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BC550/560
BC550/560
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Old 13th April 2018, 08:42 PM   #1
Alienspecimen is offline Alienspecimen  United States
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Default BC550/560

My first question is: Why no one gets excited about BC550/560? Their specs look pretty good, no one says bad things about them, but no one raves either. The only reference I came across was "give the flat Earth sound". I really do not know what that means. I would appreciate if someone gives me an insight into this statement.

My second question is: Is there anything better from new stock offerings? I usually shop Mouser/Digikey.

Thanks in advance.

Best

P.S. Looking for high hfe types - 500+
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Old 14th April 2018, 02:11 AM   #2
mlloyd1 is offline mlloyd1  United States
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BC550/560
2 questions:
1. are the critical specs the same regardless of the manufacturer?
2. went they discontinued some time back? so what you buy now is NOS?
I've seen them in several old designs. didn't Hafler use them in the early DH101 back in the 70s?

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Old 14th April 2018, 04:29 AM   #3
tomchr is offline tomchr  Canada
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For 500+ hfe, you'll want the 'C' grade. So BC550C or BC560C. Mouser has 10k+ in stock of each.

They're the low noise version of the BC546/7/8; BC556/7/8 series as I recall.

Tom
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Old 14th April 2018, 05:02 AM   #4
dchisholm is offline dchisholm  United States
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The BC550C and BC560C are listed as "Active" status at the ON Semiconductor web site. As with all through-hole parts, future availability is uncertain but I would bet that either they are in current production, or there is at least a decade's worth of stock sitting in a warehouse someplace. The BC850/BC860 are essentially the same part in a SOT-23 surface-mount package, and I haven't heard any rumors that they will be discontinued any time soon.

The BC54x/BC55x have been favorite parts for general audio applications for decades. I suspect they will perform "good", to "very good", in 99% of audio applications where their Ic, Vce, and Pd ratings fit the circuit's operating envelope. To ask for "anything better" is like asking, "My wife and I have been making love every morning for the last 30 years. Is there anything better we should be doing?". You need to be more specific about where things fall short. Do you want higher operating voltage? Lower noise? More collector current? Greater bandwidth? Etc, etc.

As for the "flat Earth sound" comment, I don't have the foggiest idea of what this is talking about. Go back to the source and see if the originator can point you toward a part that provides, e.g., a "tetrahedral Earth sound" so you can compare.

Dale
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Old 14th April 2018, 03:07 PM   #5
Alienspecimen is offline Alienspecimen  United States
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Quote:
Originally Posted by dchisholm View Post
. You need to be more specific about where things fall short. Do you want higher operating voltage? Lower noise? More collector current? Greater bandwidth? Etc, etc.


Dale
Hi Dale,

Thank you for your reply.

When I asked the question if there are better transistors available, I had in mind the voltage capabilities of the BC550/560.

It is a different question if anyone could tell me what I could use for differential pairs i.e. min 80V Vceo and hfe of 500+. The "go to" KSC1845UBU is obsolete now according to Mouser/Digikey.

Best
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Old 14th April 2018, 03:35 PM   #6
chip_mk is offline chip_mk  Macedonia
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High hfe requires narrow base which results in lower max Vce.

Use cascoding if you need high voltage capability.
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Old 14th April 2018, 04:40 PM   #7
indianajo is offline indianajo  United States
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BC550/560 seem to be rather undistinguished transistors. 50 Vceo, hfe 270 available in C, siemens has no noise spec.
I've blown up some 2n3904, so I started using MPS8099 npn MPSA56 pnp with 80 v Vceo. Not exactly complimentary, but those are the ones newark stocked for $7 a hundred or less. I got the end of ON semi stock. Gain seemed >300, I had to employ feedback to keep them in the middle of the rail. Noise was fine, not noticeable in my AX6 front end. With the gains that high, I was able to jack up input impedance over 100k to make compatible with my 12AX7 output preamp. These also worked fine in my PV-1.3k in place of blown up MPS6531/6533 VI limiters working off 16 v supply.
Really these BC numbers, phillips is not stocked here, they had noise specs & premium features but the fairchild stock you can actually buy does not.
If the rails go above 70 I've stocked MPSA42/92. For higher idle currents that stress the heat waste ability (predrivers) I've got 100 MPSW56 but no 1 W compliment seems to be available. Trying 2n5682 in TO 39 from multicomp but thermal resistance is only 175 deg/w versus 125 for the MPSW56. TO126 devices don't fit.
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Last edited by indianajo; 14th April 2018 at 04:50 PM.
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Old 14th April 2018, 07:41 PM   #8
Alienspecimen is offline Alienspecimen  United States
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Thanks for the replies so far. At this point I am only interested in refurbishing the three receivers I have. I am looking for substitutions of the following components:

2SA872 (E)
2SA844 (E)
2SC1344 (E)
2SC1345 (E)
2SC1345 (F)
2SC1400 (UA)

My idea was to use BC550C/560C for everything but the last device. I have no clue what the modern equivalent of 2SC1400 (UA) is.

Is there anything better that I could use in place of the above devices and what would the modern equivalent of 2SC1400 (UA) be?

Thanks in advance.
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Old 21st April 2018, 07:57 AM   #9
diyralf is offline diyralf
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BC550/560 are the best for audio (very low noise).
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Old 21st April 2018, 09:45 AM   #10
adason is offline adason  United States
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I have plenty of these, and i use them often. Great for small signal, like active crossovers, phono stages and so on...
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