In my F5T V3 I use a transformer that, according to other members here on diyAudio, will give +/- 41 V DC. This higher than what Nelson describe(+/-32 V DC).With higher power than +/-32 V DC, it has been discussed to change some resistors values. It is the value of R5/6 and R25/26/ R28 that have been discussed. Voltage at the drains of the jfets should be in the range of 12 to 15 V. Using the cascoding formula and 10k + 4.75 k gives this results: 41V/14.75x4.75=13.2V. This is well within the recommded value of 12-15 V. So with my transformer, there is no reason to change the value of R25/26/28, right?? What about R5/6?? Other changes to be done??
Eivind Stillingen
Eivind Stillingen
+/-32V is for V2. not V3. R5/R6 have nothing to do with rail voltage. R5/R6 value depends on J-fet Idss and determine the voltage you can get over the source resistors.
The jfets I use is SK170/2SJ74.
Does this mean that no changes has to be done from Nelsons V3 schema(I know that the correct value for R26= 10K, not 47.5k) when power voltage is +/-41V DC?
Eivind Stillingen
Does this mean that no changes has to be done from Nelsons V3 schema(I know that the correct value for R26= 10K, not 47.5k) when power voltage is +/-41V DC?
Eivind Stillingen
Hi all,
Sorry for asking probably stupid question, but I confused a bit.
From PCB description page I do see 1 PCB kit with 6 bards. 3 boards (1 main and 2 outputs) are for a 1 channel. Now, and in order to create v3 with 100W output, we need to use mono-block architecture.
That is my question: does 3 boards (half kit - 1 main and 2 outputs) are for 1 channel with 100W output?
If yes, and that is what confusing me, 2 output board can accommodate 2 transistors and 2 diodes. I do see 8 transistor and 8 diodes per channel on schematics. So, it is half of output cascades can be populated on 2 output boards per channel.
Can you please clarify.
Thank you.
Alex
Sorry for asking probably stupid question, but I confused a bit.
From PCB description page I do see 1 PCB kit with 6 bards. 3 boards (1 main and 2 outputs) are for a 1 channel. Now, and in order to create v3 with 100W output, we need to use mono-block architecture.
That is my question: does 3 boards (half kit - 1 main and 2 outputs) are for 1 channel with 100W output?
If yes, and that is what confusing me, 2 output board can accommodate 2 transistors and 2 diodes. I do see 8 transistor and 8 diodes per channel on schematics. So, it is half of output cascades can be populated on 2 output boards per channel.
Can you please clarify.
Thank you.
Alex
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A v3 monoblock will need one front-end board and 2 sets ( two N-channel and 2 P-channel) of output boards.
Order 2 full sets of F5T boards for mono v3. You will have 2 FE boards left over. F-5T (6 PCBs, Makes 2 channels; Rev3.0) - Circuit Boards
Order 2 full sets of F5T boards for mono v3. You will have 2 FE boards left over. F-5T (6 PCBs, Makes 2 channels; Rev3.0) - Circuit Boards
And better yet, mount the FE on the back wall to get the input wiring really short and free up floorspace for everything else. Similar to this -
And better yet, mount the FE on the back wall to get the input wiring really short and free up floorspace for everything else. Similar to this -
I see your point, but at that case all wires from and to Output bards will be quite long. Is there no issue with interference of none-shielded wiring?
I would rather have those long than the input wires, when inside the case. Regardless, using shielded wire is a good idea...
I see. Thank you.
As you advised, I got another PCB kit...).
So, if someone need FE only, I have these that I do not need.....
As you advised, I got another PCB kit...).
So, if someone need FE only, I have these that I do not need.....
The boards you have featured say Version 2.2 while the store boards presently available are V3.0. What is the difference and is a clear picture of the V3.0 boards posted somewhere?
Where are C3 and C4 as on the schematic? Is it labelled C1 on the output boards?
Can I fit a 14AWG stranded wire in the OP holes and G holes on the FE and output boards? Or perhaps you can say what the hole size is?
Thanks.
Where are C3 and C4 as on the schematic? Is it labelled C1 on the output boards?
Can I fit a 14AWG stranded wire in the OP holes and G holes on the FE and output boards? Or perhaps you can say what the hole size is?
Thanks.
Why swap around the internals?
Short and compact Mains wiring would, to me, seem a better way to minimise interference. That would suit placing the transformer at the back near, the Mains input socket.
Short and compact Mains wiring would, to me, seem a better way to minimise interference. That would suit placing the transformer at the back near, the Mains input socket.
Twisted pairs, or even better screened twisted pairs, make very good signal wiring that is almost impervious to both internally generated and externally generated interference.
I think I made same mistake twice.
First mistake was to purchase 1 PCB kit for 2 monoblocks 100W, when I need 2 PCB kits. I assume now and in order to have 2 monoblocks 100W I do need 2 PSU PCB kits as well. Right?
First mistake was to purchase 1 PCB kit for 2 monoblocks 100W, when I need 2 PCB kits. I assume now and in order to have 2 monoblocks 100W I do need 2 PSU PCB kits as well. Right?
Correct. You need (2) full PCB sets, as that will give you enough output boards to mount 8 mosfet and turbo diodes on each channel. You will have (2) FE boards left over.