2. analog
  3. 194727-369

Phono Stage - The great analog tragedy

In the world of analog playback, there is an interesting observation. There has been tremendous innovation in the field of 
Turntable - Direct, Idler, Belt
Cartridge - MM, MC, MI
Tonearm - Gimbal, Unipivot, Linear Tracking

For all of the above designs we find some of the best reference components designed in the 50s, 60s, 70s and 80s. Most of the modern products are inspired from these extraordinary products of the past. But when it comes to phono stage, there is hardly any "reference component" from that era. They just standardized RIAA curve for sanity and left it. Manufacturers made large preamps and amps and allocated a puny 5% space for a small phono circuit even in their reference models, like a necessary evil. They didn’t bother about making it better. 

The result? It came down to the modern designers post 2000 after vinyl resurgence to come up with serious phono stages for high end systems. Unfortunately they don’t have any past reference grade designs to copy or get inspired from. Effectively, just like DACs, reference phono stages is also an evolving concept, and we don’t have too many choices when we want a really good one which is high-res and natural sounding. Very few in the world have figured out a proper high end design so far. And most of the decent ones have been designed in the past couple of decades. The best of the breed are probably yet to come.  

It is a tragedy that our legendary audio engineers from the golden era didn’t focus on the most sensitive and impactful component, "the phono stage"

pani

Showing 3 responses by alexberger

alexberger
945 posts
 

I could never understand how many audiophiles buy cartridges that cost more than 10 thousand dollars and at the same time don't care on the quality of phono preamplifiers.

alexberger
945 posts
 

I'm whish share my journey with external phono stages and the significant improvements I've experienced.

My first external phono stage was a Croft Micro tube preamplifier with a passive RC RIAA circuit and a cathode follower preamplifier output stage, which I acquired in 2002. Later, I purchased a used EAR 834p. Despite their different RIAA designs (active and passive), both the Croft and EAR offered similar sound quality, though I slightly preferred the EAR.

My next project was inspired by Romy The Cat's "End of Life" (EOL) phonostage, which is based on the EAR 834p schematics. The EOL design features a superior power supply (with a parallel stabilizer and LCLC filter) and air RIAA capacitors, which are improvements over the original 834p. I built this into a single box unit, and it was a significant upgrade from the original 834p. Over the years, I continued to refine it with further upgrades, including a larger and better power supply, as well as improved cathode and output capacitors.

More recently, I rebuilt the EOL into a two-box system, and the resulting difference in sound quality has exceeded my expectations. 

This experience has reinforced that while the RIAA schematic is crucial, the implementation truly makes a huge difference. My current EAR 834p version sounds vastly different from the original.

alexberger
945 posts
 

In my phonostage are only two small air capacitors 330pf and 110pf are important for RIAA equalization accuracy. All other - interstage, output, cathode filament PS and B+ PS capacitors values are not important in this schematics.

I setted up RIAA air capacitors with capacitor meter. But I don't take into account air humidity. Air capacitor advantage: the dielectric is not sensitive to polarity changes.

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