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    Question for VTA M-70



    Posts : 15
    Join date : 2012-01-01

    Question for VTA M-70

    Post by SuperB on Thu Feb 02, 2012 4:48 am

    Other than the rebuilt of my stock ST-70, I'm interested in the VTA M70 as well.

    Bob, these are the questions for you.

    1) I don't see the power transformer from this picture (see link).

    2) I know your new driver on M-70 is 6SN7 tube with tube CCS. However, I want to use 6FQ7 but the chassis layout for octal and has an extra hole for the CCS tube mounting.

    Do you have M70 made for "old" driver board with 12AU7? So I can plug in the 6FQ7 without one extra hoke for CCS and 2 big holes supposed made for octal?

    3) Can I order the M-70 without the driver section? I can hardwired this section with my own MOSFET CCS with 6FQ7.

    4) The output tube on M-70 is EL34, right?



    Posts : 1463
    Join date : 2008-11-30

    Re: Question for VTA M-70

    Post by tubes4hifi on Thu Feb 02, 2012 3:43 pm

    Hi SuperB,
    Bob doesn't supply the M70s, I do (Roy here).
    These are custom ordered as needed, so I can make whatever changes you want.
    It can use either the standard MK3/M125 driver board or the new MK3-octal board.
    So using 6FQ7 on the standard MK3 board (without CCS) is just a matter of rewiring the tube filaments,
    as those are very similar in characteristics to 12AU7 types.
    The power transformers are inside the chassis, as well as the choke.
    The power rectifier can be a 5AR4 or a 6CA4, your choice.
    Output tubes can be EL34 or KT77 or KT88, your choice.
    Send me an email or PM, thanks


    Posts : 15
    Join date : 2012-01-01

    Re: Question for VTA M-70

    Post by SuperB on Sun Feb 05, 2012 2:00 pm

    I decided to build your ST-70 from scratch by ordering some board and transformers from you. Since I want to put PI cap there. 40mf PIO, 30mf Sprague Vitamin Q JAN and ASC X386S 100mf 440VAC in the supply. Therefore, it needs way larger chassis.

    Regard the M70, I will think about it after building the VTA ST-70.

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    Re: Question for VTA M-70

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