My acoustically treated Home Theatre (updated)

[sarumbear]

I changed my amplifiers and added another pair of ceiling speakers. Here is the new connection diagram. The wiring and the equipment rack is so much simpler now. Amplitude-16 has enough power to run all speakers.

 

[sarumbear]

New Year, new system update

During holidays I updated the Trinnov Altitude 16 software and find new and very comprehensive bass management options. This made me think: do I really need a separate LFE subwoofer? It is taking too much space and unlike the Left & Right subwoofers, it is not in-wall, instead located to the left of the seating area below some shelves. Occasionally I can localise the effects coming from it.

The two in-wall subwoofers have total cone area equivalent of a 20” subwoofer. That should be plenty enough, I thought. A quick level test proved that to be the case. I played a 25Hz sinewave at a level of 110dBSPL(C) at 2m It sounded decent to my ears and as that level is 20dB higher than I will use the system I didn’t investigate distortion levels further. I decided that it is high enough for an occasional explosion to be reproduced with enough force.

The LFE sub has gone, making my partner happy as he will use the space to store more brick-a-brack.

Next job was to add more speakers. You cannot have enough speakers in a Home Theatre!

In addition to the Dolby, DTS and Auro3D templates, the Altitude16 also has a hybrid layout designed by Trinnov. This layout based on a 7.1 surround layout with additional speakers to support multiple 3D formats such as Dolby Atmos, DTS:X and Auro-3D. It uses 15 speaker plus subwoofer. I decided to modify the layout to use 16 speakers plus two subwoofers.

Dolby defines two left and right wide speakers for Atmos. They are positioned in front of the normal surround speakers. I was using JBL CBT-50-1 for the side and rear surrounds. However, I was not happy with the tonality difference to the KEF LCR speakers. I decided to switch to smaller KEF in-walls, Ci3160RL-THX, for the existing side surrounds and for the new wides as well. The front KEFs are the reference series and are pretty expensive. I opted for the standard series for the surrounds. The rear surrounds cannot physically be positioned in a wall so I left the JBL CBTs in place.

The Trinnov hybrid layout use one centre height speaker for the Centre Top front and one ceiling speaker for the Top channel (The Voice of God) for Auro-3D and DTS:X. I modified the layout to use two Front Heights instead of one, as I already had KEF Ci200RS-THX speakers directly above the L&R flush to the ceiling. I added another Ci200RS-THX to the ceiling for the Top channel directly above the main listening position. Not that I expect it to have any use of them as DTS:X seems to have all but lost the streaming market but I had a spare amplifier channel. Maybe Disney+ will finally deliver on their promise. Who knows, elephants may fly…

The above changes are in addition to the speakers on the false wall where the TV, LCR and two subwoofers are mounted in. LCR is made of three KEF Ci5160REF-THX in-wall speakers. Two are mounted to left & right of the TV in vertical and the centre one below the TV in horisontal orientation. There are two JBL Synthesis SSW-3 in-wall subwoofers. These were mounted away from the corner but now moved to the corners into the place vacated by two bass resonators, which are moved to the ceiling, next to the others. I wanted to gain as much as I can by repositioning the subwoofers to the corners. That required more bass resonators though to compensate the level increase of some room modes. Moving subwoofers to the corners has an added benefit. As they are now nearer to the side and surround speakers they can act as side subwoofers as well.

Overall the system now has 18 speakers, a 9.2.6 setup. All speakers are passive. 16 speakers other than the two subwoofers are fed by the Trinnov Amplitude-16 supplying 16x 200W. This makes the cabling very, very tidy. I still had the JBL Synthesis 2x SDA-4600 power amplifier from a previous incarnation of the system. I used it in bridge mode to supply 2x 1200W for the two subwoofers. They are fed from one of the AES3 outputs of Altitude-16 via a Topping D90SE.

There are five bass resonators hidden inside the false ceiling. These suck the five main room resonances (room modes) caused by the standing waves. Each is a tuned Helmholtz resonator made from 20cm (8”) diametre plastic water pipe. Their length set the frequency range they will operate at and the opening is adjustable for precise tuning. Once the room modes are reduced to near elimination the room frequency response became pretty flat. Only a very small amount of equalisation is required, which is done by Trinnov.

Here is the new connection diagram and the modified layout of the room. The room is roughly 10m by 10m (32’) with the listening area width reduced to 6m (20’). Ceiling height is 3m (10’). The speakers are in green and the in-ceiling bass resonators are in pink. The false ceiling is made of a combination of absorber and diffuser panels. There are shelves on the left and right of the sitting area, which act as a diffuser of sorts.

 

[Geert]

The dark pink at one end of each resonator, I assume that's where their port is?

How did you determine the tuning frequency of the resonators? Did you in advance have an idea of which modes to target (like first and second longitudinal, first oblique), or was it an experimental approach (measuring when the room was build to determine what frequencies to tackle)?

 

[sarumbear]

The dark pink at one end of each resonator, is assume that's where their port is?

Correct

How did you determine the tuning frequency of the resonators? Did you in advance have an idea of which modes to target (like first and second longitudinal, first oblique), or was it an experimental approach (measuring when the room was build to determine what frequencies to tackle)?

Correct again. Rough resonance frequencies were calculated in an acoustic simulator before the room was build and the tuning range of the resonators were selected to match them. The resonators than tuned after the room built and measured.

 

[Kyban]

They are made of 5m long 25cm diameter plastic water pipes. Ends are blocked and there are variable area opening on one end to tune the resonator. Each one cancels one room mode.

I create a rectangle opening (port) and over it slide a flap to change the port area. Once the required frequency is reached I tighten the screws (that are acting like a guide to the flap) to fix the flap in place.

So the "length" of your port tube was simply the depth of the plastic end cap (or whatever you used) say 12mm?

 

[sarumbear]

So the "length" of your port tube was simply the depth of the plastic end cap (or whatever you used) say 12mm?

Not exactly. The end is a bit more complex than just a cut on the pipe. There is a piece which is similar to the mouth of the pipe of a church organ but works different as there is no air blowing in.

 

[Kyban]

Not exactly. The end is a bit more complex than just a cut on the pipe. There is a piece which is similar to the mouth of the pipe of a church organ but works different as there is no air blowing in.

Are you willing to share the specific construction details, perhaps a diagram?

 

[sarumbear]

Trinnov sent me this link to answer my request for explanation of their new WaveForming tech. I’m sold. I started planning to double the subs on the front wall and to add two new subs to the rear wall. Front wall is easy as it’s a custom wall only for in-wall speakers and TV and there’s ample space. The rear wall will be tricky.

 

[prerich]

We may have had our back and forth's, but one thing I must say.....I love your system!

 

[sarumbear]

We may have had our back and forth's, but one thing I must say.....I love your system!

Thank you. I enjoy tinkering with it.

 

[Bjorn]

SBA is a much better solution IMO, since it covers a larger frequency area and can be combined with the best treatment for mids and highs as well. But DBA is more practical for most people.

 

[sarumbear]

SBA is a much better solution IMO, since it covers a larger frequency area and can be combined with the best treatment for mids and highs as well. But DBA is more practical for most people.

Sorry for my ignorance but what are SBA and DBA?

 

[Bjorn]

Sorry for my ignorance but what are SBA and DBA?

DBA is short for double bass array and as the name indicated you have a row of woofers (minimum 4) on the front wall and on the rear wall. The one in the rear wall are in opposite phase and delayed in order to absorb the wave from the front. It's nothing new and as far as I can tell Trinnov has simply given it a new fancy name. The original paper is in German and can be seen here: https://www.nubert.de/media/b3/5f/41/1662983943/optimierung-der-tieftonwiedergabe.pdf

SBA is single bass array where one uses an complete absorptive rear wall instead of active woofers. Either with very thick porrous material or pressure based traps.

DBA will only work up to a certain frequency which is dependend on the spacing between the woofers. But SBA will work over a much a wider frequency area and also deal with resonances in the important middle and upper bass. Plus SBA can be combined with either high frequency absorption or diffusion. While DBA with it's array of woofers in the rear will take up space for needed treatment.

 

[Hexspa]

What multiple subwoofers can’t do is to reduce decay times of room modes.

I was positive I saw someone on here post their results from having three subs and I noted that it did decrease decay in the lowest frequencies. In fact, I thought it was you who posted these results but maybe I'm mistaken. Also, subsequent measurements can sometimes result in slightly different results.

 

[FrantzM]

Hi

I maintain a "Hate List" and you, @sarumbear , are in it.
I suppose "GOD " is the main listener?
Damn!!
Great system.

Peace.

 

[sarumbear]

I was positive I saw someone on here post their results from having three subs and I noted that it did decrease decay in the lowest frequencies. In fact, I thought it was you who posted these results but maybe I'm mistaken. Also, subsequent measurements can sometimes result in slightly different results.

Multiple subwoofers and a subwoofer array are not the same.

 

[sarumbear]

DBA is short for double bass array and as the name indicated you have a row of woofers (minimum 4) on the front wall and on the rear wall. The one in the rear wall are in opposite phase and delayed in order to absorb the wave from the front. It's nothing new and as far as I can tell Trinnov has simply given it a new fancy name. The original paper is in German and can be seen here: https://www.nubert.de/media/b3/5f/41/1662983943/optimierung-der-tieftonwiedergabe.pdf

SBA is single bass array where one uses an complete absorptive rear wall instead of active woofers. Either with very thick porrous material or pressure based traps.

DBA will only work up to a certain frequency which is dependend on the spacing between the woofers. But SBA will work over a much a wider frequency area and also deal with resonances in the important middle and upper bass. Plus SBA can be combined with either high frequency absorption or diffusion. While DBA with it's array of woofers in the rear will take up space for needed treatment.

Thank you for the acronym explanation.

Trinnov may not have invented double bass array but they are the ones who are delivering it on their product. Where is the K&H product?

 

[KING DRANZER]

@sarumbear How are the KEF Ci3160LR speakers. Are they good. I am unable to decide between. Q950 and Ci3160LR. KEF R5 Meta and R6 Meta series is really expensive so cannot afford it.

Prices(for reference for 1Pc each not pair) :
KEF Q650C - $695
KEF Q950 - $1020
KEF R3 Meta - $1275
KEF Ci3160RL - $1475
KEF R6 Meta - $2125

Is the pricing in India. Which will be the best.
If I choose Ci3160LR. I plan to install them into 75L Sealed Enclosure(Can go up on enclosure size). We have Concrete Walls so cannot cut into them.

 

[sarumbear]

@sarumbear How are the KEF Ci3160LR speakers. Are they good.

They are excellent. I also have Salon2 on my music room and I know what a good spekaer sounds like

If I choose Ci3160LR. I plan to install them into 75L Sealed Enclosure(Can go up on enclosure size). We have Concrete Walls so cannot cut into them.

Then I suggest you don't use them. They are in-wall speakers that must be installed flush with the wall. Choose something else, I will say.

 

[KING DRANZER]

They are excellent. I also have Salon2 on my music room and I know what a good spekaer sounds like


Then I suggest you don't use them. They are in-wall speakers that must be installed flush with the wall. Choose something else, I will say.

What would you recommend then. Should I stick to Q950.

Will it not work in 24" wide 48"tall enclosure. Wouldn't it be similar to as installed flush with the wall.