It appears that pro tape machines were not quite designed to take the
signal from phono. Well then I would have to use a transformer, what
else can I do ?
Pro audio tape machines tend to have lower impedance inputs, and often needing some voltage at the same time. +4dbm is common. This is because they are usually driven by a mixer rather than a consumer line source like a tuner or phono preamp. Such sources are usually run through the mixer in a recording studio.
The reason for all this is so that the interconnect cables don't play some sort of sonic havoc with the signal. Its not just that its balanced- its also low impedance.
However, since we (Atma-Sphere) started this whole balanced operation thing in high end audio, we didn't think that we could get away with making a balanced product that didn't support that balanced standards used in the studio, so we supported it. So one way to use what ever phono section you want is with one of our line sections. Or you can have our phono section added to that line stage.
Otherwise you're going to find that a line transformer that can go from a higher impedance down to 600 ohms is mandatory- and since you are going to be stepping down, the output voltage will be reduced. But you might have enough gain that the latter isn't a problem- you'll have to try it and see. When I was first designing our preamps, I had an Ampex 351-2 tape machine in my living room and I found that I either had to modify the tape electronics or use my preamp line section to drive the line level inputs for recording.
That's how my Otari and my Studer behave also.
Your plan B is to run the output of the phono section into the microphone inputs, but as you can imagine that's not ideal either. Mic inputs are often lower impedance than line inputs (my Neumann microphones are set up to drive 150 ohms). But some machines can handle a 'high impedance' microphone input, although usually you see that sort of thing on consumer decks, not pro audio. So this might still require a transformer, but it would solve the potential gain issue caused by the step-down of the transformer.
