The phonopreamp T15B on miniature tubes. KIT

Discussion in 'DIY' started by Zampotech, Mar 2, 2019.

  1. Zampotech

    Zampotech Friend

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    The Moscow firm made me an order to edit the Assembly instructions for its new product. It will be a MM phonopreamp the miniature tube. My task is to assemble this product as an inexperienced assembler and edit the assembly instructions.
    The firm kindly agreed to the free publication of the materials. Using this permission, I publish this material on the forum.
    It may interest the distinguished members of the SBAF and guests of the forum.

    Unfortunately I gave only the PCB and the tube. The rest of the components will be handed over to me next week.

    This phonopreamp is built on four identical tubes 6Zh1B

    [​IMG]

    Datasheet in Russian

    [​IMG]

    This tube has the American counterparts:
    5702 Raytheon Mfg. Co.; Cambridge, MA
    CK5702 Raytheon Mfg. Co.; Cambridge, MA
    CK605CX Raytheon Mfg. Co.; Cambridge, MA
    6148

    The 6Zh1b tube is made in the exUSSR and was used only in professional equipment, in the army, in aviation and in space.

    The tubes, which were handed to me, were made in 1979 and have the stamp of aviation technical control (sign rhomb with the number 7 inside)


    The preamplifier consists of three PCB

    The first PCB - input and output connectors
    In this PCB provides a step adjustment of the input capacitance.

    [​IMG]


    The second PCB - preamp

    [​IMG]


    The third PCB - anodic stabilizer and heat stabilizer.

    [​IMG]

    I hope this work will be interesting.
     
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  2. Zampotech

    Zampotech Friend

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    I have not started the Assembly, there are already useful additions.

    Since I now have to look at the KIT with the eyes of an inexperienced collector, I will propose amendments to the instructions and specifications

    The first addition.

    For ease of installation will offer to Supplement the set of "bending master". On the PCB each element has a fixed bending.
    It is necessary to make a "bending master" for only four types of elements. These are diodes and three types of resistors.

    I draw an electronic model

    [​IMG]

    Made of hard plastic CNC milling machine

    [​IMG]

    I show the result of the work.

    [​IMG]

    [​IMG]

    All conclusions are bent equally.


    Second addition

    Tight location of flexible tube terminals can create errors during installation. This tube has two types of pinouts. In one row and the pin in a circle. Can be confused.

    [​IMG]

    I will offer colored heat shrink tubing instead of PTFE white tubes. The color of the tube will determine the purpose of the pins.

    The user must be a table for each tube. "the name of the output-color heat shrink tubing-length shrink tubing"

    [​IMG]

    [​IMG]

    This will reduce the likelihood of installation errors.

    Third addition

    According to the instructions, the tubes are installed on copper wire loops. Microphone effect in microtubеs is very small, but it is better to avoid it.
    I will offer additional silicone tubes.

    [​IMG]

    On the PCB, it looks like this.

    [​IMG]


    My criticisms were approved by the manufacturer and allowed for publication.
     
  3. Zampotech

    Zampotech Friend

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    Continuation. Amplifier-corrector PCB


    Yesterday the exact capacitors arrived and I started the installation.

    To install the resistors at a distance from the PCB, I used a piece of glass fiber
    [​IMG]

    Installation is not very spacious, so was the order of installation of the elements.

    The result of the installation (still without tubes)

    [​IMG]

    Note the capacitors that define the RIAA curve. This type of highly stable precise capacitors is used in professional communication equipment. Near are the main and corrective resistor.

    [​IMG]

    The RIAA curve should be very accurate


    Prepare the tubes

    [​IMG]

    [​IMG]

    Color corresponds to the purpose of the tube pins. Length of shrink tubing is optimized for installation. Everything is signed on the PCB, very convenient.


    Result of work

    [​IMG]
     
    Last edited: Mar 17, 2019
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  4. dBel84

    dBel84 Friend

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    I love symmetry in PCB artwork and this is just beautiful :)

    .. dB
     
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  5. Zampotech

    Zampotech Friend

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    Continuation. Case

    Today I had a prototype housing. He is still without a front panel and accessories.
    Made of thick steel, for magnetic shielding.

    The power supply and amplifier are made in separate cases.

    Front view.

    [​IMG]

    At my request, the manufacturer added ventilation slots closed with steel mesh. The front part of the body is adapted for different types of front panels

    Rear view

    [​IMG]

    Will be located in the back of the input RCA, output RCA and adjustable incremental capacitors

    Right side view

    [​IMG]

    Between the power supply housing and the housing of the amplifier will be non-magnetic gap of 8-10 mm. Magnetic interference from the power transformer should be greatly reduced.
     
  6. Zampotech

    Zampotech Friend

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    Will share some photos of the assembled phonopreamp

    General appearance. So far without inscriptions and without the front panel. The front panel I will make for my phonopreamp out of wood.

    [​IMG]

    Back. On the input connector switches the additional capacitors.

    [​IMG]



    Installation view with the top cover removed. I need to Refine the appearance of the wires a bit.


    [​IMG]

    The view from the top. The vents are just above the tubes.

    [​IMG]


    View of the tube in the dark.

    [​IMG]
     
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  7. dBel84

    dBel84 Friend

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    @Zampotech is this kit going to be made available to anyone through a webstore?

    I would be curious to build it and compare to my phono.

    .. dB
     
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  8. Zampotech

    Zampotech Friend

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    This kit is supposed to show on ebay. If the moderators will permit, I'll link. While the kit passes the test run.
     
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  9. Zampotech

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    testing T15B in the main modes is finished.
    The scheme has been adjusted and changed slightly.

    [​IMG]

    Removed capacitors C2 and C10. The gain was reduced, but the sound was much better. Also changed the values of some resistors.

    main technical characteristics:

    Input / Output (1 kHz) = 5mV / 300mV
    Noise = -62...65dB (the faint hiss of)


    Today me brought 5 power transformers on 115 volts. It is possible to manufacture 5 sets of power voltage 115 volts.

    [​IMG]

    The tubes will be tested and marked when picking.
    Of course, this kit is not for the first Assembly in life. Requires attention and accuracy.
     
    Last edited: Apr 16, 2019
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  10. Zampotech

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    Result of work.

    This is what the basic KIT T15B looks like after assembly.



    Unfortunately I did not have a normal camera. I took pictures on my smartphone and there were color distortions of brightness and contour.

    [​IMG]

    [​IMG]

    On the front panel of the phonopreamp are T1, T2. T3. The manufacturer has several options for old correction curves.

    The KITs will be 115 volts and 220 volts.
     
    Last edited: May 7, 2019
  11. JK47

    JK47 The Beer Houdini

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    After sitting in Customs for almost a full month, my T15B kit arrived a few weeks ago, and I slowly started to assemble it.
    IMG_2280.jpg
    IMG_2288.jpg
    This kit is not for a first time DIY project, that's for sure. @Zampotech provided me with schematics, a few wiring diagrams, and I had to ask for help to correct errors multiple times. He was always quick and responsive, same day (keep in mind the time zone difference between the USA and Russia) and within minutes once a PM conversation was under way.

    I got the T15B up and running earlier this morning, and started to put it through it's paces. It run's quite quietly without much background noise, no 60Hz humm in my system, it does have a bit of hiss and crackle (I'll let the tubes settle for a while longer before making judgement). The EC Classic phono has a faint 60Hz humm which is more than the T15B, but the EC has virtually no hiss. I do have another set of Russian tubes as well as some Raytheon equivalents. It's not really fair to compare the two until the T15B tubes have some more time on them, maybe a few more weeks or so, but the initial feeling is that the T15B has more punchy pronounced bottom end and denser mid range. Almost U shaped, maybe V... and the EC has a more even FR, and resolving/thinner mid range. The EC also has more gain, as well as gain in price, $250 vs $1000. Not really a direct comparison tone wise (well maybe a little), but similar to comparing the HD650 to the HD800 technicality wise... so far, however that may change.
    58809394260__9BFEAE7E-8D46-4F86-A0FC-98A4A99357B3.JPG
    IMG_2337.jpg

    The T15B case is solid as a Russian tank and feels substantial in hand. I'm thinking of making an umbilical cord for the main unit and power supply àla EC amps. It's a product that feels and sounds like more than the sum of it's parts and price.

    IMG_2338.jpg
    My audio chain... VPI Classic 1/Center weight/Periphery ring/Phoenix Enginnering Eagle PSU and Tach--> DIY Cinemag 1254 SUT--> EC Phono Classic/T15B-->Pioneer M-22/DIY Whammy amp--> Fostex custom BLH/HD600

    Initial tracks used other than the usual DS and MJ albums:

    Was (Not Was) - "Walk the Dinosaur"

    Trans-X - "Living on Video"

    Timex Social Club - "Rumors"

    Whoudini - "Back to Black" album

    I'll do a more in depth comparison in a few weeks with the EC and T15B.
     
    Last edited: Aug 21, 2019
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