KEF KIT100 - No Sound from BD80 Blu-ray Disc Player with Blu-rays

[raytw]

Hello there!

I've got BD80 that's connected to the input of my humble Kef KIT100 home theatre system via one of its S/PDIF inputs. I understand perfectly that this limits me to the old 'lossy' codecs. Unfortunately, I can't even make this work properly.

With the BD80 set to 'bitstream' I seem to be getting perfectly good surround sound with DVDs (with the Kef this isn’t always obvious, but the fact that I'm hearing anything with 'bitstream' selected makes me think all is in order) but with Blu-ray discs I don't get ANY sound unless I switch to 'PCM', which of course means I'm in boring stereo. As far as I can see, I've set everything correctly, including putting 'BD-Video Secondary Audio' to 'on' and turning 'HDMI Audio Output' 'off'.

I suppose the BD80 could be faulty, but that seems unlikely, since with 'HDMI Audio Output' set to 'on' our Panasonic television always gives sound via its HDMI input. Perhaps it's simply that the Kef doesn’t like the transcoded bitstream data, but I don't see why not.

Any ideas? I'm at a loss!

[MrBoylan]

Hello there!

I've got BD80 that's connected to the input of my humble Kef KIT100 home theatre system via one of its S/PDIF inputs. I understand perfectly that this limits me to the old 'lossy' codecs. Unfortunately, I can't even make this work properly.

With the BD80 set to 'bitstream' I seem to be getting perfectly good surround sound with DVDs (with the Kef this isn’t always obvious, but the fact that I'm hearing anything with 'bitstream' selected makes me think all is in order) but with Blu-ray discs I don't get ANY sound unless I switch to 'PCM', which of course means I'm in boring stereo. As far as I can see, I've set everything correctly, including putting 'BD-Video Secondary Audio' to 'on' and turning 'HDMI Audio Output' 'off'.

I suppose the BD80 could be faulty, but that seems unlikely, since with 'HDMI Audio Output' set to 'on' our Panasonic television always gives sound via its HDMI input. Perhaps it's simply that the Kef doesn’t like the transcoded bitstream data, but I don't see why not.

Any ideas? I'm at a loss!

Not sure how old this KEF system is but there are a few early Dolby Digital-equipped decoders (receivers, etc.) including those by Sony, JVC, B&K and others which choke on Dolby Digital soundtracks that are encoded at 640 KBPS. Dolby Digital tracks on DVDs are limited to 448 KBPS, which works fine on these older devices. Most Blu-ray Discs with Dolby TrueHD soundtracks have a Dolby Digital "companion track" which is used for the S/PDIF outputs (fiberoptic and coax). Guess what encoding rate it uses? Yup - 640 KBPS. It's valid in the Dolby Digital spec, but it was never seen until the advent of Blu-ray Disc.

Unfortunately if this is your problem, then there really is no workaround short of using the multi-channel analog outputs (assuming your KEF system has multi-channel analog inputs, which it may not) or setting the Digital Audio Output to PCM for Dolby (but with PCM output over the S/PDIF fiber or coax outputs, you will be limited to 2 channels).

If the KEF system supports DTS input, then you should be OK setting DTS to bitstream on the BD80 and this will get you standard DTS sound for both DTS and DTS-HD titles. Also, if the KEF supports DTS, then you could consider getting a Samsung or LG player instead as these have an option to re-encode all titles as high bitrate standard DTS (even Dolby TrueHD and Dolby Digital soundtracks) and output these over the S/PDIF digital outputs. Then you'd get discrete multi-channel DTS sound for everything.

As a last ditch effort, though, reset the BD80 to defaults in the setup menu and then try holding in the power button on the player for 5 seconds to do a hard reset and see if the behavior changes. I doubt it will in this case, but it's quick and worth a shot.

Good luck and let us know how it goes.

-CB

[BADuHamel]

Chris,

Do any of the older systems have problems with the high bitrate (1.5 Mbps) DTS? Because most of the BDs that utilize DTS-HD HR or MA use that bitrate for their DTS "core." Of course, those kinds of bitrates were hardly if ever used on DVD.

[MrBoylan]

Chris,

Do any of the older systems have problems with the high bitrate (1.5 Mbps) DTS? Because most of the BDs that utilize DTS-HD HR or MA use that bitrate for their DTS "core." Of course, those kinds of bitrates were hardly if ever used on DVD.

Actually, yes, but it's not as widespread as the Dolby Digital issue (which technically is not all that widespread either). The earliest pieces of DTS software encoded for home use were laserdiscs and CDs, each of which used a 1235 KBPS encoding rate and 44.1KHz sampling. When the first DTS DVDs came out with their 1509 KBPS (1.5 MBPS) encoding and 48 KHz sampling rates, there were some compatibility issues with then-current DTS hardware, due to the DTS decoding chips in use at the time. But these issues occured and were addressed in 1998/1999. At that time, most of the early DTS DVDs actually did use the full-on 1.5 MBPS encoding. It was only later, with titles like "Saving Private Ryan" that studios opted to go with the 768 KBPS DTS encoding in order to save disc space.

Meanwhile, with Dolby Digital, although the 640 KBPS rate was always part of the spec, there was no actual software that used this until the advent of Blu-ray Disc. DVDs were capped at 448 KBPS and I think broadcast ATSC TV may be capped at 384 KBPS (not positive about that). But with Dolby Digital, we now have most (if not all) Dolby TrueHD releases with a 640 BKPS Dolby Digital companion track (which is output over S/PDIF) so now we're discovering limitations in older decoding hardware that we never knew existed before.

There's a really good (if somewhat dated) article on the differences between Dolby Digital and DTS, as well as milestones in their development and use in consumer software and hardware here:

DTS, Dolby Digital and DVD: A History

Hope that helps.

-CB

[raytw]

Many thanks MrBoylan! I don't think many people would know something so obscure. It's a pity that manufacturers don't think about older equipment a bit more, but I suppose they wouldn't sell anything then would they?

The KEF KIT100 came out in around 2004, so I suppose it's a bit 'long in the tooth' now, although the sound is excellent (even though it doesn’t have 'real' rear speakers) and I'm reluctant to part with it. Sadly, it doesn’t have any analogue inputs either. I'd be prepared to modify it to have them but KEF refuses to release any circuit diagrams, so I suppose I'll be in stereo for a bit longer!

Many thanks again for your very informative replies.

PS: If anyone's got a KEF KIT100 service manual under their bed, please let me know!

[BADuHamel]

Many thanks MrBoylan! I don't think many people would know something so obscure. It's a pity that manufacturers don't think about older equipment a bit more, but I suppose they wouldn't sell anything then would they?

The KEF KIT100 came out in around 2004, so I suppose it's a bit 'long in the tooth' now, although the sound is excellent (even though it doesn’t have 'real' rear speakers) and I'm reluctant to part with it. Sadly, it doesn’t have any analogue inputs either. I'd be prepared to modify it to have them but KEF refuses to release any circuit diagrams, so I suppose I'll be in stereo for a bit longer!

Many thanks again for your very informative replies.

PS: If anyone's got a KEF KIT100 service manual under their bed, please let me know!

Wow, is 2004 actually considered "old" for playing back 640Kbps Dolby Digital?

Well, I guess when they say pre-Blu-ray, they really mean it. Oddly enough, I had a Sony DA4ES A/V receiver that was from around 2002 that I replaced in 2007 with an Onkyo 805. The Sony had no issues whatsoever with the high bitrate DD playback.

[BADuHamel]

Actually, yes, but it's not as widespread as the Dolby Digital issue (which technically is not all that widespread either). The earliest pieces of DTS software encoded for home use were laserdiscs and CDs, each of which used a 1235 KBPS encoding rate and 44.1KHz sampling. When the first DTS DVDs came out with their 1509 KBPS (1.5 MBPS) encoding and 48 KHz sampling rates, there were some compatibility issues with then-current DTS hardware, due to the DTS decoding chips in use at the time. But these issues occured and were addressed in 1998/1999. At that time, most of the early DTS DVDs actually did use the full-on 1.5 MBPS encoding. It was only later, with titles like "Saving Private Ryan" that studios opted to go with the 768 KBPS DTS encoding in order to save disc space.

Meanwhile, with Dolby Digital, although the 640 KBPS rate was always part of the spec, there was no actual software that used this until the advent of Blu-ray Disc. DVDs were capped at 448 KBPS and I think broadcast ATSC TV may be capped at 384 KBPS (not positive about that). But with Dolby Digital, we now have most (if not all) Dolby TrueHD releases with a 640 BKPS Dolby Digital companion track (which is output over S/PDIF) so now we're discovering limitations in older decoding hardware that we never knew existed before.

There's a really good (if somewhat dated) article on the differences between Dolby Digital and DTS, as well as milestones in their development and use in consumer software and hardware here:

DTS, Dolby Digital and DVD: A History

Hope that helps.

-CB

Thanks for the link, CB.

[MrBoylan]

Many thanks MrBoylan! I don't think many people would know something so obscure. It's a pity that manufacturers don't think about older equipment a bit more, but I suppose they wouldn't sell anything then would they?

The KEF KIT100 came out in around 2004, so I suppose it's a bit 'long in the tooth' now, although the sound is excellent (even though it doesn’t have 'real' rear speakers) and I'm reluctant to part with it. Sadly, it doesn’t have any analogue inputs either. I'd be prepared to modify it to have them but KEF refuses to release any circuit diagrams, so I suppose I'll be in stereo for a bit longer!

Many thanks again for your very informative replies.

PS: If anyone's got a KEF KIT100 service manual under their bed, please let me know!

2004 is pretty recent to be having this problem. Definitely try resetting the player to its defaults *first* before assuming that the 640 KBPS Dolby Digital bitrate is causing the problem. Also, test out some DTS discs and see what the results are. If DTS tracks also fail, then it's not a DD compatibility problem.

If the KIT100 is incompatible with 640 KBPS Dolby Digital bit rates then *everyone* who owns it would have the problem as soon as they try try connecting a Blu-ray Disc player and playing a Dolby TrueHD or 640 KBPS Dolby Digital title. So there may be something else at work here.

-CB

[raytw]

Thanks! I'll have a go at this again when I get a free moment, although I suspect it won't work, since the machine was in a pretty-well virgin state when I received it. It has had a region-free mod, but surely that wouldn't have any bearing on the issue, would it?

Actually there don't seem to many KEF KIT100s around, or not that I can see. Despite not having rear speakers they give a really good sound.

[raytw]

Well, I tried resetting and all to no avail. I suppose it's *possible* that I have a faulty Blu-ray disc, but I thinks that's unlikely (although it does seem odd that the 'pre-menu' part of the disc actually produces sound correctly, but I suspect that this is done in plain old Dolby Digital, which would be at the lower data rate). The disc I'm using is a film called 'The Notebook' (romantic stuff, I'm afraid!). At this stage, I'm a bit hesitant to get many more Blu-ray titles!

The KEF correctly indicates 'Dolby Digital' (but not every time!) when playing the transcoded Blu-ray track, but no sound is ever produced. I suspect that this means that it's usually identifying the source signal when first received but then 'loses the plot'. I've contacted KEF in the UK to see if they can confirm whether or not it supports 640 KBPS. I suspect that I'll never get a reply from that direction, but I'll let you know if I do!

I'm a bit confused by the idea of using a DTS disc. Are we talking Blu-ray here or just plain DVD? And are you saying that DTS always uses a lower bitrate than DD?

Thanks again!

Ray