lower noise version of C458 transistor?

gadget73

gadget73

junk junkie
Subscriber
Is there a lower noise drop-in replacement for a C458 transistor? The ones in the phono pre on my Allied are horribly noisy and I'm tired of it. I was planning to replace them, but if I can just drop in an upgraded part without having to change anything else, I'm all for that.
 
The very best low noise transistor I know is the 2SC3329, quite expensive if you can find them.

As a second best, you can buy 2SC2240, 2SC2545, 2SC2546 or 2SC2547. Anyone of them is much better than the 2SC458.

They have the popular ECB pinout, but check the pinout of your 2SC458 because this one is available in different pinouts. Not a problem since you can fit the legs, but it is better to know before...
 
G'day mate, do you mean the 'BC548' transistor? If that's what you mean, then I recommend the BC549 or BC550 transistor. They are excellent for your application and very low noise at 'lowish' collector current (around 1 Ma or so). Regards, Felix (vk4fuq) aka catman.
 
no, it definitely says C458 on the package, which I seem to recall is short for 2SC458. Its the early type with the square body and a beveled top, not the half round style that I'm more used to.

Thanks ecluser, thats the info I was after. I'll double check the current pinout and compare it to whatever I replace it with. Its been a long time since I've dealt with circuit boards and transistors so this will be a re-learning experience for me. Other than the possible pin layout being different, this should be a drop-in replacement right? I won't need to mess with other circuitry values?
 
G'day mate, the BC549/550 should be a direct replacement for the 2SC458 although as you'd expect, the pinouts are different but 'sleeving' will easily solve that problem.

Interestingly enough the noise figures for the three transistors are exactly the same (4db), but from personal use I know that the BC549/550 series are very low noise.

I wonder if your phono preamp uses carbon resistors, as they tend to be quite noisy. I only use metal film resistors as they contribute very little noise compared to carbon resistors. Regards, Felix vk4fuq aka catman.
 
yeah, they're carbon comp. I have a stock of metal film 1% resistors on hand that I can replace them with if neccesary. I expect some of the resistors have drifted over time anyway.
 
Is it branded "Hitachi"? Those were notorious for a short lifespan, and cause alot of problems in Akai reel-to-reel decks. Should be some recent references to it in the tape forum. Several folks have changed out all their C458's.
 
Bringing back this thread because I have the same problem: these "C458" are extremely noisy!

I'm putting a Picture of it to make sure which one from "BC458" or "2SC458" I'm dealing with.

p4070372.jpg


Also, in the same amplifier I have these two (very old and noisy) TRs:

"A673" and "C1214"

p4070373k.jpg


p4070374i.jpg


If you know low noise equivalents for these three TRs, please let me know.

..
 
First one is a 2SC458, replace with BC549

2SA673 i would replace with BC327

2SC1214 --> BC337
 
I can get those for 25 cents a piece at my local elektroboer, dont know if you have one where you live.
Not sure if the pinout is the same, you will have to look at the datasheets for that.
Note that the last two are a complementary npn pnp pair. Change one, you have to replace the other one too with its 'new' partner. The datasheet of one will tell you what the other is.
 
Alienz said:
I can get those for 25 cents a piece at my local elektroboer, dont know if you have one where you live.
Not sure if the pinout is the same, you will have to look at the datasheets for that.
Note that the last two are a complementary npn pnp pair. Change one, you have to replace the other one too with its 'new' partner. The datasheet of one will tell you what the other is.
Click to expand...

Yes I do have it here in A'dam! :thmbsp:

http://www.dickbest.nl/index.php?_a=viewCat&catId=175&page=1

But, as you can see there are several types of, for exemple, BC337:

BC337-16, BC337-25, BC337-40
 
I just recently searched AK for C458 replacements and one that seems to be available is the KSC1845 from Mouser. I need about 10 of them for a Marantz 1030 that I forgot to put on the last Mouser order which arrived today. At least the SP-3A-1 is done and ready for a break-in and audition. The 1845s will be on the next order.
 
dr*audio said:
I use 2SC2240 as a replacement. Replaced all the C458's in my Akai GX-625 with them. It's dead quiet now.
Click to expand...

Where does one source the C2240 for a reliable, known original unit? These seem to be of Chinese build now. I guess those that know bought a couple thousand of these when Mouser was deleting them from their stocks.
 
Last edited:
I guess one needs to know the full name of the item at B & D. That is going to leave me out most of the time. The search did not show any 2SC2240 but you have shown the 2SC2240BL as being available.

I've got the 1845s on the order I'm building for Mouser but will look at the 1815, too.
 
oh wow, an old thread of mine. How embarrassing. I still haven't ordered parts for that receiver. its only been what, 3 years now?
 
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