Has anyone tried Tantalum resistors in the ST-70 kit? They are expensive but may be worth it in a few selective areas if they improve the sound. Also, the kit has 1k ohm resistors on the grids of the tubes. Are these grid stopper resistors and should they be replaced by carbon film resistors or ?
The Dynaco VTA ST-70 amp kit comes with 1000 ohm 1 watt carbon film grid stopper resistors. You can always try to change them out for some "boutique" resistor but (IMHO) you won't hear any differences in the amp's sound.
I've never tried tantalum resistors but I do use Takman brand premium carbon film resistors in grid stopper locations on my preamps, they are about 75 cents each (plus $9 shipping!!) Carbon film is usually noisier than metal film but supposely (I haven't seen any real data on them) these are supposed to be very low noise. Carbon film on grids though is generally known to lessen the chance for any oscillation from RF or EMF pickup.
I had some Riken carbon resistors in my resistor box that I installed. They seemed to make a nice difference but I would probably not bought them, at their price, if I had not already had some. I may try some of tantalums in the amp later once I get a moment.