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Reporting Valve Art 274B Flash Over (Read 507 times)
Rizlaw
Senior Member
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Posts: 90
Reporting Valve Art 274B Flash Over
08/01/13 at 19:29:59
 
When I received my Taboo III this past April, Steve included the Valve Art 274B as the stock rectifier. Notwithstanding his belief that this is really a 5U4G, I can now report that I have seen it flash over twice in the last 24 hours. It looks like an quick electrical arc between the two heaters at the top of the tube. No noises associated with the brief flash overs. The tube itself had less than 50 hours use since I was alternating it with my Philips 5R4GYS rectifiers to see which I one I like better.

To play it safe, I have removed Steve's 274B and replaced it with one of the two new cryo'd Valve Art 274Bs I just received from Cryoset (and which I had ordered 2 days before the flash over of last night and this afternoon). It looks like I should have waited a little longer before purchasing more VA 274Bs. Cry  I do enjoy the VA 274Bs lively open sound.

I put the second new VA 274B in my CSP+. They both turned on the first time without flash overs. It will be interesting to see if they last longer given the cryo treatment.

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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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SteveC
Seasoned Member
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Posts: 111
Re: Reporting Valve Art 274B Flash Over
Reply #1 - 08/01/13 at 20:12:32
 
This may be related or not.  I reported arcing rectifiers on my tori long ago using the stock ruby's that came with it (1.5 years ago?).  I was comparing left and right channels by turning the power off and on alternately per channel.  I'd notice arcing in the rectifier on power up. I realized this never happened when the amp was cold (off for quite a while).  It only happened when powering on immediately after powering off.  The only differences I can think of between the 'cold' vs 'warm' scenarios are some caps still have a charge in them, and all the cathodes are still warm too.  My solution was: don't power cycle the tori in short durations like this.  No arching with normal use.  No dead rectifiers yet.

My se84ckc has the 274B in it.  never see it arc.  But guess what, I just tried it. I just turned it off for 1 second (it's still playing music actually).  turned power back on, and there's a tiny amount of arcing.  

for me, any of these rectifiers arc when powered up shortly after powering off (ie: when you're looking for an arc).

Anyway, I just don't do this anymore.
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Rizlaw
Senior Member
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Posts: 90
Re: Reporting Valve Art 274B Flash Over
Reply #2 - 08/01/13 at 20:29:40
 
SteveC,

Thanks for the info.

But, in my case, the arcing occurred after the amp had been off all day or all night since it happened once at night and once during the day. I rarely, if ever, cycle my tube equipment on/off as you described. I force myself to wait, at least 30 minutes for everything to cool down if I'm doing any tube rolling, which is infrequent.
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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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