Amplifier wattage question

[James S.]

I put this up on AVSforum, and I figured I would see what the members here thought also.
I was trying to answer another member's question about getting an amplifier vs. just using the receiver. I looked up the power needed for my speakers using the Peak SPL Calculator (hometheaterengineering.com) that is recommended. So putting just two speakers in the calculator and adjusting the watts until I got down to 60db at listening position, I got to .008 watts needed. I used 60db as I listen usually around -15db. Calibrated at 75db, so -15 from 0 would be 60db. He answered, correcting me, that the test tone in the receiver is recorded -30db from reference, so I would need to be at 90db at my listening position, instead of 60db. Reference being 105db, if calibrated at 75db. In that case, I would be at 8 watts to get 90db at listening position with 2 speakers. He also stated I should use only one speaker in the spl calculator. I didn't want to hijack his thread, so I am starting a new one.

Questions are:
Should I use one speaker in the calculator to get the closest needed wattage rating?
Once a movie is started, is it at 105db at reference, so 90db for me, or is that accounting for peaks?

Hopefully, it is not too confusing.
Thanks.

 

[lovinthehd]

Well, depends what you mean calibrated at 75dB (test tones may be 75dB, but that's not reference level in the end).....that's not the normal reference level. 85dB average would be (with allowance for 20dB peaks), which makes quite a bit of difference power-wise.

ps I generally use just the two main speakers in the calc

 

[James S.]

I calibrate at 75db at 0 main volume. Usually listen at -15db based on that.

 

[lovinthehd]

Then your reference level is 85dB, so -15 is 70 dB average level. They used to use 85dB test tones but found that's simply too loud for people, so the adjustment is done internally now.

 

[James S.]

Wouldn't I be at 60db if I set 0 main volume at 75db on my SPL meter?

 

[lovinthehd]

No, while the test tone is 75dB, reference outside of the test tones should be 85dB average level. They simply reduced the test tone volume to make it less painful, and make an internal adjustment to make up for it......what particular avr do you have?

 

[lovinthehd]

Try this https://forums.audioholics.com/forums/threads/why-75db.80477/

 

[James S.]

Yamaha RX-A3050. Ok, so if I watch a movie, at 0MV, it should play at 85db, so 70db for me as you stated.

 

[James S.]

Ok, thanks for that.

 

[PENG]

Wouldn't I be at 60db if I set 0 main volume at 75db on my SPL meter?

It depends on what you meant by that..

If you ran auto setup/YPAO and then check it with you spl meter at volume 0, you should get about 75 dB from you mlp, but that's with the test tone and assuming Yamaha also record the pink noise at -30 dBFS.

That means if yo are going to watch a THX movie, you should expect to get 85 dB average as lovinthehd told yo earlier, and 105 dB maximum/peak that could be in some of those movie contents.

The person on AVSF was wrong, or you misunderstood him.

THX reference level explained - Acoustic Frontiers

 

[lovinthehd]

Ok, thanks for that.

No worries, confuses a lot of guys.

 

[James S.]

Ok, that is what I do. Run YPAO and verify all are at 75db at MLP.

 

[lovinthehd]

Back to the spl calculator a bit, what are your speakers and what is sensitivity spec'd as? Sometimes you need to adjust the figure used for the calculator due to practices in spec'g the sensitivity, or even being a bit dishonest sometimes with 4 ohm speakers....

 

[James S.]

Basically, was just trying to check the watts needed. To see if I would benefit much from an external amp. If I use the peak SPL calculator just as a guideline, then one speaker at 85db, I need 5 watts. Go to 105db for peaks and the receiver tops out at 150watts at 100db, don't have enough power, it seems.

 

[lovinthehd]

So you do listen at "0" occasionally?

 

[PENG]

Basically, was just trying to check the watts needed. To see if I would benefit much from an external amp. If I use the peak SPL calculator just as a guideline, then one speaker at 85db, I need 5 watts. Go to 105db for peaks and the receiver tops out at 150watts at 100db, don't have enough power, it seems.

Now you know why on this forum we (such as me and HD) repeatedly asked members to use an online calculator first such as what you have done, before rushing to get an external amp. The main reasons are:

a) Whether a more powerful amp is needed depends mostly on one's spl requirements/volume setting, speaker's sensitivity (needs to adjust for non 8 ohm speakers) and distance between speakers and mlp.

b) Need to double the power output to gain 3 dB spl.

Because of b) adding external amps such as the often asked about Emotiva Bas X amps or even the 200 W Monolith amps won't make much difference other than taking some load off of the AVRs or for the ease of mind of someone who would listen to multichannel stereo for a long period of time and want high spl everywhere within their medium to large size rooms.

 

[James S.]

To answer the above questions, my speakers are all SVS. Prime Pinnacle for L/R (88 sensitivity), Ultra center (87 sensitivity), Prime bookshelves for surrounds x4 (87 sensitivity). Monoprice alpha in-ceiling for Atmos x4 (88 sensitivity). They are all rated at 8ohm, but I saw that the Pinnacles can hit around 5 at a certain frequency. I don't listen at 0 at all. Usually -15, give or take. So basically, if I use that in the calculator, then at -15, which would be 70db, based on 85 reference, I would need .15watts, with 90db peaks at 15watts. So as Peng said, I wouldn't benefit from and external amp.

 

[PENG]

To answer the above questions, my speakers are all SVS. Prime Pinnacle for L/R (88 sensitivity), Ultra center (87 sensitivity), Prime bookshelves for surrounds x4 (87 sensitivity). Monoprice alpha in-ceiling for Atmos x4 (88 sensitivity). They are all rated at 8ohm, but I saw that the Pinnacles can hit around 5 at a certain frequency. I don't listen at 0 at all. Usually -15, give or take. So basically, if I use that in the calculator, then at -15, which would be 70db, based on 85 reference, I would need .15watts, with 90db peaks at 15watts. So as Peng said, I wouldn't benefit from and external amp.

Some people (dealers included) will still tell you or try to convince you that even at low volume you will hear more details, dynamics, deeper/wider soundstage etc. if you add an external amp. Logically speaking, if they did, it wouldn't be because of "power", but people can be very illogical...

 

[James S.]

Thanks to Peng and lovinthehd. I got it now. My Yamaha is good for my listening volume.

 

[lovinthehd]

Long ago I went from a 2ch receiver to separate pre-amp and power amp and raised my wpc by 3x. I was a bit disappointed how little difference that extra power actually made.....then again it's nice to have more amp than you need sometimes, too, and can be useful in a variety of ways over the years. That said my major use for power amps these days are diy subs.