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Ravindra Desai

Well-Known Member
Joined
Feb 13, 2018
Messages
327
Points
93
Location
Kolhapur, Maharashtra. India.
Hello all,

I am an electronics engineer. I like hardware design and have good skills in Analog design and PCB design. I have worked with GE as a design engineer developing industrial controls (4-20ma inputs and outputs, Thermocouples, RTDs, LVDT, Servo Actuators) for turbine control applications.

I have a passion for audio and have designed my own sound system (processor, amplifiers, speaker systems) I have done several installations, for Cinema theaters, Home theaters, Conference rooms, Multipurpose Halls, that has involved either or both sound system and acoustics.

Through HiFi Vision, I wish to learn from other audio experts and share my work with you all.

With warm regards,

Ravindra Desai.
 

tuff

Well-Known Member
Joined
Oct 26, 2014
Messages
2,019
Points
113
Location
Thane
Hello all,

I am an electronics engineer. I like hardware design and have good skills in Analog design and PCB design. I have worked with GE as a design engineer developing industrial controls (4-20ma inputs and outputs, Thermocouples, RTDs, LVDT, Servo Actuators) for turbine control applications.

I have a passion for audio and have designed my own sound system (processor, amplifiers, speaker systems) I have done several installations, for Cinema theaters, Home theaters, Conference rooms, Multipurpose Halls, that has involved either or both sound system and acoustics.

Through HiFi Vision, I wish to learn from other audio experts and share my work with you all.

With warm regards,

Ravindra Desai.
Nice. Hope we can learn some things from you too. Welcome.:)
 

sanjivnayak

Active Member
Joined
Nov 13, 2017
Messages
622
Points
43
Location
Bhubaneswar
Welcome Sir.
Mr. Rabindranath, we are eager to know your audio equipments installed at your home.
The specs if you have your own design.
 

efernand1

Well-Known Member
Joined
Jul 6, 2012
Messages
5,516
Points
113
Location
Mumbai
Hello all,

I am an electronics engineer. I like hardware design and have good skills in Analog design and PCB design. I have worked with GE as a design engineer developing industrial controls (4-20ma inputs and outputs, Thermocouples, RTDs, LVDT, Servo Actuators) for turbine control applications.

I have a passion for audio and have designed my own sound system (processor, amplifiers, speaker systems) I have done several installations, for Cinema theaters, Home theaters, Conference rooms, Multipurpose Halls, that has involved either or both sound system and acoustics.

Through HiFi Vision, I wish to learn from other audio experts and share my work with you all.

With warm regards,

Ravindra Desai.


Welcome to HFV

It is great to know we have an esteemed experienced person with us who will contribute to the greater goal of achieving the best Audio / Video gizmos in our home at an affordable and justified price.

HFV is a great place to be....you will also learn a lot through various past threads and even the fresh ones.....this definitely enhances experience and know how!

Happy browsing....
 

elangoas

Well-Known Member
Joined
Nov 4, 2009
Messages
7,536
Points
113
Location
Madrasapattinam
Hello all,

I am an electronics engineer. I like hardware design and have good skills in Analog design and PCB design. I have worked with GE as a design engineer developing industrial controls (4-20ma inputs and outputs, Thermocouples, RTDs, LVDT, Servo Actuators) for turbine control applications.

I have a passion for audio and have designed my own sound system (processor, amplifiers, speaker systems) I have done several installations, for Cinema theaters, Home theaters, Conference rooms, Multipurpose Halls, that has involved either or both sound system and acoustics.

Through HiFi Vision, I wish to learn from other audio experts and share my work with you all.

With warm regards,

Ravindra Desai.

Hi @Ravindra Desai

Wc to the forum.. You seem to have vast expereince..

Glad to have a professional/commercial installer on the forum.. Hope you could shed some light on topics..

Am curious to know,
- How many subwoofers does a theaters have?
- Where do they usually place it in the theater ?..
- Roughly how much power (or) SPL is required from each..
- How many measurements (for bass) do you take, until you deem they are good..
- I don't know the logic behind Atmos channels being placed flat overhead (spread across the theater), but would it be better if these over head channels are placed in hemisphere type overhead?..

Appreciate you inputs..
 

Ravindra Desai

Well-Known Member
Joined
Feb 13, 2018
Messages
327
Points
93
Location
Kolhapur, Maharashtra. India.
Hi @Ravindra Desai

Wc to the forum.. You seem to have vast expereince..

Glad to have a professional/commercial installer on the forum.. Hope you could shed some light on topics..

Am curious to know,
- How many subwoofers does a theaters have?
- Where do they usually place it in the theater ?..
- Roughly how much power (or) SPL is required from each..
- How many measurements (for bass) do you take, until you deem they are good..
- I don't know the logic behind Atmos channels being placed flat overhead (spread across the theater), but would it be better if these over head channels are placed in hemisphere type overhead?..

Appreciate you inputs..

Hello elangoas,

Let me give your questions a try:
- How many subwoofers does a theaters have?
For subwoofer, there is no limit. Its the budget that constrains it. All the 5 theaters where I installed the sound system, the wattage to the subwoofers was 2-4 times the center channel. spread over 2 x 18" drivers. Practically speaking, 2 x center channel wattage gives correct sound and feel with safe headroom. But sometimes the theater owners insists on more punch based on the mood of their local crowd. This was for 400- 650 seat capacity
I know Apsara theater in Hubli has 8 x 18" subwwofers. But their theater size is around 850 seats.
Sterling in Mumbai has even more, but I don't have the exact count.
Remember, most of the times, the number is increased to spread the load. You cannot just go on adding subs as it would drown the mids and the highs.

- Where do they usually place it in the theater ?..
No fixed place. Usually at 1/3 and 2/3 distance from side wall.
Remember, even the walls behind the screen are treated heavily. So there is no booming even if they are all placed in one corner.

- Roughly how much power (or) SPL is required from each..
The B-chain settings (EQ) uses a compressor and a limiter on all the channels including the LFE channel. You can push the subs hard and still be OK. If the person doing the settings does not know what he is doing, you will have konked off subs and HF units every now and then.
To answer your question: Calibration is done at 85db for all the channels including the subs. So if you use one sub, the response, theoretically, should be flat. If you use 2 subs, you will have 3db more bass and so on. Remember, the dynamics of the recording can go as high as 120db but the compressor/ limiter is set at the onset of amplifier clipping. Also, no one can and should watch a full length movie with full dynamic range.

- How many measurements (for bass) do you take, until you deem they are good..
Gain, 27-band graphic eq, 6-band parametric eq, delay and phase settings are done. A good installer will do it all manually. An experience installer will manually fine tune the settings after a round of auto-eq.
People do the settings differently. Some use the calibration mike at the center and that's it. Some take readings at three different places.
Again, to answer your question: There is no definate pattern/ method.

- I don't know the logic behind Atmos channels being placed flat overhead (spread across the theater), but would it be better if these over head channels are placed in hemisphere type overhead?..
I don't know. I have to think.
The installations that I did were in theaters with very limited budget. We had to cut down from 5.1 to 2.1 (Center, Mono surround and sub-woofer). Trust me, no one could tell the difference in any of my 5 theaters over a period of 15+ years.
Coming back to your question, our head needs to be in a mood to resolve the sound position as we would be engrossed in the movie.
You tell me: Will you be able to tell the difference if you were un-aware of what the configuration is? Panned effects is a very small part of the entire content. I would feel happy with top class vocals, good (not too much) bass and surround that creates an ambience of the scene. Personally, I don't care how many surrounds. I also don't like installations where I can tell where the surround speaker is located. I like to be enveloped by surround, not distracted from my heroine on the screen.

I hope that I have answered your questions.
Note that I have expressed some personal opinions in here. So don't take me word for word.

b.t.w. don't you agree that with the technology that we have and the money that we spend, the user should not have to do anything. He should be able to un-box the system and use it. That's it. If the likes of A. R. Rehmaan spend hours recording their stuff, who are we to change it? Makes sense?

Yes, systems that need no calibration also exists!! Interested?

Regards,

Ravindra.
 
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tuff

Well-Known Member
Joined
Oct 26, 2014
Messages
2,019
Points
113
Location
Thane
Interesting stuff. This thread should be in some other place than introductions. I watch most movies at the Viviana in Thane, and have noticed variations of sound quality in each movies that i have watched, to the point that they can be absolutely muddy or way more rumble for everything, from a car engine to a spaceship or explosions. What also seperates theater sound is there seems no left/right panning on screens as it seems all three channels are right behind the screen making it sound like everything is coming off the center of the screen. Weird, thing is the voices also have no natural tone that you might expect but have a lot of low end in human voices. Good info here. Thanks, am sure will have more questions in the near future.:)
 

elangoas

Well-Known Member
Joined
Nov 4, 2009
Messages
7,536
Points
113
Location
Madrasapattinam
I hope that I have answered your questions.

Thank you very much for the detailed explanation..

For subwoofer, there is no limit. Its the budget that constrains it. All the 5 theaters where I installed the sound system, the wattage to the subwoofers was 2-4 times the center channel. spread over 2 x 18" drivers. Practically speaking, 2 x center channel wattage gives correct sound and feel with safe headroom. But sometimes the theater owners insists on more punch based on the mood of their local crowd. This was for 400- 650 seat capacity
I know Apsara theater in Hubli has 8 x 18" subwwofers. But their theater size is around 850 seats.
Sterling in Mumbai has even more, but I don't have the exact count.

Two subwoofers for 400 - 650 seat capacity seems less.. But 8 subs (or) more looks good because of the area it has to cover..

Remember, most of the times, the number is increased to spread the load. You cannot just go on adding subs as it would drown the mids and the highs.

Right.. Understand that additional subs must only be added for flattening the response..

Calibration is done at 85db for all the channels including the subs.

Ok.. 10 dB more than Home theaters..

People do the settings differently. Some use the calibration mike at the center and that's it. Some take readings at three different places. Again, to answer your question: There is no definate pattern/ method.

Some home theater AVR like the Audyssey use 8 calibration points.. I was assuming since the theater is a very large area, there would be more calibration points..

The installations that I did were in theaters with very limited budget. We had to cut down from 5.1 to 2.1 (Center, Mono surround and sub-woofer). Trust me, no one could tell the difference in any of my 5 theaters over a period of 15+ years.

VoW.. 2.1 only and not observed for 15 years, is something revealing..

You tell me: Will you be able to tell the difference if you were un-aware of what the configuration is? Panned effects is a very small part of the entire content. I would feel happy with top class vocals, good (not too much) bass and surround that creates an ambience of the scene. Personally, I don't care how many surrounds. I also don't like installations where I can tell where the surround speaker is located.

I can't say for sure if i could observe the difference..If the movie is really good and the sound is convincing, i watch the movie fully..

But if the movie (or) sound is not up to mark, i start to observe things...

I like to be enveloped by surround, not distracted from my heroine on the screen.

Precisely.. I would love to hear the best surround experience.. Ha ha..Good one..

b.t.w. don't you agree that with the technology that we have and the money that we spend, the user should not have to do anything. He should be able to un-box the system and use it. That's it. If the likes of A. R. Rehmaan spend hours recording their stuff, who are we to change it? Makes sense?

This is where i like Audyssey and its benefits to the user..

Yes, systems that need no calibration also exists!! Interested?

Yes (If i was aware of few technical things)..
 
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Ravindra Desai

Well-Known Member
Joined
Feb 13, 2018
Messages
327
Points
93
Location
Kolhapur, Maharashtra. India.
I agree tuff. I request the moderators to move this part of the thread elsewhere.

tuff, you brought up something I should have mentioned in the first place and has reference to elangoas question: ....until you deem they are good..

The sound for movies is recorded with an X-curve pattern, similar to EQ for turntables. Recording is done with lows down and highs up.
The settings for a channel stops (deemed good) when the RTA fed with the mike (placed in the audotorium) matches the other half of the X with highs low and lows up for an effective flat response. This method of recording and playback settings helps improve signal to noise ratio.

Kindly note there is no 'until I deem they are good.' It is 'until it matches the X-curve.'
This will clarify a lot of things.

{QUOTE="tuff, post: 762799, member: 79702"]What also seperates theater sound is there seems no left/right panning on screens as it seems all three channels are right behind the screen making it sound like everything is coming off the center of the screen. [/QUOTE]

If the screen width is narrow, left to right panning becomes less obvious. That's physics.
It is the narrow screens where I suggest a 2.1CH configuration. Saves a LOT of money and service is only a local call away!

Regards,

Ravindra.
 
Last edited:

Ravindra Desai

Well-Known Member
Joined
Feb 13, 2018
Messages
327
Points
93
Location
Kolhapur, Maharashtra. India.
- Two subwoofers for 400 - 650 seat capacity seems less.. But 8 subs (or) more looks good because of the area it has to cover..

In mono days, 650 seat theater used a 60Wrms amplifier for center channel. Today I use 160Wrms for center channel.
For TV theater systems (for living rooms and small home theaters) that I sell, I use 20Wrms per channel. Digital processor helps me make this possible.


- Some home theater AVR like the Audyssey use 8 point calibration for each listening position.. I was assuming since the theater is a very large area, there would be more calibration points..

I told you what is done. However, I, as an engineer, have my doubts. Will the net effect of multi-point calibration not be zero? So in effect arn't we doing nothing?



- VoW.. 2.1 only and not observed for 15 years, is something revealing..

Like I mentioned in my earlier post, it makes sense at a lot of places.
For TV theater systems, this is still what I offer. People can't use and sustain 5.1 and above. Room size, cost, ease of use.....


- I can't say for sure if i could observe the difference..If the movie is really good and the sound is convincing, i watch the movie fully..
But if the movie (or) sound is not up to mark, i start to observe things...

Same here!


- Yes (If i was aware of few technical things)..
I am inviting you for a demo. As a user of Audyssey based systems, your review comments about what I have will be of much value to me.

Great, this was fun.

Regards,

Ravindra.
 

elangoas

Well-Known Member
Joined
Nov 4, 2009
Messages
7,536
Points
113
Location
Madrasapattinam
In mono days, 650 seat theater used a 60Wrms amplifier for center channel. Today I use 160Wrms for center channel.

Hope those are active speakers..60W RMS for a theater is unbelievable..

I told you what is done. However, I, as an engineer, have my doubts. Will the net effect of multi-point calibration not be zero? So in effect arn't we doing nothing?

Am an enthusiastic joe, but will attempt to put it on my own words / understanding..

Audyssey is an Automatic room calibration, which first measures all the speakers in the room from 8 different listening positions, sets the 75 dB SPL for all speakers w.r.t listening position and set the delay too.. It also tries to apply EQ and tame peaks..Some presets are also aval, which are really useful.. (Dynamic Vol)..But beyond that, i have no understating..

Like I mentioned in my earlier post, it makes sense at a lot of places.
For TV theater systems, this is still what I offer. People can't use and sustain 5.1 and above. Room size, cost, ease of use.....

Yes.. Understand the budget issues.. Especially in rural places, where they can't afford to expand to immersive audio..

I am inviting you for a demo. As a user of Audyssey based systems, your review comments about what I have will be of much value to me.

Thank you for the invite.. While i reside in a village near chennai, incase you happen to drop to chennai for any installation, please ping me and i would be happy to join you..

Am just an average enthusiast..Nowhere technically good to explain how Audyssey works...

Great, this was fun.

Sure.. It is.. Thanks once again for the detailed explanation..
 
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