if you are in the UK, Cricklewood Electronics have them listed
Cricklewood Electronics - CCTV. CCTV Equipment. CCTV Systems. Digital CCTV Cameras
(I have no connection with this company)
(they also have BF471)
Cricklewood Electronics - CCTV. CCTV Equipment. CCTV Systems. Digital CCTV Cameras
(I have no connection with this company)
(they also have BF471)
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Some years ago I was playing with Phase Linear clone which uses funny vintage nixie tube driver transistors for drivers.....of course i stick Mje340/350 inside and what happened? There i found nasty spikes and overshots when amp goes to clip......then i tried huge amount of different types of transistors and those BF video transistors worked best of all. i have 8xx series. But there was a problem because they just can't dissipate enough power....And at the end i install MJE15030/31. They work nice if you can bias them correctly. It's worth to try instead searching some obsolete vintage stuff. Believe me i tried various types Hi voltage 2N......BF.......2S......
Best regards
Best regards
BF469, 470, 471, 472 are specified at 50mA RMS and 100mA peak.
Pd is specified at 1.8W for case below 114°C, wich translate
to about 4 to 5W at a coolest ambiant and with a correct heatspreader.
Since maximum current is low, these devices are not suited as drivers
but do excellently as VAS.
Indeed, the archaic MJE340/350 are also low current capability
and doesn t suit as drivers as well, while as VAS, well, they are
the devices of choice for who is in search of distorsion, low
open loop gain and instability...
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Bob Cordell is offering a free support service to his readers.
You have obviously not bought his book nor read many/any of his posts.
Do you deserve to benefit from his magnanimous gesture?
Hi lineup,
Those additional models will be coming to my site at CordellAudio.com - Home very soon. I had hoped to get the updated and added models up sooner, but I have added a number of additional transistors, and each transistor involves quite a bit of effort. I do include MJE340/350 models.
Cheers,
Bob
Hi all
MJE340/350 seemed to be low current, high voltage transistors and I was surprised when Doug Self used them in his "blameless" as they did not seem to me to be the fastest available drivers. The model parameter tf=7.65n shows that the expected ft is going to be around 20 MHz. That is in the same order as 2N3440/2N5415 class which I would also avoid for hifi amps.
Stick to BD139/BD140 for 50W drivers or the excellent 2SC2238/2SA968 or updates (2sC4793/2SA1837 etc) for higher power amps! You can also use these in VAS or try SANYO's 2SC2911/2SA1209 which are excellent- a sort of lower current higher voltage BD139...
John
John
MJE340/350 seemed to be low current, high voltage transistors and I was surprised when Doug Self used them in his "blameless" as they did not seem to me to be the fastest available drivers. The model parameter tf=7.65n shows that the expected ft is going to be around 20 MHz. That is in the same order as 2N3440/2N5415 class which I would also avoid for hifi amps.
Stick to BD139/BD140 for 50W drivers or the excellent 2SC2238/2SA968 or updates (2sC4793/2SA1837 etc) for higher power amps! You can also use these in VAS or try SANYO's 2SC2911/2SA1209 which are excellent- a sort of lower current higher voltage BD139...
John
John
Hi John,
These seem to be good suggestions.
As you know, I like Locanthi Triples, so I tend to use 15032/15033 drivers, sometimes preceded by pre-drivers of types like the ones you mention.
Cheers,
Bob
I am not going to get involved in this discussion, except to point out that sticking with devices that are in production is the way to go. There is a reason why anyone can find 2n3055, BD139, etc. I like the BF469/BF470 myself, but alas, no longer available !!!
MJE340/MJE350 are robust, but do have terrible high-frequency behaviour.
I have resorted to using IRF610/IRF9610 as drivers now...
MJE340/MJE350 are robust, but do have terrible high-frequency behaviour.
I have resorted to using IRF610/IRF9610 as drivers now...
Transit frequency is too low indeed, but what audible effect is actually to observe (resp. to expect) in cases, where MJE340/350 is used in a VAS stage and in a driver stage of an output power darlington ?
There are a lot of top class power amp with MJE340/350 in use
I am looking for a full insulated replacement of the MJE340/350. Thanks for an advice.
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Here we go again with another npn & pnp matching discussion 
Oh Chris, where are you?
How about it is not required in many cases esp if you are using a 3EF design. Bob Cordell wrote a lengthy dissertation on the subject a while back, it needs to be a sticky, I'd have to search for the post. was it was in the DH-200/220 mod thread? I do not remember.
Oh Chris, where are you? How about it is not required in many cases esp if you are using a 3EF design. Bob Cordell wrote a lengthy dissertation on the subject a while back, it needs to be a sticky, I'd have to search for the post. was it was in the DH-200/220 mod thread? I do not remember.
Thank you. Not for resurrection. For an easy high-voltage regulator - go to post #11 under
Help needed for unknown SEMELAB Power Zeners "8136 8215E"
for schematic.
I think, this part is useful for replacement of mje350.
I just note this is only TO126 and not this iso outline under
Free shipping KSA1381ESTU KSA1381 KSC3503DS KSC3503 TO 126 new original|original|original new - AliExpress
that I am looking for.
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Was this the one?
Post: #1666
Thread: hafler dh-200/220 mod
But I am firmly of the opinion that matching is important. Distortion can be reduced if the output stages are matched. Every amp I've built to date using driver/output doubles has benefitted from matched transistors. Not necessarily exactly, but closely helps.
I'm sure distortion in a triple would still benefit but the rewards probably less so. It seems transistor manufacturers are relying on triples as I have many TO-220 drivers where the PNP gain is up at around 180 and the NPN at 100 and could not be matched even with tens of devices purchased on three occasions. Applied to MJE1503x types as well as 2sA/2sC versions that I wondered if they were all made from the same batches!
For small signal stages matching is essential. Recently I updated an old small signal DC coupled amplifier for mV measurements. Previous circuit only had matched input pair and in the current mirror. Update had fully symmetrical (complementary push pull VAS) and matched transistors thermally coupled in all key stages. Drift went from a few mV/min to less than 0.1mV- almost immeasurable. Offset also needed less adjustment.
Post: #1666
Thread: hafler dh-200/220 mod
But I am firmly of the opinion that matching is important. Distortion can be reduced if the output stages are matched. Every amp I've built to date using driver/output doubles has benefitted from matched transistors. Not necessarily exactly, but closely helps.
I'm sure distortion in a triple would still benefit but the rewards probably less so. It seems transistor manufacturers are relying on triples as I have many TO-220 drivers where the PNP gain is up at around 180 and the NPN at 100 and could not be matched even with tens of devices purchased on three occasions. Applied to MJE1503x types as well as 2sA/2sC versions that I wondered if they were all made from the same batches!
For small signal stages matching is essential. Recently I updated an old small signal DC coupled amplifier for mV measurements. Previous circuit only had matched input pair and in the current mirror. Update had fully symmetrical (complementary push pull VAS) and matched transistors thermally coupled in all key stages. Drift went from a few mV/min to less than 0.1mV- almost immeasurable. Offset also needed less adjustment.
I do not think semi mfgs are in tune with exactly how power amps are designed. The issue with matching npn/pnp is that as as nice as it is to do, the process variations are not as wide as in earlier times. Thus they are not required to test/grade anymore. So there are no practical means to do it even if it is a requirement.
If you'd like BF469/470 series transistors for a VAS in modern format (i.e. SOT 223) why not look at using SMT or using little adapter boards/copper flags with these:
https://www.onsemi.com/pub/Collateral/BF720T1-D.PDF
https://www.onsemi.com/pub/Collateral/BF721T1-D.PDF
I believe Infineon also make these or variations of, in the same series BF720-724
https://www.onsemi.com/pub/Collateral/BF720T1-D.PDF
https://www.onsemi.com/pub/Collateral/BF721T1-D.PDF
I believe Infineon also make these or variations of, in the same series BF720-724