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different volume between KT88s


2013-10-16 4:18 pm
Hi Guys
I was swapping my older GL KT88 to much newer Psvane KT88 tii suddenly I noticed that the Psvane is less loud playing the same music at the same volume.
So I thought could it be different bias requirement that's causing this but then again my Primaluna Dialogue 7 has this so call auto bias circuit that's suppose to automatically adjust bias to get best performance. What's your thoughts Gents ?

Different valves will have different optimum bias, different gain.

Not everything labelled 'KT88' is actually a real KT88, but could be some rough approximation.

Extra distortion makes things sound louder.

If you have a good circuit (e.g. well-chosen bias point, adequate feedback) and good valves then you are very unlikely to hear any difference.
Wrong DF96 since KT88's is already an old & established tube, Im naive in thinking that it would be as good if not better even in reproduced form with the help of modern technology.


Unfortunately electrons in a space charge know nothing of "modern technology", they just behave according to basic physics and the geometry of the electrodes.
There's not much you can do to tweak the performance of a vacuum!
But you can do a lot to tweak the performance and life of a cathode. It seems that cathodes were very much a matter of trade secrets, which may partly be why Mullard had such a good reputation. Also, modern valves are often not evacuated to as low a pressure as in the past - not because the technology is lacking but because it takes time and so costs money.