[quote name='peted' post='211161' date='Jun 2 2008, 03:37 PM']You can't control the voltage to the pre-amp valve in the Hartke HA3500, the dial is just a 'blend' between the solidstate and valve pre-amps. You'd need to put in an valve which overdrives at very low voltages.
I swapped the stock valve in my HA3500 for a Groove Tubes Mullard and it doesn't sound in any way overdriven or gritty. I think you would be best served by putting something like a Sansamp or DHA pedal before the input to get an overdriven sound.[/quote]
Fair enough - been trying to buy a Mullard or the Groove Tube equiv (which seems to be out of stock the world over......). I have a Line 6 bass floor pod which I love but it doesn't get so much use since I bought the Hartke as I like the sound of it. I tend to use the Pod in bypass mode a lot and it seems a waste to have it sat there for the occasional overdriven track.
Thanks for all your input, Guys!
Phil