• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Vacuum State RTP5.

So, I've been searching the site and found very little information on the subject, so I thought I try a more direct approach.

I am looking to have built a fully balanced tube phono stage [hybrids are OK], and while searching, came across the schematics for the Allen Wright designed RTP5:


I am not by any means an expert [having one built] but I was hoping to get some opinions / comments from people that have actually built this. The good point about this design is that it actually contains a line stage as well [replacing the solid state preamp is also a benefit].

However, the only reference to it I found was a thread about a balanced phono stage where one member said his first stage is based on the RTP3/5.

Can anyone offer any thoughts, comments on this design? Performance wise, bang-for-buck value etc?

I might have some more questions, but I would like to see whether anyone has actually implemented this schematic in a DIY effort to begin with.


2002-01-07 6:02 pm
I've built a couple of versions as well as FVP's. It is one of the best phono pre's I've ever heard, but it is a lot of work to build it.

However, using it as a combined linestage and phono pre wasn't too successful: the line section has too much gain for most CDP's and for me worked best as a pure phono pre (change vol pot to 50k resistors) and a passive linestage with TVCs. I also preferred my second stage to Allen's, but that's a personal choice and his is fine.

I have no phono setup at the moment, but when I move somewhere I can another will be built.