bass tube pre-amp into ss amp

[Scsoul]

   My bro-inlaw got rid of his svt and now wants a tube pre-amp to run into his ss amp,  What's the best way to go on something like this? I've never done a pre-amp or a bass amp so something well documented would be great.   thanks  scsoul

[Ed_Chambley]

Build a Ampeg preamp.  I have a preamp box for bass and plug it into the loop on a Ashdown.  I am not the bass player, my wife is and she too prefers a tube tone for some things.  If you have a chassis, preamps are fairly cheap to make.  I made one with a couple of different preamps in the same chassis.  Schematic for the amp you want and just leave out the power section.  I have used a reverb transformer to make them.

Still they will not sound like a SVT as she has one of those as well.  It is too big of a rig for most everything these days.  It is the old blue Ampeg with 8, 10's cab.  Bass tends to draw a lot of tone from the power tubes and they compress nicely.  After making a few it ended up with me using them more as the difference is not really that great pushing a SS amp and you bypass the features of the SS bass amp like compression/limiter if it has them.

Sorry I don't have anything documented, but if you look at a schematic the voltage on the last node is all you need.  Look at some old Marshall schematics where the pre and power sections are different schematics if it is confusing.  Then you can substitute the idea using any values for tubes, pots, resistors and caps for any amp you are interested in.