Some impressions of update to Csg Siemens with LD MK3:
Thanks to fellow head-fiers on this thread for instructions and tips for this update. So far I have been impressed by these tubes. For about $150, I consider this to be a significant and worthy update.
As compared to some tubes I used previously, the C3gs produce an overall fuller sound, closer to what I get from three vintage receivers. I have been primarily using HD650 and Sony CD3000 for testing. The fullness seems to result from both an extension of dynamic range and an expansion of sound stage. For the former, the enhancement of bass is very obvious. The quality and texture of the bass are nice too. More to my pleasure, the trebles are improved too---the hotness and clipping I heard before with some other tubes are gone. This may come from both an extension of high frequency range or some roll-off or both. Anyway, I am pleased with the overall sound signature.
At this point, with the Csgs, I have no desire to explore other tubes. As some head-fiers noted, this may indeed be an, if not the, ultimate update with the LD MK3. Though I have been using headphones with vintage receivers a lot lately, the LD with C3gs still offers some tube joy: that fresh, smooth, and 3-D sound effects. The other day I got a chance to audit a Fisher 500c. Though the unit has been restored, there were noises between the songs and during the songs. So I was not convinced that the Fisher would be a worthy and practical update to the LD (I am sure a perfect working Fisher would be much better, but it will need both significant money and good luck to get such a unit).
Other observations: The C3gs, covered with metal, do not give that charming tube glow. They run pretty hot. There are some minor noises which I am not sure the source of. Could the tubes need more hours of burn-in? Or the 7-pin socket saver is not that good in construction: unclean pins and so on. I did try to scratch the pins and apply some deoxit. Maybe more cleaning is needed.
Overall, I am pleased with the C3gs. They are the most significant update and improvement of the LD MK3 I have ever experienced.
Edit (5/25/2015): I thoroughly scratched and deoxited the pins of both socket savers. This seems to completely get rid of the noise. The LD and C3gs sound really clean and nice now.
Edited by TomNC - Today at 6:43 pm