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Room Info in SO
2018-07-12, 17:56
Post: #1
Room Info in SO
I have 2 questions about SO that I hope someone can shed some light on?

My understanding, please correct me if I’m wrong, is that SO applies a constant to derive the bandwidth for each mode. I say this because within my optimisation, if I multiply bandwidth X frequency for any mode, I get the same value, 3.22.

If I enter different room information, e.g. change everything to ‘concrete’ the bandwidth narrows because the constant, now 1.88, is much lower.

If I change everything to ‘unknown’ the bandwidth widens for each mode because the constant, 3.53, is greater.

If I change everything to ‘partition' the bandwidth widens to its maximum for each mode because the constant, 4.00, is greatest.

So, it seems ‘concrete’ represents the hardest surface, ‘partition’ the softest with ‘unknown’ somewhere between.

Entering my room information into the reverberation calculator at http://www.sengpielaudio.com/calculator-RT60.htm gives me an estimated reverb time of 1.13 seconds – far from desirable I know. So, I’m keen to make sure I enter the right information into Konfig.

Q1 My rear wall is fully glazed with 3 equal sized sliding panes. Does SO treat windows as bare glass or does it presume some sort of covering? I have floor to ceiling blinds that cover the windows when I’m listening as they greatly reduce the reverberation in what is an acoustically ‘bright’ space.
If SO treats these windows as bare glass, would I be better to exclude the windows and simply treat the wall as ‘unknown?’ Would someone in a similar situation but using heavier curtains/blinds be better specifying the wall as ‘partition?’

Q2 Has anyone measured their room or had it measured professionally using a recognised software app and a decent mic at the listening position, to find out the actual modes? If so, were the results very different to the calculations in SO? If you were able to implement the real-world frequencies, (I understand that within the range of adjustment in Konfig and having only 4 custom modes this may not have been possible), did it enable you to better optimise the sound for your room?

Sorry, rather more than just one question here! Wink

AEDSM, Exakt Akubariks, Innuos Zenith MkII, Supra mains & ethernet cables (main room) : Sneaky DSM in bi-amp mode, 4 x Sekrit 104C_R, K20 cable (kitchen/diner)
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2018-07-12, 18:19 (This post was last modified: 2018-07-12 18:20 by DavidHB.)
Post: #2
RE: Room Info in SO
(2018-07-12 17:56)RobF Wrote:  So, it seems ‘concrete’ represents the hardest surface, ‘partition’ the softest with ‘unknown’ somewhere between.

Yes. Linn have said in the forum that this is the case.

(2018-07-12 17:56)RobF Wrote:  Q1 My rear wall is fully glazed with 3 equal sized sliding panes. Does SO treat windows as bare glass or does it presume some sort of covering? I have floor to ceiling blinds that cover the windows when I’m listening as they greatly reduce the reverberation in what is an acoustically ‘bright’ space.
If SO treats these windows as bare glass, would I be better to exclude the windows and simply treat the wall as ‘unknown?’ Would someone in a similar situation but using heavier curtains/blinds be better specifying the wall as ‘partition?’

No, I don't think so. I think that it's best to 'document' the room as accurately as possible. As a reflector/absorber of sound, glass behaves very differently from partition. You can deal with the combined effect (and it is combined) of textiles and other absorbent materials in subsequent adjustments, typically by reducing the depth and possibly the bandwidth of the originally calculated mode filters.

(2018-07-12 17:56)RobF Wrote:  Q2 Has anyone measured their room or had it measured professionally using a recognised software app and a decent mic at the listening position, to find out the actual modes? If so, were the results very different to the calculations in SO? If you were able to implement the real-world frequencies, (I understand that within the range of adjustment in Konfig and having only 4 custom modes this may not have been possible), did it enable you to better optimise the sound for your room?

There have been a number of approaches tried and documented in this forum. Linn themselves say that measurements using a microphone are less reliable. You can read Gilad Tiefenbrun's blog on the subject here, and decide whether or not you agree with him. For myself, I like the Linn system because, conceptually at least, it is clean and tidy and doesn't require messing around with extraneous equipment. Also it is an heuristic system that allows the user to adjust the initial results.

David

Main system: [LP12* > Lejonklou Gaio >][Roksan Kandy Mk III >] KEDSM > Akurate Exaktbox 10/1 > Linn Silvers> A4200 x 2 and A2200 > K600 > Akubariks.
*LP12: 1987 fluted plinth; Cirkus; Lingo 4; Trampolin; Kore; Basik Plus arm; K5 cartridge, Paratrace stylus.

Second system: Kiko.
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2018-07-12, 19:07
Post: #3
RE: Room Info in SO
Yes, SO seems to calculate a constant value for the whole of your room and that dictates the bandwidth of all room modes. I did wonder once in the past why it was always a constant - eg if the front and back walls were concrete and both side walls were partition, you'd think ideally the calculated bandwidths for the length modes would be different to those of any width modes. The reply (from a Linn employee no less!) was to drink wine and not worry about it. That seems to be a general theme on here - drinking alcohol makes your system sound better. Personally I'd think that was a pretty poor marketing ploy Big Grin

Anyway - as to the blinds - remember that SO is dealing only with standing waves in the lower bass region - 80Hz and below - sound waves of that wavelength will likely not be too troubled by a bit of cloth. For higher frequencies of course they will and do make a difference - and I expect they help with that RT60 time as a result.

Q1 Adding windows and doors into SO does absolutely nothing concerning reflected sounds - all they do is to modify that constant absorption number that you've discovered - and makes a corresponding alteration to the depth of the cut. Make a 'window' bigger and you'll get a wider & shallower filter. So, you could theoretically use window and door dimensions as a way to fine-tune the results - though the amount of adjustment you can get is pretty limited. Similarly changing the construction materials has the same effect. In the end though, it's probably best to keep it 'real' as future improvements in SO would be working with an accurate model.

Q2 Measuring the room with a microphone - I'm not sure if that will give you the opposite of what SO is giving you. ie SO is calculating a depth of cut which will prevent standing waves forming at that particular frequency. If your room is measuring a 15dB hump at xHz due to a room mode, taking 15dB out at that frequency will give you a flat response, but may still excite the room at that frequency and create a standing wave which takes time to decay. SO I think is overshooting the value which gives a flat response in order to prevent the standing wave forming. That's why it's such a delicate balancing act trying to fine-tune it.

All imho of course.

ADs/2 -> Klimax Exaktbox/1 -> Silvers -> 2xKCT/D -> K200 -> Ninka
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2018-07-13, 13:33 (This post was last modified: 2018-07-13 13:49 by Glyn Ruck.)
Post: #4
RE: Room Info in SO
Velodyne's 5 calibrated Microphone kit with the SMS 1 or DD Series Subs works very well & allows you to view on screen/TV what is going on in the room.

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2018-07-13, 13:54 (This post was last modified: 2018-07-13 13:55 by Glyn Ruck.)
Post: #5
RE: Room Info in SO
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2018-07-13, 17:33
Post: #6
RE: Room Info in SO
Thanks for the replies. Smile

Particular thanks to you Glyn for the images.

How did the real-world frequencies compare to those calculated by Space? If they differed, were you able to apply them in a SO and how did that sound compared to calculated modes?

AEDSM, Exakt Akubariks, Innuos Zenith MkII, Supra mains & ethernet cables (main room) : Sneaky DSM in bi-amp mode, 4 x Sekrit 104C_R, K20 cable (kitchen/diner)
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2018-07-13, 23:31 (This post was last modified: 2018-07-13 23:36 by Glyn Ruck.)
Post: #7
RE: Room Info in SO
I don't use SO as I don't use Linn electronics or speakers. Many here use subs & I wanted to show some alternatives & real room measurements. I only use DSP on my 4 Subs. I have tried some of the worlds finest DSP units in my system & don't find them transparent further up the frequency range. I'm contemplating a Linn Streamer amongst others. So I read Paul's SO quests with great interest.

As such I don't necessarily agree with Gilad's comments other than possibly complexity.
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2018-07-16, 12:38
Post: #8
RE: Room Info in SO
My experience with sound improvement through tuning calculated SO brought bandwidth of room modes as maybe most influential parameter. Changes of modes bandwidth were not done manually because of so many combinations possible, but I relied on changes that came through inserting or deleting room features as noted above.
Through listening to many different combinations of adding or deleting room features, changing room modes gain and speaker positioning in relation to back wall, one thing was always constant, the best clean, musical and enjoyable sound was always achieved with wider room modes that are achieved with adding single glazed cabinet glass door and double glazed window.
Changing other parameters did result in some audible changes in sound but all combinations with wider room modes happened to be superior in sound to those with narrower room modes regardless of other changes.
Of cause one of this combination with wider room modes turned to be the best compromise and this was as could be expected in line with tune dem procedure of best speaker positioning in room without SO turned on.
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2018-07-16, 18:15
Post: #9
RE: Room Info in SO
Thanks. I’ve found the same. It depends on your room, but in mine the audible effects of each mode extend over 3 – 4 Hz. So, for me, so a wider bandwidth is better. Particularly if it means I can reduce the amount of cut.

The problem is that in order to force Space to widen bandwidth I have to enter false information about the room, e.g. specifying the rear wall as ‘unknown’ or ‘partition’ rather than three 2.5m x 2.25m double glazed units. I feel that an option within Space to enter window dressing is important. I know that LF sound waves behave differently when meeting glass but in my room I always pull down the tight cotton blinds as they reduce the reverberation time. The glass surface is never exposed.

The reason I asked about acoustically measuring a room is because I presumed Space would get the mode frequencies correct as they are, by and large a consequence of the room dimensions. However, it does presume a rectangular room and I don’t have that.

Using test tones I hear a noticeable resonance through 25Hz and 27 Hz. Space identifies this at 27.52 so I can reduce the calculated freq.

The next resonance is between 30Hz and 33Hz, but Space doesn’t calculate this at all. So, I need a 31Hz custom mode for this one.

The next is through 56Hz and 59Hz. The nearest in Space is 55.04Hz but beyond the range of adjustment. So, an alternative custom mode is needed.

When I stumped up my £30k for the Akurate Exakt system, I really didn’t think that getting it to work at its best in my room would be quite so onerous. No wonder so many set all to 0db and live with the downsides.

Years ago I recall the founder of Linn, Ivor Tiefenbrun, being taken to task over ‘subjective’ listening and his reply was that on the contrary, measurements were of tremendous importance – so long as you measure the right things. Space, of course, doesn’t measure anything. Its just a calculated guess but it is based on the room info we enter. If I could only enter more complete information, the better that guess might be.

AEDSM, Exakt Akubariks, Innuos Zenith MkII, Supra mains & ethernet cables (main room) : Sneaky DSM in bi-amp mode, 4 x Sekrit 104C_R, K20 cable (kitchen/diner)
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