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Interest for Final GB for F5X Power Amp
Interest for Final GB for F5X Power Amp
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Old 19th November 2018, 05:25 PM   #11
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Please help me by updating the list yourselves.
Thanks.

Lbud4
passive 420
Juntuin
pjkaka2020

4 down, 6 to go.


Patrick
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Old 21st November 2018, 09:36 AM   #12
soldersober is offline soldersober  Hong Kong
diyAudio Member
 
Join Date: May 2016
Lbud4
passive 420
Juntuin
pjkaka2020
soldersober


5 down, 5 to go.


I am counting on a pre amp fitting in a matching case to be available as well hopefully
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Old 21st November 2018, 12:25 PM   #13
Dennis Hui is offline Dennis Hui  Canada
Hoopy Frood
diyAudio Member
 
Join Date: Aug 2002
Location: Toronto, Canada
Interest for Final GB for F5X Power Amp
Hi Patrick,

Will there be any (significant) SMD work required?

Thanks,
Dennis
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Old 21st November 2018, 05:34 PM   #14
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
SMD work is required for the speaker protection board.
But I am sure someone can help you out with that.




Patrick
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Old 21st November 2018, 09:13 PM   #15
Dennis Hui is offline Dennis Hui  Canada
Hoopy Frood
diyAudio Member
 
Join Date: Aug 2002
Location: Toronto, Canada
Interest for Final GB for F5X Power Amp
Thanks for the info Patrick.

Lbud4
passive 420
Juntuin
pjkaka2020
soldersober
Dennis Hui

6 down, 4 to go.
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- NP 2002
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Old 22nd November 2018, 04:47 AM   #16
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Welcome back to DIY.


Patrick
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Old 22nd November 2018, 05:03 AM   #17
markus22ch is offline markus22ch  Switzerland
diyAudio Member
 
Join Date: Aug 2007
Interest for Final GB for F5X Power Amp
Lbud4
passive 420
Juntuin
pjkaka2020
soldersober
Dennis Hui

7 down, 3 to go.

also waiting for the preamp....
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Old 22nd November 2018, 05:04 AM   #18
markus22ch is offline markus22ch  Switzerland
diyAudio Member
 
Join Date: Aug 2007
Interest for Final GB for F5X Power Amp
and now with my name on the list:

Lbud4
passive 420
Juntuin
pjkaka2020
soldersober
Dennis Hui
markus22ch

7 down, 3 to go.
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Old 22nd November 2018, 03:49 PM   #19
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
I have been asked whether one can join the GB without the case.

As you can see in the main thread, the entire PCB layout is designed round the case.
So many of these PCBs are close to useless to you if you use some other case.

Maybe in the future I'll change my mind and just let you have the amp PCB only.
But for this particular GB I wish to have 10 more of our reference amp built properly.
And that means including the case.


But many thanks for your interest nonetheless,
Patrick
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Old 22nd November 2018, 04:31 PM   #20
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
One more important point to mention up front, as I discover today.

I just checked our inventory and unfortunately we only have 5 sets NNNNPPPP perfect matched octets for the 2SK1530 / 2SJ201 to offer.
They have Vgs matched to << 10mV, and transconductance matched to < 2% for all 8 FETs.
Matching is done using our own designed curve tracer, under continuous mode and at 65C (10kg) heater block temperature.
So this is identical conditions to a working amp in the F5X.

The first subscribers will (eventually) have priority to those NNNNPPPP devices (first come first serve).
And of course perfection has its price.

For the remaining subscribers, you may :
1) chose to buy those MOSFETs from someone else (and trust his matching); or
2) obtain NNNN-PPPP sets from us at reduced price.

Our NNNN-PPPP sets typically have a Vgs difference between N and P of < 150mV.
Within the NNNN or the PPPP, the match is just as perfect as mentioned above.
Using NNNN-PPPP has, IMHO, little or no disadvantage in a F5X, as opposed to a single-ended F5.
The left and right halves will compensate each other to cancel >90% of the residual even harmonics of each phase.
And you will also get a recipe from us how to tweek the circuit to cancel the N-P unbalance.

This is different from the famous P3 pot from Nelson for the F5, in that we restore the imbalance in the open loop.
And not by fiddling with the feedback circuit (as in the P3 pot).

Details you can see here :
F5X -- the EUVL Approach Post #597
F5X -- the EUVL Approach Post #789

Note that the measurement shown in post #789 are all ONE single-ended phase output of the F5X.
When you applied the load across the balanced outputs, all even harmonics will be reduced by 20~30dB, from our experience.
That is of course assuming you have tightly matched devices for left and right halves of the amp.


No issues with the JFETs. We have more than plenty.


Patrick
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