Hi
I have asked Profusion manufacturer if they would be interested in producing new lots of the famous obsolete audio application Toshiba mosfet complementary pairs (2SK1530Y/ 2SJ201Y or 2SK2013Y/2SJ313Y) and they responded that they would consider it if there was enough demand. This manufacturer is already producing the famous audio lateral mosfet that are copy of the 2SK1058/2SJ162 and other copies of famous BJT also for audio applications.
So this thread is a poll to get the number of Diyaudio members that would be interested in buying some of the mosfet. Just add you name in the list.
LIST:
Member name / Qty of pairs (2013/313) / Qty of pairs(1530/201) / Note
Fab / 10 / 10 / comitted to
…..
If we get enough interest I will report the results to Profusion. Ensure that you are very interested in your indicated quantity. You can add a note for your interest level such as “Possibly/Very/ Comitted to”
Have in mind that they could be pricey such as the Exicon mosfet (example: >= 6 Euro or so per transistor).
I can also ask for “S” grade (selected VGS group matching for same type channel.
For the possible use I can see great potential in replacing IRF610/IRF9610 (or FQP3X) by 2SK2013/2SJ 313 and IRFP240/9240 in existing amplifiers while adjusting some resistors values for VGSoff difference of course. For example, in an F5 amplifier it made quite a sound improvement in my experience.
As you already know, there are also already good existing designs using these mosfet.
Additionally, I have recently designed and built new prototype amplifiers using my remaining stock of 2SK1530/2SJ201 based on USSA3/5 or FSSA variations. More to come on that.
Fab
I have asked Profusion manufacturer if they would be interested in producing new lots of the famous obsolete audio application Toshiba mosfet complementary pairs (2SK1530Y/ 2SJ201Y or 2SK2013Y/2SJ313Y) and they responded that they would consider it if there was enough demand. This manufacturer is already producing the famous audio lateral mosfet that are copy of the 2SK1058/2SJ162 and other copies of famous BJT also for audio applications.
So this thread is a poll to get the number of Diyaudio members that would be interested in buying some of the mosfet. Just add you name in the list.
LIST:
Member name / Qty of pairs (2013/313) / Qty of pairs(1530/201) / Note
Fab / 10 / 10 / comitted to
…..
If we get enough interest I will report the results to Profusion. Ensure that you are very interested in your indicated quantity. You can add a note for your interest level such as “Possibly/Very/ Comitted to”
Have in mind that they could be pricey such as the Exicon mosfet (example: >= 6 Euro or so per transistor).
I can also ask for “S” grade (selected VGS group matching for same type channel.
For the possible use I can see great potential in replacing IRF610/IRF9610 (or FQP3X) by 2SK2013/2SJ 313 and IRFP240/9240 in existing amplifiers while adjusting some resistors values for VGSoff difference of course. For example, in an F5 amplifier it made quite a sound improvement in my experience.
As you already know, there are also already good existing designs using these mosfet.
Additionally, I have recently designed and built new prototype amplifiers using my remaining stock of 2SK1530/2SJ201 based on USSA3/5 or FSSA variations. More to come on that.
Fab
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As much as you and others would like them to be put back in production, do you really think that you can generate enough volumes to have them spend $ on development? I would think that they would want annual order numbers in the thousand and one usually signs a contract to the effect. At one time I worked for a big mfg we had to sign a letter of intent to persue such dealings with a semi mfg
Good luck
Good luck
I was thinking the same. Before we get too excited, can you please ask them what numbers they have in mind to even consider a new production batch?
Tha said, I'd be interested in 50 + 50 pairs.
Agree with rsavas, I think it would be helpful for everyone to know more specifically what "enough interest" really means? Especially because whenever a qty is given a manufacturer might think "monthly offtake" whereas a diyer thinks "one-off GB" 
Genuinely interested in this as an idea, but it would be good to understand if it is really feasible before everyone spends time on it
Genuinely interested in this as an idea, but it would be good to understand if it is really feasible before everyone spends time on it
Thanks for your comments.
As indicated this is only a survey to see if we can get a high number for a first order based on interest. My understanding is that Profusion does not need that high a number based on Exicon mosfet (copy of lateral 2SK1058/2SJ162) stock. They seem to be specially dedicated to audio application parts if you look at their items list. Their price is high and I suppose it is their market ( low quantity of first class part thus high selling price). Just like exotic cars with a limited production but a high selling price. Maybe they buy the old mask of the wafer….who knows…
Of course at one point Profusion will have to provide a minimum order number (and maybe more to see potential ). I can understand that less of 1000 or more units can not be interesting even for Profusion. It is just that we need to start somewhere…. I am thinking, for example, at Linear Systems with LSK jfet where they seem to have small lots and quite high price…. In order to get some interest from Profusion in this initiative, we will need to provide an order of magnitude of the need.
I can see commercial manufacturers such as Pass Labs that is using 2SK1530/2SJ201 in their XA__.8 amplifiers series. Their amps are using tens of pairs!
Of course getting the needs also from these commercial manufacturers would greatly help!
So please stay positive and do not quit before the start !
If it does not work, at least it was worth a try.
As for your time, only indicate your quantity of interest and I will do the rest…
To summarize, so far:
Member name / Qty of pairs (2013/313) / Qty of pairs(1530/201)
Fab / 10 / 10
Arthur / 50/ 50
Mbrennwa/ 50/ 50
….
Fab
As indicated this is only a survey to see if we can get a high number for a first order based on interest. My understanding is that Profusion does not need that high a number based on Exicon mosfet (copy of lateral 2SK1058/2SJ162) stock. They seem to be specially dedicated to audio application parts if you look at their items list. Their price is high and I suppose it is their market ( low quantity of first class part thus high selling price). Just like exotic cars with a limited production but a high selling price
. Maybe they buy the old mask of the wafer….who knows…Of course at one point Profusion will have to provide a minimum order number (and maybe more to see potential ). I can understand that less of 1000 or more units can not be interesting even for Profusion. It is just that we need to start somewhere…. I am thinking, for example, at Linear Systems with LSK jfet where they seem to have small lots and quite high price…. In order to get some interest from Profusion in this initiative, we will need to provide an order of magnitude of the need.
I can see commercial manufacturers such as Pass Labs that is using 2SK1530/2SJ201 in their XA__.8 amplifiers series. Their amps are using tens of pairs!
Of course getting the needs also from these commercial manufacturers would greatly help!
So please stay positive and do not quit before the start !
If it does not work, at least it was worth a try.
As for your time, only indicate your quantity of interest and I will do the rest…
To summarize, so far:
Member name / Qty of pairs (2013/313) / Qty of pairs(1530/201)
Fab / 10 / 10
Arthur / 50/ 50
Mbrennwa/ 50/ 50
….
Fab
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unfortunately from the discouragement of some….and lack of enthusiasm of others….with so low interest….. I have not pursuit more this avenue….
From what I remember from very basic initial discussion (Profusion ?) I suppose that less than a few thousand parts (confirmed order) or so no facility would bother to start the initial setup work….even one batch only may not be interesting…
So unless someone else wants to take the ball, I will use remaining available parts and live with it…
Fab
From what I remember from very basic initial discussion (Profusion ?) I suppose that less than a few thousand parts (confirmed order) or so no facility would bother to start the initial setup work….even one batch only may not be interesting…
So unless someone else wants to take the ball, I will use remaining available parts and live with it…
Fab
Nelson Pass ordered a batch of SITs made to special order years ago.
https://positive-feedback.com/reviews/hardware-reviews/first-watt-sit-3-stereo-power-amplifier/2/
6 figures USD.
Setup cost is much more than wafer cost.
If someone will take multiple 10,000 pairs, maybe 100USD a piece or so.
Reality is not discouragement.
Patrick
https://positive-feedback.com/reviews/hardware-reviews/first-watt-sit-3-stereo-power-amplifier/2/
6 figures USD.
Setup cost is much more than wafer cost.
If someone will take multiple 10,000 pairs, maybe 100USD a piece or so.
Reality is not discouragement.
Patrick
Attachments
Quote :
Nelson said about the event, "Sometimes, though, things just fall into your lap. A couple years ago I was talking to Jeff Cassidy at SemiSouth and he mentioned that at one time they had made a special run of static induction transistor devices on some kind of military/industrial contract, and that one of their technical people had remarked that they were nearly ideal for use in audio amplifiers. "Really", says I, "Do you have any of them left over?" No, the customer scooped them all up, but they would be interested in making more. The price of a small run was astronomical (to me, at least) and I spent quite a bit of time pondering the risk. And then I wrote the check and didn't look back. After a few months I had a small batch of SITs with my name on them, and I started playing. It took about a year and a half to arrive at the designs of the SIT-1 and SIT-2 amplifiers, and it has been a revelatory experience."
That was probably using existing photomasks fron the military contract.
Patrick
Nelson said about the event, "Sometimes, though, things just fall into your lap. A couple years ago I was talking to Jeff Cassidy at SemiSouth and he mentioned that at one time they had made a special run of static induction transistor devices on some kind of military/industrial contract, and that one of their technical people had remarked that they were nearly ideal for use in audio amplifiers. "Really", says I, "Do you have any of them left over?" No, the customer scooped them all up, but they would be interested in making more. The price of a small run was astronomical (to me, at least) and I spent quite a bit of time pondering the risk. And then I wrote the check and didn't look back. After a few months I had a small batch of SITs with my name on them, and I started playing. It took about a year and a half to arrive at the designs of the SIT-1 and SIT-2 amplifiers, and it has been a revelatory experience."
That was probably using existing photomasks fron the military contract.
Patrick