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    Weber WZ68 now NOT recommended on Weber website!

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    sKiZo

    Posts : 1411
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by sKiZo on Sun Sep 27, 2015 12:55 pm

    arledgsc wrote:
    If B+ has increased closer to 550V I will wire up my unused ST120 rectifier heater winding as a bucker with the incoming line voltage to effectively reduce the AC coming in about 5V.  This should reflect to 15-20V less HV AC at the rectifier input.  

    Hadn't thought of that ... I made an external bucker instead, using a transformer that's good for 6a. Will that spare winding handle the current?

    Wonder if you could wire up that extra heater winding for hot switching? Turn it on when needed, or not. I know my line voltage was at 124+vac when I first got going here due to a recent upgrade in the grid for a new housing development down the road. Power company has since got things back to normal, and the bucker is out of the loop ... for now anyway.
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    Kentley

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    Join date : 2015-03-06
    Age : 65
    Location : Worcester, MA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Kentley on Sun Sep 27, 2015 5:24 pm

    Today I switched out rectification in my VTA ST-120. I replaced my trusty Mullard GZ-37 with the Weber WS1. The sound is comparable. One caveat -- lower your bias adjustments to minimum before you switch to the WS1. What used to be spot-on .54 VDC with the tube when the pots were at 2 o'clock became dramatically different with the Weber and now .54 VDC is achieved with the pots at 10 o'clock. Caveat rector!
    I've run it at moderate volume for an hour now and the temp. on the copper-cap reads at 156F. Way cooler than the WZ-68 which I melted down several months ago!
    DON'T TRY THE WS1 if you don't have the time-delay relay installed -- unless you wish to be blowing output tubes left and right. Bad pun intended. It blasts B+ voltage instantaneously -- no delay whatsoever.
    The WS1 is less than $20 from Weber Speaker Co. That is a good thing.
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    arledgsc

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    Join date : 2012-11-30
    Location : SF Bay CA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by arledgsc on Sun Sep 27, 2015 6:47 pm

    Good job Kentley!  I probably need some form of inrush current reduction with the straight diode replacement.  I will work on that.  The lights dim a little for a second when the delay relay kicks in - more than usual.

    Skizo I wish the bucker idea with the main transformer was mine as that is a brilliant solution.   I got the notion from our forum member "peterh".   I'm sure a in/out switch would work on the bucker but would recommend only changing with power off and recheck bias afterward.
    http://dynacotubeaudio.forumotion.com/t2403-howto-cut-5v-from-the-mains-line?highlight=line+voltage
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    Roy D

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    Join date : 2018-01-14
    Location : Netherlands, Europe

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Roy D Yesterday at 4:36 pm

    Reading up on the rectifier options for the ST-120 build coming across this thread now and reading the current page for the ws1 rectifier on their site there is now an option for having a thermistor included in it for a few seconds warm up period - so would this ws1 with the thermistor require the delay board or not?
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    deepee99

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    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by deepee99 Yesterday at 11:09 pm

    Roy D wrote:Reading up on the rectifier options for the ST-120 build coming across this thread now and reading the current page for the ws1 rectifier on their site there is now an option for having a thermistor included in it for a few seconds warm up period - so   would this ws1 with the thermistor require the delay board or   not?
    IMHO, the delayed start-up board should be required on all VTA amps, regardless of rectifier style. It's the cheapest insurance money can buy. Also Roy's "yellow sheet" mod. From there your options are limitless.
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    Kentley

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    Join date : 2015-03-06
    Age : 65
    Location : Worcester, MA

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Kentley Yesterday at 11:35 pm

    I agree with deepee. The thermistor may provide a modicum of delay, but it may not provide enough (how many seconds in "a few"?).
    The TDR allows you to choose any rectifier without concern. It's worth the piddling extra expense.
    I've been running the naked Weber WS-1 for well over a year (with the TDR) and the real concern is, without sag resistors, your B+ may rise above the prescribed max. of 410 VDC. This will depend on your line AC. If that stays below 118, like mine (thank some god or other!) you should be fine.
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    Roy D

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    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Roy D Today at 4:20 am

    hmm ok, I will put the TDR on the list.. thanks deepee, Kently!
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    Roy D

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    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Roy D Today at 5:01 am


    so   my knowledge of circuits is not yet up to the point where when I look at the TDR board on the VTA site I can determine all the functions so
       would the TDR also eliminate 'filament flash' such as detailed in this circuit in the Carlsons Lab video?

    *edit* re reading the tubes4hifi page on the TDR unit, I think the answer is   yes =}
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    peterh

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

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by peterh Today at 10:17 am

    Roy D wrote:
    so   my knowledge of circuits is not yet up to the point where when I look at the TDR board on the VTA site I can determine all the functions so
       would the TDR also eliminate 'filament flash' such as detailed in this circuit in  the Carlsons Lab video?

    *edit* re reading the tubes4hifi page on the TDR unit, I think the answer is   yes =}
    Gaasp ..
    This guy don't even know that telefunken tubes are not mullards, and that the
    kind of "flash" discussed is limited to mullards ( phillips volvo etc)
    BTW, the mullards don't exhibit broken filaments, thus this issue is a non-issue.
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    Roy D

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    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by Roy D Today at 10:24 am

    yay I like non issues ^^ But overal I gather this TDR does indeed slowly up the voltage on the heaters then enables the high voltage to come on which will indeed help the lifespan of the tube set which is a good thing. The only questionmark I had was the remark that the WS-1 has some construction differences which may result in 'not good things' when the main voltage rises too much..
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    deepee99

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    Location : Wallace, Idaho

    Re: Weber WZ68 now NOT recommended on Weber website!

    Post by deepee99 Today at 3:03 pm

    Roy D wrote:yay    I like non issues ^^   But  overal I gather  this TDR does indeed slowly up the voltage on the heaters then enables the high voltage to come on which  will indeed help the lifespan of the tube set which is a good thing. The only questionmark I had was the remark that the WS-1 has some construction differences which may result in  'not good things' when the main voltage rises too much..
    Roy, not sure about that with the TDR. I think the filaments light straightaway, burn for about 15 seconds, then the B+ comes on. Bob L,, Roy M., correct me if I'm wrong here. I'm not aware of an off-the-shelf device that defers filament lighting, although after watching your video it seems like a good idea.
    Unlike light-bulbs, tube filaments are pretty tough so I don't believe much thought is put into their longevity.

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