Linn Forums

Current time: 2017-12-15, 03:35 Hello There, Guest! (LoginRegister)

Linn Forums / Linn Music Systems & Hi-fi Separates / Network Music Players & Music Streamers / Space Optimisation v / Space optimisation problem

Post Reply 
Space optimisation problem
2017-07-17, 16:22
Post: #21
RE: Space optimisation problem
(2017-07-17 14:29)fredbatch Wrote:  
(2017-07-16 12:54)Dave W Wrote:  Having played around with SO on both my systems I will chip inShy

My main room is rectangular so relatively easy to enter the SO criteria.
This led to an immediate improvement getting rid of obvious resonances.

My second system is in an L shaped kitchen/dinning room with very oddly positioned speakers due to wifey constraints.
SO here still sounded a bit "odd" ,although better than without.

Lacking Paulsurrounds magic ears I then went through a HiFi test disc (Hi Res). Listening to the lower frequency tones up to about 200Hz showed lots of issues in the L shaped room. So I added custom filters to 'equalise' the test tones (by trial and error).
That improved things massively.
Good way to while away a few hoursTongue

Any way the result is musical happiness.Big Grin

Managing L-shaped rooms is difficult.

Managing Wifey constraints is very difficult.

Managing L-shaped rooms combined with Wifey constraints is pretty much impossible. Good luck.

Yep,

In both cases you never quite know what's round the cornerTongue

KDSM3/Aktive Akubariks/Innuous Zen11
LP12/Ekos/Dynavector XX2/Lingo/Cirkus/Kore/Rega Airia
Kitchen-MDSM/PMC DB1
Find all posts by this user
Quote this message in a reply
2017-07-18, 07:49
Post: #22
RE: Space optimisation problem
(2017-07-14 21:56)fredbatch Wrote:  Regarding carpets vs. structural materials, don’t forget that SPACE is concerned primarily with counteracting the unwanted effects of modal frequencies below 100Hz. In an enclosed resonant chamber such as a room, the absorption and dissipation of these lower frequency energies, and the subsequent remaining amount of resonant energy that has to be managed, is more dependent on wall, floor and ceiling construction materials than it is on the surface material properties. Coverings such as carpets, curtains, cushions, etc. are more relevant to higher frequency absorption, and hence reverberation time (i.e. affecting whether the room tends towards sounding live or dead).

It’s worth noting, though, that the bandwidth (rather than amplitude) of resonance modes varies inversely with reverberation time. It stands to reason that compensatory modal cuts, however they are applied, should have correspondingly broader or narrower bandwidths in accordance with reverberation times. To generalise, if your room is scantily clad, it might be worth experimenting with further narrowing the default calculated SO bandwidths, and vice versa.

Mostly correct, except that reverberation time varies with frequency. It is most often given as a single figure (RT60) which is calculated as averaged over the octave bands between 125 Hz and 8 kHz. This, rather importantly, does not include the reverberation time at the frequencies of most interest to Space optimisation.

Space uses the provided room dimensions and construction information to estimate the reverberation time in the 63 Hz octave band and uses that figure to provide the bandwidths for the applied mode filters. As stated, carpets and curtains will have little to no influence on such low frequency content.
Usually absorption values are used for generating estimates of reverberation time. For the low frequencies of interest to Space optimisation there is little to no absorption data available, so instead I used transmission data (what scant data I could find, the rest calculated either theoretically or empirically). Absorption and transmission can be considered as equivalent in this instance as they describe the amount of sound energy lost from the room (not reflected back by the surface). When considered this way it is quite apparent that single and double glazing will have a marked difference at low frequencies.

Phil.
Find all posts by this user
Quote this message in a reply
2017-07-18, 23:08
Post: #23
RE: Space optimisation problem
(2017-07-18 07:49)Phil Budd (Philbo) Wrote:  
(2017-07-14 21:56)fredbatch Wrote:  Regarding carpets vs. structural materials, don’t forget that SPACE is concerned primarily with counteracting the unwanted effects of modal frequencies below 100Hz. In an enclosed resonant chamber such as a room, the absorption and dissipation of these lower frequency energies, and the subsequent remaining amount of resonant energy that has to be managed, is more dependent on wall, floor and ceiling construction materials than it is on the surface material properties. Coverings such as carpets, curtains, cushions, etc. are more relevant to higher frequency absorption, and hence reverberation time (i.e. affecting whether the room tends towards sounding live or dead).

It’s worth noting, though, that the bandwidth (rather than amplitude) of resonance modes varies inversely with reverberation time. It stands to reason that compensatory modal cuts, however they are applied, should have correspondingly broader or narrower bandwidths in accordance with reverberation times. To generalise, if your room is scantily clad, it might be worth experimenting with further narrowing the default calculated SO bandwidths, and vice versa.

Mostly correct, except that reverberation time varies with frequency. It is most often given as a single figure (RT60) which is calculated as averaged over the octave bands between 125 Hz and 8 kHz. This, rather importantly, does not include the reverberation time at the frequencies of most interest to Space optimisation.

Space uses the provided room dimensions and construction information to estimate the reverberation time in the 63 Hz octave band and uses that figure to provide the bandwidths for the applied mode filters. As stated, carpets and curtains will have little to no influence on such low frequency content.
Usually absorption values are used for generating estimates of reverberation time. For the low frequencies of interest to Space optimisation there is little to no absorption data available, so instead I used transmission data (what scant data I could find, the rest calculated either theoretically or empirically). Absorption and transmission can be considered as equivalent in this instance as they describe the amount of sound energy lost from the room (not reflected back by the surface). When considered this way it is quite apparent that single and double glazing will have a marked difference at low frequencies.

Phil.

Thanks for this further clarification. Some interesting reflections.

It all demonstrates that, with the lack of hard data available, the SPACE mode filter model is breaking into ever new territory. Onwards and upwards, fascinating stuff.
Find all posts by this user
Quote this message in a reply
2017-08-25, 18:22
Post: #24
RE: Space optimisation problem
(2017-07-18 07:49)Phil Budd (Philbo) Wrote:  
(2017-07-14 21:56)fredbatch Wrote:  Regarding carpets vs. structural materials, don’t forget that SPACE is concerned primarily with counteracting the unwanted effects of modal frequencies below 100Hz. In an enclosed resonant chamber such as a room, the absorption and dissipation of these lower frequency energies, and the subsequent remaining amount of resonant energy that has to be managed, is more dependent on wall, floor and ceiling construction materials than it is on the surface material properties. Coverings such as carpets, curtains, cushions, etc. are more relevant to higher frequency absorption, and hence reverberation time (i.e. affecting whether the room tends towards sounding live or dead).

It’s worth noting, though, that the bandwidth (rather than amplitude) of resonance modes varies inversely with reverberation time. It stands to reason that compensatory modal cuts, however they are applied, should have correspondingly broader or narrower bandwidths in accordance with reverberation times. To generalise, if your room is scantily clad, it might be worth experimenting with further narrowing the default calculated SO bandwidths, and vice versa.

Mostly correct, except that reverberation time varies with frequency. It is most often given as a single figure (RT60) which is calculated as averaged over the octave bands between 125 Hz and 8 kHz. This, rather importantly, does not include the reverberation time at the frequencies of most interest to Space optimisation.

Space uses the provided room dimensions and construction information to estimate the reverberation time in the 63 Hz octave band and uses that figure to provide the bandwidths for the applied mode filters. As stated, carpets and curtains will have little to no influence on such low frequency content.
Usually absorption values are used for generating estimates of reverberation time. For the low frequencies of interest to Space optimisation there is little to no absorption data available, so instead I used transmission data (what scant data I could find, the rest calculated either theoretically or empirically). Absorption and transmission can be considered as equivalent in this instance as they describe the amount of sound energy lost from the room (not reflected back by the surface). When considered this way it is quite apparent that single and double glazing will have a marked difference at low frequencies.

Phil.

I heard what, I think, was a practical example of absorption and transmission this morning. I was out walking my dogs and passed a neighbour's house where he happened to be playing his piano. What was interesting was that I could clearly hear some bass notes through his double glazing and yet others were almost inaudible. If you consider that the energy associated with just those notes was leaving the room, you can see the value of SO.

'troll
Find all posts by this user
Quote this message in a reply
Post Reply 


Forum Jump:


User(s) browsing this thread: 1 Guest(s)