It seems that every time I start the unit I hear a cracking sound briefly from the headphones. I changed the output tubes this morning and the sound persists.

I placed 3 6DJ8's in the amp, after cleaning the pins with steel wool. About 5 seconds after I turned the unit on I heard the cracking and saw a light show in the left power tube. Does this mean the tube is now compromised?

The unit was previously cracking on startup with some RCA 6BQ7's; then with some CBS 6BZ7's.

I put a 7308 in the input position and some 6N1P-EV in the driver positions, started it up and no cracking.

It must be that some of the tubes I have been using are prone to arcing.

The same thing happened to mine last night . After I heard some humming , i tried replacing all OTKs with 3  x Siemens E88CCs . The humming became louder. So I replaced the front tube with 1 OTK , this time the humming was louder on just 1 side , so I switched the left and right tubes . True enough the humming shifted. Since I had one  more E88CC i replaced the right tube.  Immediately on power up the right tube lit up and I heard a distinct popping sound on the headphone.  Turned the amp off and waited a few  minutes and then replaced the right tube. This time the left E88CC tube sparked and i heard the HP pop before I turned the amp off asap.  I  unplugged the headphones before replacing both tubes with the stock OTKs.  Now it is quite again no hum at all. And sound seems ok .  

Should I have the amp checked ?

Thank you. Glad to know that the amp should be ok. Although I feel bad that my E88CCs =6922 w/c according to the manual can be used on the CSP2+ are probably dead.  I ordered some Mullards to try out and i'm now wary of using them as they might meet the same fate as the Siemens.  Is there a specific way or guide on how to safely roll tubes on the CSP2+?

Like-  front tube only , or all 3 drivers /inputs at the same time?

TIA

Could your tube rolling problems be due to your choice of Tube rectifiers?
I have tube rolled various types and makes of 6DJ8, E88CC, E188CC and 7DJ8s without any problems.

I have been consistently using a 5Y3GT tube rectifier all the time. My base configuration is a Tung Sol 5Y3GT with a matched pair of Siemens E188CCs for the left and right channels.

Once, I even tube rolled an E188CC in front and and E88CC on the left channel and a PCC88 on the right channel!

Hi S1,

Up front, I'm using a Lorenz PCC88 Grey Shields made in Stuttgart Germany.
I have finally settled on this after comparing it with other tubes such as the famous Siemens CCa Grey shields, Valvo Holland CCa Grey shields, Telefunken Tubes and a Frenchmade Philips E188CC amongst many others.
I have a pinched waist Amperex 6922 landing at my doorstep soon. I expect a "Clash of the Titans" to take place very soon.

BTW, I think Steve will be able to comment on the accuracy of my hypothesis. If you refer to the preamp design notes over here, https://www.decware.com/paper56.htm
and scroll all the way to the last paragraph, the CSP preamp was designed such that the 5Y3 rectifier would run your smaller tubes at the lowest voltages. The use of a 5U4 based rectifier would be more taxing on your 3 tubes by running them at a higher voltage.

As I mentioned earlier, I have tube-rolled almost all makes and brands of tubes such as Siemens, Philips, Valvo, Telefunken, Lorenz etc in my CSP2+. The only consistent tube throughout was the use of a Tung Sol 5Y3GT rectifier. I believe that because I have been tube rolling at the lowest voltages, I have not experienced any of the tube arcing phenomenon. This is just my hypothesis and hopefully Steve can verify this?