Is fairchild SS9014 a good LTP choice. ?? - diyAudio
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Old 5th December 2010, 03:53 AM   #1
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Default Is fairchild SS9014 a good LTP choice. ??

Came across this good deal at Mouser... ss9014

My intent was to search/source an equivalent for the MPSA18 low noise input pair and be able to buy 100 at a price that would allow for a mistake. With 100, one can be assured to at least find several that are close matches. For 4$/100 , why not.

The device has almost the same NF as the mpsa (.9db) a Ft of over 200mhz , and a lower Cob of 2.7pF. I am all cascoded in my designs now so I can "play" with a lot of low voltage/ low noise devices. Would there be any attribute in the datasheet - http://www.fairchildsemi.com/ds/SS/SS9014.pdf
to disqualify this for my main input pair choice ??

thanks. OS
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Old 5th December 2010, 04:07 AM   #2
CBS240 is offline CBS240  United States
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If you cascode why not use J-fets? If you must use BJTs, although there is a significant difference in price, why not use something like this? Guaranteed match every time.

I don't see anything particularly special with those devices other than under certain circumstances they may exhibit a lower noise. Max NF is 10dB with a fairly large Rs for the test, seems like a significant range in the datasheet.

The thing you will lack with the THAT transistors is current gain, but for an input stage this is not really a factor.
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Old 5th December 2010, 04:14 AM   #3
Krisfr is offline Krisfr  United States
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Hey OS

Have you bought much from that company in Thailand?
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Old 5th December 2010, 04:18 AM   #4
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Quote:
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If you cascode why not use J-fets? If you must use BJTs, although there is a significant difference in price, why not use something like this?

I don't see anything particularly special with those devices other than under certain circumstances they may exhibit a lower noise. Max NF is 10dB with a fairly large Rs for the test, seems like a significant range in the datasheet.

The thing you will lack with the THAT transistors is current gain, but for an input stage this is not really a factor.
I bought some Jfet's ,too. And the smd's will likely be at least my next generation input stage. The SS's were just so cheap , would they not be any better than the ksa992/ksc1845's ??

"lab handouts" (your link) that's funny... I also bought some of the mpsa18's. Noise is my last imperfection on my amps , most of the other distortion mechanisms have been addressed. That "max / min" NF is suspicious , does that mean some will be ultra quiet and others can be noise SOURCES ??

OS
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Old 5th December 2010, 04:19 AM   #5
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Hey OS

Have you bought much from that company in Thailand?
I'm sure mouser buys from Thailand , I only buy direct from mouser (my account) , digikey occasionally.
OS
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Old 5th December 2010, 04:21 AM   #6
Krisfr is offline Krisfr  United States
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You recommended me a company in Thailand for the OPS devices the other day is why I asked.
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Old 5th December 2010, 04:23 AM   #7
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You recommended me a company in Thailand for the OPS devices the other day is why I asked.
I think SNG001 knows that one. I just searched and shared .
OS
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Old 5th December 2010, 04:25 AM   #8
Krisfr is offline Krisfr  United States
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ok

Thanks

I am about ready to make some PCB for a KO amp, That is a Keantoken-OStripper
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Old 5th December 2010, 04:33 AM   #9
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ok

Thanks

I am about ready to make some PCB for a KO amp, That is a Keantoken-OStripper
Kool , ... when mouser gets to me next week , my "spree" will start , a lateral board, 2 "KO" type amps and 2 of the updated/cascoded "Carlo's DX ES" type amps. Some sort of "double blind" A/B "shootout". I will try both at first with the best SS9014's I can pick out of the 100. Good luck on your builds , we should be the first ones..
OS
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Old 5th December 2010, 04:48 AM   #10
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have been using KEC version of 9014 for diff pair and they work very well
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