Increase gain with DOD201

[bal704]

I've just built a small chipamp, which I plan on using as a small guitar practice amp.  Plugging my guitar straight into the chipamp, I get some sound, but not a lot.  I realize the amp is expecting a line level input, not an instrument level input, so I'm trying to build a preamp booster to boost my guitar signal. 

I just built the DOD201 JFET preamp:

http://aronnelson.com/gallery/album18/DOD_201_JFET_PREAMP_VERO

I'm using a 2N5457 JFET instead of the J201, otherwise I built it per the layout.  Also, I'm running this on 12V, rather than 9V.  I've run the preamp into my chipamp, and it makes the sound louder.  However, when I use my rackmount Ampeg SVP-PRO preamp into the chipamp, it's much louder.  I'm assuming the DOD201 isn't giving me as much gain as the Ampeg, and I'm wondering if it's possible to increase it.

Realizing I probably need at least 10db of gain to get my instrument level up to line level,  is there any way to change the resistor values or type of JFET to get the gain I need to drive the chipamp properly?

[MartyMart]

Change te 22k from 12v to a 50k/100k trim pot, with two lugs tied to 12v and one ( outside lug )
to drain of fet.
Reduce the 10k from source to around 1k.
Adjust trimpot to about 1/2 V ( 6v ) at drain.
This should give you much more level.

MM.

[bal704]

Made the changes, and it sounds quite a bit louder.  Thanks for the help!

[Dragonfly]

..lowering the 220k resistor to 47k-100k will help a bit as well....

AC