Leach Amp 2N3440/2N5415 substitute?

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#21
JojoD818 said:
So I can use MJE340/MJE350 then?

Jojo
Click to expand...

If you are referring to my post, then I didn't say that. Maybe
you can, maybe you cannot. First one has to figure out how
sensitive the Leach amp is to the choice of transisistors and
what parameters are important. I haven't done that, so I cannot
say. Second, as I pointed out, some potentially important
parameters of the 2N3440/2N5415 are not available in the
datasheet, so if these parameters are important in the Leach
it is difficult to say which transistors can be used instead.

I am myself planning to build an amp using these transistors
and possibly also a Leach and I will most likely replace the
transistors by either 2SB649/2SD669 or 2SA1837/2SC4793,
which seem to be very good choices for VAS transistors.
However, as I said, this may require some changes to resistors
values or other modifications, and for the Leach I haven't even
looked into this matter yet.
 
#22
Christer said:

Second, as I pointed out, some potentially important
parameters of the 2N3440/2N5415 are not available in the
datasheet, so if these parameters are important in the Leach
it is difficult to say which transistors can be used instead.
Click to expand...

Hi, Christer, JoJo
I'm not a datasheet expert but this one maybe has the necessary parameters you are looking for:
http://www.semiconductors.philips.com/acrobat/datasheets/2N5415_5416_CNV_2.pdf

The 2SC3440 has replacements all over it seems:
http://www.semiconductors.philips.com/acrobat/various/SC04_1998_REPLACEMENT_1.pdf

Hugo 🙂
 
#23
Netlist said:

I'm not a datasheet expert but this one maybe has the necessary parameters you are looking for:
http://www.semiconductors.philips.com/acrobat/datasheets/2N5415_5416_CNV_2.pdf
Click to expand...

Thanks Hugo, but I already have that datasheet and two or three
others giving exactly the same info. This is really the bare
minimum of data and not enough in my opinion. For the Leach,
perhaps it is sufficient for a decision, but for another amp I have
been looking at it is not enough data.


The 2SC3440 has replacements all over it seems:
http://www.semiconductors.philips.com/acrobat/various/SC04_1998_REPLACEMENT_1.pdf
Click to expand...

I hadn't seen that one before. However, one must always be
carful with such tables. A device suggested as equivalent to
another one may differ quite a lot in data and can be entirely
unsuitable as a replacement in some applications.
 
#25
jojo.
the stage that uses the 2n3440/2n5415 transistors operate at a quiscient current of 5 ma in a class a mode, so therefore a transistor with a collector current rating of 500ma is sufficient imho.....i have used a 92pu06/92pu56 combination in one amp, then abailable at alexan...i bet u can use mje340/350 or MJE243/253 , use heatsink though to be safe....
 
#26
All you people discussing plastic replacements for the 2N3440/5415 make me nervous.

Yes, you can use the MJE243/253, Leach did in his original one. But if you allow 10% for saftey then the maximum ±V you can use would be ±45V, they(and the TIP41C/42C) are only 100V parts.

The MJE340/350 would be better as they are a 300V part. They only run at less than 50mA so that is where the spec is most important.

You will have to lay out your own board, the pin-out on the plastic parts is different.

The secondary breakdown on plastic parts usually stinks vs metal parts, you will probably need a bigger heatsink on the second voltage amplifier, depends on your ±V.

You may need to change the frequency compensation.

This is all do-able, but may be a bit much for a first-time project.

www.mouser.com sells the orginal 2N3440/5415 for $1.44 the PAIR in one lot quantity, no minimum order. Why not buy the right part and save all the hassle?
 
#27
djk,
i fully agree with you, i understand what you're thinking....in the "us of a" you can buy all transistors you need and at a reasonable price....but you see, we live in a far away land, where resources are not as easily available as in the states....so we have to do with what's available, not that we want to, but we have to,. but rest assured we understand the implications of our actions, i read leaches' double barreled amp article in the audio magazine, i still have my copy of the magazines (two months intallments) with me from way back 1981.....
 
#28
djk,

Hi, I just want to "adopt" the leach amp to the parts which are "locally" available in my country. By doing so, the circuit may "behave" somewhat different as the original but that is expected since I did not use the recommended parts.

The problem buying abroad is not the listed price but the shipping and taxes that my country applies to such shipments. I just wish that this process change in the future.

joan,

Where can I find/buy 2SC510a/2SA510a? I'll be digging up my stocked parts just to see if I can find anything useful to this project.

jojo
 
#30
Hi Jojo
Give these guys a call or mail:
Access Frontiers Technologies Inc.
702 Greenbelt Mansion,
106 Perea Street
Legaspi Village,
Makati City
Philippines
Tel: ++ 63 (2) 892 3883
Fax: ++ 63 (2) 892 3882
eMail: sales@afti.com.ph

It's a daughter company of Farnell. Here in Belgium they sell the
2N3440/2N5415.

/Hugo 🙂
 
#31
Jojo

I built both the LOW TIM and Super Leach Amp 4 years ago,I did not use the 2N2440/2N5415 but I used 2SD669/2SB649 instead.Both amps performed OK no problem at all.But I have to modify the PCB to mount the Transistor.Both these transistors are readily available in "DEECO".But be careful with DEECO other than this transistors most of the Transistors they sell are mostly fake.For the output it would be better to use the 2SC5200/2SA1943 Toshiba pair but you would have to modify the compensation capacitors.Most of the Leach amps I built are now being used by MOBILES,LOW TIM for Mid/high and Super Leach for LOW (Woofer).I hope this Helps.

MGR
 
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