English Premier or International (HiFi) - Tournament Preparations Begin

[Innocent_Bystander]

Interesting because rather different from reviews I had read a few years ago on the Torus, the IGx’s predecessor! Regarding roll-off, I assume it is to match with main speakers having a similar rolloff, as you suggest probably with their own in mind. In terms of moving air, IIRC it is an 18” driver, with large excursion, which in all but the largest rooms should be quite capable - though as with any sub I’d expect a pair to be better than one. From the specs (of Torus) and reviews I expected it to do wonders (though only for music not cinema effects).

I’m unclear why upwards firing at such low frequencies should be an issue - I wouldn’t expect any difference from horizontal, my only reservation about that was risk if something were to fall on it (also dust pickup, but soon blasted off!). I suppose you could use on its side, with a couple of chocks to prevent runaway!

[Edmund-of-Essex]

Hi again @Innocent_Bystander . I really wanted to like this WG IGx.

The way I see it is there is still quite a bit of innovation going on in very low frequency sound reproduction. As a research engineer, I note the effort by WB to really change the landscape. However they have fundamentally fallen short in the electronic control and integration aspects with this product. In contrast, Linn, with their PWAB and digital DAC in their most recent top of the range floorstanding loudspeakers have something interesting.

Magico, with their American conventional sub bass concept and brute force approach but integrated intelligently with a fantastic DSP.

The DSP permits so much direct control over time delay, filter characteristics (choices of Bessel, Critical, Butterworth and Linkwitz Riley) along with filter order, (variously, 1, 2, 3, 4, 5 & 6 depending on filter type selected), corner frequency, gain AND, having done all of that selection, additionally an audio band graphic equaliser, each band with tuneable corrections of filter Q and centre frequency.

In contrast the IGx can only be limited down to 30Hz corner frequency, continuously variable gain and phase (that can easily be knocked out of position) and a semi random ‘ears’ based tuning approach - Ugh.

Now, combine elements of all three of the above, and maybe we have something useful!

PS: The IGx cannot be operated tipped on its side, but I am sure you knew that!

[Innocent_Bystander]

Yes, I’m a big fan of DSP AXOs, and it was a bit surprising that WB use passive. Re tuning, as I know you know you can of course use a third party monitor like REW, provided the XO frequency isn’t too low for the mic.

[Innocent_Bystander]

@Edmund-of-Essex, I just stumbled upon a sub I’d never come across before, which might fulfil your desire for air movement…

Also called an Infrasonic Generator it is the Ascendo SMSG50. The driver is a mere 50”!

[Edmund-of-Essex]

Hi IB, wow, if only you had mentioned this sooner! I too had not been aware of this product, but the manufacturer does seem to know what they are doing. However, somewhat moderated by the fact that they also do ported designs? For the Financial budget required, it is perhaps just beyond what I might consider for one sub. But perhaps more importantly, having completed the construction of my media room, the reconstruction required to integrate two of these (because it would need to be two) is just too much to ask.

Thank you for mentioning this company and this specific product. Maybe other forum members will see your contribution (and this reply) and take a look for themselves for something that might suit their home listening environment?

[Innocent_Bystander]

@Innocent_Bystander

Ascendo SMSG50

At 1.8m square face, and 0.6m depth, I suspect few domestic rooms could physically accommodate one, let alone a pair! And at 400kg you’d need to get placement right first time, or before the forklift truck leaves the building!

[Edmund-of-Essex]

Hi All,

The new signing is confirmed for the team!

Thanks to all the forum contributors (particularly @Innocent_Bystander) in helping me to get to this point. I plan to post information soon about how this latest signing gets on with the other players, and how the team as a whole integrates and performs.

E of E

[tt33]

First of all, thanks @Edmund-of-Essex for all the info you provided here, especially the Linn SO part. Kudos!
You seem to understand it very well, so I followed your guide to set it up for the first time, including adding the GIK room treatment I have. Your suggestion on how to model room treatment was very helpful.
Roon PEQ was something I used till now to tame room modes, but since I’m moving away from Roon, SO seems like a great option. I’m still playing around with different settings, however it sounds promising in initial tests.
One question on the Optimisation ratio between flat frequency and shorter time impact. Is there anything else that SO does except lowering the gain for problematic frequencies under 100 Hz? What would it do if it put 100% toward shorter decay time?

[Edmund-of-Essex]

Hi @tt33 , thanks for the compliments. FYI I have not personally used Roon PEQ, however there may be others on the Forum who have? Nevertheless I can confidently claim to understand what Roon PEQ is trying to do because since your posting I have been busy reading the manual and some online guidance for Roon PEQ.

In summary, the difference between Linn Space Optimisation and practically all other room compensation or correction methods is the Linn approach of using human hearing and room acoustics theory and computational modelling for room acoustics correction. My understanding is all other methods use microphone measurements. This is the key point that becomes relevant to answering your question:-

@tt33

What would it do if it put 100% toward shorter decay time?

In Roon PEQ, it seems one can adjust the Qs of selected filter(s) that one might apply to tame low frequency room modes. But how does one make the choice of the right value or setting of ‘Q factor’ to get the best results? Is it by listening, or is it by measuring using a microphone? If by measuring, what measurement view might we use? Furthermore, if there are a number of modes closely spaced together (as there often are), how are the ‘Q’ values to be set for each separate nulling filter?

For those who have an awareness of the translations between impulse response (time domain) and frequency response (frequency domain), the setting of the ‘Q’ varies the bandwidth of the null of the filter, and correspondingly affects the length of the impulse response in the time domain. Ideally one wants to match the time decay of the filter, with the original extended time decay of the room resonance(s) so that the run time ‘correction’ added to the music, exactly cancels out the resonance in the room.

Linn SO solves all of these questions with the single slider of Flat Frequency vs Short Decay Time. If you set to the slider to give 100% Short Decay Time the correction simply applies the corrective impulse response (representing the best combination of nulls for your room) with the shortest impulse response. Of course this does equate to leaving more energy in the room at the room mode frequencies (with longer decaying room resonances), but that could be the preference for the listener, which is why Linn have done it this way!

I hope the above answers your question?

For your information, Phil Budd (Head of Acoustics and Mechanical Engineering, Linn) has a presentation that I sent him earlier this year describing a method that combines the ‘theoretical’ aspects of Linn SO, with my enhancements by using supplementary microphone measurements and REW analysis.

If you use REW, just respond to this posting and I will explain more how you may better set the Optimisation parameter for Linn SO, other than using your own ears and preference.

[Edmund-of-Essex]

Whilst I am waiting for the ‘new signing’ to arrive (and be installed and integrated) I thought I would keep the team busy testing some different sports equipment. You know the kind of thing, boots and studs and perhaps the performance of such on different turf?

What would be the HiFi equivalent of this?

Different analogue interconnect or different loudspeaker cables perhaps?

I guess we are ALL SIGNED UP to the ‘CABLES MAKE A DIFFERENCE’ mantra? After all there are quite a few historical threads on this topic with the ears always being the judge!

But what if I did such a comparison of analogue interconnect or loudspeaker cables and actually measured the acoustic differences at the listening position😎.

Would anybody be interested in this?

[tt33]

Thanks for the clear explanation Ed, this SO is a really interesting tech. Yeah, I’m using REW with Umik mic to setup my Roon DSP.
I would love to learn more how can I use REW to compliment Linn’s SO. Many thanks!

[Innocent_Bystander]

There was a thread a year or two where someone was going to do some testing re alleged “burn in” of cables, with discussion of protocols etc, but sadly the anti blind-testing brigade got very negative and there was unpleasantness, causing the thread to be pulled. To my mind all objective testing is to be welcomed, no matter how subjective the subject, though we must bear in mind that where finding a measurable difference proves something, not finding only show within the limits of the parameters and sensitivity tested.

[Edmund-of-Essex]

Hi I_B, thanks for the ‘heads up’ on the history of the forum! Very much appreciated. I suppose you are not surprised that I thought few people would respond to the posting, but that you most likely would be amongst them - so thank you again.

Anyway, I am sometimes a very cautious person. And would it surprise you to know that I do in fact already have six datasets, all recorded in a half hour period during last week corresponding to three very different loudspeaker cables? Of course, as this was quick and I could not get the full blind testing protocol implemented I have nevertheless formed a view as to which is best to my ears?

Having done this quick check, I have now sent requests to certain cable manufacturers for them to provide me with technical data so I can absolutely choose cable on the basis of ‘close to perfection’ amp-cable-loudspeaker system that delivers broadband ‘critical’ damping for transient response WHEN MEASURING ACOUSTICALLY at the listening position!

What do you think?

[Innocent_Bystander]

It will be interesting to see if there is a clear correlation between effect on sound and cable characteristics, which I would expect, and might be expected to show a relationship enabling prediction of performance based on characteristics, at least to a broad degree, though of course varying by amp output characteristics and speaker load characteristics, whence with some combinations there may be very little difference between cables, others a lot more. But I wonder how many manufacturers will give full data?

Same with interconnects, though effect of source and sink may be less signifivant.

[Middle]

If you would be willing to take the time to test and share, that would be terrific. Of course I imagine this could be quite a project, so please do not feel obligated!

[Edmund-of-Essex]

Hi @Middle and @Innocent_Bystander , I will try to present the current data soon (the six data sets from three different loudspeaker cables that I obtained last week). However I would first like to get the technical data from the manufacturers as that information might help me better explain the measurement results.

Meanwhile I am going to concentrate my next postings on the Linn Space Optimisation request from @tt33 , so hang on in there for loudspeaker cable testing results.

[Edmund-of-Essex]

Hi @tt33 ,

The whole expalnation will take several postings - mostly to make it easier to respond to any questions that come up regarding the specific topic covered in the posting.

This is the First Posting and represents the Introduction:

The intention of these postings is to provide owners of Linn DSM streamers a precise and accurate method to extract the maximum performance from Linn Space Optimisation.
The method substitutes the key concept of the Linn method - specifically the use of the ‘Tune Dem’ method to evaluate the sound (i.e. “if it sounds better, it is better”). This concept is included – but only at the very end of this method – and only as a final check.

The reason why I consider this method superior (to the Linn approach) is because Space Optimisation uses Computational Fluid Dynamic (CFD) modelling - which in practical implementation has demonstrable limitations (and which Linn have attempted to mitigate):-

1. Without acoustic measurement for confirmation, Linn SO (CFD) may inaccurately compute the centre frequencies of the predicted room resonances.
2. Without acoustic measurement for confirmation, Linn SO (CFD) may inaccurately compute the decay (in time) of the predicted room resonances.

PS: Later, I may include a posting on the general limitations of Computational Fluid Dynamics - but that will be to help inform and educate for those interested - it is not necessary to understand to sucessfully apply the method.

Note: I should mention that personally I like a very ‘dry’ sound with very short reverbaration times. I have my own media room with lots of acoustic treatment fitted. Neverthless, the practical examples used thoughout will be for more ‘regular’ rooms.

[Edmund-of-Essex]

This is the Second Posting and represents an Overview of the Method:

Creating a Good Space Optimisation – Enhanced Approach

1. Preparation: Establish which ‘distorted frequencies’ are to be addressed:
   a) Measure the room physical characteristics.
   b) Measure the actual acoustic room response using Acoustic Measurement system.

2. Combine Acoustic Modelling (Linn) and Acoustic Measurement (using REW):
   a) Create appropriate Room Design (by choosing appropriate complexity) and corresponding Optimisation(s).
   b) Evaluate Room Design by inspecting candidate Optimisation Filter Design.
   c) Evaluate Room Design by using Acoustic Measurement System.

3. Select Optimisation possessing Critical Damping and Final Check.

4. Summary.

[Edmund-of-Essex]

This is the Third Posting and includes the actions to be taken by the user:

Creating a Good Space Optimisation – Enhanced Approach (1):

Preparation: Establish which ‘distorted frequencies’ are to be addressed:

a) Measure the room physical characteristics (to an accuracy of 1cm).
User action - first think about ‘where are the (low frequency) sound reflecting boundaries’ (also known as large area hard surfaces).
User action - measure room dimensions to accuracy of 1cm.
User action - for rooms with carpet, measure ceiling height to the top surface of the hard floor material underneath carpet.
User action - note the main material type for each significant boundary surface.
User action - note any significant Room Features that have dimensions >10cm and note the size and position of these.
User action - prevent ‘oversizing’ of Room Features in the Room Design for example by NOT entering door or window frames!

b) Measure the actual acoustic room response using acoustic measurement system.
User action – set up equipment and test measurement arrangement (see next posting no. 4).
User action – understand the measurements to be taken and why (see next posting no. 5).
User action – capture reference measurements (No Space Optimisation) to be used for later comparisons (see next postings nos. 6, 7 and 8).

[Edmund-of-Essex]

This is the Forth Posting and represents a typical Equipment List and Arrangement:

Note that the diagram shows a miniDSP UMIK-2 measurement microphone.
When the method was developed I was using miniDSP UNIK-1 and all results presented are based on UMIK-1 obtained data.