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Interest for potential GB for UDNess PCBs and matched FETs.
Interest for potential GB for UDNess PCBs and matched FETs.
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Old 1st February 2020, 05:50 PM   #41
touchdown is offline touchdown  Italy
diyAudio Member
 
Join Date: Mar 2006
Location: Vicenza
It seems I'm late to the party ... hoping to have a chance, I've added my name. Thanks!


ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
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Old 3rd February 2020, 07:42 PM   #42
samoloko is offline samoloko  Bulgaria
diyAudio Member
 
Join Date: Jun 2006
Interested at pcb set shipped to EU

ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
samoloko 1 pcb set
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Old 3rd February 2020, 08:32 PM   #43
billyk is offline billyk  United States
diyAudio Member
 
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Join Date: Oct 2005
Location: North Central Mass, USA
Interest for potential GB for UDNess PCBs and matched FETs.
Things move quickly around here. . . But if so inclined to add more I would love to participate!

ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
Billyk 1 Set
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Old 3rd February 2020, 08:55 PM   #44
samoloko is offline samoloko  Bulgaria
diyAudio Member
 
Join Date: Jun 2006
@billyk,
please update your vote correctly
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Old 5th February 2020, 08:48 PM   #45
BuzzLiteYr is offline BuzzLiteYr  United States
diyAudio Member
 
Join Date: May 2011
Default if lucky and these are available...

ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
Billyk 1 Set
BuzzLiteYr 1 pcb set (would take 2 extra sets pcbs for a total of 3 sets)
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Old 5th February 2020, 09:11 PM   #46
samoloko is offline samoloko  Bulgaria
diyAudio Member
 
Join Date: Jun 2006
ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
samoloko 1 pcb set

Billyk 1 Set
BuzzLiteYr 1 pcb set (would take 2 extra sets pcbs for a total of 3 sets)
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Old 5th February 2020, 09:58 PM   #47
ItsAllInMyHead is offline ItsAllInMyHead  United States
diyAudio Member
 
Join Date: Mar 2019
Location: The great state of Minnesoooota.
Hi All -

Apologies for not providing an update in a few days.

All parts and boards are ordered. I am waiting to hear back from JLCPCB re: firm timing. I used DHL for shipping. However, they sent an advisory re: the coronavirus and potential delays. So, I'm crossing my fingers and wishing everyone there is healthy and that they'll remain so.

Once I have boards in hand or a firm date, I'll let everyone know.

I'll also get in touch with everyone re: addresses etc. once I have a bit of time.

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Old 6th February 2020, 01:30 PM   #48
ItsAllInMyHead is offline ItsAllInMyHead  United States
diyAudio Member
 
Join Date: Mar 2019
Location: The great state of Minnesoooota.
Hi All -

This may not be the perfect place for my question, but you all have a vested interest in me doing things properly... I've been looking into how to improve my matching process and techniques.

I started down the rabbit hole by searching references for the Peak DCA55 and DCA75 since the jig Patrick recommended for the SOT-23 parts was created by the same company and intended to be paired with it. Then... I searched the forum for curve tracers / how to match etc. I'm willing to make an investment for this and future projects to make my work go a bit more quickly and get more reliable / repeatable results. No costs passed on.

It seems one limitation of the Peak devices mentioned is max 10V / 0A010. So, it is not suitable for the output devices (I think). Do any of you have a recommendation for a thread or two I could read or any specific device(s) I could build or buy for properly matching a range of FETs like for our build?
Budget needs to be ~$200USD or less. I'm not ready for an APXXXX

Something like the DCA75 seems ideal for a person like me in terms of UI and ease of overall use, but it doesn't seem to have the capability we need for at least one of our parts. I had been using a DMM, a lab supply, and a jig for all my previous builds. Those went well, and my process was reasonably efficient, but if there's a better (?) way...

Suggestions appreciated. I can also move this to a new thread if it clogs things up here.
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Old 7th February 2020, 02:32 PM   #49
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
There were some questions about matching.

It has been mentioned many times before, including how to measure a number of parameters using just a DMM, etc.
FET Measurements with Just A DMM

But for the purpose of the UDNeSS,
J113 -- match Vgs at 6mA
2SK209GR --match Idss and optionally Vp
FQA9P25 -- match Vgs at 1.3A.

You can refer to Fig. 5 of Borbely :
JFETs: The New Frontier, Part 1 | audioXpress

And for MOSFETs :
PassDiy

Of course there are more sophisticated methods.
But it is not relevant for your purpose here.


Cheers,
Patrick
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xen-audio.com
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Old 7th February 2020, 02:38 PM   #50
ItsAllInMyHead is offline ItsAllInMyHead  United States
diyAudio Member
 
Join Date: Mar 2019
Location: The great state of Minnesoooota.
Hi Patrick - Greatly appreciated! I'll review everything again. I have read all but the AudioXpress article.

Note to all - I have everything but the boards and the output FETs. So, work should begin after a bit of reading tomorrow.



Patrick
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