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.

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 R.S.C – Take Two

Introduction

In a previous blog post, I introduced YPAO R.S.C. (Reflection Sound Control), which is Yamaha’s room equalisation system. If you’re new to room equalisation, please read this post first. I will present some measurements below to show what R.S.C. is doing exactly.

Function of R.S.C.

According to Yamaha, the pure function of R.S.C. is to remove unwanted first order reflections from the sound. This should improve stereo imaging and intelligibility. As we will see there are other added benefits.

R.S.C. filters are applied before any Parametric Equalisation. In fact, all further measurements were taken using the following method on an RX-V3073 (the equivalent of the RX-A3020.

Running a multi-position YPAO with all 8 speaker positions.
Copying the flat curve over to the manual curve. This also copies the R.S.C filters as we will later see.
Zeroing out the PEQ filters manually (to 0dB on all) as this will keep the R.S.C. filters but remove any parametric equalisation. This has also been confirmed by Yamaha Japan – and the measurements that follow.

Measurements

YPAO succeeds in its goals – with some speakers and seating positions better than with others. I will show an example below with a centre speaker measurement. The centre speaker is located underneath a tensioned screen. The speaker is tilted upwards towards the listening positions. However, because of the room dimensions and multiple hard surfaces between the speaker and the listening positions on the sofa, the 70Hz to 250Hz region is a real issue with room modes – peaks and dips galore – that reduce intelligibility and are hard to deal with using PEQ alone.

Frequency Sweep

The below frequency sweep has 1/6 octave smoothing so all that is visible that R.S.C. cut some reflections in the 60Hz to 200Hz region. The green line was measured in the “through” position, while the pink line in the manual setting with no PEQs applied. Please note that R.S.C. is applying some attenuation to the signal output. The attenuation is dependent on the filters applied by the system, so it varies from channel to channel. The graph below has been adjusted to take this into consideration.

It is interesting to note that there is some activity going on above the modal region (above 250Hz). This isn’t necessarily bad as long as the robustness of the correction is taken into consideration. For example, Dirac Live does this across the whole spectrum also, but the higher frequencies are corrected, the more correlation needs to be between samples.

Now let’s have a look at the modal region with less smoothing to see what’s really going on there. Now this is more interesting. R.S.C. actually dealt with a dip in the 70Hz to 80Hz region, where the subwoofer crosses over to the centre speaker and removed some frequency build-up because of the back and side walls between the 80Hz to 200Hz.

So what is actually going on in the 70Hz to 80Hz region? Obviously no PEQ filter would be able to fill that region in since waves are cancelling each other out – as that has been tried before on this set-up. Let’s have a look at what is going on in the phase of the signal to answer that question.

Phase Measurements

As can be seen in the below measurement without any R.S.C. filters applied, there is a phase shift in the crossover region. This is quite common.

As can be seen in the below measurement with R.S.C. applied, the subwoofer and centre speaker phase are better aligned in the crossover region, therefore removing the dip in the frequency measurement. So far so good.

Ringing

Finally, let’s look at the spectrogram to see whether ringing has been improved. To be honest, ringing wasn’t much of an issue for this speaker / seating position. But as we can see in the after diagram, the crossover region looks a lot smoother and overall sound pressure levels have been better equalised in the modal region.

Subjective Listening Tests

After the above measurements were made, the PEQ filters got re-applied that smoothed the frequency response out, now having a much easier job of doing so.

Having the same PEQ applied over R.S.C. and no R.S.C. filters, though not a perfect test, the sound with R.S.C. filters applied just seemed more 3 dimensional with a better stereo image from the front and surround channel pairs. The sound of the centre channel is also improved in terms of smoothness.

What’s also clear is that the bass region is improved in terms of tightness. Even though amplitude was corrected with PEQ filters, the bass still sounded boomy in some listening positions without R.S.C. applied.

Tips and Tricks

The above does pose a challenge for those that like to have the Yamaha presence channels going along with the base 5.1 or 7.1 set-up and want to do a “full manual” configuration with R.S.C. applied. How do you measure the frequency response of these speakers after R.S.C. has been applied? Here’s a neat trick:

The easiest is to feed the left, right or surround left and right speakers with the frequency sweep signal while having the receiver in 9 channel / 11 channel stereo mode.

To hear the signal only come through the corresponding presence speaker, configure the 9 channel stereo to maximum high balance, maximum strength and maximum front / rare – left / right balance as needed. This will channel around 80% of the energy through the measured speaker, which is good enough to get an accurate measurement.

Happy Listening!

The Home Cinema PC – Simply!

Introduction

I love packaged media such as DVD – in the old days – and now Blu Ray. Packaged media will always have the upper hand when it comes to quality of picture and sound so let’s hope it’s here to stay. Nevertheless, there are so many of us who download TV shows or even want to have easy access to a library of movies without having to lift our back sides off that comfortable couch.

Since this problem is not new, many options are now available to do just what we want from Microsoft Media Centre PCs and appliances to games consoles like the Xbox One. In the following pages, I will show you my favourite solution that delivers the best balance of usability, features and quality.

XBMC – now Kodi

XBMC – or Kodi by its new name – is an open source, free application that anyone can download from the net. It has been around for years and it is my favourite choice for the following reasons:

The audio and video quality when using an HDMI connection is excellent, regardless of the platform used: from Windows to Apple OS X to Linux.
It is fully configurable to how you want it.
It integrates with online movie and TV databases and downloads art, trailers and everything in between to store locally in your media library.
It just works.

Choosing the hardware

having A dedicated PC

After much research, I chose to use an Intel NUC. Intel NUCs are small – actually tiny – form factor PCs that come with a processor, but not RAM. You will need to buy that separately. What is great about them is that they are cheap, don’t require a lot of effort to build, look great and have all the connections you need – including an infrared sensor for your remote.

If you’re only after 1080p (full HD) playback, any of the NUCs will do, even the celeron based ones. If you have a new 4K TV and want to future-proof your media playback device, you should buy one of the top performing NUCs as 4K is very CPU intensive: it uses a new codec (HEVC) that cannot be hardware decoded on current graphics processors.

Now you may find other off the shelf PCs for a similar price, so do have a look around.

The other option – if you’re adventurous, don’t have a lot of money and want to build your own PC – is to use a Raspberry Pi. There are many guides on how to build one on the Internet. Google is your friend!

openelec – turn your pc into an appliance

If you’re using a dedicated PC for your home cinema and you want to use XBMC, there is no better option than Openelec. Openelec is a stripped down Linux distribution that boots straight into XBMC without any other hassles. While you could make Windows or Linux boot straight into the desktop and then open XBMC, Openelec starts up faster, is more stable and can be upgraded with a remote control. The same cannot be said for Windows, but especially Linux. Plus with Openelec you remove all the added distraction that Windows brings with itself.

There are also many guides on the net on how to install Openelec so we won’t go into that here. Again, Google is your friend!

Installing xbmc / kodi on your current computer or other device

It is also possible to install XBMC on your current Windows, Apple or Linux computer and even on the Apple TV and android device. It is great to do this to try our XBMC and see if you like it first. You simply download the relevant installed from the Internet and off you go.

Choosing a remote control

Pretty much any remote control that’s been built for Microsoft Media Centre will work. The one pictured below can be had for as little as AU$15 on Ebay and has been tested to work. In fact I use one of these in my Home Cinema.

Configuring XBMC / Kodi

audio / video configuration

To get the most out of XBMC, pay extra attention to the following configuration aspects under settings. You may need to switch the settings pane to “Expert” to get access to some of the settings.

For maximum picture quality, XBMC allows you to match the refresh rate of your display to your video OR match the refresh rate of your video to your display by speeding it up or down as necessary. These settings are under System –> Video and should be enabled. One or the other should work on all systems.
For maximum sound quality, especially if you’re using an external receiver or amp that has Dolby D and DTS decoding, set the audio to bitstream in settings and tick which formats your receiver supports. These settings are under System –> audio.

LIBRARY CONFIGURATION

It is best to store files on a NAS – such as a QNAP – or alternatively using external HDDs. Whatever the case, XBMC allows you to add new folders to your library under the file menu for movies and TV shows.

Once you have added the folders, XBMC will ask you what the folder contains and what (online or local) service to use to download movie / TV show information and art.

SPICE IT UP – SKINS

XBMC comes with a default skin called Confluence. It is functional. But XBMC can do a whole lot more. You can download and install new skins within XBMC or by downloading them from the Internet. One of my favourite is Aeon MQ (3/4/5 or 6). The skin is highly configurable and very functional and pretty.

I hope that wetted your appetite for building an easy to use media playback device easily and cheaply. Enjoy!

What is Room Equalisation (EQ) and why should you care?

The Perfect Loudspeaker

Loudspeaker design nowadays is advanced to a point where loudspeakers have a pretty much flat frequency response between 20Hz to 20Khz, which are the lower and upper boundary of human hearing. In an ideal home cinema, the main speakers reproduce frequencies from 80Hz up while the subwoofer is reproducing frequencies from 80Hz down (in simplified terms). Sounds below 80Hz cannot be localised by human hearing (that is you cannot tell where the sound originated from) and because of the complexities of sound waves interacting below 80Hz in small rooms, it is best to have only one (or more) carefully placed subwoofers reproducing these lower frequencies.

Here Comes the Room

It’s great we have such advanced loudspeaker design, but once you put the speakers into a room, things get messy. The sound waves will reflect off the surfaces of the walls and furnishings and interact to create drips and peaks in the frequency response, making some frequencies louder, others quieter and yet others to echo and ring as they decay.

Example of frequency response of a loudspeaker in a room

What is even more upsetting is that this is not uniform in the room. As you move your head, sit somewhere else or walk around, the dips and peaks change. If you have just spent 100’s or 1000’s on speakers, the situation is rather unacceptable. You obviously want to get the most out of your equipment.

EQ to the Rescue

There are two main ways to combat the above: digitally using equalisation and with acoustic treatments. The former is somewhat easier to implement and a lot more wife (or for our lady enthusiasts, husband) friendly.

Digital Room Equalisation is built into most receivers nowadays. Some are more effective than others. Let’s have a look at some of what is currently on the market:

Audyssey MultiEQ XT and MultiEQ XT32: Audyssey’s technology deals with the most problematic frequencies below 200Hz very well, especially when it comes to MultiEQ XT32. At the same time, higher frequencies may not sound natural to some listeners. Some manufacturers (such as Denon) allow you to apply it to only the bass frequencies for this reason. MultiEQ XT32 was also available in standalone products as SVS AS-EQ1 and Audyssey’s own branded subwoofer equalisers. They have been discontinued, however. It’s worth picking up a used one if you have a receiver that lacks a good subwoofer equaliser.

Yamaha YPAO and YPAO R.S.C: Yamaha YPAO and YPAO R.S.C are discussed in detail here. They both do a great job with frequencies above 80Hz. Fortunately, the implementation in most recent Yamaha receivers is fully editable using Parametric EQ, which gives you enough resolution to tackle most issues. The only exception to this is ringing of the modal frequencies (see below), which is important for subjective sound quality.

Parametric EQ solutions: a fully parametric EQ solution, such as the ones from MiniDSP, allow you to target the modal frequencies in the room precisely, therefore allowing the reduction of ringing / echoing of sound in the lower frequencies. A good parametric EQ is therefore essential for frequencies below 80Hz and good to have below 200Hz. Neither Audyssey or YPAO tackle ringing at these problematic frequencies.

Dirac Live: Dirac is at the forefront of audio equalisation research and seem to be overtaking even Audyssey. Their impulse response correction algorithms seem to be gathering great reviews. More recently, they are also available in MiniDSP NanoAVR DL product, which makes it affordable. It is also very easy to use for those with not a lot of experience in equalisation, but who want to get the most out of their equipment. The highest end home cinema kits feature Dirac Live.

How to EQ?

If you’re new to home cinema, at the very least read your receiver’s manual and run the automatic calibration routine with all its feature set. If you’re more adventurous, you can supplement your system with a fully configurable parametric EQ for your subwoofer to tackle the modal frequencies in your room. For this, you will need:

A parametric EQ connected between your receiver and your subwoofer
The free Room EQ Wizard (REW) software from HomeTheatreShack.com.
A compatible USB microphone.

To know more about how to measure your room and configure a Parametric EQ, the MiniDSP or HomeTheatreShack websites offers some good guides, but in essence you will have to:

Install all the software
Measure the room response (in this case for the subwoofer)
Calculate the EQ filters automatically or manually in REW
Input the filters into your choice of EQ
Re-measure the altered frequency response
Repeat until you get satisfactory results

Modal Frequencies and What to Do with Them

Modal frequencies in effect are frequencies excited or affected by the size of a room. The modal region is the region below which modal excitation happens. This is normally somewhere below 250Hz for medium to large home cinema rooms. What happens in the modal region is that certain frequencies – very accurately predicted by room dimensions – will combine and re-enforce each other or cancel each other out in a way that creates big differences in loudness and decay time of the frequency. This will make the rest of the frequency spectrum – especially frequencies close to the mode – smeared, masking detail and transparency of the sound reproduction. To resolve this, the modes need to be calculated and measured using REW using the Room Simulation module, then checked using a frequency sweep and waterfall diagram. Once the offending frequencies are found, Parametric EQ filters need to be designed to EXACTLY match the mode’s frequency and Q to rob the mode of its energy. This will help reduce decay time also and make the waterfall diagram more even.

Waterfall plot showing increased decay time in the modal region. The most offending modal frequencies are clearly visible at 29.6Hz and 71Hz. Interestingly, speech intelligibility is affected by a modal at 83Hz, even though it is not as visible on the diagram.

We have really only touched on some basic concepts when it comes to equalisation. Nevertheless, the topic deserves the attention of anyone serious about home cinema. Learn it or get a friend or consultant who has the knowledge. It makes more of a difference to the perceived sound quality than your choice of speakers or amplifier. This is because the tonal quality that you like in your speakers is a lot to do with the above graphs. Even cheaper speakers can sound fantastic with the right equalisation and a good quality subwoofer.

How to build a $300 screen that performs like a $2000 one

Now you can order pre-mixed paint from us. Please contact us for more.

The difference a screen makes

You can project onto a white wall and get a really great picture, but if you’ve spent more than $500 on a projector, you will notice a marked difference with a purpose built screen. The benefits of projecting onto a great screen include the following:

Increased sharpness / perceived resolution of the image
Increased contrast
Better ambient light rejection (when using a grey or silver screen as below) which means you can watch TV, movies or Sports with some ambient light on without completely distorting contrast

Enter Projection Paint

There are some – may I say – rather expensive paints on the market that you can use to build a DIY screen. In this article, I will show you how to get the materials yourself, mix the paint, paint the screen and hang it.

Please note that this is a fixed frame projection screen, which means it is not really possible to paint a roll-up screen with the below method.

Getting the screen

There are a few options on where to paint the screen.

If you have the wall-space you can paint the screen on the wall with a black frame or even paint the whole wall with the paint mix below to create an invisible screen… until the projector is turned on that is.
If you cannot paint the wall, you have the option of getting an MDF sheet to paint or even better…
Paint on 3-5mm foamex / forex PVC sheets. These sheets are really light and easy to work with. You can nail them to a wooden frame for hanging or even nail them to the back of some bookshelves.
Any other rigid material that is paintable.

Forex Sheet

You can calculate the screen size you need at http://www.projectorcentral.com/projection-calculator-pro.cfm and get the materials cut to size, leaving enough outer rims for nailing and hanging.

Getting the paint

The paint mix is called Black Widow. I will show you how to mix and variate the colour shade of this paint mix to get the desired results. For now, let’s look at the base, no frills mix, for which you will need the following:

A matt white water based paint. Any will do such as the Dulux Wash and Wear Matt white. The most important thing is that it is water based and matt. 2L is plenty for upto 140″ screen.
You will need to ask the paint to be tinted using black paint to a grey to a shade of N7.8. If this is not possible an N8 will provide the right shade of grey also. If your trade centre doesn’t know how to tint paint using the N tint codes, ask them to call Dulux or a Dulux Trade Centre.
You will need Auto-Air Colors 4101-16 Aluminum Base Fine paint, which is a water-based silver paint formula. You will need 4 parts white paint to 1 part Auto Air Colors. If you’re using 2L of white paint, this will mean 480ML of Auto Air Colors. Be sure to buy the “fine” coarseness.
A short nap roller
Fine sandpaper

Auto Air Colors

You will mix the above together using a drill and paint mixer head for 2-4 minutes

Painting the screen

Using the paint mix, you will paint the surface with the roller in one direction only (vertical or horizontal) using quick movements. Go over it once quickly.
Do NOT go over the surface again until it has dried.
Once the first layer has dried, use the fine sandpaper to remove any imperfections from the surface.
Remove any dust created by the sanding using a duster or a dry cloth.
Repeat until you have at least 4-6 coats and a smooth even surface.
Let the screen dry out completely before using it.
Enjoy!

Variations on the above mix

The mix above comes out to a light to medium grey that is perfect for rooms with light coloured walls and bright projectors. It rejects ambient light well and has great contrast characteristics with the lights off as it rejects reflection from the light coloured walls.

If however, you are building a dedicated home cinema room with dark or black walls and you don’t intend on using the projector in ambient light, and you have a projector with great contrast (such as a JVC), you will want to mix a slightly lighter mix.

For a lighter mix, simply tint the white paint closer to N8.5, N9 or even N9.5. For 3D projection, which needs a lot of light, you could even try mixing with only a white base, as opposed to grey.

Recreating the cinema experience: Yamaha’s Cinema DSP

Cinema versus Home

Movies are designed for the big screen and movie soundtracks for the big auditoriums of cinema multiplexes. When played back through a home cinema system in a smaller room, the perceived tonal balance of the soundtrack changes.

Tonal Balance: in simple terms, it is the amount of perceived bass, mid-range and treble present in a soundtrack.

All modern receivers have a way to combat this through equalisation of the speakers / room and filtering of the high frequencies which removes the perceived treble push of smaller, undampened spaces like your living room. However, you may notice that even after such equalisation, something is missing no matter how loud you play your equipment. This is because the big cinema auditoriums have different reflection and reverberation of the sound as it bounces around the room than in a smaller room.

This is what Yamaha went on to solve using their expertise in musical instruments and sound recording. Enter Yamaha Cinema Digital Soundfield Processing (DSP),

Yamaha Cinema DSP

Yamaha knew about this issue before all other manufacturers and they went onto recording and analysing the real-world behaviour of sound in cinema (and other) spaces. The extensive amount of data collected allowed them to digitally recreate the spaces using digital signal processing and in 1985 they released the Yamaha DSP-1, a standalone processor that could re-create cinema soundtracks as if they were being played back in a cinema.

Fast-forward almost 30 years and Yamaha’s Cinema DSP is in all Yamaha Home Cinema Receivers and have advanced to a point where it requires serious attention from anyone interested in home cinema.

What you need

You will need

A recent Yamaha Surround Receiver with at least 7.1 channel capability. Although Yamaha’s lower end units can do virtual Cinema DSP through a 5.1 set-up, it is not nearly as effective as having separate speakers.
An additional two speakers that will be used for the Front Presence speakers. They can have lower power handling and efficiency than your main speakers. Small bookshelves or satellite speakers will do with a frequency response from 100Hz to 20Khz.
More wires

Speaker Configurations

In essence, Yamaha’s Cinema DSP reproduces the reflections and reverberations of the cinema spaces through 2 height speakers at the front called Front Presence Speakers. Although you can use the front left and right speakers to reproduce the soundfield (called Virtual Cinema DSP), it produces a muddy and indistinct sound and does not compare well to the real set-up.

Yamaha’s more advanced Cinema DSP called Cinema DSP HD3 uses an additional set of speakers for the back soundfield called Rear Presence Speakers. When using DSP HD3, the Front Presence Speakers are more important to install than the Back Presence Speakers. Please see the full configuration below:

Cinema DSP 3D and Cinema DSP HD3

Cinema DSP 3D only has the capability to use Front Presence Speakers. Yamaha’s lower and mid-range receivers have this version. The rear soundfield data is mixed into the surround speakers. For this reason, it works better if the surround speakers are not at ear height but at least half a meter or more above the listening plane.

dsp

Receivers of this class are capable of 7.1 or 9.1 channel output. For 7.1 channel receivers, the back surrounds will not output sound when the Front Presence Speakers are being used by Cinema DSP. The 9.1 channel receivers have the capability to power all 9.1 speakers at the same time.

Cinema DSP HD3 improves on 3D with two things:

An additional two channels at the back (Rear Presence Speakers) that only reproduce the CinemaDSP effects for additional clarity. This expands the speaker configuration to 11.1.
Double the processing power to calculate more precise soundfield data both in the frequency and the time domain. For example, this means that sound reflections are tracked in space for double the time than with DSP 3D providing even more clarity.

From Adventure to Sci Fi

When Cinema DSP is configured well, you will experience your walls literally melting away and your home cinema opening up to sounding like a big movie theatre. To configure it, do the following:

Ensure that the Front Presence Speakers are placed wider and higher than your front left and right speakers.
Run the YPAO automatic calibration even if you will not use the EQ function of your receiver. This is because higher end Yamaha receivers will adjust the Cinema DSP parameters dependent on the already existing acoustic characteristics of your room.
Select a Cinema DSP program (called movie) on your Yamaha Receiver.

There are 6 movie soundfields on all modern Yamaha receivers. Read your Yamaha manual to understand the differences between them. As a guide:

Select Sci Fi for any action or Sci Fi movie or where the soundtrack has lots of precisely steered effects.
Select Drama for movies with lots of dialog or for TV programs.
Select Adventure or Spectacle for older movies or movies with big musical scores.
Mono movie for – you guessed it – mono movies.
Select Standard when no other soundfield sounds right for the movie or when you want to leave the front soundstage intact.

In addition there are many parameters you can adjust for each soundfield to make it sound less or more spacious. It is rather difficult to configure these manually, so download the Yamaha iPhone and Android app to your phone that allows you to configure them easily.

I recommend this even if you have an older receiver that doesn’t allow you to configure soundfield data using your phone. You can simply use the app in demo mode and copy in the parameters using your remote manually.

What about other manufacturers?

Even though other manufacturers have started using DSP soundfield programs, they don’t have the sophisticated algorithms Yamaha uses. Most simply add echo or reverb to the soundtracks to create some kind of effect as opposed to precisely measured soundfield data. I recommend auditioning the difference between them.

Yamaha YPAO and YPAO R.S.C.

What is Yamaha YPAO and YPAO R.S.C

If you have a Yamaha Surround Sound Receiver from the last few years, it will most likely have a room calibration system called Yamaha Parametric [Room] Acoustic Optimiser. In simple terms, using a microphone, YPAO will take you through a process to optimise the speakers in your room to ensure you get the best surround sound experience from your receiver. You should use it when you’re setting up your Yamaha receiver for the first time and every time you move your speakers to a new position or new room.

If you’re a beginner to home cinema, you should refer to your receiver’s manual (or read my new article here), go through the YPAO process and stop reading here. At the same time, if you are an advanced reader and want to understand how to get the very best out of your receiver, keep reading. Since there isn’t a lot of information on the internet about YPAO, this article will go into some fairly advanced topics. Please read the basic and intermediate articles on SimpleHomeCinema first if you’re new to home cinema. Our advanced articles will not explain basic terminology.

Please note that not all statements are backed up by measurement graphs, but the article was written after being in email communication with the engineers at Yamaha Japan who designed YPAO (with the help of Yamaha Australia, thank you!) and taking hundreds of measurements and configurations for testing. These may be published at a later time. For the benefit of contributing to the community, the findings are published without wait.

The Difference between YPAO and YPAO R.S.C

Basic YPAO will do the following:

Measure and set speaker delays (called – inaccurately – distance)
Measure and set speaker levels / volume
Measure the frequency response of your speakers and use a parametric equaliser (PEQ) to flatten the frequency response of the speakers/room in the frequency domain only (what it is doing really is match the timbre of the speakers to each other)

YPAO R.S.C (R.S.C. stands for Reflected Sound Control) is more advanced. It actually has TWO sets of filters:

It will measure the impulse response of the main speakers (not the subwoofer even if the model has sub EQ) AND will create filters that will modulate BOTH the phase and the frequency of the response. This is to allow for removing the first reflection of the speakers in the room and it allows YPAO to tackle both the dips and the peaks in the frequency response. YPAO basic will only be able to tackle the peaks effectively and do a hit or miss with the dips. This is true of any type of parametric EQ. These filters are not actually displayed on the screen and are not editable.
The second set of filters are only in the frequency-domain with a minimum phase: these are the PEQ filters that are used in the YPAO basic equalisation. But here, more broad filters can be used since the main / most difficult issues in frequency response have been corrected.

This is why manual editing of filters for YPAO and YPAO R.S.C have to be done differently. Let’s have a look…

How to tweak YPAO and YPAO R.S.C manually

So why would you tweak YPAO and YPAO R.S.C.? There are two reasons:

Even when they have the capability on the higher-end receivers to do subwoofer equalisation, they don’t actually set filters that work in more difficult rooms. Yes, the subwoofer is the most important speaker to equalise.
YPAO and YPAO R.S.C. don’t always get the filters right. Sometimes a manual calibration will get more precision.

What do you need to manually calibrate YPAO and YPAO R.S.C.?

A high-quality USB microphone like the UMIK-1 OR if you have a receiver with YPAO R.S.C. the microphone that came with your receiver and a cheap USB sound-card with microphone line input. Please note that I have tested the YPAO R.S.C. microphone against a calibrated UMIK-1 and the microphone is accurate enough to calibrate to 1/6 octave resolution. You should NOT be working with a higher resolution anyway, especially since YPAO can only do about 1/3 octave resolution accurately, which is plenty to get your speakers sounding fantastic.
REW – Room EQ Wizard. You will need to Google this program and download it from Home Theatre Shack.
An strong will to learn and succeed if you’re new to equalisation.

How to set up the receiver

All Yamaha receivers give you the option to copy one of the equalisation curves to the manual curve for editing. This may be a good starting point for you. To find out if it is, measure your speakers both with the EQ off and on and see which response is flatter / closer to where you want it to be. Start there.

Alternatively, clear the manual PEQ settings and start from scratch by measuring the response.

IMPORTANT POINT!!! With YPAO R.S.C, when you copy one of the YPAO curves (such as Flat or Natural), the Impulse Response Filters (IRF) will also be copied, even though they are not editable. This means that you need to copy the curve and then MANUALLY set all filters to 0 decibels and measure your speakers that way if you want to start from scratch but still keep the IRF filters.

A proof for this is measuring the manual EQ on with all PEQ filters in the 0dB position and EQ off (called YPAO Through) to see what the IRF filters are doing. You will notice a difference and that is the first layer of filters being applied by YPAO R.S.C. The following diagram illustrates the difference. The centre speaker was measured both with no EQ (pink line) and with the manual setting with all EQ filters set to 0dB and only IRF filters active (darker purple line). You can see that the purple line is smoother especially in the 80Hz to 500Hz where YPAO R.S.C. is most active. Ignore the subwoofer measurements (below 80Hz).

How to equalise your speakers

Mathematically, YPAO’s 1/3 octave resolution is enough to get a flat enough frequency response for all your speakers. This is in spite of the fact that people on the forums like to complain about YPAO not giving us a higher resolution.

Adding YPAO R.S.C to the mix and you have way more resolution AND manual control to get excellent sound rivalling equipment costing 10x as much, if you’re willing to do the work. Here are some charts to prove this from a purely mathematics point of view, and then I’ll tackle reality. Darker purple line is the original response. The pink line is the new predicted response with only 6 filters, all configurable in YPAO.

As you can see on the before and after frequency response curves calculated by REW, you can match the response of all speakers within 2db of the desired curve using only the YPAO PEQs. That is not perfect but pretty close.

Ok, so how does this work in reality? REW’s predictions for cutting filters will be 95% spot on regarding how the PEQ filters will behave. The other 5% is slightly different behaviour OR – in the case of YPAO R.S.C. – an interaction with the Impulse filters. So set the filter, and re-measure.

Peaking or boosting filters will almost always not behave how you expect them to and may even cause audible artefacts. This is because dips in frequency response are most often than not will be due to standing waves, which PEQ cannot correct effectively or if it can, it will only do so for certain listening positions, while produce artefacts for others.

This is why you should equalise using only cutting filters if you can or if you cannot, use careful listening and re-measurement of all listening positions to ensure the filter hasn’t caused artefacts. To be perfectly honest, having played with different PEQ filters with or without impulse filters applied, in 99% of cases narrow Q boosting filters used to tackle sharp dips will produce some kind of artefact that is audible to trained ears. For untrained ears, this may not be so, but it is best to leave them be or lower the rest of the frequency spectrum instead.

There is a lot more to say about YPAO, but this is the take-away:

YPAO’s resolution is enough to correct frequency response to 2dB to the desired target. It will take time to experiment with the filters, though, to get this right.
YPAO R.S.C. applies impulse response filters that are not editable but will copy over to the manual setting.
Use cutting filters only to avoid audible artefacts, especially if you have any critical listeners in the audience. Otherwise re-measure all listening positions.
Use the subwoofer EQ on the higher-end models to equalise your subwoofer. Again, use only cutting filters here and tackle dips in the response by moving the subwoofer to a more ideal location in the room. PEQ is not there to do that.

Should you have any questions regarding more advanced set-up of your Yamaha receiver, please contact us at Simple Home Cinema. Happy listening!

Please note that a follow-up to this article has been posted here.