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    Mark III Driver Board - R16 Question

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    SoundBound

    Posts : 13
    Join date : 2011-07-31

    Mark III Driver Board - R16 Question

    Post by SoundBound on Tue Aug 02, 2011 10:29 am

    Hi,

    Started putting the components on my Mark III VTA driver boards and came across something that has me guessing.

    In the parts list R16 (6.8K) is listed only as a 1/2W resistor, yet I wonder if this is not supposed to be a 2W rated resistor similar to the other resistors in this part of the circuit (ie R20 R22)?

    Can anyone confirm the correct wattage for this resistor?

    Thanks. SoundBound

    snav

    Posts : 18
    Join date : 2011-05-18

    Re: Mark III Driver Board - R16 Question

    Post by snav on Tue Aug 02, 2011 11:11 am

    I have seen that listed variously as 1w or 2w but never less. I would err on the side of the larger rating especially with newer resistors being smaller than vintage Carbon Comp.

    Bob Latino
    Admin

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    Join date : 2008-11-26
    Location : Massachusetts

    Re: Mark III Driver Board - R16 Question

    Post by Bob Latino on Tue Aug 02, 2011 11:33 am

    Hi,

    Roy Mottram can correct me if I am wrong BUT > I believe the confusion about R16 may be because on the VTA Mark III standard gain board that uses 12AT7 driver tubes > R16 is a 6.8K 1/2 watt resistor. On the LOWER gain board that uses 12AU7 or 12BH7 driver tubes R16 is a 6.8K 1 watt resistor. That resistor does not have to be a 2 watt resistor.

    Bob

    SoundBound

    Posts : 13
    Join date : 2011-07-31

    Re: Mark III Driver Board - R16 Question

    Post by SoundBound on Tue Aug 02, 2011 12:50 pm

    Thanks Bob and Snav;

    I am building the lower gain version with the 12AU7s, so it makes sense to me that the 1/2w resistor is a bit low, I will go ahead and substitute a 1W or better for the 6K8. Maybe if Roy sees this post he can correct the documentation for the low gain version.


    Last edited by SoundBound on Tue Aug 02, 2011 10:25 pm; edited 1 time in total

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Mark III Driver Board - R16 Question

    Post by tubes4hifi on Tue Aug 02, 2011 1:50 pm

    yes, should be a 1 watt, if I sent you the wrong part email me directly and I'll send you the correct part
    Roy info@tubes4hifi.com

    SoundBound

    Posts : 13
    Join date : 2011-07-31

    Re: Mark III Driver Board - R16 Question

    Post by SoundBound on Tue Aug 02, 2011 2:51 pm

    Hello Roy,

    I purchased the bare boards, supplied my own parts. The confusion is in the documentation (VTA MK3 v11 LG manual.pdf) for the low gain configuration, R16 does not have a wattage specified in the parts list, thus as per all other resistors where wattage is not specified, 1/2 watt is understood to be the wattage value. This is the error, it should be marked as a 1 watt (according to Bob and Roy).


    Last edited by SoundBound on Tue Aug 02, 2011 10:26 pm; edited 1 time in total

    Bob Latino
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    Re: Mark III Driver Board - R16 Question

    Post by Bob Latino on Tue Aug 02, 2011 2:58 pm

    SoundBound wrote:Hello Roy,

    I purchased the bare boards, supplied my own parts. The confusion is in the documentation (VTA MK3 v11 LG manual.pdf) for the low gain configuration, R16 does not have a wattage specified in the parts list, thus as per all other resistors where wattage is not specified, 1/2 watt is understood to be the wattage value.

    Hi,

    I think that the "LG" in the manual name > (VTA MK3 v11 LG manual.pdf) means LOW GAIN. If that is the case, then you need a 6.8K 1 watt resistor - not a 6.8K 1/2 watt resistor.

    Bob

    tubes4hifi
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    Posts : 1261
    Join date : 2008-11-30

    Re: Mark III Driver Board - R16 Question

    Post by tubes4hifi on Tue Aug 02, 2011 7:59 pm

    Bob is correct, and I have updated the manual to show that resistor is a 1 watt

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