MuneebM

Attention all Yamaha RX-V1400/RX-V2400 owners who use Cinema DSP!

I started a thread here about an issue I discovered with the Yamaha RX-V2400. I spoke to Yamaha Canada about it and ran some more experiments that have led to more conclusive results, which is why I am starting a new thread to inform people who own these receivers. This is not a critical or even major problem, but more of an annoying anomaly; I still think the RX-V2400 is an awesome receiver.

Set up and calibration:
I have a 6.1 set up, I've set the AVR to "6 spkrs" and surround back to "SMLx1". I used the 75 dB Dolby Digital EX test tones found on Digital Video Essentials to calibrate each speaker to 75 dB at my primary listening position with the AVR set to "STRAIGHT" (Cinema DSP off, native multichannel signal used). My resulting reference volume level is -2.0 dB, and although it doesn't matter much, here are the resulting levels of my speakers:
Front Left: 0.0 dB
Front Center: -2.5 dB
Front Right: +1.0 dB
Surround Right: +1.5 dB
Surround Back: +3.5 dB
Surround Left: +2.5 dB

Cinema DSP experiments:
My system sounds much better in STRAIGHT mode ever since I calibrated it to reference level. However, when I enable the Cinema DSP (e.g.: "Surround Enhanced", "Adventure", "General", "Spectacle", "Sci-Fi", etc.) I always feel like the surround field is imbalanced: louder on the left side than on the right side. After finally coming to terms that there wasn't something wrong with my right-side hearing, I decided to measure the SPL levels of the DVE test tones with the Cinema DSP enabled. I was not paying any attention to the actual numerical reading on the SPL meter when measuring the test tones, because I didn't expect them to be 75 dB anymore since the Cinema DSP "enhances" the surround field, so when the meter was reading as high as 80-85 dB, I wasn't surprised. I was actually taking into account the delta (difference) between the readings of the right surround speaker vs. the left surround speaker. I ignored and bypassed testing the surround back speaker, because when the surround back test tone is played, there is a "residual" test tone in both the surround left and surround right speakers, which I assume is to broaden the back surround field. On the other hand, when the surround left and surround right test tones are played, there is no "residual" test tone in the surround back speaker, so it was easier to measure those speakers. Well, with any of the Cinema DSP modes enabled, I discovered that the surround left speaker had a 1-2 dB higher reading on the SPL meter than the surround right speaker. I had to increase the surround right speaker's level by 1.0 on the AVR to match the surround left speaker. With the Cinema DSP off (STRAIGHT mode), this new level (as expected from the STRAIGHT mode calibration results above), results in the surround right speaker being louder than the surround left speaker. So, with any of the Cinema DSP modes enabled, I have the following speaker levels (note that only the surround right speaker's level changed when compared to the native/STRAIGHT mode levels above):
Front Left: 0.0 dB
Front Center: -2.5 dB
Front Right: +1.0 dB
Surround Right: +2.5 dB (+1.5 in STRAIGHT mode)
Surround Back: +3.5 dB
Surround Left: +2.5 dB

Yamaha Canada told me that some of the Cinema DSP modes are imbalanced since they are based on real venues, however I SPL measured all the Cinema DSP modes that I care for ("Surround Standard", "Surround Enhanced", "Adventure", "General", "Sci-Fi" and "Spectacle") and they all had the same imbalanced results. The service manager also told me that I could send my receiver in to have it verified, but I truly don't think there is something wrong with my particular receiver, but rather with the Cinema DSP on the RX-V1400/RX-V2400.

Can owners of either of these receivers please try my experiment above and post their results? If more and more of us discover this issue, then maybe Yamaha will agree that there is something wrong and perhaps provide a firmware upgrade.

Thanks!

MuneebM

So, any RX-V1400/RX-2400 owners tried this yet?

MuneebM

Well, in order to confirm my suspicion that there may be a bug in the Cinema DSP of the RX-V1400/RX-V2400, I did some more experimenting.

I disconnected all my speakers from the back of the receiver except for the surround left speaker. I played the surround back test tone on the Digital Video Essentials disc and attempted to measure the level of the "residual" test tone heard on the surround left speaker with or without the Cinema DSP active. In STRAIGHT mode, there was a very low-level negligible residual test tone heard in the surround left speaker that measured below -50 dB. However, with any of the Cinema DSP modes active, the residual surround back test tone heard in the surround left speaker was measurable, which is of course a normal characteristic of Cinema DSP. Here are the measured values of the "residual" surround back test tone heard in the surround left speaker with the following Cinema DSP modes active:
Surround Enhanced : 71.5 dB
Movie Theater - Adventure: 72.0 dB
Movie Theater - General : 73.0 dB
Movie Theater - Sci-Fi : 72.0 dB
Movie Theater - Spectacle: 72.5 dB

I did the exact same experiment with all the speakers disconnected except for the surround right speaker. Here are the measured values of the "residual" surround back test tone heard in the surround right speaker with the following Cinema DSP modes active:
Surround Enhanced : 68.5 dB
Movie Theater - Adventure: 69.5 dB
Movie Theater - General : 70.0 dB
Movie Theater - Sci-Fi : 69.0 dB
Movie Theater - Spectacle: 69.5 dB

As you can see from the results above that with any of those Cinema DSP modes active, the "residual" DVE surround back test tone is 2-2.5 dB louder in the surround left speaker than it is in the surround right speaker. I also measured the level of the calibration disc's surround left test tone on the surround left speaker with all other speakers disconnected and the same for the surround right speaker and found, as I had discovered with the other speakers still connected (in first post above), that with Cinema DSP active, the surround left speaker is 1-2 dB louder. Given that DVE's surround left speaker test tone is 1-2 dB louder on the surround left speaker than that of the surround right speaker, and then add to that the fact that the "residual" sound of DVE's surround back test tone is 2-2.5 dB louder in the surround left speaker than in the surround right speaker, there's no wonder why I find the surround field to be stronger on the left side with any of the Cinema DSP modes active.

I understand that certain Cinema DSP modes are intentionally imbalanced as they are based on real-world venues. However, I have found all of the Cinema DSP modes I use or care for to be significantly imbalanced in favor of the left side, and based on my measurements above I don't have a doubt in my mind that there is something wrong with the Cinema DSP on the Yamaha RX-V1400/RX-V2400.

The question is: is there something wrong with just my receiver or is this common among all RX-V1400/RX-V2400 AVRs? Anyone else care to do this disconnect-all-but-one-speaker test and post their results please?

I've sent this data to Yamaha Canada via email; we'll see what they have to say.

TimMc

Did you happen to swap your speaker wires? How about your interconnects? I only ask because I just don't have the time to futz around with the 2400 Cinema modes (heck, I hardly have time to turn that puppy on these days) yet I'm still a little curious about your findings.

TiA disclaimer - I've only had a 2400 hooked up since the weekend, I played w/ Basic and later Auto Setup, and haven't yet found the time to run the full frequency sweeps & analysis. But to my time-worn (& time-starved) ears, the small amount of listening I could get in did not sound at all unbalanced. I did check a couple of the DSP modes just 'cause and they sounded better than I remember from prior Yamaha days. After Auto Setup I did slightly tweak the LFE level by ear just 'cause, but that's really the only thing I heard that was obvious. Even my tin-earred better half (it's hereditary - needs the operation) noticed & commented on the really fine sound.

I know it's stupid and that I probably didn't grasp all of your description, but since I'm the paranoid village idiot I'd still go and swap speaker wires and run those tests. Otherwise you're going just going to pique my curiosity and then I'd have to set aside time to meter the darned thing - I don't have that kind of time so you need to find another logical reason ;~). Good luck!

MuneebM

TimMc, swapping the speaker wires won't make any difference because I've SPL calibrated my system with the Yamaha set to "STRAIGHT" mode, and the resulting surround speaker levels were as follows:
Surround Right: +1.5 dB
Surround Back: +3.5 dB
Surround Left: +2.5 dB

Given the fact that it was SPL calibrated, the Cinema DSP modes should therefore be balanced with my speaker levels set to what I've listed above, however they are not as I've measured the surround left speaker to be 2-3 dB louder than the surround right speaker.

You may not be able simply hear the imbalance at first but once you notice it it'll bug the hell out of you. That's what happened to me: at first I thought the Cinema DSP sounded great until I started noticing that the surround left sound field is stronger. I wasn't at ease until I measured everything and realized that my ears aren't all messed up afterall. Now that I know the Cinema DSP is imbalanced, I now always watch movies in "STRAIGHT" mode and will probably never go back to the Cinema DSP until a resolution is found for this problem.

It'd be great if you could get your meter out and do the disconnect-all-but-one-speaker test I described in my previous post and see if you get the same results as I do. Thanks.

MuneebM

I just got an email response from the Service Manager at Yamaha Canada and he is asking me to send my receiver in so he can test it out and confirm that there is nothing wrong with my receiver. All I want to know is if the Cinema DSP has a yet undiscovered bug in it because I really think there's nothing wrong with my unit in particular.

Can someone who owns the RX-V2400, has access to an SPL meter and the DVE disc please test it out?