EAR-Yoshino 834P
Primyl Vinyl, Vol. 2 #6 (November/December 1997)
by Bruce Kinch

This, straight away, is a bargain. Tim de Paravicini, the head honcho and designer of all things EAR (formerly Esoteric Audio Research), has for many years been regarded among the UK’s foremost tube gurus. He also has had a long-term involvement with analog recording - everything from designing custom microphones to actually mastering LPs. In the EAR 834P we have a product that clearly benefits from those experiences. In absolute terms it isn’t cheap, but that’s relatively inexpensive for the audiophile phono stage category - and it’s a bloody import too!

Tube phono circuits are inherently constrained by a thermonic device’s noise floor - the "tube rush" one hears when the volume is turned up - and which limits the phono gain to some 40 odd dB, what with RIAA EQ and all. That’s plenty for the relatively high output of "moving magnet" cartridges, but inadequate for the much lower output of the typical "moving coil" pickups favored by many audiophiles. Therefore the engineers designing a phono stage are faced with the dilemma of increasing the gain without compromising the sound. Adding an additional tube gain stage can exacerbate the noise problem, so some develop "hybrid" designs, typically using a solid state input stage to amplify the low voltage output before sending it to the tube section, thus improving the S/N ratio. But there is another way, for while the MC cartridge’s voltage output is low, the current is surprisingly high. This means a transformer can be used, trading some of that current for voltage gain, and keeping the noise level low. The problem, of course, is that you need a very good transformer. Audiophiles have been arguing the relative merits of transformers vs. active gain stages for years, some finding the transformer more natural sounding, others finding it limiting dynamics or bandwidth.

While several companies (notably Ortofon) have offered outboard transformers as MC step-up devices, EAR is unusual in incorporating them within the unit itself, and this choice seems crucial to the design’s performance/price ratio. The unit is small (5"x9"x3.5"), light (around 7 lbs.), and the circuitry is relatively simple: the power supply only has to support the main gain section, and the MC trannies can be simply switched out when MM cartridges are employed. That is not to suggest the power supply is inadequate - the circuit board is essentially split in two (and shielded) from front to back, and the power supply, toroidal transformer and all, takes up half the interior space. On the other side is the audio circuitry, employing three 12AX7 dual triodes (or equivalent) and the step-up transformers, housed in small metal cans almost the size of marshmallows. Component quality seems very good but not boutique; the input/output jacks are gold plated, and the AC cord is standard IEC detachable. The basic black version I auditioned has two front panel controls: a "knob" which is actually an on/off switch, and an Alps pot which allows the user to match the unit’s output level to other sources-or drive a power amplifier directly in dedicated analog systems, i.e., without an intermediary preamp. The more expensive, chrome plated version is functionally identical except that the level control is omitted. The black model is also available without level control, for those who use a preamp and wish to avoid having an extra volume pot in the signal path. The MM/MC switch is located on the back panel, between the RCA in/out jacks. There is no provision for balanced connections, or for changing cartridge loading (47Kohms) or capacitance. The relatively compact chassis gives the EAR extra flexibility in placement. In many systems it can be situated adjacent to the turntable, keeping cabling losses to a minimum.

I first used the EAR in MM mode, with the Grado Reference Platinum on the Well Tempered. This little guy puts out a big sound, notably dynamic, with excellent rhythmic punch and drive on rock and jazz. On classical material, it sounded a bit dark and unsubtle, but promising. Stock tubes are either EI (Yugoslavia) or Edicron (the English importer for EI). Time out for tube-rolling, I figured. Sure enough, things opened up a bit with a set of UK Gold Aero MC Phono 12AX7As, but sonics were still a bit threadbare through the upper mids. Swapping those for the readily available Sovtek 12AX7WBs was a major improvement, with much more air and articulation at HF. I was quite happy with the Sovteks, but the field was swept by a set of NOS Telefunkens (not the first time that has happened). The sound field was markedly richer, fuller, and natural. Nothing like playing 50s recordings with 50s tubes.

Thus encouraged, I decided to try changing the power cord. I plug any phono stage into an isolated tap of a Power Wedge line conditioner on general principles - RFI and AC grunge can be a problem when you’re talking upwards of 70 dB gain. But sure enough, a filtered and shielded AC cord (I had the JPS Labs version in for evaluation) brought a bit more refinement. Time to switch over to the van den Hul MC-10 Special and engage the transformers, Scottie. The differences between the two setups were obvious through the EAR, but the overall sonic portrayal was essentially retained. I was not aware of any significant reduction of dynamics or tonal aberrations that would point a finger at the transformers, but perhaps the presentation was a bit more "civilized". The sound was silky, detailed, and enticing; staging was very good on depth, but not quite as wide a panorama as perhaps could be. But I quibble. The bottom line here, I feel, is to go for the basic black model and put the difference into better tubes and cables if you can. For reasonable money, you get a true high-end designer original, and a major payback on playback.