Difference between Siemens CCa & 7308

Cozva- If you really are using the pre-amp 10 hrs each day, that's 3650 hrs/yr, or 18,250 over 5 years. Most high quality pre-amp small signal tubes are rated for 10,000 hours but of course many run longer and many burn out more rapidly. If the amp stays on 10 hours at a clip, I would think that you would get more hours than average, but the quality/consistency of your AC power is also a factor. Lots of surges, or high voltage conditions would probably stress the tubes and shorten their life.

Audiofeil, how do you spot a great quality CCa by virture of its sound? Would the above description of my set constitute great or am I missing something?

You seem to know this tube, what would you look for both materially and sonically?

Thanks,

Anacrusis

>>Audiofeil, how do you spot a great quality CCa by virture of its sound?<<

That's like asking what spinach tastes like.

To my ears the great Cca are very airy, detailed, and impart a "dimensional" aspect to the presentation. You have to listen for yourself and decide; therein lies the rub. You could put 10 experienced listeners with a series of 6922/7308/Cca tubes and more than likely there would not be clear "winner"

That being said, unless your system is up to the task, it makes little sense to spend money on Cca. I would seek out some lesser priced tubes from the same family; they will give you 98% of a top Cca at a much lower cost. I love the mid 60's Amperex Bugle Boy 6922 for example. Andy at Vintage Tube Service sells high quality products at fair prices.

Know your tube vendor. There is a plethora of counterfeit and junk tubes on the market.

Audiofeil...

A food critic can tell me what spinach tastes like. Sound has much more definable characteristics. Airy, detailed, dimensional says it nicely.

Rather that picking a winner amonst the available 6dj8 variants it might be helpful if the cognoscenti of the CCa in particular could lead the poster and other readers in the right direction. What are the classifications of CCa (date range I presume) and how do they differ in sound from other CCas? I think Andy at Vintage Tube Service could sell a lot more tubes, especially CCas if from these postings people really knew what they were getting. The mystery surrounding this tube is over the top.