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Experimenting with an Exaktbox Sub
2017-11-30, 22:20
Post: #41
RE: Experimenting with an Exaktbox Sub
(2017-11-30 09:25)Phil Budd (Philbo) Wrote:  
(2017-11-30 02:20)sunbeamgls Wrote:  The 74Hz is probably not a 'take over'. It will be a nominal crossover point.

For example, a mid-bass driver might have a nominal crossover point of 1500Hz. Depending on the crossover slopes of the design, that could mean that both driver are making a significant contribution from 1000 to 2000 Hz. As one fades out, ths other ramps up, leading to an approximately flat response.

Similarly for the sub. What would be interesting to understand please Philbo, is this: Does the steepness of the subwoofer roll-off to the main speakers vary depending on the model of main speakers? Using hypothetical examples, is an Exakt sub connected to 109s at full output from 10Hz to 50Hz and then rolling off quite steeply through to 74Hz and silent by 90Hz, but when paired with Akubariks is at full output from 10 to 30 Hz and then rolls off gradually and is silent by 80Hz?

The quoted 74 Hz corner is the corner of a 4th order very low Q roll-off, not a brickwall filter. The gain from the sub at 74 Hz is about 12 dB down, but due to the low Q of the filter it still only builds gradually as frequency decreases (-6 dB at 42 Hz, -3 dB at 30 Hz, close to -0 dB at 10 Hz). This allows the single filter to work well as both bass re-enforcement and bass extension.

Thanks for providing this additional information about the crossover characteristics of the Exaktbox Sub, Philbo. Now it makes sense to me.

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2017-11-30, 22:44 (This post was last modified: 2017-11-30 22:50 by Tin.)
Post: #42
RE: Experimenting with an Exaktbox Sub
Just one last question, as Exakt can handle subs both to extend the fronts, as provide the .1 channel in a surround setup, does that imply that for the .1 channel there is a standard steeper filter at 100 or 120Hz?

And the lastestest question:
I have to admit that the very slow filter with -12dB @ 74Hz seems really a smart solution to get the best for all relevant speaker sizes at the same time. Linear phase does change the rules (*)
I do wonder though, are all speakers able to attentuate at the same slow rate with lower frequencies?

*) This is the best sales argument for Exakt for me yet. So you've won. Still can't afford it though. Wink

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2018-04-17, 16:03
Post: #43
RE: Experimenting with an Exaktbox Sub
Will Linn ever revive and update its exaktbox sub and subwoofer range or has it gone the way of the pre-amp and CD player?



(2017-11-28 11:38)Phil Budd (Philbo) Wrote:  
(2017-11-28 10:14)Tin Wrote:  Hi Phil,
Is that 80Hz a prefixed value?

Yes, though having now checked the actual figure is 74 Hz.

(2017-11-28 10:14)Tin Wrote:  In the https://forums.linn.co.uk/bb/showthread.php?tid=37480 thread you mention that for measured 350s you achieve 85% phase linearity.

This variation is across the full operating bandwidth of the speaker. Most of the 15% is due to not modelling the mid-band response of the drive units in the array. The bass drivers are better defined. This will be common for all of our speakers.

The bass system in the Twenty.26 is less well defined by the model, thus my comments above.

(2017-11-28 10:14)Tin Wrote:  I'm not sure if this means that for an unmeasured, or even unknown, sub that means that the phase linearity will be less, say 75%?

The phase error on an unmeasured sub could be up to about 10 degrees. This error in relationship to the main speaker will be constant over the shared frequency range. The issue I highlighted with SunBeams set-up is that the error will not be constant due to the less accurate modelling of the transmission line in his main speakers.

(2017-11-28 10:14)Tin Wrote:  If so, and assuming that the phases are reversed to each other, that would imply that in the case of 350s both the speakers and the sub their mutual deviation down from 80Hz to the lower end of the 350s is quite a long trip.
For e.g. 109s the mutual journey down would end a lot sooner, giving better integration with a sub, even though the sub may still be a massive unknown.

I am trying to learn here, so if this is complete and utter bollocks, just say so. Smile

Not utter b******s but certainly a misunderstanding of what a subwoofer in a linear phase system will do. For a full range speaker it will provide bass re-enforcement, for a smaller speaker the same filter will provide bass extension.

(2017-11-28 10:14)Tin Wrote:  If however I sort of have a point (in the broadest sense of that word), wouldn't it be better to have lower crossover points, depending on the capabilities of the main speakers? SunbeamGLSs didgeridoos achieve 27Hz @ -3 dB if I remember correctly, so a crossover at around 35Hz for the sub would probably suit him much better.

Possibly it would be advantageous to provide the capability of altering the crossover frequency but we found that the current implementation works very well in the vast majority of cases.
The complications in implementing a variable filtering scheme are significant, not least because of the huge processing requirement of a linear phase filter at low frequency, something that would then need to managed by the customer or installer.

(2017-11-28 10:14)Tin Wrote:  The above is really a sanity check for me if I understand the phase linearity thing, this is such a confusing subject to grasp. Sad

Linear phase should make things easier to understand. If poor integration is usually due to phase variance between the subs and mains, then a linear phase system should always integrate better, whether it acts as bass re-enforcement or extension. Though as Sunbeam's system has highlighted this does depend on just how linear phase the system is...

Phil.
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2018-04-17, 17:41
Post: #44
RE: Experimenting with an Exaktbox Sub
(2018-04-17 16:03)LINN1989 Wrote:  Will Linn ever revive and update its exaktbox sub and subwoofer range or has it gone the way of the pre-amp and CD player?

Two questions here, really. The Exaktbox Sub is a current product, and will work with almost any sub-woofer (though it is better if it is one of the measured models). I'd expect Linn to keep it up to date as necessary, but I doubt that it's a candidate for a Katalyst upgrade.

As regards the sub-woofers themselves, all of them have been discontinued for some time and there has been no hint that Linn will introduce a replacement any time soon, or indeed at all. The sub-woofer market is dominated by use in AV rather than music systems, and the two requirements are arguably somewhat different. It could well be that Linn do not consider the development of a new sub-woofer model to be a commercially attractive proposition.

David

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2018-04-17, 21:54
Post: #45
RE: Experimenting with an Exaktbox Sub
(2018-04-17 17:41)DavidHB Wrote:  As regards the sub-woofers themselves, all of them have been discontinued for some time and there has been no hint that Linn will introduce a replacement any time soon, or indeed at all. The sub-woofer market is dominated by use in AV rather than music systems, and the two requirements are arguably somewhat different. It could well be that Linn do not consider the development of a new sub-woofer model to be a commercially attractive proposition.

Even my admittedly luddite-like nature can now see some commercial logic in Linn discontinuing the manufacture of CD players and standalone pre-amps. However, I can't for the life of me understand why Linn chose to stop making sub-woofers within months of releasing a dedicated Exaktbox for them. It seemed tantamount to dooming sales of the Exaktbox Sub pretty much from the outset, except to those lucky souls already in possession of Linn subs. I wonder what effect the decision has had on Exaktbox Sub sales?

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2018-04-18, 06:50
Post: #46
RE: Experimenting with an Exaktbox Sub
(2018-04-17 21:54)Fitter Stoke Wrote:  
(2018-04-17 17:41)DavidHB Wrote:  As regards the sub-woofers themselves, all of them have been discontinued for some time and there has been no hint that Linn will introduce a replacement any time soon, or indeed at all. The sub-woofer market is dominated by use in AV rather than music systems, and the two requirements are arguably somewhat different. It could well be that Linn do not consider the development of a new sub-woofer model to be a commercially attractive proposition.

Even my admittedly luddite-like nature can now see some commercial logic in Linn discontinuing the manufacture of CD players and standalone pre-amps. However, I can't for the life of me understand why Linn chose to stop making sub-woofers within months of releasing a dedicated Exaktbox for them. It seemed tantamount to dooming sales of the Exaktbox Sub pretty much from the outset, except to those lucky souls already in possession of Linn subs. I wonder what effect the decision has had on Exaktbox Sub sales?
I think it might be because of the Exaktbox sub tbh.
With an Exaktbox sub the added value of a expensive sub becomes less relevant. Modern expensive subs add all kind of features like room correction and fancy filtering techniques.

Without room correction Linn wasn't be able to compete against B&W, Velodyne or Paradigm.
But adding room correction to them would be pointless to any Linn customer owning a DS(M).
So suddenly Linn found themselves competing against cheaper brands like REL and BK.

With the Exaktbox sub it has become worse as even subs without sophisticated crossovers suddenly can be used.
Also, if someone comes at a dealer they'd be able to test between Exakted Akubariks without, and Exakted Akudoriks with a pair of Exaktboxed 345s. I'm sure you can guess what that would do with the sales of the more expensive proposition.

So, in a way, SO and the Exaktbox-sub killed the probably already declining sales of their older range of subs.

What they could try however is making a new range of subs with an integrated Exaktbox sub, but that should be able to assist Akubariks and Exakted 350s in a meaningful way too, without being too expensive for 109 and 140 owners.
Or, they could try to talk to BK or another brand and try to have a combined proposition.

My 2 cents etc etc

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2018-04-18, 07:54
Post: #47
RE: Experimenting with an Exaktbox Sub
Having experimented and purchased REL T9/i's with Exaktbox i would strongly recommend anyone to look at the REL range. I heard some of the discontinued Linn Subs via Exaktbox and they didn't come close to the performance of the RELs.

Most importantly the RELs did far more than bass reinforcement or bass extension, they opened up the whole soundstage - in many recordings I heard detail that had eluded me before. I couldn't;t live without them now!

Regards

Peter-Marc

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2018-04-18, 08:39
Post: #48
RE: Experimenting with an Exaktbox Sub
(2018-04-18 07:54)fortune Wrote:  Having experimented and purchased REL T9/i's with Exaktbox i would strongly recommend anyone to look at the REL range. I heard some of the discontinued Linn Subs via Exaktbox and they didn't come close to the performance of the RELs.

Most importantly the RELs did far more than bass reinforcement or bass extension, they opened up the whole soundstage - in many recordings I heard detail that had eluded me before. I couldn't;t live without them now!
As you have a pair of 350As and a pair of T9/i's in another setup, could you describe the difference in bass performance between the 2?
I'm collecting opinions about subs and differences between them and large floorstanders. Smile

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