A number of amp designs use the pair 2N3440/2N5416 in the VAS.
The only datasheets I have found are from ST and they are
very brief, giving just the mandatory data and void of diagrams.
However, they seem not very impressive judging from the data.
Is there any reason why it is not a good idea to use eg.
2SB649/2SD669 or 2SA1837/2SC4793 instead (assuming, of
course, we do not need the very high voltage rating of the
2N devices)? I did find a comment by Jocko that they have low
Cob (not specified in the datasheets), but since the japanese
alternatives have a much higher fT, I assume they also have
a lower Cob, right?
Links to more detailed datasheets than the ST ones are also
wlecome.
The only datasheets I have found are from ST and they are
very brief, giving just the mandatory data and void of diagrams.
However, they seem not very impressive judging from the data.
Is there any reason why it is not a good idea to use eg.
2SB649/2SD669 or 2SA1837/2SC4793 instead (assuming, of
course, we do not need the very high voltage rating of the
2N devices)? I did find a comment by Jocko that they have low
Cob (not specified in the datasheets), but since the japanese
alternatives have a much higher fT, I assume they also have
a lower Cob, right?
Links to more detailed datasheets than the ST ones are also
wlecome.
This probably belongs in the solid state amp forum, but I've used the 2N parts in designs and find they have above-average linearity before you apply feedback. I learned about them from Borbely and I think he claims they're the best he's found (at least for use in bigger amps). Motorola (before they became On Semi) used to make 'em.
But the above information is dated. There may well be some better options out there today in the Asian parts. Most US and European semiconductor companies don't seem very focused on discrete transistor development anymore. I doubt there's much money in it.
But the above information is dated. There may well be some better options out there today in the Asian parts. Most US and European semiconductor companies don't seem very focused on discrete transistor development anymore. I doubt there's much money in it.
nw_audiophile,
I have checked Borbelys website and I cannot find him mentioning
these transistors anywhere. In those cases he uses BJTs for the
VAS he seems to use japanese devices, so probably he doesn't
use the 2N devices anymore, as you suggested.
BTW, I realized much later that I had posted in the entirely wrong
forum (was probably too tired when posting) so I reposted in
the appropriate forum since nobody had answered. Then people
started to reply to the first post, in the wrong forum!!
Fred,
I assume the double negation was unintentional. I suppose you
are right about most 2N devices being ancient. I always get a
feeling that those popping up in designs every now and then
are types that have been around for ages. I also know that
there has been a lot of discussion about transistor choice for
VAS's and that japanese ones are usually the preferred choice.
I did not expect the 2N3440/5416 to be better, or as good as,
obvious japanese choices, like the ones I mentioned, and had
planned to use japanese ones instead. However, I don't like
the idea of just replacing transistors in a design without having
enough data to know if a slight redesign, like modifying resistor
values, is necessary. For instance, the Vbe figure given suggests
that these 2N devices may have higher Vbe than most other
similar transistors. An Ic vs. Vbe diagram for non-saturated
case would have been useful in the datasheet, for instance,
but maybe it is just my ignorance finding such info helpful?
I have checked Borbelys website and I cannot find him mentioning
these transistors anywhere. In those cases he uses BJTs for the
VAS he seems to use japanese devices, so probably he doesn't
use the 2N devices anymore, as you suggested.
BTW, I realized much later that I had posted in the entirely wrong
forum (was probably too tired when posting) so I reposted in
the appropriate forum since nobody had answered. Then people
started to reply to the first post, in the wrong forum!!
Fred,
I assume the double negation was unintentional. I suppose you
are right about most 2N devices being ancient. I always get a
feeling that those popping up in designs every now and then
are types that have been around for ages. I also know that
there has been a lot of discussion about transistor choice for
VAS's and that japanese ones are usually the preferred choice.
I did not expect the 2N3440/5416 to be better, or as good as,
obvious japanese choices, like the ones I mentioned, and had
planned to use japanese ones instead. However, I don't like
the idea of just replacing transistors in a design without having
enough data to know if a slight redesign, like modifying resistor
values, is necessary. For instance, the Vbe figure given suggests
that these 2N devices may have higher Vbe than most other
similar transistors. An Ic vs. Vbe diagram for non-saturated
case would have been useful in the datasheet, for instance,
but maybe it is just my ignorance finding such info helpful?
I meant that it is not hard to find better Japanese semiconductors for the VAS stage. I don't ever remember Mr. Borbely using these either. Some of the B and K amps used these as a common emitter and current source VAS to drive the gates of paralleled Hitachi or Toshiba mosfets. They were biased at about 30 mA and ran quite hot as I remember. I have replaced several of them and they were not adequately heat sinked in the B and K amps.
http://katalogi.iele.polsl.gliwice.pl/en/download.php?id=58433
http://partsandkits.com/2N3439.pdf
http://www.microsemi.com/datasheets/2N3439.PDF
http://katalogi.iele.polsl.gliwice.pl/en/download.php?id=58419
http://perso.wanadoo.fr/jm.plantefeve/2N5416.pdf
http://www.semiconductors.philips.com/acrobat/datasheets/2N5415_5416_CNV_2.pdf
http://www.microsemi.com/datasheets/2N5415.PDF
http://www.semelab.co.uk/pdf/bipolar/2N5415_16CSM4.pdf
http://www.angliac.co.uk/st/data_from_st/5233.pdf
http://katalogi.iele.polsl.gliwice.pl/en/download.php?id=58433
http://partsandkits.com/2N3439.pdf
http://www.microsemi.com/datasheets/2N3439.PDF
http://katalogi.iele.polsl.gliwice.pl/en/download.php?id=58419
http://perso.wanadoo.fr/jm.plantefeve/2N5416.pdf
http://www.semiconductors.philips.com/acrobat/datasheets/2N5415_5416_CNV_2.pdf
http://www.microsemi.com/datasheets/2N5415.PDF
http://www.semelab.co.uk/pdf/bipolar/2N5415_16CSM4.pdf
http://www.angliac.co.uk/st/data_from_st/5233.pdf
Fred,
It seems I have to find a better search engine than Altavista
and Google. I only managed to find the datasheets from ST.
Unfortunately, the other ones you found are just as brief as
the ST ones. My problem is that I would like to estimate the
bias current in a particular design so I can build it with
other transistors, modifying resistor values when/if necessary to
get the right current. To do that, a Ic vs. Vbe diagram would
be helpful to get a better estimate, I think.
It seems I have to find a better search engine than Altavista
and Google. I only managed to find the datasheets from ST.
Unfortunately, the other ones you found are just as brief as
the ST ones. My problem is that I would like to estimate the
bias current in a particular design so I can build it with
other transistors, modifying resistor values when/if necessary to
get the right current. To do that, a Ic vs. Vbe diagram would
be helpful to get a better estimate, I think.
Hi, Christer
Datasheet with detailed characteristic of 2N3439, 40 are obviously very hard to find. But, you can measure this caracteristic on real samples, or maybe find somewhere Spice models. I will tend to use this transistor in one small Leach amp. My local suppliers have those transistors on stock, I have few used but working. If you have not possibility to get some samples, and you desperately need this characteristics, I can measure this for you (not all transistor characteristic please
), or I can send to you few samples of 3439 and 5416, for free, of course.
Regards
Datasheet with detailed characteristic of 2N3439, 40 are obviously very hard to find. But, you can measure this caracteristic on real samples, or maybe find somewhere Spice models. I will tend to use this transistor in one small Leach amp. My local suppliers have those transistors on stock, I have few used but working. If you have not possibility to get some samples, and you desperately need this characteristics, I can measure this for you (not all transistor characteristic please
), or I can send to you few samples of 3439 and 5416, for free, of course. Regards
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.