Power needed for home theater

[Theriverlethe]

I am trying to figure out how much power I need in my home theater. I have read a few threads here but want ask if I am on the right track... As a starting point I am using this calculator:
https://myhometheater.homestead.com/splcalculator.html
On that page, it says to enter 3 channels if doing multichannel. So if I put in the following info in the calculator:
93 for speaker sensitivity
60 watts
14 feet distance
Near wall
With this info I get 105.9db spl. It is my understanding, if listening at reference level, I need to get to 105db, so in this scenario it looks like 60w is enough. Is this a correct conclusion, or am I missing something? Thanks

14ft seems pretty far for a domestic listening room. Are you able to form an equilateral triangle with the mains? For best sound, you should generally be seated around 1/3 or 2/3 the length of the room.

 

[Dj7675]

14ft seems pretty far for a domestic listening room. Are you able to form an equilateral triangle with the mains? For best sound, you should generally be seated around 1/3 or 2/3 the length of the room.

Room isn't a living room the unit is in right now (in the process of first sending it back for repair to due the atmos static issue). It is a theater room with a 122" W 2.35 Scope screen. I remeasured and setting distance is actually @ a little more than 13feet and and Speakers are sitting just outside the screen width, so around 13feet. Speakers are pointed at the MLP. It is a little wider than I would like and may go to an acoustically transparent screen at some point as well for better L/R speaker placement and to get the center speaker at ear level. But it sounds good as is so I just haven't bothered.

 

[Theriverlethe]

Room isn't a living room the unit is in right now (in the process of first sending it back for repair to due the atmos static issue). It is a theater room with a 122" W 2.35 Scope screen. I remeasured and setting distance is actually @ a little more than 13feet and and Speakers are sitting just outside the screen width, so around 13feet. Speakers are pointed at the MLP. It is a little wider than I would like and may go to an acoustically transparent screen at some point as well for better L/R speaker placement and to get the center speaker at ear level. But it sounds good as is so I just haven't bothered.

Ah, I’m surprised you’re even looking at consumer-grade receivers at this point.

 

[Dj7675]

They certainly haven’t measured very well compared to 2 channel DAC’s and amps but I think they can measure good enough for me in our theater. Just looking for a product that is “transparentish” or “good enough” at this point. I have abandoned the idea of trying to get to the level of my main 2 channel system in our theater. When high end products like the NAD M17 or the Marantz AV8805 don’t seem to measure all that well either relative to their price. Why not try to identify a receiver that is relatively “good enough”. Shooting for something around CD quality SINDAD (96) seems possible at reference level in my room. And has already been shown, there are much better out there I really like Dirac, but the NAD T758 just doesn’t perform like I think it needs to at or around reference level (and I think objectively, as Amir has shown). It’s really too bad, the features and price are really good. What the responses to this post have shown me, it I really probably don’t need that much power with speakers with a sensitivy of 93, in particular considering the use of subs below 80hz.

 

[KozmoNaut]

If possible, spring for a receiver with pre-amp outputs. Then you can upgrade to bigger amps when/if needed.

 

[Theriverlethe]

They certainly haven’t measured very well compared to 2 channel DAC’s and amps but I think they can measure good enough for me in our theater. Just looking for a product that is “transparentish” or “good enough” at this point. I have abandoned the idea of trying to get to the level of my main 2 channel system in our theater. When high end products like the NAD M17 or the Marantz AV8805 don’t seem to measure all that well either relative to their price. Why not try to identify a receiver that is relatively “good enough”. Shooting for something around CD quality SINDAD (96) seems possible at reference level in my room. And has already been shown, there are much better out there I really like Dirac, but the NAD T758 just doesn’t perform like I think it needs to at or around reference level (and I think objectively, as Amir has shown). It’s really too bad, the features and price are really good. What the responses to this post have shown me, it I really probably don’t need that much power with speakers with a sensitivy of 93, in particular considering the use of subs below 80hz.

I wouldn’t recommend Audyssey or any other consumer-level room correction systems unless you have the measurement equipment and knowledge to “fix” their mistakes. Where do you have to set the NAD to reach reference level at the seating position? Amir hasn’t shown anything that I’d even entertain as potentially audible below the -6dB point.

 

[Theriverlethe]

They certainly haven’t measured very well compared to 2 channel DAC’s and amps but I think they can measure good enough for me in our theater. Just looking for a product that is “transparentish” or “good enough” at this point. I have abandoned the idea of trying to get to the level of my main 2 channel system in our theater. When high end products like the NAD M17 or the Marantz AV8805 don’t seem to measure all that well either relative to their price. Why not try to identify a receiver that is relatively “good enough”. Shooting for something around CD quality SINDAD (96) seems possible at reference level in my room. And has already been shown, there are much better out there I really like Dirac, but the NAD T758 just doesn’t perform like I think it needs to at or around reference level (and I think objectively, as Amir has shown). It’s really too bad, the features and price are really good. What the responses to this post have shown me, it I really probably don’t need that much power with speakers with a sensitivy of 93, in particular considering the use of subs below 80hz.

You don’t say which speakers you’re using, but if Grimsurfer’s assertion that the sensitivity could be closer to 87dB is accurate, I think you’d be pushing the limits of any receiver in that room. You might look at something like an Emotiva XPA-3, which can deliver 300 watts. Remember that every 3dB increase requires a doubling of power. The Emotiva claims it only needs 1.5V input to reach full power, so the pre-outs on the NAD shouldn’t be a problem.

 

[Dj7675]

You don’t say which speakers you’re using, but if Grimsurfer’s assertion that the sensitivity could be closer to 87dB is accurate, I think you’d be pushing the limits of any receiver in that room. You might look at something like an Emotiva XPA-3, which can deliver 300 watts. Remember that every 3dB increase requires a doubling of power. The Emotiva claims it only needs 1.5V input to reach full power, so the pre-outs on the NAD shouldn’t be a problem.

I would agree if they were only 87dB sensitivity. The 93dB sensitivity is accurate. They take great care in providing accurate measurements of their designs. The particular model I have isn't available now, but here is a link to their very popular 1099 with 99dB sensitivity link. Attached is a pic of the speaker (it isn't mine, but the model).

 

[Dj7675]

I wouldn’t recommend Audyssey or any other consumer-level room correction systems unless you have the measurement equipment and knowledge to “fix” their mistakes. Where do you have to set the NAD to reach reference level at the seating position? Amir hasn’t shown anything that I’d even entertain as potentially audible below the -6dB point.

I have used Audyssey before and thought it did well with the lower frequencies. I didn't care for it full range, but now with Denon/Marantz models working with the Audyssey app you can limit the frequency range and also adjust the house curve. I thought the evidence shown by @amirm provided very good evidence of the issues regarding audibility. I'm no expert, so maybe Amir can comment, but it seems his comments regarding Masking might be applicable. https://www.audiosciencereview.com/...o-nonlinear-distortion-audibility.4784/page-2
"In addition, since music has tons of primary tones, each creating their own harmonics, they add up in energy. This then competes with what is normally in music in that range. High frequencies drop exponentially in music so it does not take a lot to change their overall energy and with it, cause the high frequencies to be exaggerated.
We have all heard this effect in extreme distortion of amplifiers where the sound gets harsh. In lower amounts, this harshness is not there and gets replaced with exaggeration of high frequencies."
A graph and discussion of multitone tests follow which also seem to apply to me.

 

[GrimSurfer]

I have used Audyssey before and thought it did well with the lower frequencies. I didn't care for it full range, but now with Denon/Marantz models working with the Audyssey app you can limit the frequency range and also adjust the house curve. I thought the evidence shown by @amirm provided very good evidence of the issues regarding audibility. I'm no expert, so maybe Amir can comment, but it seems his comments regarding Masking might be applicable. https://www.audiosciencereview.com/...o-nonlinear-distortion-audibility.4784/page-2
"In addition, since music has tons of primary tones, each creating their own harmonics, they add up in energy. This then competes with what is normally in music in that range. High frequencies drop exponentially in music so it does not take a lot to change their overall energy and with it, cause the high frequencies to be exaggerated.
We have all heard this effect in extreme distortion of amplifiers where the sound gets harsh. In lower amounts, this harshness is not there and gets replaced with exaggeration of high frequencies."
A graph and discussion of multitone tests follow which also seem to apply to me.

This is interesting. If you're right (and your explanation is entirely plausible) the issue isn't power per se but clean and undistorted power.

I've always had the feeling that this is one of reasons why people purchase amps with an excess of power, instead of the more scientific approach of buying the power that's needed in both a quantitative and qualitative sense.

 

[Theriverlethe]

I have used Audyssey before and thought it did well with the lower frequencies. I didn't care for it full range, but now with Denon/Marantz models working with the Audyssey app you can limit the frequency range and also adjust the house curve. I thought the evidence shown by @amirm provided very good evidence of the issues regarding audibility. I'm no expert, so maybe Amir can comment, but it seems his comments regarding Masking might be applicable. https://www.audiosciencereview.com/...o-nonlinear-distortion-audibility.4784/page-2
"In addition, since music has tons of primary tones, each creating their own harmonics, they add up in energy. This then competes with what is normally in music in that range. High frequencies drop exponentially in music so it does not take a lot to change their overall energy and with it, cause the high frequencies to be exaggerated.
We have all heard this effect in extreme distortion of amplifiers where the sound gets harsh. In lower amounts, this harshness is not there and gets replaced with exaggeration of high frequencies."
A graph and discussion of multitone tests follow which also seem to apply to me.

Regarding Audyssey, it can do a decent job, especially in the low end. In my case, it set the sub delays wrong and created a huge dip around the crossover frequency, while making an inexplicable 5dB boost around 2.5kHz. As you might guess from the Fletcher-Munson curve, this was almost painful to listen to. It might actually be worth checking your Dirac calibration to make sure something strange didn’t happen. I have yet to see Dirac come back with a remarkably bad result, but I’m sure it’s possible. Are you using it full-range or just with 500Hz cutoff included “free” with the NAD?

I’ve already presented my interpretation of the masking research, so I won’t repeat it here.

 

[Dj7675]

Regarding Audyssey, it can do a decent job, especially in the low end. In my case, it set the sub delays wrong and created a huge dip around the crossover frequency, while making an inexplicable 5dB boost around 2.5kHz. As you might guess from the Fletcher-Munson curve, this was almost painful to listen to. It might actually be worth checking your Dirac calibration to make sure something strange didn’t happen. I have yet to see Dirac come back with a remarkably bad result, but I’m sure it’s possible. Are you using it full-range or just with 500Hz cutoff included “free” with the NAD?

I’ve already presented my interpretation of the masking research, so I won’t repeat it here.

The unit will be heading in for service and then sold. I have used Dirac quite a lot..ddrc24/minidsp shd/nad t758. Ran it many times with the T758. Dirac was the full version and no complaints whatsoever regarding Dirac. Regarding the NAD, the only issue in regard EQ I found lacking was dealing with multiple subs. Audissey, actually does that pretty well. In the app you can also now turn off the midrange compensation at 2k that I think you are referring to. You cannot do this from the build in Audissey (just the app) which I find a bit strange. My plan is to eq below 500hz with Audissey, disable the midrange compensation, and see how it sounds when I get my replacement receiver.

 

[Theriverlethe]

The unit will be heading in for service and then sold. I have used Dirac quite a lot..ddrc24/minidsp shd/nad t758. Ran it many times with the T758. Dirac was the full version and no complaints whatsoever regarding Dirac. Regarding the NAD, the only issue in regard EQ I found lacking was dealing with multiple subs. Audissey, actually does that pretty well. In the app you can also now turn off the midrange compensation at 2k that I think you are referring to. You cannot do this from the build in Audissey (just the app) which I find a bit strange. My plan is to eq below 500hz with Audissey, disable the midrange compensation, and see how it sounds when I get my replacement receiver.

No, Audisssey thought there was a null at 2.5kHz and decided to boost. I was already using the app to disable MRC and turning it back on didn’t affect the boost much. Maybe it existed at some of the measurement points, but definitely not at the main listening position.

 

[Dj7675]

No, Audisssey thought there was a null at 2.5kHz and decided to boost. I was already using the app to disable MRC and turning it back on didn’t affect the boost much. Maybe it existed at some of the measurement points, but definitely not at the main listening position.

Limiting correction below 500hz though, these issues won’t be an issue though, correct?

 

[Theriverlethe]

Limiting correction below 500hz though, these issues won’t be an issue though, correct?

Not the midrange issue... You definitely want to check the sub crossover and levels.

 

[Dj7675]

Trust... yet verify I always like to double check with REW after any auto eq.