B1 Xformer

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Joined 2000
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Can we start a dialog on the B1 Xformer preamp? Does it fall under some other existing/similar design, so it's not being discussed?

From BAF 2017.
 

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Official Court Jester
Joined 2003
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pretty much everything known about concept

so , design specifics left to talk about

I hope 6L6 (and Boyz) will soon arrange Store about Iron Pre , which will certainly Swiss Knife when speaking about modest gain preamps (both SE and Bal) , so Greedy Boyz will have more things to choose from ...... be it from Mithrandir ...... or Dwarfs around

:clown:
 
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Joined 2004
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Jensen JT-123-FLPCH costs $37.78 (600/600 1:1)
according to Papa - 50% Nickel core

Specs:

Impedance ratio: 600:600
Turns ratio: 1:1
Maximum 20 Hz input: +20 dBu
THD @ 20 Hz: 0.025 %
Frequency Response: 20 - 20 KHz, -0.04 / +0.04 dB
See spec sheet for additional details


Edcor equivalent would be PC 600/600 and costs $7.23 just like any other one from that line at consumer quantities. Most definitely not close in price but relative to the total cost of building, it's not a deal breaker IMO. The problem seems to be why NP chose the Jensen for the F6 in the first place:

Taken from 6moons F6 Production article:

"Interestingly, the two transformers (M2 and F6) required different core materials to get their sounds. The M2 has an Edcor M6 steel core and the Jensen in the F6 is 50% nickel. The primary difference is that the steel has a high tolerance for saturation, the nickel alloy gives higher permeability and lower distortion at the lower levels required by the F6. It is a case of horses for courses..."
 
Can we start a dialog on the B1 Xformer preamp? Does it fall under some other existing/similar design, so it's not being discussed?

From BAF 2017.

The switch selects between 6 or 12dB gain. If I want a 3 step switch and the 3. position to be 0dB, then all the transformers windings in series will be parallel with the output...will this be a problem for B1?
 
PSU have V(-) , GRD and V(+) high probability buffer are similar to this one..
Two first B1 Xformer resistors around the switch are 1M Ohm's.
After the switch log volume potentiometer of 50K maybe..
Schematic source : Passworks
 

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Or something similar to M2 buffer.btw is nice low distortion preamp. Schematic source : First Watt
 

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