Axiom Home Page Forums General Discussion Home Theater Calibration / Avia test disk

Either this new receiver I got(HK 745) has outsmarted me or it's not working correctly. I'm betting it's got me outsmarted. I've been messing around with it for several days now, well, for about as long as my patience will allow. I've read the instructions over and over and even consulted tech support. Now I'm asking for a broader opinion.

It all started when I heard how great HD/DVD's sound if you send an HDMI equipped receiver a L-PCM audio stream. And for clarification, I have the Toshiba HD-AX1 and have installed the 2.0 firmware update, so the X1 'should' be working correctly according to the gazzilion posts at the HD DVD forum at AVS.

So I select PCM with the X1 and give it a whirl. Everything sounds clearer, and the surround speakers come to life. Then I notice that there is no center channel. HU?? I go into the HK's menu and start messing with my settings. IE: channels, X-overs, delays, etc.....no matter what I do, I can't get the center channel to work when PCM is selected. Even though the HK's display shows PCM / 96 hz / Dolby PLIIx, I just don't have a center channel.

I called HK tech support again and they tell me to use the EZ EQ settings. I don't' know what good that would do, but I try it anyway. No luck, still no center channel with PCM selected.

I call Toshiba and they tell me if I select PCM, all I get is two channels. I read the Toshiba instructions and they clearly state that with True Dolby or Dolby plus, PCM, there is multi channel. So Toshiba tech is full of it.... so much for their help.

Thinking this might just be the Toshiba's fault, I pull out the Avia test disk. Still no luck with the center channel. So then I try the Avia test disk with my Oppo 970 and select PCM output. Not only do I not have a center channel, but All I have is the mains.

For clarification, when I select bitstream from the Toshiba or Raw on the Oppo, I do have all channels. Same thing if I run six channel analogue.

Are there any of you with HDMI that has messed around with PMC had similar problems?

So now that I've given up on getting PCM to work, out of curiosity I run the Avia disk again through both players to do some tweaking with the sub / LFE channel. When the test tone cycles back and forth between each speaker and the sub, the LFE channel is there for the mains, but about 15 db's lower than all other channels. This is with both players. When I ran this test with my last two HK's, the LFE test tone was balanced between each speaker and the sub.

No matter what I do to the LFE set up by selecting R/L + sub or just LFE, or the channels or the X-overs has any effect on this. It is as if there isn't any LFE for any channel but the mains.

Has anyone else ran this LFE test with the Avia calibration DVD? If so, can you tell me if you have an LFE presence with all the speakers or if it's just the mains?

:::WARNING::: I could be totally off-base here and/or talking out of my a$$ but, i have been researching the pioneer vsx84tsi receiver and have seen a lot of mention of an LFE bug on hdmi where there is difference of about 10db. i have seen it in reference to tosh hd dvd players as well as ps3 and on multiple receivers yammie 2700 yours and the pio. try avsforum for further clarification.

I believe you are correct. There is a bug. Unfortunately, that does not seam to be my problem or I would only see it with the Toshiba and not both players. I also pulled out the Oppo 971 and tried it. As expected, same problems.

I asked about PCM at another forum and a pretty sharp feller broke it down for me in a manner even I can understand.

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"PCM is the most simple way of digitising sound. It's what CD players use, it's what PCs use, it's what everything digital uses (except SACD). It works by measuring the position of the speaker/microphone thousands of times a second, and storing that position to a certain accuracy. On a CD sound is sampled 44100 times a second to an accuracy of 16 bits.

On a CD, this data is stored raw - 44100 16-bit samples a second. That means 44100*16=705.6kbits per second. Then times two because it's storing two channels for stereo: 1.4Mb/s.

Raw uncompressed PCM for a 5.1 channel film would be pretty bulky: 48000*16*5= 3.8Mb/s, plus a bit for the LFE. No way could you fit that onto a 35mm film print. And it would be rather a lot on a DVD too. Hence Dolby Digital, et al.

Dolby Digital, DTS, and all these other formats are just different ways of compressing PCM to take up less space on the disc or film print. Dolby Digital, DTS, MP3, AAC etc do this by throwing away information they think you can't hear.

Dolby Digital can squeeze 5.1 sound down to 0.4Mb/s or so - a factor of ten less space than raw PCM. The decoder takes the Dolby Digital compressed bitstream, and turns it back into raw PCM. It won't be exactly the same as it started with, but it shouldn't sound too much worse (to human ears, at least - an alien with a different hearing system might think it sounded dreadful. But then they wouldn't be convinced by our 3-colour TV either.).

The simplest way to think of it is that Dolby Digital and DTS are "MP3 for surround sound". They get the data down to a manageable size.

Now, DVD-Audio and the new HD formats have extra space for audio. So they can store either raw PCM, or they can use a lossless compression system. (DVD-Video can actually use raw PCM, but this is rare except for some 2-channel tracks on music discs, as there's usually not enough room).

These lossless systems typically can compress PCM by a factor of up to 2 or 3. Nowhere near as small as Dolby Digital, but you lose nothing in the process - the decoder gets back the original PCM undamaged. These systems are MLP (used on DVD-Audio), Dolby TrueHD (basically MLP with a few extensions) and DTS HD Master Audio.

With these lossless systems, they are all totally equivalent in sound quality, so anyone who debates whether PCM, Dolby TrueHD or DTS HD Master Audio sound better needs their head examined. They can only differ in how much they compress, or extra facilities like better downmixing, dynamic range reduction, etc. The important point when comparing soundtracks will be what resolution they're at (48kHz/16-bit, or 96kHz/24-bit, etc).

Super Audio CD is different - it uses a totally different system from PCM, called DSD. This is hard to explain, but basically it's performing 1-bit sampling at 2.8MHz. Again, this data is bulky (2.8Mbit/s per channel) so it can be compressed losslessly, using a system called DST, which typically compresses by a factor of three. DSD has pros and cons over PCM.

Now, in a sane world, all these compression systems would be handled inside the player, and interconnects between components would just use PCM or DSD. But before HDMI and i.Link came along, there were no digital interconnects that could handle 6-channel audio. So as a fudge, the Dolby Digital and DTS bitstreams were squeezed into the 2-channel space of S/PDIF and TOSlink, and the receiver had to have decoders (as well as the player, for its analogue outputs). This fudge only worked for the highly compressed bitstreams. There's no room in S/PDIF to pull the same trick for the lossless formats.

But now we have HDMI and i.Link, with their support for multiple channels of hi-res PCM/DSD, there's no need to send a bitstream across them. The player can do the decode, and the receiver can just accept raw PCM or DSD."

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That was extremely informative for me. Thanks Mdrew

(Should I be scared for myself that I've only been hanging out here a month and that actually was interesting???)

Great info Mike. It only seems to make sense to me that your receiver doesn't fully understand the PCM it is getting over the HDMI. Could this be an HDMI version incompatibility with the receiver and the player? Seems like you had to have 1.1 for multichannel PCM audio to work? I can't remember, sorry. I think it would be worth checking into or trying a different HDMI receiver, even though your HK 745 should be new and up to the task. Maybe take your disc to some store displays with different recievers and see how they behave.

The last reply I got from HK tech support was "this may be in the receiver, our engineers are looking into it".

I'm beginning to feel like an unpaid beta tester. The 745 does have HDMI 1.1 and "should" support multi channel PCM.

I just think I've got another HK lemon. I'll wait and see what they offer me as a solution. In the meantime, as suggested by HK tech, I'm running the six channel analogue cables. This 745 has a neat feature not available in other models/brands of receivers. It has a six channel DVD audio selection that I can select any of the surround formats with including PLIIx or DTS + PLIIx. It also allows me to adjust the channels at will. pretty cool.....Sounds great too!

Ah mdrew, the bugs just never end eh?

Does it also happen with toslink cable? Another option is 5.1 analog

Yeah Mike, that is a great feature of the receiver. I agree that it is very nice to have. It has the processing power to convert the multi-channel analog inputs to digital so you can apply any of the modes, bass management, a fantastic feature if you need to use the analog outs from your HD player. I'm doing the same thing right now with my RV-8 since it doesn't have HDMI. Sounds great for now, and when I get HDMI then I will have the full benefit of the extra rear channels (for the disks that have the extra surround content).

Ya Chess, another bug for me to eat...... I found a few bugs with my VP50 too. DVDO engineering is trying to figure out how to fix them. Then I found a bug with my Anamorphic lens and I'm working with Prismasonic to fix that one. I must have a freaking stencil on my forehead "screw with me, please, I really like it".

The weird LFE issue happens no matter what input I use withe the exception of the six channel direct inputs. The HK is doing something with the LFE channel to where it's only present with the Mains.

I am running the 5.1 analogues from the X1. I'm getting a 96k and the AVR is converting those channels to digital and then applying its own bass management. Sounds very good with the exception of the weird LFE thing. But at least I'm getting a very clean 7.1. Plus, the 600 makes up for any shortcomings of the AVR.

I am a bit confused (even after reading the PCM vs Bitstream from mdrew).

Last night, when first testing my surround sound, nothing was coming on the receiver with Bitstream, as soon as I switched to PCM a light came on the receiver as "recieving Dolby Digital".

I read another article today to keep your DVD player audio set to Bitstream and PCM off, so how does that explain that the only way for me to get a signal was to have PCM on? Was I using the wrong audio output?

Need more info to diagnose your problem.

Multi-chanel PCM in a lossless format can only be transmitted via HDMI. If you select bitstream on your dvd player, I'm at a loss why your receiver would not recognize it.

I wouldn't jump to conclusions or make assumptions just yet.

Pick up the Avia disk, a meter and do a good job calibrating your system first. I don't have much faith in internal test tone generators.

This may seem like a dumb question so please forigve me in advance.

Since my speakers are crossed over at 80hz, what frequency should the sub be calibrated at?

Yeah Robb, how 'bout them M22s(especially for solo classical piano)! On the sub cal bit, the receiver calibration is at 75dB, and this applies to the low bass tones for the sub as well. I used a different receiver to calibrate my EP500, but the test tones are essentially the same level; although I wouldn't call it a "barely hear" level, the calibration at that level isn't intended to shake the room either, so I suspect that what you heard the 659 do was about right. The fact that the LOTR segment was shaking things up would tend to confirm that the sub calibration was done well and the test tones you heard from the sub were at the intended level.

Another point on the EP500 is the importance of setting the trim control. You might find, depending on room size and sub location, that the half or even full setting better balances the room gain.

Robb,

Not sure I understand your question.....but it's early and I'm still slamming espresso.

When you use the Avia disk, just run through the steps. First you calibrate the speakers, then the sub. It's a piece of cake. You will come to the part where the LFE cycles between each speaker and the sub. The disk sends a High freq to each speaker and a LFE tone to the sub. They say these test tones should match in volume. I never could get them to match with the 745, but was able to with my previous HK's. I haven't tried the Marantz yet, but will sometime today. If you can't get all the speakers to match, concentrate on matching the LFE tone to the mains.

The theory of matching all speakers like this is for proper X-over setting for each group of speakers. You may not have that option with your AVR.

I like my sub running at a -5 DB setting on the AVR, but about 5 DB higher in volume than the mains. (that way I can always bump it up some with the AVR and keep my fingers away from the sub's volume knob after it's set)

I played with the EP 600's trim in a much smaller room than yours. I keep it flat. I don't like using the trim on the sub. It seams to kill some of the kick ass LFE tracks.

>>Yeah Robb, how 'bout them M22s (especially for solo classical piano)!>>

John, I am absolutly taken back, I have never owned a piece of Audiophile equipment (even though I have always wanted to). I would like to think that I have a producers mind and always hear things in tracks that other people can't hear simply because I am just looking to learn more about production. The M22s just blow anything I have heard out of the water for the price.

I sat my wife down in the sweet spot last night, and played some ambient beats from Craig Armstrong (keep in mind that right now the speakers are set up in a corner setup and the sweet spot isn't at the top of the triangle). Let me first say when I was listening in the sweet spot, I have never heard the album sound so good...back on topic...When the vocals kicked in in 2 channel, she instantly said "you just turned the centre channel on didn't you?". Thats when I knew that these speakers are THAT good.

Thanks for explaining the Sub Calibrating bit, even though I can't really hear 75db of LFE doesn't mean that it isn't outputting 75db for calibration.

As for the trim, I tried the full setting last night, it seemed to boost output a bit. I will mess around with it and figure out which is the best. The room right now that they are in is upstairs that opens to a big kitchen through a doorway...I think my sub is only at about 5 o'clock and -7db on the reciever and it still shakes the pictures on the wall.

>>The theory of matching all speakers like this is for proper X-over setting for each group of speakers. You may not have that option with your AVR. >>

I can't do individual crossovers for the different speakers. Part of the reason I chose the M3s over the M2s is because they have a similar response curve to the M22s. The M3 centre sounds awsome BTW with the 5.1 stuff (I have yet to hook my M3s up in parallel, waiting for the projector).

Thanks for all the help guys, I should be able to borrow an SPL metre tonite and calibrate my system properly.

Hey Robb, you should try a comparison between the M22's and the M3's in 2 channel and let us know your impressions.

I plan on doing that as soon as my basement is set up, right now, the speakers are not an even triangle and the listening test wouldn't be in an optimal setting. The left speaker is farther left than the right speaker is right if you know what I mean...

Not an equilateral triangle but an obtuse one or is it closer to an isosoles triangle. Any way I think I got it.

Quadrilateral. That's my favorite kind of triangle.

Robb, if you haven't read the Axiom newsletter which came out today, besides some CES observations by Alan, there's another published M22 review referenced. This is, of course, the Axiom flagship M22, although Larry(LT61)thinks that his M60s hold that position, and some others(e.g.,Ian)contend for the M80s.

Speaking of setup, I just read this in the EP500/600 manual...

Quote:

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Step 3:

CROSSOVER: if you are using the Bass Management crossover menu settings in your A/V receiver or processor, turn this control to “BYPASS” to eliminate the EP500 or EP600 internal crossover from the circuit.

If you are using the HIGH LEVEL (Speaker Level) binding-post inputs, set the crossover switch to 80 Hz for initial setup. If you have floor-standing speakers (M50, M60, or M80), try a 60 Hz crossover frequency, for the M80 try 40 Hz. If your main speakers are bookshelf models M3 or M22, try the 80 Hz setting, for the M2 try 100 Hz. Ultimately you want to use a crossover frequency that produces the smoothest blend of sound between the subwoofer and your main speakers.

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Axiom is suggesting a crossover of 40 Hz for the M80s? Wouldn't the HIGH LEVEL binding post inputs produce the same result as using the AVR's internal crossover settings?

If you look in the Outlaw ICBM manual it says to find the +/-3 point , with the M80s this would be 34Hz, then add 10 Hz to it. That would put it to 44Hz with the M80s. It would seem like the ideal crossover point, according to Outlaw, would be 50Hz but the ICBM does not allow for this setting. I ended up using the 60Hz setting for my system.

Rick, they don't do the same thing: the crossover in an HT receiver is a real crossover that rolls-off the sub above the selected frequency and also rolls-off the speakers below that frequency; the "crossover" control on the sub itself is simply a variable low-pass filter that affects only the sub. The speakers aren't affected at all by the control on the sub and continue to play whatever their full range is, and this is the case even when the main speakers are connected through speaker-level outputs on subs that have them.

So, the suggested settings for the EP500/600 "crossover" attempt to roll-off the sub above where the "natural" rolloff of the speakers begins. This might achieve a fairly good blend, but the bass management on the receiver does it more precisely and also takes some of the low bass load off of the speakers. When available, the receiver bass management should be used.