#002 Steel String Singer - almost there

[martin manning]

On the long run, I want the boost to be footswitchable anyway. The FET boost by its own is not usable for me if I have to stick the cable from one input to the other. I'll give the FET a try, Erwin offerd me a 2N4416A.

Well, there is an option to make that happen. See in he files section here: https://ampgarage.com/forum/viewtopic.p ... 08#p365408 , DIY ODS Eyelet Boards. A foot-switchable FET boost is described in that .pdf.

[Richard1001]

https://www.reichelt.nl/nl/nl/jfet-s-c8417.html?r=1
Very suitable as audio input amp. Low noise, low bias, high transconductance

In my own amp i used this one:
https://www.reichelt.nl/nl/nl/transisto ... 1.html?r=1

[martin manning]

I have a 12V tap left on the transformer, so I'm not bound the FET or the LND boost.

Not quite sure what you mean there, but if you have a 12VAC source then you will need a rectifier and filtering to make that usable for a transistor boost. The Dumble JFET or the LND boost could be powered from B+5.

I guess what you were saying is that you have 12VAC available for a relay power supply.

[Lothy]

I guess what you were saying is that you have 12VAC available for a relay power supply.

Yes. But there is nothing that holds me back to put an additional regulator and electrolytic to step down from 12 to 9V for a booster. Or is there something I've missed?

[Lothy]

https://www.reichelt.nl/nl/nl/jfet-s-c8417.html?r=1
Very suitable as audio input amp. Low noise, low bias, high transconductance

In my own amp i used this one:
https://www.reichelt.nl/nl/nl/transisto ... 1.html?r=1

yet I found some 2N4416A in my stash. I don't know the source, from where I ordered them, but they all test good.
I put a socket in and try other ones, too.
Cheers
Gerhadr

[martin manning]

...there is nothing that holds me back to put an additional regulator and electrolytic to step down from 12 to 9V for a booster. Or is there something I've missed?

No, all good!

I found some 2N4416A in my stash. I don't know the source, from where I ordered them, but they all test good.
I put a socket in and try other ones, too.

Add a source resistor trim pot to your FET board so you can adjust the bias easily for each one.

[Lothy]

I buttoned it up for the first time.

IMG_20240314_195203.jpg

IMG_20240314_195130.jpg

Cheers
Gerhard

[Lothy]

Here is the final result:

IMG_20240321_114524.jpg

IMG_20240321_114550.jpg

IMG_20240321_114600.jpg

I finished the FET boost with relay switching:

IMG_20240321_114600.jpg

There was a diffrence between Martins drawings and what I have done with Erwins relay board, NO2 and COM2 needed to be switched around. But other than that it worked out fine and it gives a good solo boost or just a little hair to the overall sound. Very nice.

And I spend a set of new knobs, I couldn't find oxblood chickenheads so I go with Davies 1470. I think it fits very good to the over all look of the amp.

Cheers
Gerhard

[martin manning]

Very nice! Adding the FET boost was worth the trip, eh?

[Lothy]

Very nice! Adding the FET boost was worth the trip, eh?

It's a nice feature, and prevents me from leaving an unused jack in the amp.

G.