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9090 or 9090db is one better than the other?

Discussion in 'Exclusively Sansui' started by lilwing, Apr 5, 2018.

  1. lilwing

    lilwing CAGE FREE AUDIO ZOO Subscriber

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    Assume new or both rebuilt at same level. Other than the output power what is different / better?
    Personal preferences??
     
    Last edited: Apr 5, 2018

     

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  2. avionic

    avionic " Black Knights " Subscriber

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    I've listened to both. Worked on both. 9090 is easier to work on.Both sound like sansui's..I don't know. Flip a coin.:biggrin:
     
  3. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    I can't comment on if either sounds better or not, but the dolby board is pretty much useless in this day and age unless you actively use a tape deck that doesn't have it. FM Dolby is dead as a doornail. (of course, says the guy with a Marantz 4270...)
     
  4. tnsilver

    tnsilver AK Subscriber Subscriber

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    There's tons of info about the technical differences in older threads in this forum. Sound wise... Both of my units (in my avatar) are in excellent shape. It's very difficult for me to tell the difference, but I could swear the 9090DB is a tad more punchier. I'm using the 9090 in my main system for a few weeks now, and I'm amazed how clean it sounds. It's a very tough call to make!
     
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  5. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    +1
     
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  6. spark1

    spark1 Super Member

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    I've had good experience with the 9090. I've always been under the impression that the dolby board in the 9090db can be a source of significant trouble; it seems that everything runs through this board, so problems there affect all inputs/functions. I'm sure someone with more expertise can confirm/correct, and perhaps provide more insight.
     
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  7. tnsilver

    tnsilver AK Subscriber Subscriber

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  8. Tom B

    Tom B AK Subscriber Subscriber

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    I believe the 9090db is rated a little higher in power. The 9090DB also uses the classic push pull amplifier using double PNP and double NPN outputs (2 NPN and 2 PNP per channel), while the 9090 uses all NPN outputs. (4 per channel). I would assume that the design difference would result in a slight difference between the 2 units
     
  9. moefuzz

    moefuzz Active Member

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    .

    As others have mentioned the the 9090db Dolby board can be problematic or present problems as well it is central to the design which can in turn
    cause unexpected problems to manifest in many forms.

    For me the choice was easy even 50 years ago,
    I am not a dolby fan so no Dolby - no 9090db.
    -Avoidance of the design with central Dolby board
    that to me was useless, well unless you prefer to
    "record all your home made cassette tapes using Dolby"






    charlie-brown.jpg







    Remember 11 14 2017,
    the past proves the future.




    .
     
    Last edited: Apr 6, 2018
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  10. LBPete

    LBPete Rolling Along Subscriber

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    The 9090 is rated at 110 WPC, the 9090DB is 125 WPC. In the link that Tinsilver posted above CDFixer outlines the design differences between the two models. Jim's post in that thread is the definitive description of these differences. It's much more than just Dolby/No Dolby.

    What's often overlooked in these discussions is the revisions that were made to both of these great receivers during their production.

    The 9090 had a significant revision to the power supply and driver boards to improve stability. Early production units won't have this important modification. There were other modifications to the driver board, mostly transistor substitutions and the addition of many fusible resistors in the later production units.

    The 9090DB had production changes as well but none as significant as the revisions to the 9090. The most significant was a revision to the driver board. The bias transistor was dropped in favor of a bias diode. It's likely this change was made because the transistor used in the early models was going out of production. The early and late boards are completely interchangeable. I don't know if the earliest and latest driver boards for the 9090 are interchangeable. Later DB models have improved wiring for the Dolby board. The pass throughs on Dolby board were revised late in production. Most of the boards produced have rivets in the pass throughs. These were eliminated in the very late production runs. The multvoltage transformers were eliminate in late production and the two 1 ohm 2 watt fuse resistors on the power supply board were replaced with actual fuses.

    There were other minor changes in the 9090DB. Sansui couldn't decide how best to mount the filter cap for the tuner power supply to protect it from the heat coming off the transistor heat sink. It's sometimes straight up, sometimes on it's side, sometimes with a plastic sleeve. The protection board on the earlier models has fuses in the signal path. These were dropped in later production.

    As I've mentioned many times, the Dolby issues of the 9090DB and 8080DB are overstated. Every time one drops a channel the chant starts Dolby board, Dolby board, Dolby board. It gets the blame when it's no more likely to be a Dolby board issue than any other contact point on an old receiver. This was probably Sansui's highest production receiver of all time and even now thousands are being enjoyed every day on both channels. The 9090DB has more switches than the 9090. The audio path goes through some of these switches adding more points for a channel drop

    Another point that often overlooked in these discussions is the difference in the dial lighting circuit between these models. The dial lights and dial pointer lights on the 9090 are only on when AM or FM are selected. They switch off when the other functions are selected. The dial lights on the 9090DB are on in all function positions but the dial pointer light switches off when not using the tuner.

    So which is better? The only real way to tell is to listen to two fully restored examples and decide for yourself.

    - Pete
     
    Last edited: Apr 7, 2018
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  11. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Excellent post Pete, exploded a myth or two that needed exploding. :)
     
    Last edited: Apr 6, 2018

     

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  12. spark1

    spark1 Super Member

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    So the dolby board is not a significant source of problems? If myth, it certainly is a popular one! Good to know, as I have avoided the 9090db because of it.

    I don't have nearly the knowledge of the esteemed Sansui experts in this thread, but if the fact that the 9090 was designed to turn off the dial display lamps when not in tuner mode is troublesome to the owner, there is an extremely simple "modification" which will leave the lamps on regardless of input selection. No expertise required!
     
  13. Tom B

    Tom B AK Subscriber Subscriber

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    I think a lot of the issues with the Dolby board pair on the 9090DB is related to how people at times try to clean the controls and switches sometimes resulting to damage to the connections board to board, as well as making the feed through connections worse by trying to squeeze the boards out as a pair. I have seen some that have no issues and haven't been repinned. I have seen some that were repinned, and are a mess because of damaged connections as well as shorts created by the repinning. Extreme care needs to be taken when repinning near the multi section rotary switch as there are a number of locations where it is easy to short the connection to the metal frame of the switch, or to an adjacent foil run. I have always looked at it with the "If its not Broken, don't try to fix it" attitude. Of course you need to verify that there arent any problems usually by slowly rotating the controls for the board set, and loosing the 1 non grounding screw on bottom and flexing the board a little to see if you lose any signal in any of the 6 or so functions
     
  14. lilwing

    lilwing CAGE FREE AUDIO ZOO Subscriber

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    Wow. Initiation by fire!!!
    Thanks for everyone's extra effort.
    Not a bad question for a Sansui noob eh?
    Like I touched a nerve or somethin
     
  15. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    IMO... Sound wise, I take the 8080db and 9090db over the 9090, specially with revealing speakers.
     
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  16. LBPete

    LBPete Rolling Along Subscriber

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    Don't get me wrong. I'm not saying the Dolby board is not an issue. It definitely can be, especially on the earlier production models. What I'm trying to say is it is not the first place to go when you have a channel drop out in one of these receivers. Like any 40+ year old receiver, almost ANY of the switches, relays and pots can cause channel drop and this receiver has a lot of them. In many cases, it just needs to be cleaned, don't jump to the Dolby board.

    Absolutely true. The early production units have the green flex pc boards connecting the push switches to the Dolby board. They are very fragile and tear easily when handled. Unfortunately it's hard to get access to the Dolby switch without moving those push switches out of the way.

    This discussion has focused on the 9090 and 9090DB. With the excetion of the power supplies and output transistors, it all applies directly to the 8080 and 8080DB.

    - Pete
     

     

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  17. LBPete

    LBPete Rolling Along Subscriber

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    One more suggestion. Currently the Serial Number Database has not been tracking the production changes mentioned here. I can tag notes to the serial numbers so we can start trying to determine approximately when in production these changes occurred. I think the driver board version is a good place to start. For the 9090/8080 does it have glass fuses on the driver board? For the 9090DB/8080DB does it have a bias transistor or bias diode? Additional items for the 9090DB/8080DB are: ribbon cable or the flex pc board on the Dolby board? Fuses on the protection board? Gold chassis? Multi voltage or single voltage. We can get a pretty good idea if we get enough accurate report. So if you have a new serial number or have already reported a serial number and want to state I'm all ears.

    To report this additional information, please put it in the 2017 Serial number thread in the database link at the top of the Sansui Forum main page. To get there you can just click on the link in my signature block.

    Thanks,
    - Pete
     
  18. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    All I,ll say is of all the 9090dB's I've repaired, only one had the improved feed thrus on on the Dolby board. All the rest of them had to have the Dolby board rebuilt to get rid of intermittent channels. There is no way to know before opening the receiver if it has had the changes, so I always advise people to buy the 9090, NOT the dB. Also, the dB has the audio signal running in and out of the Dolby board several times, adding un-needed circuitry and cabling in the signal path to degrade the signal.
     
  19. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    Pete,

    Little bit of a sidetrack here. Are you tracking when the change occurred in the driver boards of the 5000 series?
     
  20. LBPete

    LBPete Rolling Along Subscriber

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    That's a tough one to track because of all the replacements under the extended Sansui warranty. All of the 5000, 5000A and early production 5000X models were built with the early board. Since early production 5000X could have either board as a result of that warranty campaign, we would need a lot of serial numbers with the board identified to pin it down. That said, I can record that information.

    Warren, no doubt that the units you see have problems. After all, you are the hospital. If you judged all people from a hospital perspective, you might say that all people are sick. There are probably thousands of these receivers that work pretty well without needing the Dolby board pined. The 9090 has problems too, especially the early production units with those funky transistors. Does the Dolby board add complication to the DB model absolutely but it definitely has a more robust amplifier and that's why I prefer it.

    - Pete
     
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