Phono Preamps with "balls" ?

first that the phono-preamp has enough gain for the cartridge output level and be by preference a SS ( bipolars. ) design with no single tube inside, second that be an active high gain design

FWIW, it is a lot harder to build a solid state phono section that does not have RFI issues than it is to do the same thing with tubes. This is because semiconductors can act like diodes and thus rectify RF noise, thus making it audible.

I would add that phono stability (which includes but is not limited to RFI susceptibility) and overload margin are pretty important too, as such will mean that special loading considerations for LOMC cartridges are not needed (IOW, no loading resistors). The lack of loading resistors will allow the cartridge cantilever to track high frequencies better and with less distortion. A nice side benefit is far less ticks and pops as well as they are often a symptom of a phono section with poor overload margins and stability issues.

@atmasphere :  "   is a lot harder to build a solid state phono section that does not have RFI  "

maybe you can't or don't know how to do it.

Anyway you have always to " say something " against. Try to be an audiophile, take-off your tube builder hat because is useless in this regards.

R.

Ralph, although I completely agree with you regarding the overriding importance of designing sufficient overload margin and circuit stability into phono stages, while rectification of RF energy (and subsequent intermodulation) is indeed an issue with bipolar transistors due to the base-emitter connection functioning as a diode, JFETs are free of this effect.

A phono stage with JFET front-end devices can therefore be run with input resistors in the megohm range without problem.

The RF rectification issue of bipolar transistors can be reduced if local feedback (emitter resistors) are added, but doing so will worsen the noise, which is the main reason for using a bipolar transistor front end in the first place.

A further problem with a bipolar transistor front-end is the base current, which will go through the cartridge coils (gradually magnetizing the coil former, which is definitely undesirable). And if the input resistor is of high value, the base currents will cause DC offsets, unless the input is capacitor-coupled (a band-aid that wouldn't be necessary with a JFET front-end).

The main difficulties with JFETs are their comparatively low maximum voltage rating, and significant device-to-device variation.

Unlike the situation with bipolar transistor front-ends, both JFET issues are solvable cleanly; the voltage rating with cascoding, and the device variation by measuring and sorting prior to assembly (although this does mean extra work).

kind regards, jonathan

PS. Nor do I accept that there is a need to insert the extra Neumann constant, as listening tests (LP vs. master tape) have not necessarily shown it to be an improvement. And with half-speed LPs, the target frequency will be an octave wrong.

@jcarr

I agree that jfets are the way to go- although I like some of the aspects of the MAT-12s (which are bipolar, but a popular goto for phono front ends), getting them to actually sound right has been a problem so far. The jfets I want to use though aren't made anymore, and even then we had to sort through a pile of them just to find a pair that not only matched (since our circuits are fully differential) but were also quiet.


<snark>

maybe you can't or don't know how to do it.

</snark>

@rauliruegas 

Or maybe I'm just pickier than you. I'm not interested in getting it sound like a good stereo. It has to sound like real music. 

Dear @jcarr : I respect your opinion but bipolars electrically are a better LOMC cartridge. I'm not saying than bipolars are perfect devices ( nothing is. ) but  better match. 

About the Neumann pole exist an advantage and I don't have to explain it to you. The main issue is to have the knowledge level and skills to implement it in the rigth way with out side problems. That Neumann constant must exist in any phono design and has to be the owner who decides if used or not. The cutterheads impedes that the RIAA eq. goes beyond 50khz because burning it self. There is no doubt exist an advantage to listen with than with out it, the issue is how that constant is implemented/designed.

You are not the only one ( @atmasphere here. ) that shares that kind opinion but other designers think the other way around and implemented with good results. Btw, did you try it in your phono stage?
Half-speed?, there are so many " myths " around that kind of recording tool.
@atmasphere , yes you are pickier than me, fine with that.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.