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Potential EUVL F5X designed case user distribution check

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#761
We might get them (unmatched) from Zhou and do the matching ourselves. My reason for posting was that I think we need to determine the number of sets we need and estimate the number devices that have to be matched to get to it.
I also already a set from Zhou and I will measure this when I find out how to set up a rig.
So much care has been put in to every little detail of EUVL's F5X that I would hate that the sonically most important components are suboptimal.
Cheers,
Nic
 
#762
Zhou did not use a jig.
He wired D to G.
Applied a current of 503mA when Ta was (I think he said 63degrees) and measured the Vgs to 5 significant figures.
A complete whitewash, implying accuracy that is not there.
Have you seen a circuit with the output mosFETs wired D to G?
 
#763
While tie D to G to match fets is not as precise, this method is commonly suggested. See Nelson's 1993 matching devices article and Anthony Horthon's AV800 build guide.

I also bought my OT's from Zhou, but I honestly didn't expect Zhou's match method was anything but this common approach. It was still better than random picks and potentially fakes.

Nic,
Zhou's unmatched (based on his matching method) stocks are likely to be unmatched. You have better chance if you start off his matched sets, but then this will add the cost; however, if the EU price is at 11 euro ea (2SJ102), then Zhou's US$28 matched N-P isn't not a bad alternative especially they are started at some form of matching.
 
#764
Fred,
I fully agree, but Zhou told me he does not have anymore of the N-P matched devices until he matches again. Considering this, I am afraid that getting devices from his "value match" or "precision match" pairs will mathematically yield no N-P matches (as he has already sold these as N-P matched).
😕
Nic
 
#765
NicMac said:
Fred,
I fully agree, but Zhou told me he does not have anymore of the N-P matched devices until he matches again. Considering this, I am afraid that getting devices from his "value match" or "precision match" pairs will mathematically yield no N-P matches (as he has already sold these as N-P matched).
😕
Nic
Click to expand...
Hi Nic,

That's exactly what I thought. My gut feeling was that these were AFTER the N-P match (Zhou's method) screening; therefore, those are of good chance to be N-P not matched!!! It is probably better off to start from a "raw" batch.

Just for the sake of exploration, I just ordered 10 pairs from the US seller that I told you. I will give them a test for authenticity and matching after I receive them. I hope that will give an idea of what is ahead in this game.
 
#766
Quote:
Originally Posted by heinz1
How many of us F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):
NicMac 1
CanAm Man (1 stereo set)
ramallo
oneaclock
andrewt
Studley

How many have already bought from Zhou?
NicMac 1
andrewt
Studley
 
#767
Quote:
Originally Posted by heinz1
How many of us F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):
NicMac 1
CanAm Man (1 stereo set)
ramallo
oneaclock
andrewt
Studley
ashaw 8 stereo sets.

How many have already bought from Zhou?
NicMac 1
andrewt
Studley
 
#768
As for the testing method, it is probably useful to have a Pelteir Module attached to a vapor chamber heat spreader, and then have this bolted to a heatsink in a controlled loop.

This will require an accurate CCS, Signal generator that can produce a clean 1hz triangle wave and a pair of high quality isolated Multimeters with computer control and at least 5 1/2 digits.

An example of a multimeter that would be perfectly suited would be this: SMU2055 Portable USB Multimeter

However doing this will require some programming, and lot of time. probably something like 10s per fet for measurement and a warm up time of a few minutes per fet.
 
#771
How many of us F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):
NicMac 1
CanAm Man (1 stereo set)
ramallo
oneaclock
andrewt
Studley
ashaw 8 stereo sets.
triode4 1 set
heinz1 1 stereo set

How many have already bought from Zhou?
NicMac 1
andrewt
Studley
 
#772
> Just curious, where did the testers source the matched Toshibas?

The test team bought theirs from Zhou a while ago while he still has NNPP matches.
I myself bought a total of 100 (random) from a Japanese source and picked 8 for the proto build after curve tracing at 16V 0~4A on heatsinks.

> It is probably better off to start from a "raw" batch.

Correct.

One advantage of the F5X as opposed to F5 is that there is not only harmoinic cancellation between top & bottom halves (N-P), but also left to right. So a slight mismatch between N-P is not totally detrimental. I shall make sure that fitzfish addresses this N+P mismatch issue when he publishes his build & test thread, whenever he has time to do so. He is not even getting enough sleep these days (due to work). So please be patient with him.


Patrick
 
Last edited:
#774
Quote:
Originally Posted by heinz1
How many of us F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):
NicMac 1
CanAm Man (1 stereo set)
ramallo
oneaclock
andrewt
Studley
ashaw 8 stereo sets.
Mravinsky

How many have already bought from Zhou?
NicMac 1
andrewt
Studley
 
#775
Quote:
Originally Posted by heinz1
How many of us F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):
NicMac 1
CanAm Man (1 stereo set)
ramallo
oneaclock
andrewt
Studley
ashaw 8 stereo sets.
Mravinsky
JBdV 8 pairs for 2 F5X

How many have already bought from Zhou?
NicMac 1
andrewt
Studley
JBdV 9 pairs
 
#776
How many F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):

NicMac 8 pairs (2 stereo F5X)
CanAm Man 4 pairs (1 stereo FX5)
ramallo 4 pairs (1 stereo FX5)
oneaclock 4 pairs (1 stereo FX5)
andrewt 4 pairs (1 stereo FX5)
Studley 4 pairs (1 stereo FX5)
ashaw 8 stereo sets?
Mravinsky 4 pairs (1 stereo FX5)
JBdV 8 pairs for 2 F5X

How many have already bought from Zhou?
NicMac 6 pairs
andrewt
Studley
JBdV 9 pairs

I just cleaned up a little to facilitate counting. @ashaw: are you really looking for sets for 8 F5X amps (i.e. 32 pairs) or just for one amp?
 
#778
Posting #771, in which I added triode4 ("I need a set!"; #770) and myself was omitted.

How many F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):

NicMac 8 pairs (2 stereo F5X)
CanAm Man 4 pairs (1 stereo FX5)
ramallo 4 pairs (1 stereo FX5)
oneaclock 4 pairs (1 stereo FX5)
andrewt 4 pairs (1 stereo FX5)
Studley 4 pairs (1 stereo FX5)
ashaw 8 stereo sets?
triode4 4 pairs (1 set)
heinz1 4 pairs (1 stereo F5X)
Mravinsky 4 pairs (1 stereo FX5)
JBdV 8 pairs for 2 F5X

How many have already bought from Zhou?
NicMac 6 pairs
andrewt
Studley
JBdV 9 pairs

BTW, I got 4 pairs from Blues already (point matched at +/-24V, +/-1.3A).
 
#780
How many F5X case buyers still need to source output devices (matched 2SK1530/2SJ201 pairs):

NicMac 8 pairs (2 stereo F5X)
CanAm Man 4 pairs (1 stereo FX5)
ramallo 4 pairs (1 stereo FX5)
oneaclock 4 pairs (1 stereo FX5)
andrewt 4 pairs (1 stereo FX5)
Studley 4 pairs (1 stereo FX5)
ashaw 8 stereo sets?
triode4 4 pairs (1 set)
heinz1 4 pairs (1 stereo F5X)
Mravinsky 4 pairs (1 stereo FX5)
JBdV 8 pairs for 2 F5X
smyslow 4 pairs (1 stereo F5X)

How many have already bought from Zhou?
NicMac 6 pairs
andrewt
Studley
JBdV 9 pairs
 
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