Interesting. Could you elaborate on this?
Ok, here's my humble opinion.
I compared some 5840 with 5654/6AK5W/E95F directly in identical mic preamp and mic circuits.
My experience are as follows:
5840 and the 5654 are technically almost identical and can be directly interchanged without circuit modification. (is also mentioned in some datasheets).
The socket of the 5654 is big advantage over the 5840, especially for microphones! Anyone who has ever changed directly soldered tubes (during selecting for best tube) knows the difference, especially with PCB mounting. It is not only easier and faster but also much better for the sensitive High Z areas.
Look at the solder pads after the fifth tube!
There are also sockets for the 5840 but they are not of the same quality as the better ceramic 7pin sockets. The socket also makes the 5840 lose a lot of the size advantage over the 5654.
In direct comparison, the 5840 was on average more microphonic than the 5654. That was my impression with the tubes I had available. Whether this is true for all tubes I can't say....
The same applies to the noise floor, also here the 5654 types had slight advantages. I had two 5840 which were first good and then after a few weeks became increasingly noiser.
Due to the limited number of test tubes this result is not scientific, whether this can be generalized I do not know.
Ultimately, I found purely subjective that the 5654 sound better, I like the high-frequency response better. This was true for all manufacturers, the tendency was always the same and much more consistent.
For me the 5654 family is the best overall package and due to the small design ideal for LDC microphones. Very consistent good performance, they have never disappointed me so far. They are also still very available and really cheap for the performance.
coool, very cool! Also LF Noiselevel is better now.
