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Group Buy for the Through Hole Folded Cascode CEN IV boards

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#342
Hi all,

I have been able to supply namghiwook, longranger and sterlingmck with their needs.

So the good news is that I still have boards and can supply those no problem as before.
The less good news is that I have no mosfets left, and as far as I know they are still out of stock everywhere (other than ebay)
However, the good news is that we have found new mosfets suitable for this build and they are in stock and widely available, but you will still need to buy/match them.

I will message both Reima and Tame now.

fran
 
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#345
Hello Patrick,

I received the MFets / boards for the FC CEN IV build, and I was wondering what calculation was used for determining R1 thru R4 ?.


The MFets were:

N-Channel avg Vgs = 2.171V
P-Channel avg Vgs = 1.800V

If I remember correctly, R1 was 10k, R2 was 10.2k, R3 and R4 were around the 6-7k range .

Thanks for the help,
 
#348
Patrick,
As noted above by RickRay, you asked RRay for the average Vgs for the Nmos and Pmos transistors which resulted in the .371V difference. You mentioned that you would figure out the resistor values. Please see the attached sheet for the MFets that were sent to me. All is good🙂

I am asking for the equation(s) for calculating the total resistance of the divider for my own knowledge and understanding, (Newb here).
Thanks again for the help,
Myles

RR MFet2.jpg
 
#350
Sorry Patrick, I am going to have to review the history and all the information on these how these IV conversions work. I am lost at the moment, wish I knew more but I don't. I feel that this should be a simple Ohm's Law calculation, but I don't know what values I am supposed to use. Thanks for the help so far.
 
#356
Someone else was comparing the FC CEN with a 6N2 IV stage while listening to our latest F5Pi :
https://www.diyaudio.com/community/...tage-perfectly-integrated.406024/post-7543018

"Female vocal the 6N2, Alt Country the FC Cen, overall I think the FC Cen is a tad better match with the F5Pi, but rich vocals are in the realm of the 6n2. Not a whole lot in it but identifiable, depending on what you fancy on the day or the type of music played."


Patrick
 
#357
I've finally begun assembling my copy of the CEV IV version 2.1 June 2022 and have a question. At this point I've got all of the smd parts installed except for R13 and R14 on the bottom of the boards. They aren't listed in the BOM that came with the boards so I didn't order them at the time. However now that I finally got around to this build I see that they are installed on the pics in the assembly guide. I also noticed that the values of R13 and R14 in some other pictures in this thread differ than the pics in the build guide. Do I need to populate them and if yes what values do I need to populate R13 and R14.

Thanks
 
#358
@PJN - can you remember did you get mosfets and matching resistors from RickRay back when you bought the boards?

Those are not R13 and R14 I think, they are Rt3 and Rt4 which are used for trimming current through the mosfets. But if you got mosfets and matching resistors from RickRay at the time, you don't need to populate those positions. In my beta build (the one in the photos) I had to use these to trim current through the mosfets, and that is why they are populated.

Let us know and we'll get you running 👍
 
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