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    Rectifier Tube Option?



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    Rectifier Tube Option?

    Post by t8ter on Tue Feb 21, 2012 11:27 pm

    I was reading an ad for rectifier tubes and the seller stated that a direct replacement for a GZ32,GZ34,5AR4,5U4G, with a slower soft start was a 274B. Has anyone used a 274B, or is a 274B a good replacement tube for a GZ34? I am sure Bob could give me the low down on this tube if no one else can.

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    Re: Rectifier Tube Option?

    Post by tubes4hifi on Wed Feb 22, 2012 12:36 am

    you'll probably learn alot more doing a 15 second google search than waiting for answers here,
    but the quick answer is that the 274B is closer to a 5U4G than anything else, and it has several specific requirements for use. It is a directly heated rectifier, and it is only good for about 150ma max current, compared to a 5AR4 which is good for 250ma. Thus, it might be fine in a MK3 amp for example, but definitely not in an ST70 or ST120 amp, as both use much more current. It also requires the first capacitor to be 10uF or less.


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    Re: Rectifier Tube Option?

    Post by GP49 on Wed Feb 22, 2012 12:40 am

    The specifications say that functionally, the 274B could be a substitute for a 5AR4, except that it actually looks to
    be closer to a 5U4 than a 5AR4; it will drop the B+ more than a 5AR4.

    There is a page with information about the ORIGINAL 1930s-era Western Electric 274B here:

    Western Electric 274B

    However, with prices for original 274B (they date from the 1930s) reaching four figures, WHY would one want to use one?

    There is supposed to be a modern reproduction from China but I (and others) suspect it is actually a "rebottled" and relabeled

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    Re: Rectifier Tube Option?

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