The Official "Build" thread for the V4 WYN Phono preamplifier

as i'm listening to the V1.3 stage right now killing it, but having been out of the loop for a while: is it worth doing anything with my spare V1.3 board that i originally sat on the shelf, or should i hop straight to the V4 if i want to add a second stage into my spare chassis space?
 
The V4 is a step beyond the earlier versions, both in flexibility and performance, but it's much less DIY friendly as it uses quite a few surface mount devices.
 
cdfac said:
as i'm listening to the V1.3 stage right now killing it, but having been out of the loop for a while: is it worth doing anything with my spare V1.3 board that i originally sat on the shelf, or should i hop straight to the V4 if i want to add a second stage into my spare chassis space?
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I’ve got a v3.2 board if that's of interest.
 
URGENT QUESTION FOR BUILDERS.
I'm building two v4 board sets.
There seems to be a discrepancy between the BOM present in the Dropbox file and the latest Kicad schematic.
There is a 4v7 Zener diode in the BOM and a 1N914 diode in the schematic.
Has anyone built the v4 using the BOM and not the Kicad schematic?
 
:)
I'll construct the boards as is.
I've built the supply sections and now it's time for the input buffers.
It seems possible that the V4 will be commercialized, but will go to SMD, so more work to do.
 
wyn palmer said:
It seems possible that the V4 will be commercialized, but will go to SMD, so more work to do.
Click to expand...

Great!

Is the Zener/1N914 swap likely to make a difference? On power up I certainly get a delay before the outputs are enabled, as you intended. I haven't wired up the mute switch but presumably that would result in the same delay?
 
sim1970 said:
Great!

Is the Zener/1N914 swap likely to make a difference? On power up I certainly get a delay before the outputs are enabled, as you intended. I haven't wired up the mute switch but presumably that would result in the same delay?
Click to expand...
The zener/1N914 change is there just to make the operation of the emergency turn off more certain by ensuring that the voltage on the control line does not rise too high.
It would only affect the turn on delay if the zener leaked too much at the switching voltage for the control fet so that the fet would not turn on sufficiently to trip the relay.
The control voltage depends on the combined leakage of the low leakage cap and the diode, whether it be.a zener or the 1N914, dropping voltage across the 5M1 resistor.
The delay for the mute is the same.
A more complicated circuit could have had this delay free, but I chose not to do that, and noone has requested it.
 
The 4.7v Zener should indeed be a 1N914. It's not a significant issue, but the BOM is incorrect.

Update:
I have, as of 3/10/2026 modified the BOM to have the correct diode for D18.
So far, with only a few dozen resistors to go, D18 is the only discrepancy when the schematic and BOM are compared.
 
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All is assembled now except for half a dozen or so transistors. There seems to be 18 rather than 16 10 ohm Rs in the BOM
so, I'll check that out when I get a chance.
 
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