1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Parasound P/DD-1500 Digital Surround Decoder

Discussion in 'DACs' started by SoNic67, Jul 26, 2016.

Tags:
  1. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    I am always hunting for older DAC's/CD's with multibit chips, that I can mod, listen, re-sell. Well, today I just paid on eBay for a Parasound P/DD-1500 Digital Surround Decoder - supposedly new in box.
    Features
    • 20 bit Zoran 38500 Dolby Digital Decoder,
    • 20 bit filters
    • 20 bit Burr-Brown PCM-63-J D/A converters (L, R, C channels),
    • Burr-Brown PCM-1702 D/A converters (left surround, right surround, and low frequency effects channel),
    • Low jitter Crystal CS8412 digital receiver,
    • Independent regulated power supplies, 32,000uF Main Power Supply.
    I will definitely use it in pure stereo mode.

    Now... does anyone have a Service Manual or even Schematics for my new toy?
     

     

    Please register to disable this ad.

  2. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    I have contacted Parasound Service Department - I might soon have the full schematics for my new toy!
     
    Last edited: Jul 27, 2016
  3. belgianbrain

    belgianbrain Super Member

    Messages:
    1,202
    Location:
    Greater Toronto Area, Canada
    Hmmm....do you have to feed it exclusively Dolby Digital signals?
     
  4. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    Nope, I think it can switch between stereo PCM and DD. At least that's what I saw in the Owner Manual:

    "Two Channel
    This mode instructs the decoding circuitry to automatically route or "downmix" the center, left and right surround channels to the front left and right channels for two channel stereo playback. In this mode, the P/DD-1500 operates much like a two channel D to A converter such as the Parasound D/AC-1100 HD.
    Even if the source material has been encoded in Dolby Surround or 2 channel Dolby Digital, the P/DD-1500 will playback the material in stereo. As a result, only the front left, right and subwoofer channels are active in this mode and only the amber L and R indicators will light. You can select the two channel stereo mode from the remote control or on the front panel.
    "

    I received only a part of the schematics (corrupted pdf?) that is related to the digital input section and right in front of the digital filters for DAC's there is a switching IC (flips between the DSP and Zoran DD decoder).
    I am already thinking that I might upgrade the CS8412 SPDIF receiver with a CS8414 or even a DIR9001.
     
    Last edited: Jul 27, 2016
  5. belgianbrain

    belgianbrain Super Member

    Messages:
    1,202
    Location:
    Greater Toronto Area, Canada
    Sounds like you'll have fun. Looking forward to reading about it!
     
  6. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    I just got the rest of PDF. I am still waiting for the mail to bring the device though...
    It seems that for the I/V conversion it has AD829. I can't do anything better there...
    For filters they used a combo of AD712 and OPA 2604. Don't know, this is good stuff in there, maybe I will experiment something in that area (I'll research a little more), but it seems well thought out.
     

     

    Please register to disable this ad.

  7. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    Whohoo, finally it is here!

    [​IMG]
    [​IMG]
    [​IMG]

    And the enlarged pic of "piece of resistance" - (3) of PCM 63P-J and (3) of PCM1702 (note the AD841 instead on AD829 as I/V conversion):

    [​IMG]
     
  8. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    First steps: bought two PCM63P-K2, they will take a while to arrive...
     
    Last edited: Aug 5, 2016
  9. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    Well, I decided to start with the OpAmps in the I/V stage, since they are socketed. Time to pull out the AD841J 's...
    Brought out my trusty LME49710HE's, and getting ready to plop them in. Specs: 20V/us is fast enough for 44.1kHz OS at 8x, noise 2.5nV/√Hz is not too shabby, GBWP 55MHz, 50uV offset, THD 0.00003%... good stuff.
    [​IMG]


    But then... I remember that somebody recommended me LT1028AC (Linear). Never had the occasion to try them, but on paper they look intriguing: 15V/us (hmm, close to the limit IMO, but I'm not using it on large signal), noise 0.85V/√Hz (whaaat? that's a 50 ohm resistor thermal noise), GBWP 75MHz, 5pF input capacitance, 15uV offset, THD 0.00002%...
    So here there are in place (the left two are for the PCM63's, the right side AD817 ones are for rear channels' PCM1702):

    [​IMG]

    Time to test. I am listening to the stuff that I always go for - The Police's Reggatta de Blanc. Steward Copland is the drummer obsessed with cymbal's, hi-hat, splash and... I just love it! Those sound so fake on every delta-sigma DAC... so I know it is the ultimate test.
    I am listening to the decay of a crash while the voice and guitar are screaming above it. The better a DAC is, the longer you can follow the decay. I have other secret clues too that I listen for :)

    Well... You know that you have something good when you can't stop listening. I am almost not believing, not only that the crash doesn't stop decaying, but I hear new things! Then I'm like... did I just hear a mastering slip here? This is so reveling and so... airy! Every instrument can be heard perfectly. I have also a SACD version of those songs and that played on a Denon DVD-3910 (DAC's are two PCM1796, each in mono mode) never sounded so good.

    I switched quickly to some other go-to CD's... this is some nice surprise. I will measure the THD+N later (before and after I receiver the PCM63P K2 versions), but for now I need to go back and enjoy.
     
    Last edited: Aug 7, 2016
  10. belgianbrain

    belgianbrain Super Member

    Messages:
    1,202
    Location:
    Greater Toronto Area, Canada
    Sonic, do you find you can really hear the difference by upgrading the D/A chip to a more refined version? Where do you order them?

    What's your favorite song on that disc?
     
  11. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    The better grades are avail on eBay or aliexpress... US or China.
    Grades on datasheet where: "no-grade", J and K. I have seen K2 that seem legitimate, even if not found on the original datasheet. Philips did the same binning system with TDA1541. AnalogDevices did the same with their multibit DAC's.
    Also, there is a variant "Y" that some think sounded the best, but I seriously doubt that. I think it was a just special made for Yamaha, but nobody has a datasheet for it.

    Now, you have to be aware that those are expensive and fakes are possible. Markings of the grade should be similar with pics from older equipment, same fonts - but different for the grading letter than the rest because that was painted applied after the selection process (binning) on the already "baked" chips.
    Some fakes are usual grade chips, planed and laser-engraved to claim that are the better, more expensive ones.

    The improvement is lower THD, and I can hear it by being able to isolate the small signals of certain instruments, when covered by louder sounds of different frequency. It affects more than just that sonically, but that's how I can repetitively find it.
    Some call this with different fancy words, whatever their brain is trained to name what they are "looking for", I am just an engineer...

    Digression:
    This "masking" effect is very easy notable on delta-sigma chips almost like on the mp3 recordings (good quality ones), and you will not find it measured on datasheets. But it is from design, the noise shaping is variable with the level, that's why most of the better delta-sigma chips have multibit architecture on first 4-5 MSB and D-S for the lower - to cope with this effect where most of the people can hear it.
    Sure human ear has that masking tendency naturally but the brain can apply "software" filters if is educated in that direction.

    PS: I didn't use my studio-level ADC (E-MU 1820m) in a while for THD measurements and I think Windows 10 "broke" some driver compatibility with ASIO - just on recording part, it didn't act right anymore.
    I hope I won't need to install Windows 7 on another dedicated machine just for this.
     
    Last edited: Aug 7, 2016

     

    Please register to disable this ad.

  12. StimpyWan

    StimpyWan AK Subscriber Subscriber

    Messages:
    3,990
    Location:
    Blue Ridge Mountains!
    You make me wonder if I should 'freshen up' my Parasound D/AC-1100HD? I wouldn't want to loose it's HDCD capabilities, as some eBay mods purpose. But, if I could update the downstream op-amps, that would be nice.

    Plus, I look forwards to your progress. It sounds like fun.
     
  13. xero-D-hero

    xero-D-hero Super Member

    Messages:
    2,161
    I saw that 1100HD listed on the auction site,was seriously thinking about it too but I guess I lost track of things and the auction must've ended,then when you relisted it had a higher price on it,so I sorta gave up then as that put it just outta my price range,which is NBD really as I firmly believe I'm the one that dropped the ball on that whole situation,though I will say that your 1100HD looks like a very nice unit that's for sure,and it definitely has the "good stuff" inside,so I know I'd have a hard time letting go of it.

    Still a great deal @ the current price,and in that price range it would be going head2head with the new Modi Multibit and I kinda feel the 1100HD would be the better unit.

    Hmmmmm ????

    Anyhow SoNic67 definitely has me looking real close at these Parasound D/AC & P/DD units.

    IIRC he's fond of the PMD100 in the HD's too.

    But I digress...

    FWIW

    Bret P.
     
    Last edited: Aug 7, 2016
  14. StimpyWan

    StimpyWan AK Subscriber Subscriber

    Messages:
    3,990
    Location:
    Blue Ridge Mountains!
    Hey xero,

    I'm definitely a Parasound fan. Plus, I love the look of this particular layout that Parasound uses. I'd be nice to built a complete system, from this series, if there is a whole series like the 1100?

    P.S. I sent a P.M. about the DAC. I don't want to discuss questions concerning value here.

     
  15. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    Today I manage to make my E-MU 1820m work again (with the latest "beta" driver from Creative site).
    Looks like I will need to replace some electrolytic capacitors, because I see some elevated 60Hz (and harmonics like 120Hz) noise at about -64dB. I would like to see it at -100dB or better.
     
  16. xero-D-hero

    xero-D-hero Super Member

    Messages:
    2,161
    Any updates here ???

    Just acquired a D/AC-1000 and I'm thinking maybe some of these mods might translate over to that unit.

    TIA...

    Bret P.
     

     

    Please register to disable this ad.

  17. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    I am still waiting for the PCM63-K2 chips and for the replacement capacitors to arrive.
     
  18. BigElCat

    BigElCat Mmm Hmm Subscriber

    Messages:
    7,711
    Location:
    South of Kansas City
    Indeed, there is an entire series. I have matching HCA-750A amps. His DAC and my amps lack the rack mount ears, which is my preference for style. There are two or three Pre-amps you could chose from, each designed by John Curl, a well-respected audio designer. Best part is the cost, being early 90's stuff, the series is now quite affordable.

    Sonic doesn't have the 1100, his is a 1500.
     
  19. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    Yeah. It has more channels, and the digital filter is Zoran, but I am using it in stereo mode only (PCM not Dolby Digital).

    [​IMG]
     
  20. SoNic67

    SoNic67 Well-Known Member

    Messages:
    919
    Update: I have replaced 10 capacitors in the DAC stage - used Rubycon MUSE in place of original Black Gate ones (that are not in fabrication AFAIK). Plus I have increased them form 100uF to 220uF.
    The measurements (at 48kHz SR) show that the parasitic 60Hz improved - dropped some 10-20 dB. But the 120Hz and rest of harmonics are not giving up... Don't know where they come from.
    I still have a boatload of capacitors not changed, but...
    Below is the THD+N graph for the Parasound PDD 1500 taken with the E-MU1820m as ADC (optical connection to Parasound).

    Parasound_PDD_1500.PNG
     
    Last edited: Aug 26, 2016

Share This Page