Piggybacked Si fuzz face build

[feddozz]

Hi all,

I am in the process of making a piggybacked Si Fuzz face. The reason being that I want a fuzz face and I do not want to mess with germanium.

I am curious to understand why it seems that piggybacking seems to have been done up to a certain time and then abandoned. Almost all the posts I found on piggybacking do not seem to go beyond 2009. Is there a more modern technique that I missed?

I read about the 2N2369, but I could not find them on my usual supplier sites. Hence the piggybacking technique.

If there something better than piggybacking please let me know.

I am using 4 off 2N3904, the hfe is about 250-260 for all of them. I am using 20K Ohm trimmers between emitters but it seems I needed a bit more resistance, especially for the first couple of trannies, so I stuck a 10K resistor in series with the trimmers.

I am using this layout.

I tested the board briefly last night and it sounded like it was not biased properly but reading around it seems I still have to bias for 4.5V at Q3 collector.

The layout proposes to connect the top and the middle pins of the trimmers. I am not doing that. I am just using the bottom and the middle pins only, leaving the top pin not connected. Does it change anything?

If anyone whishes to share his experience or suggest something it'll be appreciated.

Thankz

[Derringer]

I can tell you I tried it way back when and the results were meh ...

Yes, you can dial the gains of the stages to where you want them, but it's still not going to sound like a germanium based circuit.
You'll get better results just finding a pair of silicon transistors you like and then messing with the biasing of each stage/the caps/the feedback resistor.

Gus has some really good SI FF style circuits he has posted through the years.

[Derringer]

here's a good one from Mac

http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49091&g2_serialNumber=1