loading resistor upgrade?

[pro_crip]

I was reading my copy of Rozenblitz before falling asleep last night when he was discussing RL, specifically as it relates to gain. In the crack and FP3 that would be the 22.1k ohm resistor, schematic reading skills don't fail me now. Would this resistor be a good place to upgrade to one of them thar boutique resistors and would it give better sound. What would be better in that spot, a wirewound or some sort of bulk metal foil? Btw, this isn't a crack or fp3 question only, would this upgrade be worth it in any circuit? Thanks for listening.


Rich

 

[Beefy]

Boutique resistors are silly, when you can do it properly and replace the resistor with a CCS. A good CCS presents a tube load in the megohm range, thus increasing gain and linearity. It also dramatically reduces the power supply ripple seen by the tube. No matter how boutique a resistor is, it cannot provide these benefits.

This is exactly what the Speedball upgrade does for the Crack, but the idea is applicable to any low power tube.

 

[Paul Joppa]

I fully agree with Beefy, but here are some thoughts on resistors in that position. The main technical consideration is something that does not create excess noise when current flows through it. Carbon composition, thick film, and metal oxides are the most widely cited culprits. Second consideration is not too much inductance, and the third is adequate power handling.

Bulk metal foil may have power limitations but is otherwise excellent. Wirewound would have to be non-inductive, but it's still a form of bulk metal and would be very quiet. Note that high resistances take a lot of fine wire, so they may be large, expensive, and hard to locate. Next best is metal film, which is what is in the stock Bottlehead kits.

Tantalum is a magic word that makes audiophiles swoon, but some tantalum resistors are bulk metal and some are tantalum oxide. I do not know whether tantalum oxide behaves like other metal oxides (noisy) or not - I certainly would not spend time or money on them until I did know.

 

[pro_crip]

I'd rather go the CCS route. I've already got the speedball in my crack and my FP3 is the extended version. I've got the old CF and VA boards from the anticipation (?) upgrade from my old FP2, can those be recycled in another project (like that FM3 I was talking about in another post). Thanks for listening.

Rich