Can someone please advice some good substitutes for the MPSA42 and MPSA92 for use in VAS, as I'm a bit tired of big differences in Hfe between the NPN and PNP types 
Also suggestions for substitutes for the MJE15032/33 as there are so many counterfeits around
This is for a version 3.1 upgrade of my LYNX power amp.
Help appreciated
Also suggestions for substitutes for the MJE15032/33 as there are so many counterfeits around
This is for a version 3.1 upgrade of my LYNX power amp.
Help appreciated
I've use 2N5551/2N5401 for small signal. My source has generally been a large US catalog distributor like Jameco, Digikey or Arrow. With each of these I can specify the manufacturer. The uniformity with in each polarity is pretty good especially if buy them on tape. Getting similar Hfe between NPN and PNP is moire a matter of luck, but the last time I went though the process with about 50 of each I could match up about a third of them to get Hfe in complementary pairs within +/- 20% of each other.
I don't know it that is an improvement for you.
PS: I think I recall the Horowitz and Hull advice to forget the max and "typical" spec and always choose device for the minimum. I know of a major manufacturer of communication equipment (non-audio) that violated that rule I is now in the very expensive situation of having to buy 1000 power-FETS at a time to sort through and find 5-10 that will work for them. Thew rest go back in to the brokerage market.
I don't know it that is an improvement for you.
PS: I think I recall the Horowitz and Hull advice to forget the max and "typical" spec and always choose device for the minimum. I know of a major manufacturer of communication equipment (non-audio) that violated that rule I is now in the very expensive situation of having to buy 1000 power-FETS at a time to sort through and find 5-10 that will work for them. Thew rest go back in to the brokerage market.
ACD said:Can someone please advice some good substitutes for the MPSA42 and MPSA92 for use in VAS, as I'm a bit tired of big differences in Hfe between the NPN and PNP types
Also suggestions for substitutes for the MJE15032/33 as there are so many counterfeits around
This is for a version 3.1 upgrade of my LYNX power amp.
Help appreciated
MJE15032/33 you can buy directly from Onsemi
www.onsemi.com
Thanks all
sixtek;
I'm using rails up to +/- 70 VDC and up to +/- 75V for the VAS stage
sam9;
I also always buy 50+ of each, however the MPSA42/92 has Hfe from 80 to 160 for the 42's and 140 to 200 for the 92's
QSerraTico_Tico;
I buy my MJE's and most other trannies direct from OnSemi so I have no problems, however many diy'ers building this amp are using local component pushers with bad result (counterfeits)
sixtek;
I'm using rails up to +/- 70 VDC and up to +/- 75V for the VAS stage
sam9;
I also always buy 50+ of each, however the MPSA42/92 has Hfe from 80 to 160 for the 42's and 140 to 200 for the 92's
QSerraTico_Tico;
I buy my MJE's and most other trannies direct from OnSemi so I have no problems, however many diy'ers building this amp are using local component pushers with bad result (counterfeits)
Hi ACD,
I just can't understand why you have to worry about the fake stuff problem. Should you concentrate on making progress for your amp. instead of worrying about people using fakes? Its their own problem. Even if you can find alternative for these, how can you be sure there is no fakes for the alternatives? It is just a never ending story.
However, finding substitute for MPSA42/92 is a fair move for these are getting pretty obsolete and would phase out soon.
Just my personal opinion and I hope I am not offending anyone.
I just can't understand why you have to worry about the fake stuff problem. Should you concentrate on making progress for your amp. instead of worrying about people using fakes? Its their own problem. Even if you can find alternative for these, how can you be sure there is no fakes for the alternatives? It is just a never ending story.
However, finding substitute for MPSA42/92 is a fair move for these are getting pretty obsolete and would phase out soon.
Just my personal opinion and I hope I am not offending anyone.
advise your friends to 'order samples' from here
https://www.onsemi.com/PowerSolutions/product.do?id=MJE15032
these are the guys that make 'em, so no way you will get fakes. also try Mouser
http://www.mouser.com/
and Digikey
http://www.digikey.com/
both very reputable, do not sell fakes, and they both list the MJE15032/33 in stock at the moment.
regards.
edit: if these people have trouble getting it shipped to their country just pm me i have some of these laying around i will get rid of at cost + shipping.
https://www.onsemi.com/PowerSolutions/product.do?id=MJE15032
these are the guys that make 'em, so no way you will get fakes. also try Mouser
http://www.mouser.com/
and Digikey
http://www.digikey.com/
both very reputable, do not sell fakes, and they both list the MJE15032/33 in stock at the moment.
regards.
edit: if these people have trouble getting it shipped to their country just pm me i have some of these laying around i will get rid of at cost + shipping.
bigpanda;
Yes I shouldn't care as I have no problems getting the originals, however some days I get up to 10 emails from people building the LYNX amplifier, who has problems with "exploding" transistors....
And their conclusion are "your circuit doesn't work" etc, even though many others has build this amp with succes.
And I do even warn peoples against fakes, and to get origin parts from OnSemi.....
I'm the type that feel, that I have to help and guide these people to get their amps to work, but it takes up much of my time from new circuits I'm designing at the moment.
gain;
Thanks
Yes I shouldn't care as I have no problems getting the originals, however some days I get up to 10 emails from people building the LYNX amplifier, who has problems with "exploding" transistors....
And their conclusion are "your circuit doesn't work" etc, even though many others has build this amp with succes.
And I do even warn peoples against fakes, and to get origin parts from OnSemi.....
I'm the type that feel, that I have to help and guide these people to get their amps to work, but it takes up much of my time from new circuits I'm designing at the moment.
gain;
Thanks
Hi ACD,
Although I had not been building many circuits, (somewhere like 5-6), I would take the idea that if a project that has been posted on the forum for a long time, the reason for most (if not all) failures will be the builder. Tens of reason could have caused them : sloppy pcb (made by builder); fake components; sloppy soldering, reckless wiring... and the list can go on. If 90/100 of the builders had no complaint, shouldn't the 10$ asked themselves what they have done? For me, I would always blame myself for not doing a decent job instead of pointing at the others.
You guys are generous enough to have provided every bit of information to make these projects happen and you shouldn't be too harsh on yourself as your liability goes as far as that. You are just spoiling us. Maybe if I failed on the lynx, I should sent it to you and let you fixed it for me.....(just kidding).
Why are we diying anyway? You would never learn if everything goes too smooth : a calm sea cannot make a good mariner. For every failure, I enriched my 'failure database'. If any builder is just looking for 'build something for use', then they should buy straight from the shelf and not diying. As for me, I enjoy the building process rahter than the outcome. And if you got into some trouble that you almost have your scalp peeled, you will find how enjoyable your are when you get out of it.
Although I had not been building many circuits, (somewhere like 5-6), I would take the idea that if a project that has been posted on the forum for a long time, the reason for most (if not all) failures will be the builder. Tens of reason could have caused them : sloppy pcb (made by builder); fake components; sloppy soldering, reckless wiring... and the list can go on. If 90/100 of the builders had no complaint, shouldn't the 10$ asked themselves what they have done? For me, I would always blame myself for not doing a decent job instead of pointing at the others.
You guys are generous enough to have provided every bit of information to make these projects happen and you shouldn't be too harsh on yourself as your liability goes as far as that. You are just spoiling us. Maybe if I failed on the lynx, I should sent it to you and let you fixed it for me.....(just kidding).
Why are we diying anyway? You would never learn if everything goes too smooth : a calm sea cannot make a good mariner. For every failure, I enriched my 'failure database'. If any builder is just looking for 'build something for use', then they should buy straight from the shelf and not diying. As for me, I enjoy the building process rahter than the outcome. And if you got into some trouble that you almost have your scalp peeled, you will find how enjoyable your are when you get out of it.
Try the fairchild FJP1943/5200 . Just the little brother to the famous 2sa1943/2sc5200. they come in 2 Hfe classes R- 55-100 and O - 80-160 (to-220 package).
KSA-C 44/94 are super replacements for the mpsa's (350Vce) and ALL my VAS's are strait KSA1381/KSC3503. These fairchilds very rarely are off by 10% in beta , out of lots of 20 , I usually only have a few I can't match pairs to 2-3%
.OS
In my place (Iloilo City, Philippines), people are looking for powerful amplifiers so we're making amplifiers. Our HB+ and HB- is 155 dc and our LB+ and LB- is 77.5 dc. The transistor we're using is C5200 and A1943 for the power amp and for the switching and those are the only available transistors in my place. That's why I'm looking for the drive to replace the MJE15032 because of the QSC I'm modifying right now.
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If the amp uses three current-gain stages, yes, it's best to go and use a full size output device as a driver. It sure simplifies everything. Then you can use MJE340/350 predrivers which are widely available and are easy to screen if you're worried about where they came from.
But if you're cloning the QSC circuit the driver needs to be a smaller lower capacitance higher hFE die.
But if you're cloning the QSC circuit the driver needs to be a smaller lower capacitance higher hFE die.
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