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Thread: DIY phonostage.

  1. #451
    Join Date: Jan 2016

    Location: Shenfield

    Posts: 573
    I'm Slav.

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    Simon , couple more questions , in the Calvins do you use same value R5 R6 R7 R11 (6R8 or 4R7) or as per schematic
    Did you change R104 R204 from 10R to lower value due to increased current draw

  2. #452
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 766
    I'm Sandro.

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    WP_20170927_12_35_55_Pro.jpg
    I have completed the boards
    all BC 337 and BC327 are matched between the 2 channels and the groups whit Hfe from 397 to 404
    EG the left and right channels have all 16 transistors matched at Hfe 401
    I have a question in regards to the Calvin buffers just to make sure

    Q1 =2SK170 8.2 mA
    Q2 =PF4391
    Q3=2SA1930

    C1 = C2 =220 Pf

    I have used those as they are what I have at present but I can wait and get others

    What are the best ?
    And quote from guide :

    For the input transistors, also these can be used: 2SK170 (IDSS=8...8.5mA) / cascode: PN4391
    BF244B / cascode: BF245C (C1,C2 = 22pF)
    For the output transistors, a lot of choice is possible: BD 140 (Suffix -16) ( C1,C2 = 180-220pF)
    MJE/MJD 350 ( C1,C2 = 100-47pF)
    2SB 649/A (Suffix C oder D)
    2SA 1930 ( C1,C2 = 180-220pF)
    MJE 253 ( C1,C2 = 47-22pF)

    Should C1 C2 be chosen for the input transistors as stated for the BF244 /BF245 = 22Pf
    or should it be chosen for the output transistors ?

  3. #453
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 766
    I'm Sandro.

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    Quote Originally Posted by mac72 View Post
    Simon , couple more questions , in the Calvins do you use same value R5 R6 R7 R11 (6R8 or 4R7) or as per schematic
    Did you change R104 R204 from 10R to lower value due to increased current draw
    Sorry Slav
    You got me confused should not be R5 and R7 be adjusted to get the idle current on the output transistor Q3 and Q6 and the idle current is ? I can not find this on the Guide
    and R6 and R11 are 2.2 Homes

  4. #454
    Join Date: Jan 2016

    Location: Shenfield

    Posts: 573
    I'm Slav.

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    I think Calvin on Diy thread mentioned something and came up with some simulations for same values of R5 R6 R7 &R11 but cannot find it now , I try to work my way through one more time
    What power resistor in the current sources do you use 8R2 ?

  5. #455
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 766
    I'm Sandro.

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    Quote Originally Posted by mac72 View Post
    I think Calvin on Diy thread mentioned something and came up with some simulations for same values of R5 R6 R7 &R11 but cannot find it now , I try to work my way through one more time
    What power resistor in the current sources do you use 8R2 ?
    You mean 8Ra and 8Rb 220 r and 2K2 pot ?

  6. #456
    Join Date: Jan 2016

    Location: Shenfield

    Posts: 573
    I'm Slav.

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    I meant 10ohm 3w resistor on Paradise board which need to be dropped in value to provide enough current for RIAA and Calvin, I think it should be 8.2 ohm, am I right?

  7. #457
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 766
    I'm Sandro.

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    Yes I have dropped that to 7.6 Homes and fitted same slightly larger heat sinks

  8. #458
    Join Date: Jan 2016

    Location: Shenfield

    Posts: 573
    I'm Slav.

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    Quote Originally Posted by Bksabath View Post
    Yes I have dropped that to 7.6 Homes and fitted same slightly larger heat sinks
    Thanks Sandro , I must find Calvins simulations , is there a particular reason to use 2KSA170 ?

  9. #459
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 766
    I'm Sandro.

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    Quote Originally Posted by mac72 View Post
    Thanks Sandro , I must find Calvins simulations , is there a particular reason to use 2KSA170 ?
    If you mean 2SK170 not that I know off I have used them (reluctantly as they are precious things to pass on to my gran children's eventualy) because I have BF245 but not the BF244
    same for other recommended pair

  10. #460
    Join Date: Mar 2010

    Location: Sheffield

    Posts: 2,898
    I'm Simon.

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    I use the values from the notes, not the schematic and have always built with j107 and 5102 or whatever the match is. I use mje350 and 220pf caps. On the shunt I run 8.2 ohm 5 watt non inductive wire wound five watts and heat output is modest if you use a 300mA choke regulated power supply/ pre regulator and stick to 25.5- 26v under load into the shunt.

    Slav I think I have a spare quad of those 8.2 ohm resistors. Ill include them with your coils.
    Kuzma Stabi/S 12", (LP12-bastard) DC motor and optical tacho psu, Benz LP, Paradise (phonostage). MB-Pro, Brooklyn dac and psu, Bruno Putzeys balanced pre, mod86p dual mono amps, Yamaha NS1000m

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