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Linn Sara DMS to PMS Procedure
2012-02-01, 19:05 (This post was last modified: 2012-02-01 19:06 by Dr_Eddie.)
Post: #101
RE: Linn Sara DMS to PMS Procedure
So now the Active system is truly dazzling, where do I go from here ? Mud would say WTF play about ? just listen to music. Well, that is a truly valid point, ( although I could change that Blue wallpaper you dislike. You have good company Mud, my mate John ( The Meerkat ) hates it too...........................Big Grin

The next step is to have Peter fit a Khan in a few weeks time. That is a must, because it is a no brainer.

But after that ? Well, until the better weather I'll be listening to the music with a vengeance but in the Spring when the workshop and shed become more inviting, I'll be working on my DMS pair to convert them to Active operation.

The big difference with those is that I will be using a different B200 drive unit to the one employed by Linn. Why ?

Well years ago, I used to build speaker cabinets for bass guitarists, I actually made up one for myself and a number of people asked me to build them one as well. Now one thing that is common to all drive units that employ the moving coil principle is that the size of the magnet dictates how much control the amplifier can exert on the voice coil. The more gauss, the better the speaker sounds. Its that simple.


The SP1014 used by Linn has a very small magnet, the SP1022 has one that is double the size ( in width it is almost the same diameter as the spider. It is massive. That drive unit offers better speed, control and lower levels of colouration and compression than the SP1014. Combine that with the new D2008/851200 Scanspeak tweeter and you have a Super Sara or as I intend to call it.

The Sara X ( Ten ),
You will read about it in due course.

Why? because I Kan.Cool

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2012-03-28, 01:07 (This post was last modified: 2012-03-28 01:08 by Dr_Eddie.)
Post: #102
RE: Linn Sara DMS to PMS Procedure
Before I start on the Sara X it would be a good idea to post a review of the Linn/Naim Sara system by one Peter Herring. This was a systems spotlight feature, and Peter gets to hear a full on Sara system in his own home installed by Chris Thomas Audio ( another reviewer turned retailer ).
It is a truly worthy review and sums up what the system is all about. Peter went on to work for HiFi Review as their Classical Music reviewer.



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2012-03-28, 01:34
Post: #103
RE: Linn Sara DMS to PMS Procedure
(2012-03-28 01:07)Dr_Eddie Wrote:  Before I start on the Sara X it would be a good idea to post a review of the Linn/Naim Sara system by one Peter Herring. This was a systems spotlight feature, and Peter gets to hear a full on Sara system in his own home installed by Chris Thomas Audio ( another reviewer turned retailer ).
It is a truly worthy review and sums up what the system is all about. Peter went on to work for HiFi Review as their Classical Music reviewer.

SNIP

Great stuff, Dr_Eddie; BTW, was this your 500th post?
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2012-03-28, 01:39
Post: #104
RE: Linn Sara DMS to PMS Procedure
Wow, never noticed that CFE, signs of a misspent oldage. Where did I find the time for all that ?
I'm cream crackers............................

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2012-03-30, 19:22 (This post was last modified: 2012-03-30 19:40 by Dr_Eddie.)
Post: #105
RE: Linn Sara DMS to PMS Procedure
Sara X The Next Generation

If you think I’m a greedy so and so, I wouldn’t blame you. I am now the proud owner of a classic Linn/Naim Active Sara system which I’ve always aspired to.

It doesn’t disappoint in any way, in fact it is jaw droppingly good, all the more so since Peter fitted my deck with a Khan top plate. In many ways this has played to the strengths of the Saras to such a degree that I wouldn’t have been surprised if Khan hadn’t actually been developed using a pair of these speakers, far fetched as it may seem.
Such is the synergy that results.

I’ve always said that Saras are a drummer’s speaker, well with Khan, they appear to be just about THE BEST drummer’s speaker. Never before have I heard drums sound more real and palpably there, physical and visceral in their presentation. That is a real architectural strength that is incredibly satisfying to behold. The rest of the music just falls into place around that. So you would think I’m satisfied. Well, I am……….

And yet……………. here I am about to embark on a new project to see if this awesome speaker is capable of still more performance. Greed ? or plain foolhardiness ? We’ll see.
Well, I have my old DMS pair gathering dust now, and I wish now to convert these to Active operation also.

These were made around 1984 and the cabinet work appears to be of a higher standard than the pair I converted last year. Linn had gradually improved many aspects of the build quality, although they still favoured the SP1014 Kef B200 drive unit.
As far as B200’s go though, this is a low performance model which is quite basic.
There is a sizeable body of opinion now, that there were far better B200’s available from Kef. The question being, why did Linn choose the SP1014?

The answer, I believe, is right at the beginning of this thread, in that original pamphlet supplied by Linn.
[Image: Sara_Pamphlet_2.jpg]

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The clue is in the Application paragraph. The large Isobarik DMS speaker could give problems in certain domestic situations. Particularly, if the room had a problem in the bass area. As Linn point out, in these situations the Sara could give preferable results.

It seems logical therefore that the Sara was never developed to its ultimate performance level, since this would mean putting out higher levels of bass. This, then, ultimately defeats the principle behind the development. It was more of a troubleshooter designed to augment the DMS, not to usurp it. In that context the choice of drive unit seems obvious.

However, in my case, with a good room acoustic and fairly large size, it is a question that has been playing on my mind. What if?

In this case, the what if, is to experiment with a known higher performance B200. I already have raised the tweeter performance onto a higher level with the ferrofluid Scanspeak 851200 unit which is capable of handling 150 Watts RMS output, so it seems obvious that a B200 with a huge magnet assembly in comparison to the 1014 will yield benefits in definition, speed and control, and sensitivity. In other words a much higher performance than Linn originally foresaw or intended.

The only way to find out is to try it. Of the various large magnet versions, I have narrowed down the field to 2 units. The SP1022, and the SP1039.

The SP 1039 is to my way of thinking the ultimate B200. It has a magnetic field of 117,000 Maxwells, compared to the 1014’s 58,000. ie double the flux. It also sports a 1.25 inch voice coil of aluminium which can withstand high sustained temperatures.
Each 1039 can handle 80 Watts continous program, compared to the 1014 which can only handle 50. The 1039 weighs in at 3 kgs compared to 1.47 for the 1014.

The temptation to go for broke with this unit is strong, but events have conspired against me, for the time being. I am one unit short. I have it on back order.
For now, I have to use the SP1022 instead.

Electrically and mechanically the 1022 is almost identical to the 1014. Cone material, surround, and compliance are identical. The voice coil ( 1 inch ) is exactly the same size and impedance. Power handling is the same i.e. 50 Watts R.M.S. continuous.

This power rating still means each cabinet can handle 250 Watts continuous program. It will take the full power of two Naim NAP 135’s. That is a considerable output.
Together a pair of such modified Saras will handle 500 Watts. Enough to bring the police easily.

The main difference between the two drive units then, is that the 1022 sports a large magnet. Although not as powerful as the 1039, it is still 67,000 Maxwells as opposed to 58,000. That should easily be sufficient to bring large benefits. So that is the way I intend to proceed.

The first cabinet has been stripped down to a carcass already, and I have encountered problems caused by the original build. As stated earlier the cabinet work is much better, a stronger shell, with much improved sealing and sound deadening. The inside walls being painted with bitumastic. This is better than the earlier cabinets but bitumastic flashing is better still, and will be also applied to these cabinets.

What was more disappointing was that the front extension ring fittings were compromised by whoever assembled the right hand cabinet. One of the blind brass inserts which are used for fixing the front baffle ring into position had been pushed into the plastic baffle housing so far, the screw couldn’t reach it. This fixing was nonexistent. The pressure chamber was compromised by this, but whoever did the assembly must have known, but just carried on regardless. This person also used a ridiculous amount of sealer (for the reason above) everywhere. This cabinet was literally an abortion. It should never have left the factory like that, in my opinion.
The person’s initials were JP. This person also tested it. I believe another operative should have tested it. Then any substandard work is more likely to come to light before it leaves the factory.

It was always lean and bass shy, and now I know why. To be honest there were plenty of stories that did the rounds of some Saras sounding awful. I never believed that the speaker was at fault, I always suspected the set up. Now, I’m not so sure anymore.

The build quality of the first cabinet was execrable, hot melt glue everywhere, all over the inner bass driver, causing the cone surround to become unglued in 3 places on the chassis. That completed the total lack of pressure sealing. There was none. It was made by a charlatan. Sorry Linn, but that someone shouldn’t have been let loose on the assembly line. All it takes is care. I shall be putting a lot of that into this rebuild.

With that disappointment out of the way, the good news is that the quality of the cabinets themselves is far superior to the earlier flat fronted models.

Those were made from chipboard, and lacked damping, these are made of high quality MDF, which is thicker and far more “dead” than the chipboard of the earlier model. The damping internally is far better, proper lambswool and the whole interior is now painted in thick bitumastic. The real wood veneer is applied in such a superb way, that the cabinet looks and feels like it is made from real hardwood. There is now a rounded edge front to the enclosure and a proper veneered rear back panel with a radiused edge.
The whole thing is just notched up a good few levels.

So we can expect the cabinet to have less cabinet talk, and be faster, with less overhang and even less colouration. And that is before we upgrade the drive units. This time around I’ve decided to use a much better digital readout soldering station, and employ solder that Peter recommends and uses. 60/40 Tin-Lead solder.

Before, for the first pair, I used lead free. It made things difficult and arguably we can expect better sonic performance from this amalgam solder, applied at the correct temperature. Another improvement worth having.

The internal cabling will again employ Brocot 50 Amp Transformer Litz cable, as this has proved to be highly musical, and it does the job admirably.

The first cabinet is stripped right down, and I have cut the input holes for the plates which will carry the 4mm Deltron panel sockets for the Naim plugs. This is a superior connection to the old XLR sockets, so we will stick with it again.

Work has now started on stripping the second cabinet and hopefully we won’t find any more nasties.

The next update, I do, we will have a look at the various B200 units I now have in stock, and see how they differ. Much more interesting !

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2012-04-03, 16:32
Post: #106
RE: Linn Sara DMS to PMS Procedure
Well, if I didn’t expect to find nasties in the other cabinet, given that the same person’s initials were clearly present on the serial number label, then I was deluding myself.
This operator was clearly on a lower rung altogether. The main baffle to cabinet fixing was clearly displaying evidence that the operator had experienced problems getting tight fixings. Since this is arguably the most important aspect of the whole cabinet, the portent for top performance (which I had a right to expect ) was not good.

Things were a whole lot worse than I could imagine. Where this person was unable to get fixings, they’d hammered in rawlplugs through the baffle holes. This had split the wooden rebate in 1 places causing the wood to break away, leaving the screw exposed in thin air. It required a delicate repair grafting a new piece of wood into position.
I was not pleased by this at all. What on earth is the point of making improvements in the cabinet and damping when some Neanderthal is putting the cabinets together with about as much care as a bull in a china shop?

No wonder my rebuilt early cabinets so outperformed my clunkers. The only bit of good news being, that all T-bolt fixings in the plastic baffle, were all present and correct.
I had to effect a repair on the first baffle by encasing a crossover fixing nut into Araldite using a vaselined fixing screw. The nut had been lightly tapped into an enlarged hole. You can see the repair here.

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In this next shot you can see the improved damping in this later cabinet.

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So now both cabinets are completely stripped down, repaired where necessary, and the holes for the new input plates and Deltron 4mm socket panels have been cut, sanded and predrilled with fixings. I now await my new Digital readout soldering station and tin/lead solder. Then the rewiring for Active mode will be enacted.
I also once again, await a new pair of the truly wondrous D2008/851200 Ferro fluid damped tweeters. This unit is now even cheaper (I saved a full £20=00), on my previous order a year ago, due to the weak Euro. That is a big plus, and makes this unit one of the best upgrades possible for next to no money. It outperforms units costing many times this price, blows away the early D2008 originally fitted, which is so crude by comparison. I have it on good authority from other forum members that it also blows away the Hiquaphon unit that replaced the D2008. It really is a no brainer for anyone with Kans, Saras or Isobariks., and it has improved one member’s SBLs too.

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2012-04-03, 16:41 (This post was last modified: 2012-04-03 16:45 by Dr_Eddie.)
Post: #107
RE: Linn Sara DMS to PMS Procedure
Now we come to the 8 inch bass/mid driver that forms the heart of this deceptively simple speaker. The famous KEF B200.
There were 5 versions of this drive unit made by KEF.

These were:
1. The SP1014
2. The SP1022
3. The SP1039
4. The SP1054
5. The SP1063

Here are the data sheets for each model in turn:

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First of all, take note that the final model SP1063 is identical to the SP1014 apart from the fact that the voice coil is wound in aluminium instead of the usual copper.
The effect of this can be seen in the temperature endurance of the coil.
This is raised from 180 deg. C to 250 deg. C although strange as it may seem, the power handling and sensitivity are completely unaffected. So this unit offers barely any improvement apart from a more rugged voice coil.

Let’s take a look at the physical features of each drive unit,

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This is the unit favoured by Linn, the SP1014, also known as the white belly B200 for obvious reasons. The convex cardboard dust cap is added by Linn, and was later deleted as unnecessary. What useful purpose it served is debatable. I have listened extensively to both white belly and standard Kef versions and could not detect any difference at all.

You will notice that the spider is coated in thick bitumastic paint, which is supposed to deaden resonances, but actually has very little effect. I found the roof flashing much more effective and cleaner to use. The chassis is practically inert after such treatment. Note the size of the magnet assembly.

Now we come to the SP1022 unit. Compare the data sheet of this unit to the 1014.




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Take a gander at the magnet assembly…………………………………..this is a serious rework of the complete motor assembly.
A sort of, stage 2 tuning kit, if applied to the automotive comparison.

Now we come to the SP1039……………………………………look at the data sheet again.

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The motor unit on this is one beast, trust me. This is the audio equivalent of a fast road/rally engine. If this doesn’t sound incredible I’ll eat my hat. As explained before I only have 3 of these units at the moment, it shouldn’t be too difficult to grab another though, and when I do, the inevitable re-rebuild will take place. But for now I’m content to try the SP1022. This will decide if there any merit at all in the big magnet B200’s

I’m almost certain there will be huge benefits, the reasons why Linn chose the most weedy unit will remain a mystery to me, if I’m proved right but time will tell.

Wait a minute though, there IS another B200 I haven’t yet discussed. The SP1054.
If the SP1039 is a fast road/rally unit then the SP1054 is a full race/ running on nitro.
If I ever get my hands on 4 of these…………………..well the neighbours will be quaking in their boots. A sensitivity nearly double that of the 1014 and 100 watts continuous RMS program. That means each Sara could handle 350 Watts,
700 watts the pair. That beggars belief, ye gods not even the big Briks could come close to that.

And there is one important point to note here as well, a good small 2-way speaker is always better integrated than a large 3-way. I rest my case for now.
Stay tuned to see what happens with 1022’s.

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2012-04-03, 16:41 (This post was last modified: 2012-04-03 16:48 by Tony Tune-age.)
Post: #108
RE: Linn Sara DMS to PMS Procedure
I really like your Sara speaker projects Dr. Eddie. You are doing a detailed job of rebuilding, just wish I could hear how they sound! Looking forward to reading more, I'm learning a great deal about the Sara speaker, than ever before! Good luck once again Cool.
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2012-04-03, 16:51
Post: #109
RE: Linn Sara DMS to PMS Procedure
By the way, great pictures too!
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2012-04-03, 17:00
Post: #110
RE: Linn Sara DMS to PMS Procedure
Well Tony, if you are ever in the UK ( near London ) you are cordially invited to the Toby Jug Blues Club, ( my front room ) to do just that. It would be my pleasure. Check out the Khan thread later on as I upload some pics of Peter's rebuild the night before he left on the Cymbiosis Gallivant USA Tour 2012. A lot of happy peple left in the wake of that.

Classic Linn/Naim Six Pack Active Brik System.
Turbocharger driven by a Peter Swain Signature LP12 Music Power Station
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