We love directly heated triodes for their sound, so why not put that sound in the line stage circuit?

For years I have been pursuing the single triode stage to its end.  I think I have finally found that end.  Carefully removing circuit pieces and adding others has led to this new circuit.  I finally feel done with line stages.  It is actually a great feeling.  At peace with all the units that have come and gone.  I am happy, and, most importantly, listening to music!

The circuit does use quite a few "tricks" that I have discovered the last few years.  A few choice notes:  it does not use any capacitors in the signal path.  Zero...  The final iron count is sixteen.  Yes, sixteen pieces of iron in a single stage line stage.  And yet the signal path is one tube, two transformers, and one very low value resistor.  The single triode tube is loaded with an 80% nickel cored transformer and of course the volume control is via a nickel cored transformer as well.  The secret to using the directly heated triode (the vacuum tube type of the 300b, 2A3, 45, etc.) is the proper implimentation of the filament supply.  Because a directly heated tube has the heater as a signal element, a separate, very quiet, and (here's the catch) great sounding supply must be built in addition to the high voltage supply.  This difficulty and cost keep most manufacturers from producing a DHT line stage.  But what are they missing by using indirectly tubes?  - The Sound!   That BIG and eerily transparent directly heated triode sound is just more "there" with a DHT linestage.  I can honestly say that after comparing this stage to my previous reference, the Contact, I will never again produce an indirectly heated line stage.  It is worth the trouble and expense to use the DHT.  There is only one amplifying device in this line stage.  Shouldn't it be the best available?

The first two versions of this line stage were commissioned using the 71A.  It sounds wonderful, but there are several other tubes that can be used in this circuit.   Please inquire about a personal custom commission using any of the other wonderful sounding DHT's that have been produced over the years from the classic Western Electric tennis balls (205D, 101D) to the industrial cool transmitting triodes such as the 316A.

The Line Stage

Directly heated triode line stage

two chassis - one power supply, one signal

remote

quantity of inputs/outputs per request

most hardwoods available

standard tube is the 71A

a few of the optional tubes:

western electric 216A, 101D, 205D

GE/Tung-Sol 316A

RCA 112A, 10, 45, 50

modern EML 45 mesh, TJ 2A3 mesh 

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