Loudness Correction and Yamaha YPAO Volume

Here you were thinking you had it all sorted once you applied EQ to your system, hey? Not so fast… a flat EQ is not going to give you correct tonal balance after all. Meet Loudness Correction.

What is Loudness Correction?

Human hearing is not as sensitive in the higher and lower frequency ranges as it is in the mid-range. What this means in practice is that when not listening to a recorded program – let it be music, movies or TV shows – at the volume the program was recorded at or intended to be played at, the treble and base seem to drop off quicker than the midrange as volume is decreased. This actually upsets the tonal characteristic of the program material – even though you may have a completely flat frequency response for your speakers.

Here you were thinking you had it all sorted once you applied EQ to your system, hey? Not so fast… Now you actually know why a flat frequency response for a system is only actually perceived flat if it is playing at the right volume… unless of course we apply loudness correction.

I won’t go into the biological reasons for this or the estimations of how human hearing responds to changes in sound pressure. If you want to know more about the technical ins and outs of Loudness Correction, do a search for any of the following terms on the Internet:

  • Fletcher-Munson equal loudness contours
  • Robinson-Dadson curves
  • Normal Equal-Loudness Level Contours, ISO 226:1987

Loudness correction is not something new, it has been around in stereo systems for the last 30+ years. In fact, I have a loudness control on my 12-year-old stereo system in my car. However, auto-loudness correction is relatively new in the field of Home Cinema – first introduced by Denon and Marantz and other receiver manufacturers about 8 years ago through the inclusion of Audyssey’s Dynamic Equaliser, which is still the most sophisticated to date. Since then, THX, Dolby and more recently Yamaha have come up with their own version of it.

When it comes to movies, reference level for all channels – except the subwoofer channel – is calibrated by adjusting the playback system such that a pink noise signal recorded at -20dB relative to full scale (0dB) creates 85dB sound pressure level as measured with a C weighted SPL meter at the seating locations. Volume levels are adjusted for each channel individually until they reach 85dB.

Speakerreferencelevel.gif

The premise is valid: when listening to movies below the reference level (85dB), the tonal characteristic of the movie is changed. However, since loudness correction is not an exact science – human hearing is difficult to measure precisely – the different systems implement it slightly differently.

Yamaha YPAO Volume

I took some measurements with regards to Yamaha’s YPAO Volume to see how much loudness correction is applied to the high (above 6.5Kz) and low end (between 20Hz and 400Hz). Results are below:

  • volume at -40dB : 4dB added both high and low end
  • volume at -35dB: 3dB
  • volume at -30dB: 2dB
  • volume at -25dB: 1dB
  • volume at -22dB: 0dB – originally measured this at -22dB, but actually this should be -20dB as I am looking at the graphs now.

Screen Shot 2017-08-05 at 11.40.05 AM.png

Since I don’t have a unit that has YPAO volume – Yamaha sent me a unit (RX- A3060) to test for this – I wanted to know if I could re-create the effect using simply the base and treble controls on my unit. Below are the results:

Screen Shot 2017-08-05 at 11.43.58 AM

As you can see from the graph, applying 4dB to both treble and bass at -40dB, the results very closely match the low end, but the high end is not as closely aligned between 3KHz and 8Khz. Let’s have a look at higher volume levels:

Screen Shot 2017-08-05 at 11.47.39 AM

At -30dB, adding 2dB to both the high and low end, the effect is decreased, but also the errors. Since I actually listen between -30dB and -25dB normally, I have added -1.5dB to both bass and treble permanently on my older a3020 equivalent receiver.

How does it sound in practice? I have to be honest, Yamaha’s new RX-A3060 sounds noticeably clearer than my RX-A3020, even when matching the loudness curve using bass and treble controls as closely as possible and setting them up the same. (Please note that for the graphs above, the subwoofer EQ was turned off and the Yamaha was left to its own devices when it came to EQ.)

Now was it due to YPAO Volume, which works really well when listening to both movies and music at lower volumes, or was it the difference in DACs, the new 64bit YPAO or other component changes between the units? It is hard to know, but likely a combination of all the above. In the same room, with the same speakers, the difference in clarity was noticeable.

 

 

Yamaha YPAO Configuration – The Right Way

Introduction

I have been around to a friend recently who just bought the latest and greatest Avantage Receiver from Yamaha and AU$5000 worth of speakers but didn’t bother to read the manual in how to set up the receiver correctly.

Good sound is dependent just as much on doing the setup correctly, than it is on buying great gear. I was shocked and horrified to learn that after spending almost AU$10K on his setup, he didn’t bother to go through the expert setup procedure, he simply placed the mic on the couch (a big no no), measured one microphone position and off he went. Then he complained to me that the system sounded like $h1t, pardon my French! Of course it did…

However, after fixing his setup, I realised many people do the same, so it’s time for showing you how to do Yamaha YPAO – and actually most other home cinema receiver – setup correctly. Some of the advice below can be applied generally to all receivers. I will highlight Yamaha YPAO only advice here.

General Setup

Before anything else, you should go into the Manual Setup section under Speaker Setup and set the amp assignment correctly, dependent on which speaker terminals you used for which speakers and whether you used external amplification. You will need to refer to your receiver’s user manual as it does differ dependent on the the make and model of your receiver, even if we only look at Yamaha Receivers.

Microphone Placement

Firstly, auto setup should be configured as follows:

  • Multi-position: this is true even if you are only using one chair in one position to listen to the system. Although manufacturers include a single placement setup procedure, it is nearly impossible to get great sound using only one sample. They will either over-correct or under-correct for variations in frequency response. ALWAYS select multi-position measurement.
  • Angle Measurement (YPAO only): this will ensure that CinemaDSP will be configured correctly and if you have an ATMOS or DTS X enabled receiver, the height information will be used to ensure sounds are steered correctly to the different speakers. I would recommend to always select this option as well.

Ok, now with regards to Microphone placement:

  • DO NOT place the microphone on a hard surface like a table or even your couch (either on the seat or head rest) by itself. This will allow it to absorb reflections from the couch or hard surface in a way that is not natural. Unless you plan on listening to your system by putting your ear where your @$$ is or by placing your head on the coffee table and resting your foot on the couch (sounds rather uncomfortable if you ask me!), do not do this.
  • DO place the microphone on a tripod. The microphone has a grove that goes into your standard camera tripod. If you don’t have one of those, elevate the microphone by taping it to an upside down glass (the kind you drink out of). I usually use a plastic cup that has a slim bottom so it doesn’t act as a hard surface for reflections. Make sure you only tape the bottom of the mic. When I do this, I elevate the glass or cup using soft pillows to ear height, and not some other hard surface like a box or – as my friend did – a metal hollow side table.
  • DO make sure that the microphone has a “line of sight” view of all the speakers in the room if possible – at all microphone positions. The only exception to this is the subwoofer which does not need to have a line of sight view from the mic. I sometimes make some exceptions to this when it is totally unavoidable. For example, I have the back surrounds on a bookshelf which the back seats don’t have a line of sight view of. When I switch to the calibration which includes all seating positions in my home cinema, there were some mic positions at the back that did not have a line of sight view. However, all the front seats did. Not a huge deal but I don’t listen with that calibration when we only sit in the front row as it’s not ideal.

Have a look at the diagram below which you can find variations of in Yamaha documentation. The below is the correct version with number 1 position being in the centre of the couch (or chair). Some versions of this diagram were incorrectly putting number 1 on the side of the couch.

i361_070815

However, this is where it ends for me. I usually do the following, which seems to work with YPAO and other receivers as well:

  • Position 1: in the centre of the couch with microphone at ear height, away from the  headrest of the couch. Basically, this is right in the centre of where your bum will be but at ear height. The reason this needs to be in the centre is that the delay / distance measurements are taken from the first position. If you were to place this first measurement off centre, some seats would get better distance measurements while others a lot worse. We want to even this out and have every seat experience the most ideal sound the room allows.
  • Position 2: Same position as number 1 but to the seat to the right of the centre seat. On a 3-seater couch, this will be the right-most seat.
  • Position 3: same as position 1 and 2 but to the left. In case you’re wondering, it doesn’t matter if you go left or right.
  • Positions 4-6: Now I repeat the same measurements I did in Positions 1 to 3 but with the microphone placed much closer to the headrest where your ears would be, but at just enough height that it clears the back of the couch by a cm but also that it is getting some of the reflections off the back of the couch. Why? Because this is the position your ears will be AND there will be reflections that will muffle the sound that originate from the headrest of the couch.
  • Positions 7 and 8: I normally do these positions just between positions 1-2 and 1-3 (just a little off-centre) but in the same elevation and distance from the back of the couch as positions 1 – 3. This is to ensure we give the receiver enough variation for the room acoustics and don’t overwhelm it with having to compensate for that particular couch.

If you were configuring one seating position, a chair or arm chair, do the above exactly but divide up the chair equally or do some positions to the left and right of the chair at ear height as well as just a bit in front and above ear height.

If you have multiple couches, I recommend, doing more positions on the couch that will be your primary listening position and doing the rest on the other couch(es) following the above principles.

Angle Measurement (YPAO only)

YPAO in higher end Yamaha receivers will allow you to do something called an angle measurement. You will have to do this in Position 1 above, but use the little boomerang that came with your receiver like the one below.

YPAO mic

The positions are marked. Position 1 on the boomerang must face towards your front speakers, while 2 and 3 towards the back. The boomerang can be fixed onto a tripod as well. I really recommend this. Otherwise the taping method works here as well.

Measure each position by following the on-screen guidance. Please note that the height position is only available on Atmos and DTS X receivers.

Manual Configuration

Cabling and Crossover

Once YPAO (or other Receiver config) has finished, check the following:

  1. Speaker cabling is normal in all positions.
  2. Check what the crossover frequency was set to on your speakers.

Even though your speakers may be able to do frequencies below 80hz, it is not recommended to go below this cross over for movies as those frequencies are hard to control even from the subwoofer alone. However, your milage may vary. If you don’t have a separate subwoofer EQ, but only using the Yamaha, you may want to leave crossovers below 80Hz or leave speakers as “large” so no crossover is applied to them. As a rule of thumb, if Yamaha configured your speakers with a high crossover, you should not lower it (e.g. from 100Hz to 80hz), you can however up the crossover frequency (e.g. from 60hz to 80hz).

The reason you should not lower crossover frequencies is because the setup routine determined that anything lower than the crossover frequency doesn’t reach the seating positions without major dips (-3dB which is 1/2 of the percieved volume) in frequency response. If you lower the crossover, you may still get an uneven response or may not hear certain frequencies at all as now the subwoofer is not playing them back either.

If the crossover set is much higher than you know the speakers can reproduce, you may want to repeat the setup routine paying attention to mic placement. If they still come up short, think about aiming the speakers with the woofers pointing at the main listening positions.

Equalisation Curve

The equaliser on Yamaha receivers can be set to the following:

  • FLAT: this is the default. You should set this if you listen to a lot of TV, not just movies or you listen below reference level (around -17 volume on Yamaha receivers, 0 volume on THX and Audyssey enabled receivers) and your room has lots of soft furnishings.
  • NATURAL: this is the old CinemaEQ curve. It tames the high end to make sure that movie soundtracks don’t sound too bright if you have a normal living room with lots of hard surfaces like floors and walls without carpet or other soft coverings. Also use this if you are listening to movies LOUD as otherwise even without hard surfaces, just being much closer to the speakers than in the cinema will elevate the high frequencies beyond what was intended. Please note that some DVDs and Blu Rays had EQ applied during mastering to lower the high frequencies for playback in the home. If a movie sounds too muffled with this, you have two options: up the treble 2dB which may work or switch to the flat curve.
  • FRONT: this leaves your front left and right speakers alone and will timbre match all the other speakers to them. Unless you like how your front speakers sound because they are some ultra-expensive supersonic beasts, do not set this. Leave this alone. This is there to please a special few who spent $50K+ on their front two speakers.
  • THROUGH: no EQ is applied. Why would you do this unless you sit inside an anaphoric chamber? Seriously! Don’t!

Other settings

  1. Adaptive DSP should be switched on. It variates the DSP strength based on volume.
  2. Adaptive DRC (Dynamic Range Control) should be switched on if you’re listening at lower volume levels (below -25). Anything above -25 I would recommend switching it off as it can introduce a harshness to certain sounds on any receiver without YPAO Volume.
  3. YPAO Volume should be switched on. I am going to do a review of it in June 2017, at which point I’ll make further recommendations and check if it needs to be switched off for reference listening (anything above -25 really).

Surround and Surround Back Speakers Volume Levels

The only major issue I see with Yamaha receivers – or most receivers that don’t have Audyssey – is that they don’t variate surround speaker volume levels dependent on volume. When listening to surround programs at lower volume levels, the surround and surround back speaker volumes might need to be increased in certain setups to maintain the same surround envelopment. I have heard different views on this but it seems to me like those that have their surround speakers at ear height seem to have less trouble with this than those who have them somewhat higher than ear height or further away than the front speakers.

I believe both Audyssey and Dolby researched this and found it to be true, however. I find the same when listening in my home cinema where the surround speakers are somewhat higher than my front speakers while my presence speakers are on a third plane altogether near the ceilings. I normally increase surround and surround back channels by 1-2 dB dependent on how loud someone is listening to the system in general. You could even design a reference setting and a low volume setting turning this and other features on and off. On Yamaha you can do this using something called “Scenes”.

Give me feedback in the comments below and let me know how you go! Happy Listening!