Tube Rolling - No Change in Sound

It could be that you are experiencing the 'weakest chain' issue..that another component is not good enough to reveal the subtle upgrade in another.

Welcome aboard, good luck and God Help you [(:>}

It simply may be that your vt-231's and the new wgta's have a relatively similar sound signature. Now if you had tried a tung sol 6sn7gt round plate or a Sylvania 6sn7w I believe you might hear a difference. Also however, one has to consider that some preamps are not so responsive to tube rolling as others. I have a deHavilland Ultraverve which relies on the 6sn7 tube. Each tube I try sounds unique and different and it is very apparnent each time I roll in a new type. I have tried about every NOS 6sn7 tube out there. I like the RCA vt-231 grey glass, the Sylvania 6sn7w, sylvania 6sn7gt, Raytheon 6sn7wgt...but for overall performance across the spectrum the Tung Sol round plates are hard to beat...at least for my pre...but they are expensive and disappearing quickly.

There are four possible explanations.

1. The circuit design of your Wyetech Opal may not be particularly sensitive to variations in tube parameters.

2. While the internal tube design characteristics of the same tube from different manufacturers can vary, it doesn't mean they always do. Your Ken Rad and Philips may have been closer in characteristics than some other combination.

3. There was a difference but it is masked by other aspects of your system.

4. There was a difference but you may not be particularly sensitive to it. Different people listen for different things in music and the change resulting from this tube switch may simply fall in an area that isn't very high on your list of sonic priorities.

It could also be a combination of more than one factor noted above. There are also subcategories (you needed longer burn-in or more listening time/different music in order to hear subtleties, etc.) but you get the idea.

The primary point should be you have tried it for yourself. Even though someone else may have different results from the same experiment is ultimately irrelevant for your situation.