Threshold FET 10/e cartridge amp questions

I don't own one, but I've often wondered how it stacks up against some of the other high end now vintage solid state phono stages, like Klyne and Vendetta. (I do own a Klyne.) So it might help if you would divulge the nature of the "problem". It can't be too bad if you also describe the FET10/e as "wonderful".

Etnier, From your more detailed description of how you perceive the sound of your Threshold, I think of two things: (1) The deficiencies you've assigned to the Threshold may well be due to other components in the chain, and/or (2) MM cartridges most definitely ARE sensitive to capacitative loading, moreso than MC cartridges, and you may want to look at that IF you are running an MM cartridge. But on the other hand, I thought the Shelter was an MC, and I am too lazy to look it up. Most MCs would not be adequately served by the 40db gain setting and would indeed not drive the phono stage sufficiently to drive the linestage comfortably. Could be you just need to use the 60db gain setting, as Pryso mentions. If that does not help, you might do well to have the Threshold checked out by a competent tech, also per Pryso's suggestion. Could be that power supply electrolytic capacitors are leaky, after 30 years, especially if the unit was not in use that whole time.

Best bet is to go on-line, either to the Shelter website if they have one or to Vinyl Engine, and find out the recommended capacitance for the load resistance you are probably running (47K). However, you've stated that capacitance is not adjustable for the Threshold, so it will be painful to change it. You could do so by soldering the capacitors in parallel with the input, but you probably would not want to do so.

You can figure that there is about 100pF minimum to ~200pF load capacitance already; that's typical for the phono cable capacitance plus the capacitance presented by the input transistor. Unless the Shelter needs much more, e.g., 400pF or more at 47K ohms, I would not worry about it.

Pryso, You (and I) were correct the first time. Jperry confirmed that the 501 is indeed an MC type. Other than that, your advice as an owner should help the OP most. Yes, not much need to worry about capacitance with an MC. The OP needs to be sure he is using the hi-gain setting, and then to check the load R adjustment. Possibly he is loading down the Shelter too much; that is to say that the selectable load R is too low in value. This would result in an apparent lack of gain (because energy is being lost to ground) and reduced treble, bloated bass.

Etnier, you may want to remove the cover of your unit and look for the adjusters that Pryso described. Then make certain that the load Resistance is no lower than 125 ohms, as Jperry uses for his 901. If you're not happy with that, increase load R progressively until you get better tonal balance and more apparent output from the Threshold. Or, more scientifically, find out the internal resistance of the 501 from the spec sheet. Start then with a load resistance that is at least 5X the internal resistance, and go up from there.