Threshold FET 10/e cartridge amp questions

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.

My FET 10 had adjustments for load resistance and capacitance. There are four small slider switches (I used a toothpick to move them) for each in one red block for each channel. More than four settings are available by multiple combinations of the switches. The owner's manual covers this. I cannot imagine Threshold discontinued this in the "/e".

I found the FET 10 to be a great phono stage and was very satisfied with the sonics. My reason for selling it was wanting to more easily accommodate different cartridges and those adjustment blocks are internal, not on the back for ready access. And if I remember correctly the top has 12 screws! :^(

I must admit I'm surprised by the report the Shelter 501 II is a MM, I remembered it as a MC. If so, the lowest capacitance setting as Jperry suggested should be all that is needed.

Thanks to all for your help! It's much appreciated.

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.

I have a Shelter 901 and looking at Shelter dealer's on-line information shows the 501 II as a MC with an output voltage of 0.4mV, which is about the same as the Shelter 901. I use a gain setting of 56 db for the 901 and a load setting of 125 ohms. I would use a low capacitance setting, but I am not sure it matters that much in a MC cartridge.

It looks like the only MM cartridge made by Shelter is the 201

I do apologize to all: I mis-stated things*. I have an MM cart (Shelter 501II) and have the Threshold phono pre set for maximum gain. As to "noise": it's hum, really. There's no noise issue.

If anyone knows the best capacitance setting for a cart like the Shelter, it would be a big help

* At the risk of rationalizing/over-dramatizing things I'm 4 months out from a stroke and still have a lot to learn about how I can get things screwed up: I'm not used to it.

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.

Mine is dead silent. Lower gain setting. Adjusted to manufacturing specs for MC Blue Point evo III on a Music Hall MMF 7. Internal jumpers set correctly?

Hi Etnier,

I owned a FET 10 for several years, then sold it to a friend who still has it in his system. Mine was not the "/e".

I've heard of others who's Threshold phono stages became noisy as they got older but mine was/is dead silent. So I expect it can be repaired easily. I don't have their names but there is a dealer in Reno who sells Pass and Threshold products so you might ask there. Also I've read of a tech who repairs and/or modifies Threshold electronics, possibly someone who worked for Threshold. Try googling.

I don't know the output of your shelter but you should think of the gain settings as high and low, not necessarily MM and MC. As I remember they are 60 and 40 dB which should work with most cartridges, particularly when paired with a line stage which will boost the signal a little more.

I never compared mine against the Klyne or Vendetta which Lew mentioned but I found mine very musical and with no significant sonic criticisms.

I love the preamp, which is all-original, unmodified. The problems:

It just doesn't seem to have enough gain to work with a Shelter 501II and Threshold FET 10/e line amp: I have hum problems I don't have with my Heed Quasar. AFAIK the Threshold has one level of gain for MM's.

And: while the sound is really something, it's shy on bass and a bit bright by comparison to the Quasar. I am lucky to have "tone controls" of a sort with my Yamaha NS1000 driver level controls (I pulled the mids down about 2dB!) and my subwoofer gain (up a tad), but I recognize a workaround when I see it, LOL.

I can't report the current settings on the Threshold: getting it into and out of my rack is a real process. MM capacitance is supposed to be kind of immaterial anyhow, I believe. Maybe someone familiar with this unit can recommend ideal settings for the Shelter 501?

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".