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AD797 Phono Stage Build and Help Desk Thread

Discussion in 'Turntables' started by HypnoToad, Feb 11, 2013.

  1. wyn palmer

    wyn palmer Active Member

    Messages:
    340
    Isn't the OPA727 a CMOS +/-12v MAX opamp with nearly 6x higher noise and inferior specs in virtually everything?
    I'm puzzled as to why you think that it's an optimal choice?
     

     

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  2. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    I didn't check the specs of these Wyn, there were quoted in the BOM list so thought they were ok, I like the sound of my.phne stage with them so will try out some others, what do you recommend that are not too expensive?
     
  3. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    Sorry there 627,s, slip of the keyboard lol
     
  4. wyn palmer

    wyn palmer Active Member

    Messages:
    340
    The best current production choice in my opinion is the OPA1611. The OPA627 has inferior specs in a number of areas, but does it really matter? Who can say...
    I suspect that there are a number of users of the AD797MCpre board that are actually using fake opamps without their knowledge that are quite happy with the end result.
     
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  5. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    Thanks Wyn.
     
  6. 2sixR

    2sixR Active Member

    Messages:
    206
    Location:
    NorKal
    so, was all ready to go with the Burson v5i in lieu of the LME49990 opamps and noticed the Burson V6 Classic... for those who know more about this stuff than a newbie like myself, can I use the Burson V6 Classic on this build... thanks in advance.
     

     

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  7. wyn palmer

    wyn palmer Active Member

    Messages:
    340
    I'd be very interested in the answer myself.
    I've been curious about why anyone buys any of the burson amps. Their specs are poor and I find their technobabble incomprehensible. Perhaps someone could explain a rationale for substituting them for say the opa1611 besides hifi speak, that is, something that I can actually understand.
     
  8. 2sixR

    2sixR Active Member

    Messages:
    206
    Location:
    NorKal
    well, I asked Burson about the V6 for the AD797 phono stage and this is what they said:

    "The phono stage is a bit tricky, with most design either preamp, power amp, headphone amp, CDP, DAC our V6 & V5 opamp can always work. But in the phono stage due to various design requirements some time our V6 will not work properly. Based on our experience when it comes to the phono stage our V5i will 100% work no question there. But if you want to apply our V6 opamp it will largely depend on how well the power supply of the design is. If the phono stage you talk about has a beefy power supply our V6 may work well, but if you are not sure to go for V5i for the safe option."

    since I'm going to start out with the battery power supply (I did purchase the PSU from Sachin for future build - don't know if it will take care of the stated concerns) I've decided to go with the v5i unless I hear comparo's that the opa1611 would be a better choice...
     
  9. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    IMG_20181206_131004_HDR.jpg Just finished my AD797 MC phono stage and CNC MN phono stage along with an Omishras power supply and fitted all into a satin walnut veneered enclosure with gloss black front and back plates, waiting for some blue LEDs to fit for each stage when selected. Have to thank Sachin from wwhoput me on to these and supplied the excellent made PCBs and very very happy Greatsounding stages These are my first DIY amp builds so just followed the original BOM lists as quite new to electronics so just getting my head around what does what and theses builds have helped me quite a lot especially with help from the Audiokarma members Sachin and Wyn.
    Next project will be a valve amp, any ideas for a good build that's not too expensive?
    Cheers
    Phill IMG_20181206_131004_HDR.jpg
     

    Attached Files:

    Last edited: Dec 6, 2018 at 9:31 AM
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  10. HypnoToad

    HypnoToad Ms Puss Puss Subscriber

    Messages:
    6,061
    Location:
    Melbourne, Australia
    I have the V5i complements of Burson and they are superior to the LME49990 in my humble opinion, not a huge difference but definitely a worthwhile step up.

    Great looking case you made there Phillamon. :thumbsup:
     
    Last edited: Dec 6, 2018 at 5:28 PM
    Phillamon likes this.
  11. 2sixR

    2sixR Active Member

    Messages:
    206
    Location:
    NorKal
    you might want to take a look at tubes4hifi (no affiliation) for some nice kits, and nice build on the phono stage.
     
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  12. tabarddn51

    tabarddn51 Member

    Messages:
    52
    Hi Guys I visited a friend who had build a Pearl 2. Sounded very nice, one thing he had done is arranged so he could change the capacitance & volume of the unit from outside the box. This feature I like a lot, would it be possible to do this with the AD797? I am hoping to persuade him to loan me the Peal over the next few weeks so I can do a back to back comparison.

    Cheers Derek
     
  13. sachu888

    sachu888 Spare the tigers, kill me Subscriber

    Messages:
    1,295
    Location:
    Bharat,where Tigers rule
    Very nice build Phil. The case finish is superb.
    I am not much into tubes, but as you know my friend has designed a Class AB 75?channel amp using Toshiba BJTs. They are very very good and comes as fully soldered modules including heatsinks mounted on pcb. It has onboard power supply and protection circuit.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    Regards
    Sachin
     
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  14. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    I've just finished my PTP TT but I'm getting a motor hum through my speakers that can be heard from 50% volume and upwards, before with the same tonearm and cart on a stand alone base and used with a Thorens TD 135 I used to.get it but a lot less, is there any mods to the circuit I can try to stop this interference. I have completed sheilded inside me case with silver ducting tape which is grounded and this stops any interference when using the CNC stage, tonearm is connectef to ground and I have tried grounding the motor as well but this dose not help. Any advice would be greatly appreciated.
    Many thanks
    Phill
     
  15. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    Have had a good search and think I found out that the Lenco motor is sending out emi which is being picked up by DL 103 cartridge, the Thorens motor is more sheilded so stops the emi. Think I will have to try some shielding materials to stop the emi,.
    Cheers
    Phill
     
  16. HypnoToad

    HypnoToad Ms Puss Puss Subscriber

    Messages:
    6,061
    Location:
    Melbourne, Australia
    They look great Sachin, where can we get more info on these?

    Glad you sorted it out.
     
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  17. sachu888

    sachu888 Spare the tigers, kill me Subscriber

    Messages:
    1,295
    Location:
    Bharat,where Tigers rule
    Thanks Phillip
    below are the specs of stereo amp:

    Power output : 70~120W into 8 ohms, 110~180W into 4 ohms.(continuous avg per channel.)
    THD : <0.03 % at rated power 20-20000Hz, 0.003 % @ 1kHz half power
    Signal to noise ratio : 112dB
    Frequency response : 3Hz-250kHz.(-3dB)
    Input impedance : 25k ohms
    Input sensitivity : 1V rms for rated power
    Damping factor : 200, @ 8 ohms, 20-500Hz
    Power supply : 30-0-30 for 75W, 40-0-40V AC 300-500VA for 100W, 9-0-9V AC for protect.

    The build is very straightforward, only need to make connections for transformer and RCAs.
    Here is a latest review https://www.lencoheaven.net/forum/index.php?topic=30648.0

    Regards
    Sachin
     
    Last edited: Dec 10, 2018 at 5:55 AM
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  18. Phillamon

    Phillamon New Member

    Messages:
    46
    Location:
    South east Essex
    Hi Sachin, I nearly ordered the 75watt from you from lencoheaven and you put me on to the AD797 phonostage, if you remember I didn't go for it as the Mrs got me a tube amp but I really fancy building a tube amp myself from the board up as really enjoyed building the last 2 phono stages.
    I also managed to get rid of my motor hum by simply moving my phono stage as it was basically sitting under the lenco motor, now no hum and the best sound coming out from my system, going to recap my crossovers on my mission 737r speakers next as these still have the originals and they must be 30 years old.
    Cheers
    Phill
     
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