This is not the first time this has been mentioned... In my comparisons of the these units I did recently, the TW unit had a bit of vibration on the bench with nothing else hooked up or close to it. I have found this occurs occasionally with most of the brands of of PT's I deal with. I ran a post on this topic previously that might help sort out the difference between hum and vibration and also where hum comes from and how to reduce it: https://tubeamparchive.com/viewtopic.php?t=17505 Phil at Heyboer did an excellent job of explaining some of reasons behind these issues.Richie wrote:... Hey Mark, when you do your testing, would you also give a close listen to mechanical vibration compared to other transformers. Seems that has popped up from time to time. And I have a PT here that I have to change. Or if one runs warmer than the another.
If you look closely at the pictures I posted earlier in my comparisons there is one curious item that so far nobody has mentioned... I'll make it easier to see. On the TW tranny they inserted a wood shim between the windings and the frame. I figured this was to tighten things up to reduce vibrations. I'm not sure if this is used in all the TW trannies or is unique to this specimen, I only bought one of them to compare.
I am working on a test fixture to do comparisons that are done in exactly the same amp with no change in the components or settings otherwise. Once that is ready then I'll test and measure what kind of heat each unit puts out. In my own work with the Pacific trannies I've never had one get hot on me yet, but I don't make that many amps. However, this is not a complaint I hear about very often (never so far) in contrast tot he occasional mention of the vibration issue.
The two trannies below are TW part# 11410 (with shim) on the left and the K&M Analog part# 25425 on the right (without shim).