2N5376 low-noise substitute

[Disco Volante]

Restoring GF's old hifi-amp, these NPNs have been sitting in the RIAA section since 1974. Any ideas for a low-noise sub?
Any reason I should not just go with my first instinct bog-standard BC547?
Sorry I don't have a schemo of this one, thought I'd do some maintenance and cleaning and only start drawing if it becomes necessary...
Didn't get much useable info on line, so thought I'd ask you capable gents.

Thanks!

 

[JohnRoberts]

Transistors don't dry out? If it works maybe don't fix it.

Electrolytic caps might benefit from refreshing.

JR

 

[Disco Volante]

Yup, I agree. Got all them caps in a pile right here. Just thought there might be quieter transistors around these days than in 1974. Room for improvement while I'm in there anyway.
Incidentally, I was born that year;-)

 

[Ricardus]

Yup, I agree. Got all them caps in a pile right here. Just thought there might be quieter transistors around these days than in 1974. Room for improvement while I'm in there anyway.
Incidentally, I was born that year;-)

The NTE App recommends NTE123AP. No idea if that's helpful though.

 

[moamps]

I would use 2SC2240. That transistor is low noise and pin compatible.

 

[mjrippe]

The NTE App recommends NTE123AP. No idea if that's helpful though.

Lol! NTE always recommends 123AP - it is their all around general purpose transistor

 

[Ricardus]

Lol! NTE always recommends 123AP - it is their all around general purpose transistor

I remember back in the early 80s where my dad worked they had GE and Sylvania replacement semiconductors, and in the GE book, almost every transistor you looked up was either a GE20 or a GE53.

 

[Whoops]

Any reason I should not just go with my first instinct bog-standard BC547?

I don't know if a BC547 or variant is suitable as a replacement for that transistor,
but if you want Lower Noise than you should look at the BC549 and BC550, because from the BC548 variants those are the 2 that are "Lower Noise"

"The BC548 was released with, and often is found together in datasheets with, the BC547 (higher voltage) and BC549 (lower noise) devices, that correspond to the original BC107 and BC109 variants of the BC108. This group of NPN transistors share many specifications and characteristic curves, but differ in voltage ratings - the BC546 and BC547 are essentially the same as the BC548 but selected with higher breakdown voltages, while the BC549 is a low noise version, and the BC550 is both high-voltage and low-noise"
Wikipedia

https://en.wikipedia.org/wiki/BC548

 

[CJ]

who is GF and what were the original transistors? schematic?

we want information.

 

[abbey road d enfer]

who is GF and what were the original transistors?

I need to ask my girl-friend and read the title of the thread...

 

[CJ]

Girl friend was cryptic and we still don't know what we are working on.

 

[rackmonkey]

Agree with Moamps here on 2SC2240. If you’re like many of us and keep a stash of old transistors around, other manufacturer recommended substitutes include the following (can’t speak to any of these devices’ noise figures off the top of my head, but that’s what datasheets are for):

BC337
2SC1347
2N5818

 

[CJ]

no graphs on that 2N5376, hfe does have 1ma @ 5V spec which is helpful,
parts could be graded with color code stripes on back,
3 considerations for phono preamp are stability ,noise, and channel matching.


there is a listing on evilbay with a "make offer" button,
parts have an S on them but does not look like the Signetics S.

https://www.ebay.com/itm/164395867146?hash=item2646c1dc0a:g:hCsAAOSw4iVfagPi
2N5376 data>

 

[CJ]

2SC2240has min hfe at 200@ 2ma, not too far away from 120, so depending on location in circuit, it should work fine.

2SC2240 sheet>

 

[CJ]

those Toshiba transistors sound great but can be hard to get,
and the 2240 might have different grades which can be all over the place.
note "GR" suffix on this evilbay listing >
https://www.ebay.com/itm/303255136358?hash=item469b6a2866:g:~40AAOSwlrNg
here is a listing for the KSC945,this is the type we use in the Marantz preamp resto,
they can be had for cheap from DigiKey (40 cents) and have a gain option one of which is hfe =120 (Y) , (just like the 2N5376)
and the gain figure is taken ay 1 ma, (just like the 5376)
transition bandwidth is also the same as the 5376 (300 Mhz)>

https://www.digikey.com/en/products/detail/fairchild-semiconductor/KSC945YBU/13453266
this is a modern part which should be around a while.

phono preamps love to go into oscillation, so getting the hfe right is of paramount importance.

data sheet for KSC945>

 

[CJ]

as suspected the 2240 comes in two gain ranges, make sure you get the "GR"
also note that transition freq is 100 mHz for 2240 (5376 is 300)>


better data sheet for the 2240, noise for KCA part and 2240 are the same at 4 db.>

 

[CJ]

and if you happen to see any "square" transistors, rip them out too. they are notorious for being noisy, failing completely, partially working, leaking current, you name it.
(see red arrows)
and if you see any tantalum caps (blue) leave them or replace them with a new tant.
a lot of people make the mistake of replacing those with lytics cuz tants get a bad rap for audio.
but the engineers were not stupid and they have those in there for a reason.
and that's enough out of me so i'll shut up.

 

[JohnRoberts]

and if you happen to see any "square" transistors, rip them out too. they are notorious for being noisy, failing completely, partially working, leaking current, you name it.
(see red arrows)
and if you see any tantalum caps (blue) leave them or replace them with a new tant.
a lot of people make the mistake of replacing those with lytics cuz tants get a bad rap for audio.
but the engineers were not stupid and they have those in there for a reason.
and that's enough out of me so i'll shut up.
View attachment 89582

I am not aware of problem "square" transistors. More details?

WRT to replacing tantalums, they generally have low esr, so modern low impedance aluminum caps designed for switchers are probably OK.

JR

 

[CJ]

Hitachi is the maker of the square or "outhouse" transistors as we like to call them.

2SC458, 2SC1345 are two of the worst offenders,

Thanks for the cap suggestion! Phono cartridges do not have a lot of power to spare.

"Top Ten Worst Transistors - noisy, failure-prone, whatever... and replacements">​

https://www.audiokarma.org/forums/i...ilure-prone-whatever-and-replacements.731653/
i like this one>

"Oh man, that's the part that made me a _lot_ of $$. Here's the story:

I ran a warranty repair station for many of the popular mid-70s brands of audio gear while I was in engineering school. Since I was paid by the piece, the faster I could repair something, the more money I made. As all early-20's guys, I was always scrapping for date money. Enter the lowly 2SC458.

Those little critters were heavily used by all the big brands - Teac, Sony, Pioneer, Sansui - you name 'em and they had 'em in there. So, every time I got one of those pieces in, I'd replace all the 2SC458s I could find. I'd bill the company for warranty repair. Most of them paid a flat fee for the labor and would provide the parts for free. Not a problem if you could just rip through the amp and had the right tools. I got real good at it. Oh, and I dated a lot of girls

, too.

If you find any of those little critters in an amp or receiver you're restoring, do as I did but don't try to bill Pioneer, Sansui or Sony."

 

[CJ]

looks like somebody started a replacement list on their own>

https://drive.google.com/file/d/1ASI9iOCEL7fEcuuShgY83xg-zFVPpSCL/view
a less positive experince with the outhouse silicon than our philandering engineering student upstream>

"I didn't go through all 13 pages letter by letter, but the 2SC2910 has failed on me at least twice in amplifiers. It was often used as a VGS (Voltage Gain Stage) transistor in powerful power amps. As it can handle an Uce of 180V, you may put 2X 90V DC as a rail voltage on such an amp... but if it fails, the results are dramatic if no fast DC-protection is used. The Rotel RB-890 was NOT equipped with such a protection, and this resulted in a DC on the output of roughly 75 Volts... a loud <BANG!> from the speaker and the woofer of it was gone. Literally. The other amp it failed in was an Akai integrated amp, where a 2SC2910 developed a short between B and C. In these amps, there was also the PNP equivalent (2SA1208) but in both case, these survived. I replaced all four transistors (in both channels) as a precaution. I have these - and 300 other hard to find obsolete Japanese transistors - simply in stock."