Crack assembling issue

[ztsen]

I grabbed a china made 12AU7, JJ CC802S (G) and a Jan philip 5814A at local store.

After i swapped the cheap china tube for the EH12AU7, it was so much better. No more so harsh for me.

A lot of air i can hear now. 

But still a mid high, mid bass. I will spend some time before go for speedball upgrade.

 

[ironbut]

I would give all the parts and tubes at least 100 hours to burn in before making any drastic changes. New tubes and caps can sound harsh with flabby bass and sucked out mids for a while and the caps can go through some pretty weird changes on their way to settling down. I kind of go overboard on burn in on caps ( at least 250 hours and twice that with some). Tubes usually take at least 20 hours.
I think you're wise to live with the stock Crack for a little while before going to the Speedball. It gives the amp time to reveal any issues with construction and you'll appreciate the upgrade all that much more.
I think that the more amps your ears are exposed to on a long term basis, the more educated they become. Having the stock and the Speedballed Crack is almost like having two different amps.

 

[Grainger49]

Steve,

If you are overboard I am sunk!  The last KK Teflons I burned in went 330 hours +.

I just wanted to be sure before installing in a friend's crossover last night.

 

[ztsen]

In this case, I should let it run more than 100 hours then do serious listening.

Anyone try JJ CC802S before? I think it is quite good.

 

[Grainger49]

It will take about 50-100 hours for you to make a knowledgeable decision on whether it pleases you.  There will be changes throughout that time that will not stabilize till you have run it in.  Most tubes need about 40 hours of forming.