ltp stage transistors

[sakis]

i come across these transistors and was wondering if they can be usefull in an LTP or other stages of audio .....

it looks to me that they have very fine specs but really wonder if can be used

BC 875-6-7-8-9-0
are complementary NPN -PNP DARLIGTONS + DIODE operatind at 100 v 0.8 w 200 MHZ and beta of 2000

what do you think ????

thanks

[Zen Mod]

too much of gain ?

[fotios]

Originally posted by sakis
i come across these transistors and was wondering if they can be usefull in an LTP or other stages of audio .....

it looks to me that they have very fine specs but really wonder if can be used

BC 875-6-7-8-9-0
are complementary NPN -PNP DARLIGTONS + DIODE operatind at 100 v 0.8 w 200 MHZ and beta of 2000

what do you think ????

thanks

Saki, i don't think those bjts are appropriate for audio use. If you want big Vce, then a good type is 2SA970-2SC2240 of Tos. I have tried those with success. You can find from RS.

Regs
Fotis

[fotios]

First of all, i have not idea about mosfets and my experience it is limitted mainly in ONsemi devices.
According to use, i prefer these:
1) For P.A. amplifiers and according to supply level:

Small signal stages
MPSA06 - 56 or 2N5401 - 5551
VAS & Predrivers
MJE15030 - 31 - 32 - 33
Main drivers
MJ15020 - 21 or MJL3281 - 1503
Output stage
MJ1503 - 04 - 22 - 23 - 24 - 25

2) For Hi-Fi amplifiers

Small signal stages
2SA970 - 2SC2240
VAS & Predrivers the same as above
Main drivers
MJL3281 - 1503
Output stage
MJL21193 - 94

3) For low power applications such preamps etc:

BC550 - 560
D44H8 - 45H8

4) For bias in power amplifiers

BD135 or BD137

I have tried only the above devices, because i can find them (the same for you because Greece) very easy. You know as i think "BAKIS electronics" for OnSemi, Fischer etc etc.
I am in waiting to hear your news.

Fotis

[sakis]

thanks for all these info .....

this is more or less what i use in my amps too

but these specs seemed to look like something really special and so i thought that might be used in some audio application ....

of course if so a circuit needs to be builted around them

[AndrewT]

Hi,
the MJE1503x series have far too much Cob for VAS duty.
Similarly the Power capability is wasted in VAS and pre-driver duty.

Use a low capacitance, lower power, medium hFE, high fT device in these locations.

Try 2sa1360/c3423 and many that are similar for VAS & Pre-drivers

[fotios]

Originally posted by AndrewT
Hi,
the MJE1503x series have far too much Cob for VAS duty.
Similarly the Power capability is wasted in VAS and pre-driver duty.

Use a low capacitance, lower power, medium hFE, high fT device in these locations.

Try 2sa1360/c3423 and many that are similar for VAS & Pre-drivers

Hi Andrew

Probably you are right in your suggestion. The problem it is where we can find 2SA1360/2SC3423 or similar in Europe.
As i have mentioned above, the problem it is the availability of components, for this reason we prefer OnSemis because are offered from most shops in Eu.

Regs
Fotios

[AKSA]

Fotios,

I agree with AndrewT. I use 2SC3423 as VAS; Cob is less than 2pF, 200MHz, 50mA, 120V, outstanding device. I've found low Cob is the single most significant parameter for VAS selection. Capacitance across the depletion layer is very nasty; high dielectric absorption, variability with Vce, and multiplied by beta of course in common emitter.

I'm in a very different part of the world to you, but I buy from Peacock Electronics in Singapore. As you may be aware, the Far East pretty much controls the prices of semis in the world, and I find prices from this company very competitive. Expect to pay around 40c US for 1K+.

Hugh

[Bonsai]

AKSA is right - low Cob is critical.

In Europe, you can try the SOT223 BF8xx N & P types from Philips (I think they are NXP now)

[Wavebourn]

Few years ago I used for a custom amp transistors pulled from oscilloscope, they were 250V 200 MHz devices. I don't remember their names, but surnames were Toshiba.