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Operating Vgs and Yfs matched 2SK1530/2SJ201 for the F5, F5 Turbo and F5X

NicMac

Member
2009-02-26 8:34 pm
I have recently concluded a group buy (in this thread) for the great sounding Toshiba 2SK1530 and 2SJ201 MOSFETs for the excellent balanced F5X by EUVL (see this thread).

Along with a financial deficit, this GB has left me with a large number of MOSFETs that I will not be able to use in my lifetime as amplifier builder. This thread is for the sale of these. Although the FETs were originally sorted for the F5X they will obviously also be perfect for the standard F5 and the various versions of the F5 Turbo.

You can find a detailed description of the matching procedure in the GB thread here and I believe that you will not be able to find anything even remotely similar on the DIY market. In fact, the FETs have been measured under conditions that closely mimic those found in a Class A amp. The matching was a collective effort and special thanks go to heinz1, Nikon1975 and EUVL/XEN-audio for important contributions.

Briefly, the FETs were measured at equilibrium conditions (swinging @ 0-4A) and at operating temperature (65˚C). The traces recorded under these conditions were fitted to 6th order polynomials by non-linear regression. The transfer functions obtained in this way were two-parameter sorted for Vgs and Yfs @ 2A in order to identify sets of matched devices.

I will in this thread set up for sale three types of matched devices.

Type 1 sets are Vgs and Yfs matched within the N and P devices, but also between N and P devices. This is the absolute best – and unfortunately very rare, so only few sets are available. The pricing is as in the GB (20 euro / NP-pair). UPDATE: SOLD OUT

Type 2 sets are Vgs and Yfs matched within the N and P devices, but not directly between N and P devices. Very tight matching for Vgs and Yfs between N and P devices can however easily be attained using a tiny difference in source ballast resistance for the N and P devices. I will describe these sets in more detail later. Update: I have decided to suspend the sale of these until I have actually tested the fix and this may take weeks.

Type 3 sets are Vgs and Yfs matched within the N and P devices, but not between N and P devices. Pricing is 8, 9 or 10 euro per NP-pair depending on which set-size you pick. The FETs are up for sale now!
Considering the price I'm selling at I reserve the right not to sell to people whom I suspect are buying with the idea of re-selling at a higher price. The goal of the low price is that many DIY'ers will be able to try these wonderful MOSFETs - without breaking the bank.

Match quality: unlike in the GB I will here post the actual values of every single FET (in the Google spreadsheet linked in my signature). Interested buyers will have to look at these numbers to understand/calculate the tolerance of the sets and see if they like it or not. No specific tolerance is promised.

How to buy? Send me a PM with the ID of the set(s) you are interested in. I will reserve the set(s) and reply to the PM with payment instructions.

Shipment cost: the FETs will typically be posted by registered mail at the cost of 9 euro (priced increased a bit as I will have to buy packaging), but this may vary if the buyer has specific requests. I take no responsibility for losses.

I will in the following days update this page and the spreadsheet. I will also later be supplying curve traced 2SK170/2SJ74 for the input stage of the different F5 variants.

Stay tuned and enjoy the shopping and music:)

Nic
 
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NicMac

Member
2009-02-26 8:34 pm
A diyAudio member has reserved the NNNNPPPPP-set Q1 and to document the quality of the matching I have this morning located the recorded traces and plotted these to share with you. N-FETs are in blue and P-FETs are in red.

As you can see all 8 FETs track almost identically over the entire current range. In fact, it is hard/impossible to distinguish the individual curves.
 

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NicMac

Member
2009-02-26 8:34 pm
For comparison here is a Type 2 set with a Vgs offset of about 300 mV between the N and P devices. Notice that the slopes are also different with the N devices being steeper (i.e. have higher transconductance).
Later I will show you what happens to this set when the N-devices are added a little bit of source ballast:D
 

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NicMac

Member
2009-02-26 8:34 pm
Thank you very much to everybody who have contacted me.
There has been massive interest in the offered Mosfets (not strange considering the exceptional quality/cost ratio) and I will need to get postage material to get everything paid for shipped in the best possible way. It is unfortunately holiday here tomorrow so I will only be able to get the packaging material Thursday/Friday and get the parcels posted by Monday next week.

Thanks!

Nic
 

NicMac

Member
2009-02-26 8:34 pm
I have posted a list of the FETs left for sale (see link in my signature).
I believe that the Type 2 sets may be quite accurately N-P matched using proper ballast resistor values, but I have not and will not have the time to verify this in the foreseeable future.