Here's the First Watt article in question:
http://www.firstwatt.com/pdf/art_sony_vfet_pt1.pdf
For the F6 version, just search for "diamond buffer" in the F6 thread, there are numerous posts that show lower distortion. This PCB could be used to implement that same scheme.
I have a few of these PCBs left-over that I'd like to offer up to the community. The price is $7.50/channel plus shipping. I'd expect shipping to run between $5 (US) and $15 (international) - but the amount will be paid after they ship for exact charges (so, two PayPal payments).
They are 2 layer, 1.6mm thick, 1oz copper, blue with white silkscreen, ENIG plated. I'm including a BOM and supporting files in this post. The relay allows for the buffer to be added and removed via a remote switch. Also, a jumper block which controls how the transformer primaries are configured is provided. These could all be optional and you can just use the XLR input to the transformer, if you'd like. Lots of ways to use this board.
Minimal set of transformers supported are:
Cinemag CMOQ-4
Jensen JT-123-FLPCH
Lundahl LL1684, 1690, 1948
Lundahl LL1588, 1592
Lundahl LL1527, 1527XL, 1527A, 1591, 1540
Sowter 4652
http://www.firstwatt.com/pdf/art_sony_vfet_pt1.pdf
For the F6 version, just search for "diamond buffer" in the F6 thread, there are numerous posts that show lower distortion. This PCB could be used to implement that same scheme.
I have a few of these PCBs left-over that I'd like to offer up to the community. The price is $7.50/channel plus shipping. I'd expect shipping to run between $5 (US) and $15 (international) - but the amount will be paid after they ship for exact charges (so, two PayPal payments).
They are 2 layer, 1.6mm thick, 1oz copper, blue with white silkscreen, ENIG plated. I'm including a BOM and supporting files in this post. The relay allows for the buffer to be added and removed via a remote switch. Also, a jumper block which controls how the transformer primaries are configured is provided. These could all be optional and you can just use the XLR input to the transformer, if you'd like. Lots of ways to use this board.
Minimal set of transformers supported are:
Cinemag CMOQ-4
Jensen JT-123-FLPCH
Lundahl LL1684, 1690, 1948
Lundahl LL1588, 1592
Lundahl LL1527, 1527XL, 1527A, 1591, 1540
Sowter 4652
Attachments
FS: Nelson Pass "CSX1/2" "Buffered F6" Front End PCBs
Adding the buffer and the regulators would look something like this, though mounted vertically. I will post a picture of a complete stuffed board later on.
Adding the buffer and the regulators would look something like this, though mounted vertically. I will post a picture of a complete stuffed board later on.
I don't think I am at that point. Still wanting to listen to the various combinations of buffers and transformers...
I have a new revised version of this board. I needed two DPDT relays to ensure the balanced buffers are switched in and out of the signal path properly. The new board works great and I have plenty for sale.
The two relays are SMD and one on the top and one on the bottom of the board. They are red boards. The relay coils are across the positive and negative buffer rails, so plan accordingly. Of course the buffer doesn’t have to be used and you can mount all kinds of transformers and feed them a XLR or RCA from the chassis.
These are great to play around with!
The two relays are SMD and one on the top and one on the bottom of the board. They are red boards. The relay coils are across the positive and negative buffer rails, so plan accordingly. Of course the buffer doesn’t have to be used and you can mount all kinds of transformers and feed them a XLR or RCA from the chassis.
These are great to play around with!