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    Replacement of selenium rectifier in ST-70

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    rossini

    Posts : 3
    Join date : 2017-11-04

    Replacement of selenium rectifier in ST-70

    Post by rossini on Sun Nov 05, 2017 5:50 am

    Hello,

    I know there has been already a number of discussions before about this topic, however, as I would like to replace the selenium rectifier by germanium diode, can anyone advise me the specifications of the diode which will fit for this replacement, thank

    regards,

    Rossini
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    Peter W.

    Posts : 1034
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Replacement of selenium rectifier in ST-70

    Post by Peter W. on Sun Nov 05, 2017 8:20 am

    Germanium would not be your first choice. Finding such a diode that would be rugged enough is one thing - and the basic characteristics of such a diode in that use would be another.

    I use a 1N4007 silicon diode in those applications. Fast enough, rugged enough and cheap enough that going to anything more exotic than that would be without merit.

    rossini

    Posts : 3
    Join date : 2017-11-04

    Re: Replacement of selenium rectifier in ST-70

    Post by rossini on Sun Nov 05, 2017 10:21 am

    Peter W. wrote:Germanium would not be your first choice. Finding such a diode that would be rugged enough is one thing - and the basic characteristics of such a diode in that use would be another.

    I use a 1N4007 silicon diode in those applications. Fast enough, rugged enough and cheap enough that going to anything more exotic than that would be without merit.

    I have already tried 1N4007 silicon diode and find that the sound is a bit forward and not so soft as the previous selenium rectifier. This is why I would like to look for the germanium diode.
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    Peter W.

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    Re: Replacement of selenium rectifier in ST-70

    Post by Peter W. on Sun Nov 05, 2017 11:29 am

    OK - but, consider that musicians use germanium diodes to add distortion.

    Other issues: Germanium has 'soft knees' - that is, they start to conduct on a continuum. They are not as fast as selenium or silicon.

    They do not like heat - at all.

    High current germanium diodes also decay more quickly than even selenium. Low-current, no problem.

    Mouser.com has a pretty large selection of power-diodes in Germanium - all under US$10.

    rossini

    Posts : 3
    Join date : 2017-11-04

    Re: Replacement of selenium rectifier in ST-70

    Post by rossini on Sun Nov 05, 2017 6:28 pm

    Peter W. wrote:OK - but, consider that musicians use germanium diodes to add distortion.

    Other issues: Germanium has 'soft knees' - that is, they start to conduct on a continuum. They are not as fast as selenium or silicon.

    They do not like heat - at all.

    High current germanium diodes also decay more quickly than even selenium. Low-current, no problem.

    Mouser.com has a pretty large selection of power-diodes in Germanium - all under US$10.

    So, can you advise the voltage and current specifications of the germanium diode for this replacement, thanks.
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    Peter W.

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    Location : Melrose Park, PA

    Re: Replacement of selenium rectifier in ST-70

    Post by Peter W. on Mon Nov 06, 2017 8:16 am

    http://www.mouser.com/ds/2/427/vs-25frseries-71595.pdf

    This is a range of germanium rectifier diodes.

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