Marantz 7 Questions

I think the 7C is the tube preamp and the 7T is solid state.

you are correct.

So is there a different between 7 and 7C?
Is there a 7B?

Atranz:

The "7" is SS (medicore even in it's time) and the "7C" is a tubed unit (stellar in it's time) but now surpassed, both line and phono sections, by current standards when compared to decent modern designs - some of these being even low cost/budget offerings.

Sorry if this upsets anyone. My opinions are based upon using these units long prior to them having any vintage distinction and since thrn using a restored 7C in my setup in order to compare it to more modern designs.

This is not to say that a refurbished/stock 7C does not sound nice and musical (it does), but most of its value is of a historic nature, IMO.

On a sound quality only basis many dumped their 7C's in the mid/late 70's (in my area anyway) and replaced them with the preamp/phono sections of the then new Advent 300 SS receiver (probably spent the proceeds on herb:-).

So, does one run out an pick up an Advent 300 for better sound quality? Well, probably not w/o having it rebuilt/refurbished (same thing for a 7C) as with any vintage piece the caps and other time dated parts are well past their prime.

Never heard of a 7B.

There is only one model, the 7, which is erroneously called the 7C. 7C refers to the optional wood enclosure ("C"ase).
The 7T was the transistor model.