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Bat 150 SE replacing 6C33-B power tubes problems

BAT 150 SE 6C33-B power tubes were replaced with 8 pcs new tubes. 3 of the new tubes blew out the 3 amp fast blow fuses and internal sparks were seen with loud nasty sounds emmitted from mid range and tweeter sections. These amps only feed only the non-bass sections.
The defective tubes are now replaced with good ones. Upscale Audio did not hesitate to send me replacements. Since they are out of stock on current production Upscale sent me NOS without any extra charges.
Is it normal because the 8 NOS tubes are new that the sound is now harsh, metallic and not sweet as it used to be.
Does anyone have any idea how many music hours app. this can take ?
Any advice on this matter is really helpfull to me.
Thank you.
128x128terryakhan
jfrech's avatar
jfrech
1,816 posts
 
Were the sparks internal to the tubes or inside the amp? Something might be wrong with the amp. Anyway, when I change the 6c33 b tubes on my vk75se, it does take a little breakin on the tubes...not much...like a few days. And I don't notice a very big difference. The input tubes do make a larger differnce. The power tubes just seem to have a little more "umph" when I change them.

Try your old tubes again as a test. If you have more than 40-50 hours on new the new tubes, swap to the old. Now I notice a definite change in sweetness when you power down the 75se and turn it back on like 5 minutes later. After a hour of it settling down all the magic is back.

Good luck.
atmasphere's avatar
atmasphere
11,567 posts
 
FWIW there are no 'current production' 6C33s- they are all NOS. The factory that made them was dismantled about 3 years or so ago.
jwin's avatar
jwin
101 posts
 
When 6C33B's blew in my VK-60s, the fuses never saved some conponents from getting fried. This happened on 3 different occaisions.
Good luck!
Jeff
terryakhan's avatar
terryakhan OP
109 posts
 
Thank you all for this info.
The sparks were inside the new power tubes that blew the 3 amps fuses. The amps suffer no damages. Guess I very am lucky. With the old original BAT factory tubes the sound is normal and sweet. However, several of the old tubes would not allow the green LED to stay on reason being why I had to have them replaced. I have about 8 hrs on the new set, so I will just keep the breakin going. After cleaning the pins with 400 sandpaper a bit of improvement is heard.
Jfrech, can you tell me which are the input tubes and can you suggest what type and make of others tube so I try some tube rolling.
I was not aware that the power tubes are no longer made. This a concern for BAT owners. Are ther any other suppliers around ?
trcnetmsncom
431 posts
 
Hello Terry,

Sorry to hear about your problem. Yes the 6c33 tube can be a pain in the neck sometimes but BAT has done a good job of seeing to it that the amp is well protected.

From what I've heard there is a HUGE supply of these tubes so there is no need to worry about a shortage for a very long time. I'm sure the amps will be sounding as good as ever in no time.

Best of luck,
Tom
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