Understanding Marantz T1

[archeus68]

For a while I've struggled to understand why the guys who designed the T1
went with 300B as a preamp tube?? Amplification factor of 3.9
Seems like there are much better tubes out there other than the 300B for preamplification.
Look at the 5687 http://bit.ly/2VL3GY4 Amp factor of 17 with a low 3K ohm plate resistance. 5687 rocks when compared with tubes like 5692, 6SN7, 7N7, it's a power house medium mu twin triode.
But the designer guys went with four 300Bs?
Would a better front end not be 5687 in the front to get some decent gain and yeah maybe 300B driving the 845s?
Or 6SN7 driving a 5687 driving the 845s?

Is there an advantage of using four 300Bs? Or is it all for show?
And why no negative feedback ???

Thoughts here please

 

[ramjet]

Looks like they wanted to spend as much money on tubes in the smallest space possible. The design is "old school" all the way with balanced input and interstage coupling transformers. My guess for no negative feedback is because the gain of the amplifier is low enough as it is (as you pointed out) and sticking with the vintage triode sound (distortion is what it is).

 

[archeus68]

Looks like they wanted to spend as much money on tubes in the smallest space possible. The design is "old school" all the way with balanced input and interstage coupling transformers. My guess for no negative feedback is because the gain of the amplifier is low enough as it is (as you pointed out) and sticking with the vintage triode sound (distortion is what it is).

Yeah Old School is absolutely right. There is a schematic in a 1936 UTC catalog that is pretty close to the T1. Although they were using 57 & 59 triode strapped tubes. Not 300Bs.

And Oh yeah 845 rectifiers, hmmmm I guess it gives it a Western Electric look. But that's a lot of effort for eye candy.

 

[Mike Stehr]

But that's a lot of effort for eye candy.

It seems some sort of a Sakuma San tribute catered to rich Japanese audio enthusiasts.