GB NP matched Toshiba 2SK1530/2SK201 for F5X - Page 18 - diyAudio
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Old 24th October 2012, 05:24 PM   #171
EUVL is offline EUVL  Europe
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To Buzzforb :

Your questions are legitimate.

But I cannot possibly answer all questions, especially they demand a huge effort.
The question you post will cost us at least 40 working hours, not to speak of money.
So we have to prioritise. And this one we have to pass.


Patrick
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Old 24th October 2012, 10:24 PM   #172
ashaw is offline ashaw  Australia
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Saw your post. Was actually asking about PP NN PP NN match (More interested about. Good to know about much matching for quad sets.

As far as I can understand buying stats of FETs that are in the matching peaks for the p and n channel separately should increase match quality no? and if floating X fixes the PN match problem then should a P-N match be a priority at all?

What are the benifits of close matching between channels for this amp? How would this translate to matching for a 16+ channel HOA system?
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Old 24th October 2012, 10:56 PM   #173
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Quote:
Originally Posted by EUVL View Post
To Buzzforb :

Your questions are legitimate.

But I cannot possibly answer all questions, especially they demand a huge effort.
The question you post will cost us at least 40 working hours, not to speak of money.
So we have to prioritise. And this one we have to pass.


Patrick
Cool. Just didnt know if you had done it already. I remember reading you has built other iterations of the F5. From what little I have done on the GB front, I am very aware of the time you must commit to this thing. Good luck anf thank for the bit of education.
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Old 25th October 2012, 04:20 AM   #174
EUVL is offline EUVL  Europe
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If you want 16 channels you can go for nn & PP, as you said.
They will cost much less, but you need to talk to Nic.

If left & right channels are not identical, you might end up with (slightly) different amount of feedback, and different harmonic content.
So they will sound different. The question is how much and whether audible.


Patrick
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Old 25th October 2012, 10:28 AM   #175
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"These would have to be sold for > 1000$/set"

Yes well thats taken the wind out of my sails!

mere scraps for me by the looks.

Great work and looking forward to final pricing options!
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Old 25th October 2012, 06:51 PM   #176
heinz1 is offline heinz1  Europe
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Here are two pictures of the equipment I use for data collection. The first one shows the working environment:
  • USB scope connected to computer and FET tester
  • Power supplies for FET tester (16V, current limit set to 5A, output switched off) and 12V heating circuit (delivering 2,5 A to heating block via SSR in PID controller case)
  • PID controller case and heating block
  • Multimeter with thermocouple for additional temperature monitoring
In the second picture, the heating block is slowly reaching its set temperature of 64C; the FET tester power supply is still switched off. A reference MOSFET is already connected to the tester, seven DUTs from this GB (labelled with green dots) are waiting to be tested. The Pt100 temperature sensor connected to the PID controller is covered with a (green) sponge. This sensor is very sensitive to air circulation, resulting in strange temperature readings.

I collect the raw data and send them to Nic for further analysis and processing.
Attached Images
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File Type: jpg working_env-4.JPG (413.5 KB, 215 views)
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Old 26th October 2012, 12:42 AM   #177
alazira is offline alazira  United States
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Quote:
Originally Posted by NicMac View Post
...
For those who have already bought NP-matched (not PP-matched only) devices from Zhou I am likely to be able to help in finding significantly better matched 2SK1530s for their 2SJ201s.
I will likely do this free of charge for people who are going to get matched sets from me, but this service may also (FETs permitting....) be extended to others.
More about this later.

Nic
Hi Nic,
As someone who has several sets from Zhou and Blues, I would be interested in obtaining better matches if possible (free or otherwise).
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Old 26th October 2012, 06:38 AM   #178
NicMac is offline NicMac  Italy
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Quote:
Originally Posted by alazira View Post
Hi Nic,
As someone who has several sets from Zhou and Blues, I would be interested in obtaining better matches if possible (free or otherwise).
Yes - this might still be possible.
First thing is that you PM the Vgs values written on Zhou's 2SJ201 FETs and I will let you know later. This value has to be high enough to enter my unmatched 2SK130 region (the one from nikon1575 is high enough and I am going to fix his set).
For the FETs from Blues I cannot help as even the 2SJ201 in the sample I have seen are very variable.
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Old 26th October 2012, 07:39 AM   #179
EUVL is offline EUVL  Europe
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Nic,

IMHO you need to be cautious about extrapolating any conclusions you make with one set of data.
You have measured one set from Vendor Z and one set from Vendor B.
Those measurements do not necessarily extend to other sets from them respectively.

I applaud your generosity.
But if you want to help others to rematch, there is no other way than to send them all to heinz1 for measurement,
and then pool them in together with your devices.

But the approach is correct.
If the Vgs lies outside your range then there is not much you can do.


Patrick
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Old 26th October 2012, 08:13 AM   #180
NicMac is offline NicMac  Italy
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Patrick,

that is of course all completely correct. I do mean improve, not make perfect. What I am saying is simply that the probability of having a decent PPPP-set is higher than having a decent NNNN-set. But still a lottery.

The 600+ 2SJ201 I have looked at for certain have a much tighter Yfs distribution and more similar Vgs change with temperature.

The only right way is of course to get the FETs to heinz1 and have a look at what can be done, with no guarantees and well understanding that we are not in the miracle business. This would obviously only be possible if heinz1 would agree to do it and in front of a reasonable compensation for his efforts.

We have now settled for the 26 perfect NNNNPPPP-sets and most should be able to finish their amps
We should have the time over the next months to investigate the possibility.

Nic
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