard Brik XO designed for the 8-ohm versions work in my speakers ?

Cheers.

-A-

P.s. John - Glad the grills are what you needed. [:)]


Re: Time to do the XO's.
Posted by: Jiiim
Date: 18/6/2003 03:24:00

Alan,

As far as I am aware, the only electrical difference between your model briks and the 1 year older ones is: The crossover!

It is received wisdom that the late model crossover(the lp sized thing) is actually the worst sounding.

I think you will be okay with the 2 crossovers per isobarik as supplied by falcon.


Jim.



Re: Time to do the XO's.
Posted by: PatrickD
Date: 18/6/2003 03:28:00

Alan

You buy 4 of the Falcon x/os; 2 per speaker. Each crossover feeds 1 bass, 1 mid and 1 high - so 1 x/o for the fronts and 1 for the internal bass and top mid and tweeter.

Each x/o is 8 ohms; each channel of the amplifier (1 135 or 1/2 a 250) sees 2 x/os in parallel - so 4 ohms, which is the same as the external ones.

If you fit the x/os in the speaker base you just have to identify the wires (note that the mids are wired OUT OF PHASE); if you want to site them externally you need to add 2 more pairs of connectors on the back of the speaker so that you can wire to each driver seperately.

Hope this helps.

John Baldam did have 4 Falcon x/os surplus, but I don't know if he still has or not. Might be worth asking.

My guess is that the pre 89, post 89 speakers are exactly the same except for the x/o, and the x/o design was changed simply to make it very simple to configure the speaker as PMS or DMS. Obviously with an external x/o, Linn didn't want to feed 6 pairs of wire from the x/o to the speaker, so they redesigned the x/o to feed the drivers in pairs. Changing the pre 89s between PMS and DMS is fiddly, requires a soldering iron, and the wires get shorter each time you do it!


Re: Time to do the XO's.
Posted by: Alan Ball
Date: 18/6/2003 04:06:00

Cheers Guys -

That has made some sense. I think John's spare XO's went to Stumo.

Now for an electrical question I have no idea about.

Do the electrical components in the XO have anything to do with the Ohm rating of the speakers ? I spoke to Wilmslow Audio and they have a 'Concerto' XO available for the same drive-units.

From what I understand from what they told me then the XO does not care about what the Ohm rating is (within reason). Ie. A single XO could be used to run either set of drive-units or both..

Is this correct or will the XO's fry ? If this is correct then do the design of the Falcon ones differ meaning that 2 are required per speaker regardless ?

It's all too complicated !!

-A-






Re: Time to do the XO's.
Posted by: Jiiim
Date: 18/6/2003 04:11:00

It wont work. Crossovers are designed with the impedance of the driver you are connecting to it in mind. If you change the impedance of the driver (ie wiring two in parallel, etc) then you will change how the crossover behaves - possibly in an unpredictable manner!

Jim.



Re: Time to do the XO's.
Posted by: Alan Ball
Date: 18/6/2003 04:20:00

Jim -

Not what I wanted to hear but now I fully understand.

Arse. !

-A-


Re: Time to do the XO's.
Posted by: Paul Ranson
Date: 18/6/2003 04:29:00

You definitely want to use the appropriate crossovers wired appropriately. The drive unit obviously forms part of the calculation for the filter so if you start wiring two in parallel who knows what the result will be (but probably not 'Isobariks'[ as we know and love them!)

AFAIK all units equipped with 4mm sockets have a cavity in the base where the two 'Falcon' crossovers can be fitted.

This is what the cavity should look like when filled,



You can see that the inputs to the two crossovers are paralleled and each crossover drives a bass/mid/treble drive unit.

Various people reckon that the big 4 Ohm crossover isn't as good as the pair of 8 Ohm. I'm not convinced (yet).

It's not a completely unknown mod to have 6 pairs of sockets along the rear, mainly for monster 12 pack active systems, but this would also allow the 8 Ohm crossovers to be plugged in rather than soldered. I have a set of each sort of crossover, this allows me to return the speakers to original if necessary, to normally run active, and to plug the 4 Ohm unit in when I need to run passive but don't want to spend a day soldering.

FWIW Aktiv rules.

Paul


Re: Time to do the XO's.
Posted by: Alan Ball
Date: 18/6/2003 04:44:00

Cheers Paul -

The pic explains a lot there. Oooh.. Which option to go for !?

I think the 6 pairs of connectors and external XO's is still my preferred route.

-A-



Re: Time to do the XO's.
Posted by: John and my dog Jake
Date: 18/6/2003 05:43:00

hi Alan,
spot on the Xovers I had spare went down to stumo.
Anybody know where stumo has got to, not seen him post for a while.
In my experimentation Barik boxes I tried the Concerto xovers
as it was designed for almost the same drivers.
I found them to be very revealing of detail and image if that is your thing and it worked fine. They are expensive though.
I then tried the Falcons and lost a bit of mid/high detail but gained bass detail.
I kept the Falcons for originality, nothing more.

My best advice would be to use the early Falcons, (4) at 17 each, externally.
They will make your Bariks sound like the early ones, which most people agree are the better sounding ones.

john &


Re: Time to do the XO's.
Posted by: Alan Ball
Date: 18/6/2003 06:18:00

John -

Stumo's probably trying to kill himself on his jet-ski. [;)]

To be honest, Wilmslow were very helpful and Falcon all a bit too dismissive of trying. I respect good service so may try the Concerto ones first. If I lose a bit of bass detail then I'll just stick another load of Mana under 'em. [;)] The revealing detail/image part sounds good as that turns them into good studio monitors as well.

So how did you wire the Concerto XO's up and which version did you get hold of ? What happened to the ones you had ?

-A-


Re: Time to do the XO's.
Posted by: John and my dog Jake
Date: 18/6/2003 07:26:00

hi Alan,
wilmslow label the xover as Concerto upgrade. I used the standard version which required 4, just as the Falcon ones.
Your man at Falcon is THE man as Falcon made the Xovers for Linn, here is his answer to my question regarding drivers and their xover.

"The system was designed using the sp1044,b139 and sp 1003 b110. The sp1333 and sp1228 are obviously newer specs and hence we do notknow,but they will probably be OK.
Seriel nos. March 1983 3000/1, May 1984 3939/40.
The s/no. 3024/5" mine " are OK, so if the units are original the crossovers will be OK"

sp1044 original Bass, sp1333 newer bass I've fitted
sp1003 original B110, sp 1028 newer mid I've fitted

A check with Linn will tell you whether the newer ones were ever fitted to Bariks.

The upshot of all this is that If you have the earlier units, the xover is fine. If you have later units it is still fine as I can testify as, as I write this I am constantly turning round to the Bariks as they render Eva Cassidy as I've never heard her before.

john &


Re: Time to do the XO's.
Posted by: John and my dog Jake
Date: 18/6/2003 07:31:00

hi Alan
the Concerto's come with a chocolate block attached and a wiring diagram.
I passed mine on to a newer member "Brikcult" who coincidently lives a couple of miles from me. He may still have them.
Could you please email on john.baldam@ntlworld.com asap.
john &


Re: Time to do the XO's.
Posted by: Paul Ranson
Date: 18/6/2003 09:54:00

It's interesting that my photo, which shows the crossovers that came with my Briks, which I think are original Linn supplied, differs considerably from the Falcon option here (towards the bottom).

Paul


Re: Time to do the XO's.
Posted by: John and my dog Jake
Date: 18/6/2003 22:25:00

hi Paul,
having bought the Falcons and compared them with your pic, which I saw the last time it was posted, I noticed that the Falcon was much simpler and the later one seems to have heavier duty parts that may sap power from the amp. This may explain the "sweeter" sound from early Bariks.
I had a pair of Bariks in '82 and they had the Falcon/Linn xover fitted. They were a much simpler speaker then.

You can just see the legend LINN SCOTLAND on the rear of the board.


john &



Re: Time to do the XO's.
Posted by: Paul Ranson
Date: 19/6/2003 13:35:00

Both versions seem to have 4 inductors, 6 capacitors and 2 resistors. It seems likely they're electrically pretty much equivalent.

I'm pretty sure that Hermann's Falcons looked like mine. He posted a photo somewhere.

Paul


Re: Time to do the XO's.
Posted by: Alan Ball
Date: 19/6/2003 02:45:00

John -

I'm away from email until Tuesday. Pass my interest and email on to 'BrikCult' if he wishes to part with them. [:)]

Cheers.

Alan.


Re: Time to do the XO's.
Posted by: John and my dog Jake
Date: 19/6/2003 04:42:00

hi Alan,
I've sent you an email but it looks like you won't read it till Tues.
Too long to explain here.
Brikcult doesn't seem to post here anymore but I'll contact him if I can.

john &


Re: Time to do the XO's.
Posted by: John and my dog Jake
Date: 19/6/2003 08:54:00

Hi Alan,

Have been in contact with Gordon (brick Cult) and he still has the Concerto Xovers.
He would like me to pass on his email.
Can you reach me by email?
edit
I've just passed yours on to him with your office message.

john &


Crossover Mounting
Posted by: Brikman
Date: 22/6/2003 08:01:00

Alan,

Whatever crossover you decide on, I would recommend mounting the crossovers outside of the speaker cabinets if at all possible.

I am currently using the big LP sized 4 ohm ones that go in the stands. When I removed the crossovers from the stands and placed them next to the speakers I noticed a marked improvement in performance.

I imagine that both the Falcons and Concertos would also benefit a lot from not being "shaken around" in the bottom of the cabinets.

Regards,

Mark Russell


Re: Crossover Mounting
Posted by: John and my dog Jake
Date: 22/6/2003 09:02:00

hi,
When I repaired my first set of Bariks, with the xover inside, I noticed that when the xover was too close to a speaker magnet, the xover ceased to work and all frequencies came through one driver.
Stray magnetic fields could account for the differences noticed.

John &


Linn Isobariks Mods
Posted by: BarryJHart
Date: 27/6/2003 12:26:00

Many years ago I built my own Isobar[:D] ik speakers.
You can build a better enclosure than Linn.
I used 19mm flooring grade particle board, all internal bracing 19x50 mm on edge at a minimum spacing of 150mm corner overlapped, the interior lined with 12mm jointex, these cabinets are inert .
The strength around the lf units is substantial the mid range enclosure braces the front to the rear, much better than the original rod.
Because the enclosures are finished in Formica I had the luxury of screwing the bracing etc. from outside the enclosure assuring structural integrity.
The one thing I didn't like about the original speakers is an option no one ever talks about - the top mounted mid and hf units, this is the Amar Bose aspect that robs detail, think about time smearing.
This is easily tested - just cover them up.
Anyway the pair I built use 2xKEF B139 SP1044, 1xKEF B110 SP1057, 1xKEF T52 SP1049 & 1xCelestion HF2000.
These have always been used as active speakers using 2xNAP250s per enclosure, one 250 driving each lf unit and the other driving the mid and hf pair.




Re: Linn Isobariks Mods
Posted by: John and my dog Jake
Date: 27/6/2003 02:09:00

hi Barry,
glad to meet another diy Barik builder.
Did you have access to the innards of a proper pair to copy?

There is great satisfaction to be had knowing that anything Linn can do.....

I presume from the driver count that you mounted all drivers on the front baffle.

john &


Linn Isobarik Mods
Posted by: BarryJHart
Date: 28/6/2003 12:38:00

Jake
Pleased to see another mortal out there prepared to attack a project of this magnitude, from memory it took a day just to tar coat the interior and install the jointex sound dampening.
I was working in a Hi-Fi shop at the time (the time was the initial isobarik DMS version with those crappy third party crossover networks - late 1970s), I borrowed a pair and removed both bass units to investigate what this isobarik was all about.
To my suprise the cabints were the best constructed I had seen except the aforementioned crossovers but worse than that a piece of bracing was loose in the enclosure, the heat activate adhesive had failed and it was floating around inside, also from memory it was a paltry 19 mm square.
In reality the only part I liked about the speakers was the awesome bass detail, transient response and extension. this is the reason for my selection of the components and layout. One of the reasons for chosing active amplification was that after about 30 minutes at a realistic volume the NAP250 would shut down.
I think the main reason for the top mounted drivers is to balance the two complete sets of speakers in the enclosure otherwise the two bass units would be either wired up in series (16 ohm) or parallel (4 ohm) and this would compromise the spectral balance.
The final part of the puzzle was to obtain the patent for the isobaik principle, patent number GB1500711, lodged 24/01/1975 expired 24/01/1993, just out of morbid interest hands up all those isobarik enthusiastics who have this document.
Currently I am powering these with 2xNAP135s for bass and another well kept secret 4xMeridain 105 amps for mid and hf.
The contempory reviews were critical of the power output, not suprising when one considers the amplifiers were powered in a daisy chain fashion from the 103 pre-amp.

Regards....


Re: Linn Isobarik Mods
Posted by: PatrickD
Date: 28/6/2003 05:09:00

Quote:
The contempory reviews were critical of the power output, not suprising when one considers the amplifiers were powered in a daisy chain fashion from the 103 pre-amp.
If you are talking about the Meridain 105s, each mono amp was actually in a double width box with its own PSU. The 103 was a 2 channel power amp with a built-in PSU, but you could increase power/performance by adding an addtional PSU. The 101 was a pre-amp; once again including the pre-amp PSU.

I still think that the Meridain 100 range was the most stylish hi-fi ever produced. Compact, minimalist, elegant. I don't know what happened to Mr Bothroyd, but if he styled the more recent Merdian stuff, he has definitely lost his way (IMHO).


Linn Isobarik Mods
Posted by: BarryJHart
Date: 28/6/2003 23:23:00

PatrickD
Well spotted, in fact the 105 power amps were connected to the 101 pre amplifier, they were connected daisy chain to supply the 240/110 volt AC supply and 7 pin Din to connect the audio.

The modifications I made to these units are:-
(1) - Power supply, install IEC fused/switched AC inlet.
(2) - Power amplifier, install dual binding post, XLR and RCA connectors.
With these units connected directly to the AC mains their performance is enhanced.
Regards....