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Possible 2SC2291 Replacement
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Re: Possible 2SC2291 Replacement

by pulsar256 on Thu Sep 19, 2013 3:52 am

cutoff: 50%, left channel 2xbc337a, right channel 2sc2291. Call me deaf, I don't hear any differences.

https://soundcloud.com/pulsar/right-2sc ... t-2xbc337a

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Re: Possible 2SC2291 Replacement

by antto on Thu Sep 19, 2013 4:06 am

it's the same result as i got when i swapped my 2291 with two BC337s
audiable difference: none
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Re: Possible 2SC2291 Replacement

by Arnoid on Thu Sep 19, 2013 5:15 am

Can anyone test with two BC547 plz ?
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Re: Possible 2SC2291 Replacement

by rv0 on Thu Sep 19, 2013 7:01 am

i'd say use a socket and try with whatever you can get your hands on

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Re: Possible 2SC2291 Replacement

by Arnoid on Tue Oct 01, 2013 7:22 am

I replaced the 2SC2291 with 2x BC337 without succes the problem is still there :(

You can hear a soundclip of the problem in this thread:
http://www.synthforum.nl/forums/showthread.php?t=170133
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Re: Possible 2SC2291 Replacement

by E:pp:ik on Fri Mar 14, 2014 1:22 pm

Jumping in late here obviously but isn't the NTE44 a straight replacement? The BCXXX are easier to purchase but isn't the NTE an accurate swap?
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Re: Possible 2SC2291 Replacement

by pulsar256 on Fri Mar 14, 2014 1:59 pm

@E:pp:ik if you want a drop in replacmenent then yes but it seems to me the NTE44 has been phased out and is not available for purchase, at least where I looked.

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Re: Possible 2SC2291 Replacement

by E:pp:ik on Wed Mar 19, 2014 5:27 pm

Interesting! I checked a local source and they have it. Maybe that one is on a lifeline now.
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Re: Possible 2SC2291 Replacement

by shawnsick on Fri Mar 28, 2014 7:34 pm

pulsar256 wrote:cutoff: 50%, left channel 2xbc337a, right channel 2sc2291. Call me deaf, I don't hear any differences.

https://soundcloud.com/pulsar/right-2sc ... t-2xbc337a


Hi there, how exactly did you hook both transistors together? What pins? What about biasing the transistors used? Would 2 BC337's (not BC337A) do the trick?
I am very curious and I might give this a go in my next build. I cannot find a datasheet providing the pinouts for the 2SC229, If someone can help me out here I wouldn't mind posting some audio samples to help compare the dual BC337 to the 2SC2291.

Shawn.
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Re: Possible 2SC2291 Replacement

by pulsar256 on Fri Mar 28, 2014 9:12 pm

shawnsick wrote:Hi there, how exactly did you hook both transistors together? What pins?


Check album art here:
https://soundcloud.com/pulsar/x0xb0x-2xbc337a

shawnsick wrote:What about biasing the transistors used? Would 2 BC337's (not BC337A) do the trick?


I have used these: http://www.sm0vpo.com/_pdf/BC/BC337A.pdf so a hFE of ~400. I know that there is also a different naming scheme of these transistors, BC337-25 and BC337-40. Comparing the Datasheets I would say the -25 variant comes close.

shawnsick wrote:I am very curious and I might give this a go in my next build. I cannot find a datasheet providing the pinouts for the 2SC229, If someone can help me out here I wouldn't mind posting some audio samples to help compare the dual BC337 to the 2SC2291.


The pinout of the 2SC2291 is ECBCE (pins pointing down and the label towards you). Use your head and figure out how to match these against the BC337 ;). For a permanent solution it might be a good idea to thermally couple them (using zipties or thermoglue) and match the hFE. A transistor-tester would come handy here. Otherwise I would assume that buying the transistors on a strip and picking two next to each other could give you a matched pair.

Happy building!

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Re: Possible 2SC2291 Replacement

by pulsar256 on Sat Mar 29, 2014 9:11 am

E:pp:ik wrote:Interesting! I checked a local source and they have it. Maybe that one is on a lifeline now.


grab 'em all and make a fortune selling these to crazy x0x0philes ;) Nah, just kidding. But on the other hand, I was among these, had to pay ~$7 for a single 2SC2291 replacement. Now looking back at these findings I rather doubt my sanity.

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Re: Possible 2SC2291 Replacement

by E:pp:ik on Mon Mar 31, 2014 11:55 am

I probably paid something similar for my 2291s. Even the NTE's were somewhat pricey when I looked. Well - I could grab them for all of you the shipping alone doesn't make it pay off for anyone.
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Re: Possible 2SC2291 Replacement

by shawnsick on Fri Apr 04, 2014 11:36 am

pulsar256 wrote:
shawnsick wrote:Hi there, how exactly did you hook both transistors together? What pins?


Check album art here:
https://soundcloud.com/pulsar/x0xb0x-2xbc337a

shawnsick wrote:What about biasing the transistors used? Would 2 BC337's (not BC337A) do the trick?


I have used these: http://www.sm0vpo.com/_pdf/BC/BC337A.pdf so a hFE of ~400. I know that there is also a different naming scheme of these transistors, BC337-25 and BC337-40. Comparing the Datasheets I would say the -25 variant comes close.

shawnsick wrote:

Thank you for your reply, I've just ordered the BC337-A's, I've got a a transistor tester so I'll be trying different hFE variations to see what happens.
I'll keep you all informed.
I am very curious and I might give this a go in my next build. I cannot find a datasheet providing the pinouts for the 2SC229, If someone can help me out here I wouldn't mind posting some audio samples to help compare the dual BC337 to the 2SC2291.


The pinout of the 2SC2291 is ECBCE (pins pointing down and the label towards you). Use your head and figure out how to match these against the BC337 ;). For a permanent solution it might be a good idea to thermally couple them (using zipties or thermoglue) and match the hFE. A transistor-tester would come handy here. Otherwise I would assume that buying the transistors on a strip and picking two next to each other could give you a matched pair.

Happy building!
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Re: Possible 2SC2291 Replacement

by altitude on Mon Apr 07, 2014 7:23 am

E:pp:ik wrote:I probably paid something similar for my 2291s. Even the NTE's were somewhat pricey when I looked. Well - I could grab them for all of you the shipping alone doesn't make it pay off for anyone.



FYI, the NTE parts are not modern replacements, they are simply blacktoped NOS. NTE are rip off artists, as soon as a company issues a EOL, they buy up all available stock, re-badge it (poorly, you can seen the original screen under their markings) and resell at 10x the original price. NTE should be the absolute last resource you use if you cant get original parts.

It's almost comical since they will do this to ANY older part. I've seen first hand them doing this to a common CMOS part that a vendor obsoleted to comply with ROHS despite the fact that EVERY vendor already makes said part and the new ROHS part is exactly the same thing with a different process so when you search for it at Mouser, you get the new part for $0.15, the two dozen other vendors parts for $0.15-0.25, and then the NTE part for $4.25. Dont support those parasites

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Please be positive and constructive with your questions and comments.