For group buy re-run - thank you all for continuing to add your name. Boards are on their way to me, but before we go ahead with the second run, we will need to sort out the parts availability. As Patrick has said that is now underway, but will add a little time. Hang tight and stay tuned and we will have a resolution before very long.
fran
fran
Fran is your man. 
He has ordered a good number of PMOS and NMOS from US ebay.
We shall not have them until a few weeks from now.
And then we can measure and confirm if they are genuine.
Even though Fran is super nice to promise to match them for you, we shall NOT have enough for both GB1 & GB2.
And then we have to pay delivery US-Europe, import tax, then postage again Europe-US for US subscribers.
I therefore appeal to US subscribers to organise between yourselves for group purchase and matching.
This is DIY afterall. And you would have had to order and match yourself if not for this unavailability
We'll give you links and matching instructions.
Will take you ~ 1min per device.
For the European & the few World GB1 subscribers, we shall offer matched NNPP quads at a reasonable price plus postage.
We already paid EU import tax for you.
The GB2 subscribers will get the same offer at the same price as EU GB1, but we shall ship together with the PCBs.
The "profit" will go to our development fund for future projects, as it always has been.
But this is only an offer. You are not obliged.
Patrick
He has ordered a good number of PMOS and NMOS from US ebay.
We shall not have them until a few weeks from now.
And then we can measure and confirm if they are genuine.
Even though Fran is super nice to promise to match them for you, we shall NOT have enough for both GB1 & GB2.
And then we have to pay delivery US-Europe, import tax, then postage again Europe-US for US subscribers.
I therefore appeal to US subscribers to organise between yourselves for group purchase and matching.
This is DIY afterall. And you would have had to order and match yourself if not for this unavailability
We'll give you links and matching instructions.
Will take you ~ 1min per device.
For the European & the few World GB1 subscribers, we shall offer matched NNPP quads at a reasonable price plus postage.
We already paid EU import tax for you.
The GB2 subscribers will get the same offer at the same price as EU GB1, but we shall ship together with the PCBs.
The "profit" will go to our development fund for future projects, as it always has been.
But this is only an offer. You are not obliged.
Patrick
So why not use SMD equivalent MOSFETs instead ?
The NMOS is in SOT23, The PMOS is in SOT223.
Their different package means different time constants and thermal resistances.
They will heat up differently to different temperatures.
Also they will heat up more than the E-line packages, hence more DC drift at start-up.
Also matching alone means low yield and waste.
So please wait for Fran, or at least group match.
Patrick
The NMOS is in SOT23, The PMOS is in SOT223.
Their different package means different time constants and thermal resistances.
They will heat up differently to different temperatures.
Also they will heat up more than the E-line packages, hence more DC drift at start-up.
Also matching alone means low yield and waste.
So please wait for Fran, or at least group match.
Patrick
All but 4 of the parcels that have been sent out are now delivered, plus one is marked as attempted delivery (@G600) on the 24/10. @Sadface, @BDL, @topicreader and @Yosyos - your parcels are all in the process of being delivered.
So I think there is good assurance that the method of delivery, packing etc has worked well. Hopefully I'm not jinxing it by saying this!!
Replenishing the supply of boards etc is now in process so hopefully within a few weeks GB2 can get underway. Thank you all for your patience - I know when you get boards its nice to get underway quickly, but better to get everything done correctly than quickly to avoid problems.
Those who want to join GB2, please continue to add your name to the list from the post above, and when we are ready to start, I will message each of you to get your details.
So I think there is good assurance that the method of delivery, packing etc has worked well. Hopefully I'm not jinxing it by saying this!!
Replenishing the supply of boards etc is now in process so hopefully within a few weeks GB2 can get underway. Thank you all for your patience - I know when you get boards its nice to get underway quickly, but better to get everything done correctly than quickly to avoid problems.
Those who want to join GB2, please continue to add your name to the list from the post above, and when we are ready to start, I will message each of you to get your details.
Thanks a lot EUVL & woodturner-fran
Have received my CEN IV boards and the well done and detailed documentation a few days ago.
I have questions regarding the optional to be used Sallen Key filter boards. Only the 5 passive parts have to be equiped? The PCB includes solder pads for ICs and in the documentation is mentioned that the Sallen Key filter does not provide active gain and uses just a buffer JFET (load should be 10k or greater). But I guess the JFET is the one available already on the CEN board and ICs on Salen Key board remains empty?
In Filter BOMs the resistors R1+R2 are both designation = R1. The pictures of finished board explains which of the "R1" is R2.
Have received my CEN IV boards and the well done and detailed documentation a few days ago.
I have questions regarding the optional to be used Sallen Key filter boards. Only the 5 passive parts have to be equiped? The PCB includes solder pads for ICs and in the documentation is mentioned that the Sallen Key filter does not provide active gain and uses just a buffer JFET (load should be 10k or greater). But I guess the JFET is the one available already on the CEN board and ICs on Salen Key board remains empty?
In Filter BOMs the resistors R1+R2 are both designation = R1. The pictures of finished board explains which of the "R1" is R2.
There are pads on the Sallen Key PCB that are not populated.
These are servo options which have been shown to have not benefit and not necessary.
So only the resistors and capacitors for the Sallen Key are relevant.
The Sallen Key buffer is provided by the output JFET souce follower on the main board.
This has also been shown in the original PDF document.
https://www.diyaudio.com/community/...e-cen-iv-with-fixed-rails.389776/post-7109978
Patrick
These are servo options which have been shown to have not benefit and not necessary.
So only the resistors and capacitors for the Sallen Key are relevant.
The Sallen Key buffer is provided by the output JFET souce follower on the main board.
This has also been shown in the original PDF document.
https://www.diyaudio.com/community/...e-cen-iv-with-fixed-rails.389776/post-7109978
Patrick