MJL1302 and MJL3281 best driver transistors

[AMV8]

Could someone recomend the best driver transistors to use with output transistors MJL1302 and MJL3281.
These will be used in Class A and Class AB complementary power amplifiers of 50 W to 100 w output power with between 2 and 6 output transistors in parallel.
The MJL1302 and MJL3281 are fast high beta transistors and I am not sure which current transistors would make the best driver transistors.
Should I think about using these as output transistors and also as driver transistors?
Thanks
Don

 

[Stormrider]

2sa1837/2sc4793 or 2sa1930/2sc5171 are a good choice for medium power amps if you can get them.

Fairchild has some good TO126 devices for lower power uses, such as:

KSA1142/KSC2682
KSA1381/KSC3503
KSA1220A/KSC2690A

For really high power uses the OnSemi MJE15034/35 devices work, but they are not in the same class as the 1302/3281's.

 

[djk]

Carver used the A1302/C3281 for both drivers and outputs in some of his better amplifiers.

 

[Bonsai]

The OnSemi MJE15034/35 are great devices - they are fast (c. 30MHz Ft which is fine for the drivers) and because of their dissiaption capability, if you use them in a double or triple EF 'T' you can run them heavily in class A.

What are you using for your VAS transistors? These are probabl ythe most critical devices in any linear amp.

 

[h_a]

2sa1930/2sc5171

Sweet parts - one can even use them as hot running VAS.

Hannes

 

[john_ellis]

HI

I would recommend the A1837/C4793 becuase they have a higher ft than the MJE's

But the MJE's cuold be good for driving MJ21194/5 's (having ~5..6 MHz fT output is not always bad ... ). I used the old A968/C2238 with those and got .003%THD /100W, and the A1837/C4793 seem to be updated versions.

John

 

[AMV8]

Thanks for your input guys - you are much more up to date on currently available parts than I am.
I had been looking at what was available and before your input I had thought of using the MJL1302 and MJL3281 for output and driver with the 2sa1930 and 2sc5171 for the VAS stage. Over the years experience has taught me that the the transistors are the least linear device in an amplifier so I was trying to get parts of as good a quality as the MJL1302/3281 parts if possible for all the positions.
I should probably have also asked for any advise on the VAS transistors also - any recomendations?
Thanks
Don

 

[Stormrider]

Your design choices will be somewhat based on what you can get from a reputable dealer. A lot of the Japanese parts, and some US parts, are being heavily counterfeited.

These are some parts I've seen used in VAS stages in reputable designs with no particular order of preference; you need to use what's right for your design. The Fairchild and OnSemi parts will probably be easier to get than the Toshiba or Hitachi parts.

2SA1560/2SC3423
2SC3421/2SA1358
KSA1142/KSC2682
2SA1381/2SC3503 (KSA1381/KSC3503)
KSA1220/KSC2690 and 1220A/2690A
MJE340/MJE350
2SB649/2SD669

 

[Bonsai]

The 340 and 350 are not suitable for VAS transistors. For this function you want devicves with a very low Cob, which these devices dont have. The KSC1381/3503 are good VAS devices.

 

[ostripper]

A little Cob sounds Goooood. 😀 Look at all of ampslab's kits , dr. Bora's sigma , and too many other designs to count ... all with MJE340/350's as VAS. These all work and sound exquisite , even with these old devices. 😕


OS

 

[AndrewT]

all with MJE340/350's as VAS. These all work and sound exquisite , even with these old devices.

it has nothing to do with "old".
These high capacitance, low gain, slow devices are just not a nice load to hang on the output of a delicate LTP input stage.

 

[Bonsai]

A little Cob sounds Goooood. 😀 Look at all of ampslab's kits , dr. Bora's sigma , and too many other designs to count ... all with MJE340/350's as VAS. These all work and sound exquisite , even with these old devices. 😕


OS

Clearly you are smokin' something in 'da woodz' making a statement like that.

😀

 

[fab]

Best available VAS TO-126 transistor

... for VAS transistors. For this function you want devicves with a very low Cob, which these devices dont have. The KSC1381/3503 are good VAS devices.

Hi

Am I smoking too... b/c I can not find VAS transistor in TO-126 with low Cob available from the big trustworthty distributors...They seem all obsolete such as:
sa1209/sc2911
sa1360/sc3423
sa138x/sc350x : I found some but with different HFE range for NPN/PNP and I have mainly symetric VAS...
sa1538/sc3953

What is your recommendation then?

Thanks

Fab

 

[jaycee]

Looks like everything in TO-126 that would be good for VAS is becoming obsolete. Might be time to look at SMD parts in SOT223.

Diodes Inc DZT5401/DZT5551 have my eye at the moment. FZT694B also looks good but there doesnt seem to be a decent PNP complement of it.

 

[jaycee]

Sanyo 2SA1708/2SC4488 also look good, though not sure on the dissipation of that NMP case. 2SA1507/2SC3902 looks like it might be the same die, but in a TO-126ML case.

 

[fab]

Sanyo 2SA1708/2SC4488 also look good, though not sure on the dissipation of that NMP case. 2SA1507/2SC3902 looks like it might be the same die, but in a TO-126ML case.

Thanks ,
but a Cob of 14pf/22pf or even 8.5pf/13pf is too high to my taste...

SMD parts are not practical to mount on heatsinks in my actual pcb. I am really looking for TO-126 ou TO-220 package.

Fab

 

[Ian Finch]

Save a little cash, make up a small stock order and place on Fairchild direct. That's the way I get all the the difficult parts like KSC3503/A1381 and over 12 months, it's still cheaper than messing with distributors.
http://www.fairchildsemi.com/ShoppingExperience/action/displayItems?itemType=BUY&gpn=KSC3503

 

[sajti]

For driver I use 2SC5171/2SA1930, easily get from Mouser. For VAS my vote is the 2SC3423/2SA1360, but it's hard to get, so KSC3503/KSA1381 is another good option.

Sajti

 

[fab]

For driver I use 2SC5171/2SA1930, easily get from Mouser. For VAS my vote is the 2SC3423/2SA1360, but it's hard to get, so KSC3503/KSA1381 is another good option.

Sajti

Hi
Am I smoking too... b/c I can not find VAS transistor in TO-126 with low Cob available from the big trustworthty distributors...They seem all obsolete such as:
sa1209/sc2911
sa1360/sc3423
sa138x/sc350x : I found some but with different HFE range for NPN/PNP and I have mainly symetric VAS...
sa1538/sc3953

What is your recommendation then?
Thanks
Fab

See in bold my previous post...🙄

Thanks
Fab

 

[fab]

VAS

Save a little cash, make up a small stock order and place on Fairchild direct. That's the way I get all the the difficult parts like KSC3503/A1381 and over 12 months, it's still cheaper than messing with distributors.
My Fairchild

Hi
...
sa138x/sc350x : I found some but with different HFE range for NPN/PNP and I have mainly symetric VAS...

Fab

Thanks for the link but I could not find the option to select the "E" suffix for 100 to 200 HFE range.

Fab