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    pas 2 - phono stage tubes

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    ronush

    Posts : 1
    Join date : 2016-02-13

    pas 2 - phono stage tubes

    Post by ronush on Mon Feb 15, 2016 9:23 am

    hi
    can i run the pas-2 without the phono stage tubes placed in (only the line stage tubes are in)
    will it cause any damage ?

    Bob Latino
    Admin

    Posts : 2415
    Join date : 2008-11-26
    Location : Massachusetts

    Re: pas 2 - phono stage tubes

    Post by Bob Latino on Mon Feb 15, 2016 10:17 am

    Yes - you can BUT that filament line may have a slightly higher voltage than normal because it normally has to supply four 12AX7's with current. With only two 12AX7 tubes to power on, the load on that filament line will be lower and the filament voltage will be higher than normal. Whether this will cause a problem, I can't say ? What you might want to do is put two cheapy Chinese 12AX7's on the phono board so that the filament line will still be looking at 4 tubes.

    Bob

    peterh

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    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: pas 2 - phono stage tubes

    Post by peterh on Mon Feb 15, 2016 12:20 pm

    ronush wrote:hi
    can i run the pas-2 without the phono stage tubes placed in (only the line stage tubes are in)
    will it cause any damage ?

    Possibly, the filemannt voltage might be too high. But, test it and
    measure the voltage over the remaining tubes. If it's less then 28V it's within
    allowed tolerances.


    tubes4hifi
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    Join date : 2008-11-30

    Re: pas 2 - phono stage tubes

    Post by tubes4hifi on Mon Feb 15, 2016 1:27 pm

    what Bob and Peter said - likely the filament voltage will be much higher than 26vdc, which is 13 volts per tube, and will shorten their life dramatically.

    Guest
    Guest

    Re: pas 2 - phono stage tubes

    Post by Guest on Tue Feb 16, 2016 8:10 pm

    another option is to buy our v21 or v22 regulated power supply, it uses a voltage regulator for the DC filament, and even with tubes removed, will not go higher, it will be a steady 24VDC no matter how many tubes are plugged in, as long of course, you do not overload it, which is nigh impossible with using any of the PAS2/3 pcb's and upgrade pcb's, as it is rated at 3A!
    Go to www.tubenirvana.net and click on the PAS3 Main Page link.

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