Dennis,
Please take some time to look at those posts I linked to in detail.
You will see that the very out-of-match NN-PP used in the test (0.5V vgs difference) has a single-ended second harmonics 4dB higher than a perfect quad.
After the tweek, this reduces to only 2dB higher than perfect (see post #789).
With perfectly matched left and right halves, this will essentially be totally cancelled out, to something like -115dB.
And both sets have 3rd harmonics around -105dB, which will then dominate (see post #597).
So emotionally it is not 100.0000% perfection.
Practically there is no difference that can be measured or heard.
But there is at least one source in this forum who sells NNNNPPPP to 20mV Vgs with no specs on Yfs match, if it is important to you.
My personal view is that it is much more important to have NNNN and PPPP, each quads matched tightly for both Vgs and Yfs,
rather than NNNNPPPP but only Vgs match.
Two of these FETs with the same Vgs at 2A can have differences in Yfs as much as 12% according to our data.
And because they are not measured and matched for Yfs also, there is no way to know if you can pair them for left-right or top-bottom symmetry.
You are 6th on the list.
If one above drops out or prefers to save some cost for NNNN-PPPP, you are still on for NNNNPPPP.
I am sure you will not feel disappointed any more when the time comes.
Take care,
Patrick
Please take some time to look at those posts I linked to in detail.
You will see that the very out-of-match NN-PP used in the test (0.5V vgs difference) has a single-ended second harmonics 4dB higher than a perfect quad.
After the tweek, this reduces to only 2dB higher than perfect (see post #789).
With perfectly matched left and right halves, this will essentially be totally cancelled out, to something like -115dB.
And both sets have 3rd harmonics around -105dB, which will then dominate (see post #597).
So emotionally it is not 100.0000% perfection.
Practically there is no difference that can be measured or heard.
But there is at least one source in this forum who sells NNNNPPPP to 20mV Vgs with no specs on Yfs match, if it is important to you.
My personal view is that it is much more important to have NNNN and PPPP, each quads matched tightly for both Vgs and Yfs,
rather than NNNNPPPP but only Vgs match.
Two of these FETs with the same Vgs at 2A can have differences in Yfs as much as 12% according to our data.
And because they are not measured and matched for Yfs also, there is no way to know if you can pair them for left-right or top-bottom symmetry.
You are 6th on the list.
If one above drops out or prefers to save some cost for NNNN-PPPP, you are still on for NNNNPPPP.
I am sure you will not feel disappointed any more when the time comes.
Take care,
Patrick
> I can live with just a little more second harmonics
Yes, difference between something like -113dB and -115dB H2.
Patrick
Thank you for explaining what one can expect objectively.
I'm not sure if I can even *measure* that difference.
Cheers,
Dennis
9 down, 1 to go. Last chance.
> didn't think this was a possibility!
Neither did I, 2 months ago.
It will take some time to get things organised, especially mechanical things.
Please be patient with us.
As in the last 2 GB, we'll only ask for payment when we are ready to ship.
So no risk on your side.
Patrick
> didn't think this was a possibility!
Neither did I, 2 months ago.
It will take some time to get things organised, especially mechanical things.
Please be patient with us.
As in the last 2 GB, we'll only ask for payment when we are ready to ship.
So no risk on your side.
Patrick
And those also asking for the preamp please indicate your interest here :
https://www.diyaudio.com/forums/group-buys/330508-potential-gb-f5x-preamp.html#post5614284
Thank you for your interest,
Patrick
https://www.diyaudio.com/forums/group-buys/330508-potential-gb-f5x-preamp.html#post5614284
Thank you for your interest,
Patrick
Some information on cost estimates upfront.
I was checking what we charged in the 2nd GB moore than 6 yeears ago.
https://www.diyaudio.com/forums/gro...-f5x-2nd-batch-autumn-2012-a.html#post3044430
Back then the case was already 6200 HKD.
So my previous guess of 600€ might be out, as this is (has to be) now made in the EU.
But this is now organise by another long-time member here.
And I know he is not doing this for financial gain (if you know what he does for a living).
The FET prices has gone up substantially as you all know, and is likely to be more than double of that for the GB2.
We shall explain our cost calculations later on, when we are almost ready.
There are alternative sources for NNNNPPPP matched JFETs and MOSFETs on ebay or at DIYA at a lower price than us (~25%).
So you are welcome to use (up) those sources.
We know why we can justify the difference.
PCBs will remain roughly the same.
And you need to organise the (Dale) resistors yourselves.
MPC74 power resistors are available from RS and Buerklin.
If you have problems sourcing them, we can also provide them unmatched.
In the meantime, please be patient with us.
It will unlikely be the first half of 2019, as the case will take quite some organising.
Thanks again for your interest,
Patrick
I was checking what we charged in the 2nd GB moore than 6 yeears ago.
https://www.diyaudio.com/forums/gro...-f5x-2nd-batch-autumn-2012-a.html#post3044430
Back then the case was already 6200 HKD.
So my previous guess of 600€ might be out, as this is (has to be) now made in the EU.
But this is now organise by another long-time member here.
And I know he is not doing this for financial gain (if you know what he does for a living).
The FET prices has gone up substantially as you all know, and is likely to be more than double of that for the GB2.
We shall explain our cost calculations later on, when we are almost ready.
There are alternative sources for NNNNPPPP matched JFETs and MOSFETs on ebay or at DIYA at a lower price than us (~25%).
So you are welcome to use (up) those sources.
We know why we can justify the difference.
PCBs will remain roughly the same.
And you need to organise the (Dale) resistors yourselves.
MPC74 power resistors are available from RS and Buerklin.
If you have problems sourcing them, we can also provide them unmatched.
In the meantime, please be patient with us.
It will unlikely be the first half of 2019, as the case will take quite some organising.
Thanks again for your interest,
Patrick
Some photos to show progress.
All the MOSFETs have been sorted for the project(s),
Some 60 matching rejects from 1000 FETs, after sorting (and packing) for octets, quads and (C, N or P) pairs.
2 persons, one entire working day.
Patrick
.
All the MOSFETs have been sorted for the project(s),
Some 60 matching rejects from 1000 FETs, after sorting (and packing) for octets, quads and (C, N or P) pairs.
2 persons, one entire working day.
Patrick
.
