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Denon AVR-3802 DSP problem ???

Discussion in 'AV Receivers & Amplifiers' started by vaderx, Jun 16, 2002.

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  1. vaderx

    vaderx
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    Hi everyone,

    I recently upgraded my receiver to a brand new Denon AVR-3802. :) It sounds really good in DD 5.1 mode from DVDs however I'm getting a strange problem when watching TV channels on Sky. :-(

    When I enable any of the DSP modes on the receiver I can hear noticeable distortion on material with a large vocal component. Speech sounds very harsh, even crackling and almost breaking up on the centre channel speaker and there is a lot of leakage to the other four speakers where I can hear a high frequency squawking of the speech component. :-(

    This problem is worst when I use the DPL (II or I) modes but it is also audible with DTS Neo:6 and the custom Denon DSP modes. I've also tried switching between the digital Toslink and analog phono outputs on my Skybox with no effect.

    Has anybody else experienced this or does it sound like the DSP circuitry in the receiver might be broken? I'm reluctant to go back to the retailer until I'm sure there is a problem.

    Any help or advice on this would be greatly appreciated.

    My setup is:

    - Denon AVR-3802 - AV receiver
    - Kef Q5 - Front speakers
    - Kef Q1 - Rear speakers
    - Kef Q9c - Centre speaker
    - Samsung 807 - DVD player (yes, I know this needs upgrading :)
    - Philips 32PW6322 - TV
    - Sony VTX-S760U - Sky Digital receiver
    - no subwoofer (I live in a flat :-( )

    Many thanks,

    Chris
     
  2. Jase

    Jase
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    Hi

    Does it distort etc when you play a cd with the DSP modes or PL 2 engaged?? If it doesnt, then it may be the Digibox that is the problem not the amp.

    If it does distort when you play a cd as well, then its likely to be the amp and needs to be changed under warranty.

    Sounds like the Digibox to me as you say DVDs are ok.
     
  3. vaderx

    vaderx
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    Hi Jase,

    Thanks for your suggestion. I did some more tests this evening. I tried playing some CDs with DPL II and I also borrowed my parent's Sky box and tried that out as well. The results were as follows:

    Sony VTX-S760U (Sky Box) + DPL II = Distortion
    Pace 2500S (Sky Box) + DPL II = Distortion
    Samsung 807 (CDs) + DPL II = Works fine
    Samsung 807 (DVDs) + DD 5.1 = Works fine

    So both Sky boxes don't like my new receiver. :-(

    The distortion is worst on channels with a lot of speech (eg. Sky News, ITN News, etc...) and it occurs constantly. There is no difference whether it's speech from a studio or an outside broadcast.

    Is it possible there is some sort of incompatibility between the digital processing that the audio goes through on Sky and the DSP in the Denon receiver? Please can someone with Sky Digital and a Denon AVR-3802 confirm that they don't get this. At least I will know I'm not going mad. :)

    Maybe my receiver is from an early batch and has old firmware on it.

    Many thanks for any help,

    Chris
     
  4. Geoffc10

    Geoffc10
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    Have you tried adjusting the volume on the digibox, tried it on my setup and it does effect the overall sound if you turn the volume right down on the digibox.
     
  5. Guest

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    you were talking about playing dvds and sky through DD5.1? You do know that Sky doesn't broadcast in DD5.1 only selected sky plus? I know that that doesn't solve the DPL2 problem though.

    forgive me if that fact was taken for granted anyway.
     
  6. Jase

    Jase
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    Try adjusting the volume on the sky box as Geoff has suggested. Might also be worth checking the actual cabling etc between the box and the dish and the LNB on the dish (alignment etc). We sometimes have distortion over here when watching sat programmes and have cured it adjusting the LNB on the dish.
     
  7. Guest

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    I have sky + and a denon 1802 and it preforms fantastic in all formats. i have conected the sky audio phono outputs to the vcr1 input on the denon. as far as i a aware the volume adjust is programed on the sky remote to adjust the voulume on the tv not the box & therfore will make no diference. if anything i find the sky box is slightly on the low side for output of volume. Have you tried diferent interconnects incase they are at fault ?
    Try playing your cd using the phono connects to the vcr1
    then repeat using the same conects ie sky -> vcr1 input.
    if the sound is ok on the cd but not sky then your sky box may be faulty.

    Hope this helps
    Neil
     
  8. triumphtiger

    triumphtiger
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    I live in Sweden and have a cable-box called Sagem.
    I have it connected to a Denon 3802 as well, and I'm experiencing exactly the same thing you are.

    Lots of interference in DPL2, switched to 5ch stereo and everything is ok.

    CDs works just fine.

    I tried the tuner - distortion!

    Could it be that distortion occurs if you have a weak signal?
     
  9. vaderx

    vaderx
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    Hi everyone,

    Many thanks for your suggestions.

    I tried changing the volume set in the menus on the two Sky boxes and also tried different analog phono inputs to no avail. In addition, my Sony Digibox has a PCM optical digital output with also exhibits the same distortion.

    Some people on US forums (and also 'triumphtiger' here) have suggested that either a weak signal or poor broadcast quality audio may be a problem. However, the distortion is worst on Sky News (which I would expect would have very good production quality) and also the signal strength is very high on my Sky box.

    The problem is annoying enough for me to consider replacing the receiver for a different model/manufacturer that exhibits less of this effect. Has anybody with a different receiver had this problem on Sky or is this only apparent on Denon receivers?

    Cheers,

    Chris
     
  10. triumphtiger

    triumphtiger
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    I've had some feedback from where I bought my 3802.

    Other people have been experiencing the same thing with their cabletv-box.
    The solution to their problems was to connect the audio out (from the cable-box) to the tv, if you have a stereo tv, and then to the 3802.

    I just recieved this tip, so I haven't verified it.
    I'll try it when I'm home at lunch.

    Don't return your 3802 just yet:)
     
  11. triumphtiger

    triumphtiger
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    Didn't help......

    I also tried to connect "line out" to the "cd in" on the receiver, since the cd works in DPL2, - NOPE!

    There is definately some problems here, either the cable-tv-box, or the combination of the cable-tv-box and the 3802 DPL2.

    I just cant get it to work.

    Anything else, "matrix" "widescreen" "5 ch stereo" etc, works just fine though.
     
  12. Tompo

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    vaderx

    I agree with what you are saying about PLII and Sky transmissions. I thought it was just me, but it is really noticeable. My main problem is leakage from the front channels into the rear L&R. It can only be described as a high frequency squelching sound. It is there on every channel, but to varying degrees. I have a feeling it may be due to the compression system used to transmit the channels. Maybe PLII on the Denon is more sesnsitive than other manufacturers amps/recievers to digital transmissions. I owned a Sony ES amp previously and it never exhibited this 'feature', but then again it didn't have PLII, however even setting the Denon to Prologic mode doesn't stop the leakage. I have also tried all the connection options listed, makes no difference.

    Cheers

    Tompo
     
  13. triumphtiger

    triumphtiger
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    I have started this thread on a Swedish Hometheater-forum, http://www.minhembio.com/forum/topic.asp?TOPIC_ID=12259

    One reply is of special interest from a Danish guy, for those of you who doesn't speak Danish:


    "I don't know if the problem is the same, but here is my story:

    I'm receiving all my tv-channels by satellite today (digitally).
    I have bought a Denon 3802 with DPLII. After a short while I started to hear strange "digital squeaks" - especially in the surround-channels - from DR (a tv-channel). I had at that time a sat-box from Sagem. I replaced it with a Humax-box - but it didn't change a thing - likewise it didn't matter if I used digital or analog connections between the sat-box and the 3802. I contacted DR, who told me, that they have given Viasat (a Nordic Satellite Provider) the right to transmit with a lower bitrate. That small change is possible to hear with DPLII. It's very difficult to hear it in stereo though.

    I'm now receiving DR from Canal Digital (another Nordic Satellite Provider), where they seem to be using a higher bitrate - so the problem is gone. DR will forward this problem to Viasat!

    Viasat lowered the bitrate from 256 to 192 kbit/s..."

    End of translation.
    Sorry if I missed anything in the translation.
    But I think the most vital points got through.
     
  14. vaderx

    vaderx
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    Thanks for all your help guys. At least I now know I'm not imagining the whole thing. :)

    I'm going back to my retailer on Saturday and I'm going to swap for a different make of receiver entirely. The high frequency squelching noise is simply too annoying for me to live with it. :-(

    I'll post my results after I've done a few tests. :)

    Cheers,

    Chris
     
  15. Xeonic

    Xeonic
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    I thing triumphtiger might have got this one. I've heard the same noise on a lot of satellite broadcasts, and the sound is exactly the kind of distortion you get from low bitrates. You can test this out by encoding an MP3 with a bitrate like 32k, and (trying!) to listen to it. You'll get the same kind of screeching. Basically some channel providers are putting channel quantity over quality!
     
  16. Desticado

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    I have noticed the same issue.

    Particularly noticable as 'high frequency squeclching' most noticeable during speech. Only really notice it when im up close to the speakers though.

    Problem is ONLY evident when watching sky channels and not from CD, DVD etc

    Its a panasonic box digibox (the new one)
    A 3802 reciever and KEF KHT2005 speakers

    Regards
     
  17. vaderx

    vaderx
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    Reading the thread again it seems as if only the 3802 appears to be seriously affected by this problem.

    The specs on the Denon website (www.denon.com) show that the 2802 and 3802 use different DSP chips. The 3802 has an 'Analog Devices SHARC 32-bit floating point DSP processor' whilst the 2802 uses a 'high quality 24-bit fixed point DSP processor'. Since the DSP chip is the one that performs the DPL II decoding I may try a 2802 instead. I am hopeful that the different chip will give better results in this regard, I do realise that it may be lower sound quality overall but it's worth it to stop the squelching.

    Has anyone with a 2802 heard the high frequency squelching noise on Sky News with DPL II? Also, does anyone have any more information on the DSP chips that Denon use?

    Another option for a similar amp/receiver that I may go for is the Sony STR-DA555ES. It has a similar spec (DD-EX, DTS-ES, DPL II) and power rating to the Denon 3802 but Sony claim to use their own DSP chips. What do people this of this model?

    Many thanks again,

    Chris
     
  18. nsouthga

    nsouthga
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    I have a 3802 and Kef setup and have also noticed this problem with Sky, everything else sounds great.

    I noticed this only when listening very close to the speakers, it isn't noticable in normal use.

    I have the Pace digibox FWIW.
     

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