Yet another transimpedance question

@lewm 

Thanks, yes, you are correct on all counts, the way I read it the 55 chip is for the timing/switching functions as you describe (not actual PS, sorry, that was confusing).  I was trying to explain why external LPS didn't make much sense to me since there is what essentially seems to be an internal switching PS in the Trumpet MC.  And, not the jfet is not actually needed for the variability functions, but it is there as a very quiet way to enable that (hope that makes sense?).  My ability to understand and explain these things is (obviously) limited.

At this point I lean toward not spending the $ unless someone responds that they have tried the Piccolo and the Trumpet MM and have heard a significant improvement or difference.  

I know that @mulveling has a Trumpet reference and he might have something to say...

In all cases I know about where a JFET is the input device in a tube phono, it’s simply to increase overall gain of the circuit while adding very little noise. The Herron MC phono is another example.

@oceanica Have you tried the cartridges with a suitable SUT as well as the Picolo?   So far I have always preferred the sound of a LOMC with a good SUT rather than straight into a high-gain phono preamp, whether tube or solid state.  I have never tried a transimpedance preamp so I don’t know how that fits into the options.  However, I have ordered a Hiyate from Thom so I will soon have a cartridge that can be used with a transimpedance preamp so maybe I’ll find out for myself.

@lewm 

Yes, exactly, that is what it does, I only mentioned the 555 chip since eliminating that might allow some benefit to an external LPS, though my understanding about this is very (as you can tell) limited.  Without the jfet (as in the Trumpet MM) one still need to increase the gain...

@salectric 

I really got the Piccolo more out of curiosity since it is inexpensive (a good SUT assuming I find a good match first time, could set me back 5 to 10 times the cost of the Piccolo).  Perhaps in the future I will go the SUT route, though that path is not without its own issues.  I do like the Hayate through the Piccolo better that straight through the Trumpet MC, so we'll see where things go..

Thank you both for your input

The 555 is providing a benefit that you would not want to eliminate, if I’m correct that it delays turning on the high voltage (B+/B-) until after the tube filaments are powered up. This prolongs tube life. And if that’s the case, the 555 is not in the signal path and has nothing to do with the JFET.

Modern switching power supplies are just fine.