First Watt F3 Integrated?

[cadaverdog]

Hello all,

I would like to build an integrated amp based-on the First Watt F3.

My source is an RPI with a Hifiberry DAC+Pro- and my speakers are ~96db efficient full-rangers.

My question has-to do mainly with pre-amplification.

Is there a preamp circuit that would drive the F3 to acceptable levels- yet be small enough to include in the amp chassis?

I was thinking that the B1 might be a good choice, but it's only a 1:1 buffer.

I was also thinking that I could potentially use step-up transformers on the DAC outputs- but then there would be no volume control.

Any suggestions would be appreciated.

 

[Nelson Pass]

I have a B1 buffer that drives a Jensen line transformer which does a good
job into the 10K input of the F3. I think that would give you the gain you
might want.

 

[cadaverdog]

OK, is there a particular model number you use?

 

[Nelson Pass]

The JT-123-FLPCH is functional.

 

[6L6]

Nelson, how are you wiring the transformer?

 

[Zen Mod]

for gain , you can wire it as autoformer - either for 6db or for 9.5db

http://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-123-flpch.pdf

Iron Preamp thread being enough informative

 

[Nelson Pass]

The four windings in series give you approximately 0, +3, +6 and +12 dB
assuming the output is at the top, ground is at the other end, and you
drive one the four taps.

 

[Zen Mod]

yeah

my brainfart again

2 to 4 as 6db

1 to 4 as 12db (not 9.5)