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.

31054_97_1

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:

  1. Measure and set speaker delays (called –  inaccurately – distance)
  2. Measure and set speaker levels / volume
  3. 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:

  1. 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.
  2. 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:

  1. 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.
  2. 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.?

  1. 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.
  2. REW – Room EQ Wizard. You will need to Google this program and download it from Home Theatre Shack.
  3. 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).

center with ipr versus eq only

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.

center eq'd

Screenshot 2014-10-09 22.31.19

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:

  1. 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.
  2. YPAO R.S.C. applies impulse response filters that are not editable but will copy over to the manual setting.
  3. Use cutting filters only to avoid audible artefacts, especially if you have any critical listeners in the audience. Otherwise re-measure all listening positions.
  4. 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.

21 Comments »

  1. Pingback: Anonymous
  2. Great article!!! However most reviews say that ypao receivers sound pratically the same as higher range models with ypao rsc…
    Have you ever tested both directly comparing???

    Like

    • That’s an interesting one.
      I do have both types. The answer is that it depends:
      1. Receivers with YPAO R.S.C usually have beefier components so depending on your speakers and room, they will sound different even without YPAO engaged.
      2. YPAO R.S.C does allow for more customisation so it allows you to tune it to your room (especially bass response).
      3. Depends on the person. Some people can’t hear the difference between an MP3 and a CD. Does it mean the difference isn’t there? No. Does it mean some people won’t appreciate the difference? No.

      In summary: there is measurable difference between the two. Is it going to be audible? Depends on all of the above.

      Like

  3. The rsc part of Ypao in my RX-V677 pretty much failed in my room. My room will be considered highly reflective (concrete walls & ceiling, tiled floor and thick curtains on one side. It over corrected to the point of skewing the sound field (A pronounced sound image shift to the right and very little bass in the mains). Ypao attempts to offset this by boosting the center channel volume way to loud as well as the surrounds. I even tested the rsc filters by copying the front eq setting to manual and setting all the eq curves to flat and comparing it with the through setting.

    After hours and hours of testing trying to get it to sound right, I finally just copied the parametric eq setting of my choice (in this case Flat) to the manual eq and adjusting channel volume with my sound level meter. I wrote down the eq settings for all channels and then manually input them thus excluding the rsc filters. What a difference!! Imaging was spot on and the sound stage was wider and higher with smooth full bass even in off axis listening positions. I recommend anyone with a similar problem to give it a try.

    I wish Yamaha would send an update that would allow tweaking or disabling of the filters as rooms vary greatly. I suspect (knowing Yamaha) that they might add this to future models.

    I would like to hear your thoughts on this.

    Thanks.

    Like

  4. Thanks for this info… I do have a question though. After running ypao I noticed that it applied a 6db gain to my subwoofer at 198.2hz.

    It did this after originally detecting all speakers as large. However, I changed them to small and set the crossover at 80hz. Why does ypao apply this gain at almost 200hz on my sub channel?

    Like

  5. How do you match the filter frequencies in REW, to those of Yamaha’s PEQ? The filter values doesn’t does not correspond to the adjustable values in Yamaha PEQ….

    Like

    • If you allow REW to automatically come up with the frequencies, then no they won’t match. However, you can either create filters manually or edit the auto generated filters to get an approximation. You can see the expected result straight away in REW. HOWEVER, they won’t always match real world performance so you will need to re-measure and re-adjust as necessary. With some experience, you will see what will and what won’t work.

      Like

  6. I don’t understand why it EQs a sub up that high either. One of my calibrations it +6db’d the sub at 250.0hz. Even if it does that the maximum you can XO at is 200, which is still way below the highest possible XO, and even still a XO generally only applies a 12db/ octave slope, so that 250.0hz wouldn’t even be a factor

    Must be a reason why it does, or that’s just a waste, since it’d be better EQing the sub down to 20hz and below.

    One thing with RSC, Roland, are those filters applied when you do Angle Measurements, and regardless of if you do Single or Multi Seat setup?

    Just, I do Single seat and Angles only. Never seemed worth doing Multi as my room’s so small anyway {11′ x 10′ x 7.5′}, and sounds awesome with 2 x subs EQd with the AntiMode, XO’d at 120hz all round, and with all Fronts and Surround as Standmonts and B&W CM Centre 2 S2.

    Like

  7. Hi Paul.
    I recommend you read my new article on setting up YPAO re multi measurement even for your small room it’s worth doing,

    With regards to sub EQ on the Yamaha, beyond the basic RF filters it’s a bit of a mess.

    The reason they’ve been applying that EQ that high with a high Q is to affect the lower frequencies with less of a slope if that makes sense. They are running the sub a little hot in those frequencies to make the system have more “weight” for lack of a better word.

    Filters are applied regardless of the type of calibration you do: single or multi. Angle measurement only affects sound steering into the channels using CinemaDSP or object based content (Atmos and DTS X).

    Like

    • Since one of our dogs chewed through the newer designed YPAO mic I got with the RXA3040, I’ve been using the YPAO mic I got with the RX 673. Is there any difference between them internally, or that can affect EQ quality {filters}, or is it just aesthetically different, do you know? I’ve been using it a long time and it seems no different.

      Like

      • Well, Yamaha seems to be using a different Mic design for receivers with R.S.C and angle measurement and receivers without so I would recommend you get a replacement mic if you can. I don’t know the exact reason why but from the mic designs, it looks like frequency response, sensitivity and directionality could be the differences. Unless, the only reason they changed the mic design is to accommodate the boomerang for angle measurement better but the old mic would have worked just fine with that so I see no reason for that. I can ask them this month as I send them the questions re YPAO volume and the new sound fields, etc.

        Like

      • Yeah, the only differece I can see is the design, and due to the wedge at the bottom for a secure fit in the boomerang.

        Like

      • Just ran YPAO using all 8 positions, and following Yamaha’s own recommendation. What I’ve found {vs Single point} is that it reduced the delay of my Fronts by 1ft, Centre by 0.5ft and SL by 0.5ft and SL by a few inches.

        Bigger difference still is that I can now no longer XO higher than 60hz on the Fronts, without the bass becoming overpowering. Whereas before to get the best blend/ power, 120hz was the sweet spot, any less being too weak.

        Like

      • Are you using a bass EQ separate from the Yamaha? I forget! In any case, the Yamaha is not great at managing the subwoofer EQ automatically.

        120hz is way too high for front crossovers unless you’re running small satellites speakers. Look into EQing the sub manually between 60hz and 80hz. But 60hz is good if Yamaha set that automatically.

        Like

      • Yeah, using the AntiMod SII.

        I know 120hz is very high for Standmounts, but since my room’s small I’ll likely be getting peaks which are flattened by the AM {who encourage the use of a higher XO than 80}. I’m also using 2 Subs once again too.

        I came to 120hz listening to basslines in RATM’s Renegades of Funk, after having listened via the CM10 S2 and know how the bassline extends deep on those, and 120hz sounded excellent, really cleaning up the whole range.

        … but now it’s no higher than 60hz.

        Like

  8. Also, Yamaha never sets XO to anything higher than 40hz, by default, on all 5 speakers.

    I figured it was down to my room size, doesn’t think I’d need any more bass at this distance, than any of the speakers give by themselves, which is just not true. Even the CM10’s needed some helg below 40hz, even if not much.

    Like

    • I think setting things at 40hz is quite problematic as there can be severe interactions below 80hz, hence THX recommended 80Hz from the beginning. I would get a good subwoofer EQ and set everything to 80hz which is what do at the moment.

      Like

      • As great as the AntiMode is, I’ve decided to just use YPAO Multi Position, since it includes the Sub in each of the {up to} 8 positions you can EQ for, and movies sound great {I also installed some Presence speakers too, which are doing a very nice job, and lift the dialogue, which helps since my Centre is under the TV and close to the floor}, and the AM on top of that, or even instead of, would likely do more harm than good, I’m thinking.

        I’m back to a single Sub also {using the one in the rear of the room}, since the one up front is likely conflicting against the Mains, cancelling each other out.

        As for music, I’m just using Pure Direct, as I’ve widened the distance between my Mains {back to the CM10’s}, and they have great bass extension anyway, and a Sub doesn’t add much to them since they go down to 40Hz easy}.

        Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s