Just received a pair of RCA 12au7a Clear Tops cryotreated. I bought them of ebay.
I just want to check with you guys about few things, since Im a beginner.
1. I have noticed that the side getter is pretty dark/black at times, and the RCA logo and the date text is pretty worn off on bother of them. See attached picture, I can take more if needed.
2. But a more serious problem is that I hear a hiss in the background with both of these tubes.
I am using HD800S and DT 1770-Pro.
With no music playing, the hiss goes up as I turn up the volume. but it does not get so much louder after I have reached about 15% volume.
I have no problems with my other 12au7´s (Golden Lion and Sylvania stock). pitch black background on full volume.
The power tubes I have are 2x TS 5998 JAN and the stock Raytheon 6080.
I case it could be relevant, just want to note that I installed "TKD 2CP-2500" 2x weeks ago (before I got the Clear tops).
Voltage test was spot, and its sounds better then ever with my old tubes.
But let me know if you think I got issues.. with my crack.
Here are test results from the seller, just have to admit that I have not understood tube test results, but that knowledge I believe is just around the corner
TESTED IN AMPLITREX AT1000 (
www.amplitrex.com )
TUBE 1: 64/72% EMISSION . 63/63%GM ( TRANSCONDUCTANCE ) 0.6/0.2mA/V GAS.
TUBE 2: 64/60% EMISSION . 63/63%GM ( TRANSCONDUCTANCE ) 0.0/0.2mA/V GAS.
YOU CAN´T OBTAIN OTHERS SIMILAR TUBES WITH THIS HIGH TECNOLOGY PROCESS. READ MORE.........
Can I expect a RCA 12au7a clear top to have a higher noise floor in the crack or do I have bad tubes?
Or does my crack need further servicing?