Preamp Rectifier Tube Confusion

If the 5AR4 changes the sound of the preamp (assuming the originals are good) then you have bigger fish to fry. It should not make any difference at all- the difference between good 5AR4 and lessor examples is reliability. The power supply has to be designed well enough that the audio circuit is properly bypassed and the sawtooth waveform at the output of the rectifier is filtered out. If that has been done, then its expectation bias if you think you hear a difference.


OTOH, you will hear a difference from the tubes in the audio path- if you want to hear a nice improvement that's a far better place to put your dollars!

+1, on the Mullard (Blackburn plant) being the most reliable and longest lasting, GZ34/5AR4.         You should most definitely contact Kevin Deal, at Upscale Audio, regarding whether a rectifier change will make an audible improvement, in your Primaluna gear.      He has much experience with the brand.      https://upscaleaudio.com/pages/contact-us

5AR4 and GZ34 are the same tube. I think that the Mullard is the best I have heard but the Matsushita made 5AR4s are actually very good. I am not a fan of substituting different tube types and would stick with the rectifier around which the circuit was designed. 

@jl1ny 

However, the Primaluna manual lists compatible tubes as: GZ34, CV1377, 5V4G, 5T4, 5Y3 and Upscale Audio also list the Philips 5R4GYS.

My bad, I see now you are saying that the manual lists the above tubes as compatible IN ADDITION to the 5AR4.

I had read somewhere before what atmapshere is saying, that different but properly working rectifier tubes should not change the tone of a preamp, and I also believe the same for an amp, such as my Dynaco ST-70.

When I purchased my Mullard 5AR4 a number of years ago, they were reasonably priced, and they last forever and a day.  Its one and done.