How do I choose a pair of Ge NKT275 for fuzz face build?

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Explorerman
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Post by Explorerman »

I'm about to build a clone of the AM NKT Sunface but am not sure on what to look for in finding a suitable pair of Ge NKT275's. There are a few on eBay however they also say "ASX12D" on them - are these still real NKT275?

The tested specs also have the Hfe as pretty much the same value for both of the matched pairs, whereas I read that Q1 should be 80-90 and Q2 120-140. Will the pairs with a same Hfe value be suitable? Thanks.

tonyharker
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Post by tonyharker »

There are no OEM NKT275s available any more.
Any so labelled are other more recently made germanium transistors selected for similar characteristics.
They are mostly in the incorrect case pattern. They will not be made using the same construction method that Newmarket used.
I used to work in my youth for a company which used to use exclusively NKT - Newmarket - transistors and I remember them well.
The nearest type I can find is the AC125 type. so I would try those. There are even two types of case for these. The ones to use are those without a flange and tab but those with a red spot on the case. Best of luck. Tony.

Explorerman
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Post by Explorerman »

Thanks Tony, I'm also looking at the 2N404 - would these be suitable?

Gristlepig
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Post by Gristlepig »

2n404 could be fine so long as the gains and leakages were in spec for a FF.

Read “Technology of the Fuzz Face” over at Geofex http://www.geofex.com/Article_Folders/f ... fffram.htm

Then check out Small Bear Electronics for a matched Fuzz Face pair of germanium transistors.
http://www.smallbear-electronics.mybigc ... d-similar/

Steve at Small Bear was super helpful back when my pedalbuilding knowlege was nil. I built some really nice sounding pedals using his matched sets, despite all of the sloppy wiring and cold solder joints!

Good luck!

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