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post #106 of 298
The 5AR4 is made for a much larger cap after it. The 5AR4 brings up the voltage much slower, which is very nice for the tubes and also can be used, as mentioned, with a much larger first cap. The 5U4G and other rectifiers of this type need a smaller first cap with a 4uf recommended but since the 6 operates at a lower voltage than many devices the rectifiers were intended for a larger cap can be used but not a great deal larger. I use a 22uf cap and it is about the extent of a safe area. I also discussed this with an importer of a 274B and he said he felt fine at the operating points I mentioned to him but he wouldn't want to see anything larger than the 22uf cap.
post #107 of 298
Thread Starter 
Quote:
Originally Posted by jamato8 View Post
You should not get any flash or white sparks on start up. This indicates that there is too much initial current draw for the tube as the caps are charging to their potential. My Sophia has never done this but then I use a 22uf cap vs a 150 or 200uf cap after the rectifier. No other tubes do this either.

I hope Jack comes back soon with an answer to this question. If the circuit design he has implemented is not optimal for the Sophia (which would be a shame as the sound in tremendous with the tube fitted, and annoying as he recommends the Sophia upgrade) then my choice is either ship the amp back to the US for a different capacitor to be fitted (and the hum sorted) or find another tube that closely matches the Sophia performance but would not spark on start-up (such as the 5U4G).
post #108 of 298
Thread Starter 
Quote:
Originally Posted by jamato8 View Post
The 5AR4 is made for a much larger cap after it. The 5AR4 brings up the voltage much slower, which is very nice for the tubes and also can be used, as mentioned, with a much larger first cap. The 5U4G and other rectifiers of this type need a smaller first cap with a 4uf recommended but since the 6 operates at a lower voltage than many devices the rectifiers were intended for a larger cap can be used but not a great deal larger. I use a 22uf cap and it is about the extent of a safe area. I also discussed this with an importer of a 274B and he said he felt fine at the operating points I mentioned to him but he wouldn't want to see anything larger than the 22uf cap.

So the 150 or 220uf capacitor that Jack is using is just wrecking the tube for which I paid 150 USD. Great
post #109 of 298
I don't know. I can't say this. It appears there is an inductor right after the rectifier but I don't know the henry or DCR of it. It could be a bad tube but now others are saying they also have sparks so. . . I would have to have an amp in my hands. I am sure Jack will clear this up.
post #110 of 298
I used a Svetlana 5U4G for several hundred hours with no sparking at all in my standard 6. Which leads me to believe there is a quality control issue with Sophia.
post #111 of 298
Quote:
Originally Posted by sclamb View Post
I think Jack charges 150 USD for the Sophia Princess with 30-day warranty, so he is not making much out of supplying them. Although it appears he may be toasting them
Jack has a good price on those tubes. If takezo likes Sophia better then EML, I'll order it from Jack
post #112 of 298
Thread Starter 
They are 10 USD cheaper if you order direct from Sophia Electric (140 USD vs 150 USD). Might be worth waiting to see if there is an issue with this amp/tube combination before ordering though.
post #113 of 298
Thread Starter 
Quote:
Originally Posted by atbglenn View Post
I used a Svetlana 5U4G for several hundred hours with no sparking at all in my standard 6. Which leads me to believe there is a quality control issue with Sophia.

The flash and/or spark is only at switch-on. After that the amp and tube run fine.

Did someone in this thread not mention that the 5AR4 and 5U4G would be fine - something to do with direct and indirectly heated tubes?

I have used a Sovtek 5AR4 and there is no flash or spark at switch-on. Unfortunately, listening to it after the Sophia Princess really shows how much better the Princess is - more definition, more air, more space around the instruments................

I have to get this working with the WA6 SE!

It would be interesting to see if everyone using the Sophia Princess with the WA6, WA6 maxxed, WA6 SE and WA6 SE maxxed is getting the flash and/or spark issue. If not then it may be faulty tubes and not the amp circuit.

So far we have two WA6 SE maxxed users with the problem. Anyone else care to add to this list with a Yes or No?
post #114 of 298
Quote:
Originally Posted by sclamb View Post
They are 10 USD cheaper if you order direct from Sophia Electric (140 USD vs 150 USD). Might be worth waiting to see if there is an issue with this amp/tube combination before ordering though.
I have a custom WA6 with a 22uF first cap, so I'm not worried. I made all the modifications myself, thanks to takezo & jamato8.

$10 is not an issue for me, I'm ordering some extra stuff at the same time & I love Woo Audio
post #115 of 298
I'm using an NOS RCA 5V4 indirectly heated cathode with no turn on flashing so far. I've got approximately 200 hours on it.
The Svetlana 5U4G is directly heated cathode, and that has several hundred hours with no turn on flashing.
post #116 of 298
Thread Starter 
Quote:
Originally Posted by atbglenn View Post
I'm using an NOS RCA 5V4 indirectly heated cathode with no turn on flashing so far. I've got approximately 200 hours on it.
The Svetlana 5U4G is directly heated cathode, and that has several hundred hours with no turn on flashing.
So you have a straight WA6 (not maxxed) and do not see any flashes/sparks. Four things occur to me. Either there is no problem and the Sophia tubes could be faulty. There is no problem with non-maxxed WA6 amps. There is a problem with the SE two box amp whether maxxed or not maxxed. Or, could it be the mesh plate inside the Sophia tube that is susceptible to this flash/spark. I see a white streak go up the plate to the top and then the plate turns orange. Sometimes, there is a spark a second or two after the streak, eminating from the mesh plate.

We need more people to respond to narrow this down some more.

I hope Jack responds soon.
post #117 of 298
Most of the tubes are rated for around 160mA's the perforated plate Sophia is rated for a max of 90mA's. This is one reason the Sophia would be more susceptible the the larger caps. It can not handle near as much current draw.
post #118 of 298
Quote:
Originally Posted by sclamb View Post
So you have a straight WA6 (not maxxed) and do not see any flashes/sparks. Four things occur to me. Either there is no problem and the Sophia tubes could be faulty. There is no problem with non-maxxed WA6 amps. There is a problem with the SE two box amp whether maxxed or not maxxed. Or, could it be the mesh plate inside the Sophia tube that is susceptible to this flash/spark. I see a white streak go up the plate to the top and then the plate turns orange. Sometimes, there is a spark a second or two after the streak, eminating from the mesh plate.

We need more people to respond to narrow this down some more.

I hope Jack responds soon.
The only upgrade I have is the pseudo dual PS mod on my standard 6.

The Rectifier tubes I've used so far:

Svetlana NOS 5U4G Several hundred hours
RCA NOS 5V4 200 hours
RCA NOS 5R4GY 30 hours

With no issues so far.
post #119 of 298
I've just been reading this thread.Another source that could help is the people over at Audio Asylum -- Audio Reviews, Audiophile Forums and Stereo Reviews under tubes.
post #120 of 298
Thread Starter 
Thanks for the link. An interesting comment from a thread there about the Sophia 274B:

'I have used the TJ/Sophia 274B, and find them to be very good sounding, adding a bit more air and 3-dimensionality compared with the 5U4s and 5R4s I have tried. Be careful of the size of the first cap, even going through a choke first these tubes will spark on turn on if the cap size is too big. I don't know about the long term robustness, I have had one start to spark on turn-on/off after a year or so service, in a LCLC power supply configuration with a 8H choke and 40uF first cap. Current was well within specs.'
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