GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Melquiades Amplifier
In the Thread: A different breed of 6C33C amplifier.

Post Subject: 6C33C reliability disappointment!Posted by KOTriode on: 9/15/2011

Totally disappointed today, while I was listening to music, the left channel make a small pop and quit. The bias meter showed about 25ma bias instead of 200ma. Test the tube on bench showed that the tube current stay about 25-50ma max. This tube is gone abrubtly instead of slow death after 31 hours of playing. Took another brand new tube and plug into the amp with just heater power on, nothing! Turn out a brand new tube has dead heater, amazing! Take out another tube, heat the filament for an hour, and check the bias, this time it is less than 100ma, another goner.

Check reliabilty of 6C33C on the net and found this:

I can also sell you a carton of 50 for $900, including ground shipping within the continental US. At this price they are "as is" - I will not replace any which are broken, out of spec or dead (they're a bargain anyway). Reports suggest you can expect 10-20% to be significantly out of spec.

So, it looked like that these tubes left the factory untested and it is up to the buyer to sort them out.

I order some " Ulyanov " tubes on Ebay, anybody have tried them yet? What label of these tubes proven to be reliable?

It is unfortunate that there are reliability issues with these tubes, the last few hour of music showed that the 6C33C has great potential, I was enjoying the music it was making and drawned up plan for a pair of 6C33C's mono block.

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