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March 2008
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Esoteric Rek-O-Kut
Sound Re-Equalizer II
Listening to 78s as Caruso would have wanted.

Esoteric Rek-O-Kut Sound Re-Equalizer II

Review By Jeff Rabin
Click here to e-mail reviewer

  Readers of my Hi-Fi ramblings and reviews may have noticed by now that I take a rather different stance to Hi-Fi than most. For this, I make no apologies. Indeed, I am rather proud of it. Hi-fi far too often takes itself too seriously. A succinct summary of the orthodox view is that Hi-Fi is the pursuit of 'The Absolute Sound'. 'Absolute,’ meaning, I take it, the attempt to reproduce in the closest way possible the original, live event. I do not mean to disparage such an attempt – and even though I think it is ultimately doomed to failure there is certainly great art in failure – it is just not how I view and enjoy 'Hi-Fi.’

For me, what is just as interesting is the short history of the recorded arts (just over a century) and the history of the technology that allows us to reproduce, however well or ill, the original performance. (Of course, for much contemporary music, there cannot be said to be an original performance, but we will leave that can of worms to one side.)

Another interesting, though perhaps even more doomed to failure, endeavor, I think, is the attempt to recreate or reproduce the original intent of the artist through the faithful reproduction of the spirit of the original performance and recording. This is my goal. In addition, anything that brings us closer to that performance – including the quest for the absolute sound or the use of vintage gear contemporary with the original recordings – is worthwhile and perhaps more importantly, fun. Hendrix checking the latest takes by playing them back on the tape deck in his Corvette was, I suggest, no bad thing.

Not the Best Source of Needles for Listening to and Preserving Your 78s

I am, therefore, not only a user of Hi-Fi and recorded sound, but also a collector of old recordings and old Hi-Fi. I suppose I could justify this odd behavior by suggesting that only through listening to old recordings can we really understand contemporary performance technique… or some such swill… but I will not. The simple unabashed fact is that I like old recordings and the gear it was to be played back upon.

I am not though under the illusion that old gear is always better than new gear or that a 300B single-ended, no feedback amp whose design is ripped off a Westinghouse patent from the twenties is the be all and end all of listener enjoyment. SACD, whose demise seems to have been greatly exaggerated, wide-band speakers that will misdirect bats, and the new crop of 'digital’ amps are all in their way wonderful and those who cock a snook (whatever that means) at them are missing out.

To this end – so as not to miss out on all that Hi-Fi old and new can offer – I have set up different systems with different design philosophies and I enjoy all of them.

In the basement, I have a bruiser of a solid-state multi-channel system with 15-inch Tannoys upfront, a 50-inch DLP between, two subs and 10-inch dual driver Tannoy surrounds behind. This allows me to both enjoy movies with the bass turned way up and multi-channel SACDs, DVD-Audio and the odd and wonderful pre-recorded Reel to Reel that I have been able to find. Indeed, I even have a Media pc down there with a terabyte of recorded music, films and TV that I can call up at the click of a remote control with far too many buttons. For sheer bass slam, rock and roll as Angus intended the sound of an Orchestra in full flight, or Wagner over a Helicopter’s PA, single ended tubes and full range single driver speakers can’t touch. The system also plays a mean game of Wii.

But I also have an all tube, vinyl, valve rig up stairs, complete with a mono Leak Troughline tuner, Garrard 301 turntable in a custom plinth, Audio Note Kit 1 Amplifier, EAR Phono-Stage, and Role Audio Sampans, my single driver full range favorites. There is also an SACD/CD player and a little used tape deck. It is with this system that I employed the Rek-O-Kut Re-Equalizer II, the subject of this review, to listen to 78s as god (or at least the mastering engineer) intended.

In the lounge I have a NAD all in one system with Mirage speakers. In my office, I have a Dared MP-5 Hybrid Tube-Mosfet amplifier (now sadly no longer available) with built in USB DAC and Boogie CRT. On it, I listen to Internet radio and Itunes. My son has a Sonic T-Amp hooked up to a pair of Bert Doppenberg’s TWQPs. Sid Meier’s Pirates has rarely sounded better.

Along the Hi-Fi way, I have collected many Hi-Fi ephemera and try to use it all. Everything from a reel-to-reel attachment that supposedly fits on to my Garrard 301, complete with battery powered tape equalizer, old mono pre-amps, reel to reel tapes, and all sorts of records made out of all sorts of materials. While some will shatter just by looking at them the wrong way, others are floppier than Ron Jeremy after a particularly hard day at the office.

But I digress. Or do I? As such digressions are for me the meat of this hobby.

Indeed, I would like to be able to boast that I have the gear here to properly play ever format ever recorded, including DVD-Audio, but the truthiness (a Stephen Colbert word) of that statement would be in the low single digits. From carbon traces on paper to tinfoil through wax cylinders and I suppose today’s HD and Blu-ray, people have been inventing new mediums to record sound long before the previous medium has been perfected and if I were so bothered I would have a lot of catching up to do.

Alas, there will always be more formats than I will be able to play, but one format, or I should say, family of formats that I have spend much time and energy doing my best to play in the manner intended has been vinyl. However, vinyl doesn’t just spin at 33 or 45. Indeed, half of vinyl’s life has been at 78 and has only for the last half-century or so been made from vinyl. Along with Bakelite and anything else that can be cut, much of it is made from shellac that Wikipedia helpfully informs us 'is a brittle or flaky secretion of the lac insect Kerria lacca, found in the forests of Assam and Thailand.’ And here is where the rubber (or diamond as the case may be) meets the 78 revolutions per second road where theory often plays a deserving second fiddle to practice.

In theory, there is no difference between theory and practice. In practice, however, there is. --- Anonymous

On the surface, pun intended, playing records seems a simple enough business. Spin the record at the correct speed. Drag a tiny bit of rock, more often than not precious, transforming and then amplifying the physical undulations of groove into an electrical signal strong enough to be heard through loudspeakers. We must, however, add a bit to this terrible over-simplification. We must also re-equalize the signal.

Why the equalization and re-equalization? It has to do with the practicalities of cutting a spiral groove onto a circular matrix. As the width of the groove is inversely related to the frequency recorded, low frequencies demand a very wide groove, limiting playback time by limiting the number of rotations that can be cut on each side. High frequencies will demand a very narrow groove, so narrow as to be beyond the ability of the pickup to pick it out from the noise inherent in the medium. Such practical difficulties are ameliorated by decreasing the amplitude of bass signals and increasing the amplitude of high frequencies.

And here is where we meet with one of the first of the format wars. The problem for the retro record player – such as myself that is – that it took nearly sixty years for the above curve to become the standard for vinyl record reproduction after the introduction of the LP in the early fifties by Columbia.

Before then, and indeed well into the introduction of the LP, records were recorded both without curves – the early acoustic 78s – and with a variety of equalization curves that differed between and even within manufacturers. Speeds differed as well, but that is another story.

So while the majority of 78s, with a correct needle and cartridge (another story), can be played by re-equalizing the sound with the standard RIAA curve that the majority of phono-preamps apply, listening to them that way will not be correct. Indeed, recordings made prior to the introduction of electric recording in the late twenties employed no equalization at all. Therefore, boosting the bass and cutting the treble will get you exactly what you don’t want to hear. The problem is that nearly all modern phono pre-amps – which I will go on the record as saying, ironically, are wildly superior to their vintage predecessors – adhere to the modern RIAA curve and provide little scope – aside from, if you’re lucky, a bass cut, for correctly equalizing the product of this early twentieth century format war.

Plus ça change, plus c'est la même chose.

Here is where Esoteric Sound’s brilliantly conceived and equally brilliantly executed Rek-O-Kut Re-Equalizer II comes in. Through the correct application of two dials – Turnover and Rolloff – according to the supplied chart comprehensively indexing every label’s favorite curve, you can listen to your 78s correctly.

And here is where some of the brilliance comes in. Rather than employing its own separate phono-stage with tubes, op-amps or bunnies, the Rek-0-Kut Re-Equalizer II slots in either after your phono-stage and before your pre-amp or better yet in your probably unused tape loop where it can be switched in and out of use as desired. If it slots in between your phono-preamp and line in pre-amp (as was the case in my system) a bypass switch does a very good of removing it from the chain. It is then just a simple matter of adjusting the two dials on the front, according to the supplied chart detailing every 78 label I have ever seen, to the correct settings.

You may then, voila, listen to your old recordings the way they were meant to be heard.

Here is where I might employ a variety of clichés: a veil was lifted off the music, discs showed greater bass and treble extension, or imaging was such that I felt I could take Diana Krall in my arms, but none of this would be correct. What would be is that my old records no longer seemed over-bright, muted, bass-shy or rolled off. With Esoteric Sound’s Re-Equalizer II (settings supplied by the documentation) my 78s sounded, well, right.

In addition, with this correctness came a sense of realism that was hitherto missing when I had played back these records before. Overall, I was left with the feeling that this is how the recording engineers and perhaps even the artists themselves — wished their recordings to be heard.

What amazed me using the re-equalizer was just how many equalization curves and speeds 78s were recorded at. Of course I knew that different labels equalized their recordings differently and that equalization was unheard of until the advent of electrically recorded 78s around 1927, but I had no idea just how many curves were employed and what a difference employing the right curve can make.

If you want to hear your 78s – and some early 33s – as the recording engineer intended, it is understood, you must re-equalize them correctly. The genius of the Re-Equalizer is that you can use your favorite RIAA phono-stage, adjust roll off, turnover and bass cut for just about any recording ever made, and switch it out of your system when it is unwanted.

Caveats. Most modern pre-amps do not offer the ability to listen to a recording either in mono or in one channel at the expense of another as do many classic 50 pre-amps. On these old recordings the noise level can drop significantly if you sum both channels as the noise on each channel is often in reverse phase, or with one channel occasionally exhibiting much less noise or groove damage than the other where it is best to listen to that channel through both speakers. Also, listening to these old mono records in stereo can result in certain rather weird stereo-like ways with the central image strangely shifted to one side or even with the piano weirdly placed with respect to the rest of the recording.

Esoteric Sound’s De-noiser (the subject of my next review) provides these channel features but it would have been handy if they were on the Re-Equalizer itself, though I understand that the two devices be employed in tandem. Without using the De-noiser, and suffering the noise gladly, I simply summed both channels by using a pair of Stereo RCA to mono and then mono back to Stereo interconnects. Fit and finish is very good, though the knobs could perhaps be a little sturdier, with the incorporation of the old Rek-O-Kut logo a great touch. As the Re-Equalizer is intended to be rack mounted, its face place is slightly taller than its guts and outside a rack it sits uncomfortably. Power is supplied by a wall wart with a decent length of lead, which both locates the power supply at a useful distance plus allows easy switching between 220 and 110 Volts if you should be making the transatlantic hop.

In summary, the Esoteric Sound’s Rek-O-Kut Re-Equalizer is a brilliant bit of kit. It does exactly what it says it does on the package, no more, no less, and that is a great thing. It slots easily in and out of any system, only requiring an extra (supplied) set of patch cables. It can correctly Re-Equalize any 78 under the sun. If you wish to hear your 78s as they were meant to be heard, it is essential. Plus, hearing your 78s as they were meant to be heard is an ear-opening experience. There is quite a bit that is great on these old 78s and taking the time and care to listen to them properly without damaging them is an entirely enjoyable experience. Performance styles have changed remarkably over the years and before today’s classical competition conservatory system was entrenched, there was much more variation between performers than there are now, particularly in piano and voice. And if there is one thing that these 78s have to tell us is that the format wars are as old as the formats.


Sub-bass (10Hz - 60Hz) N/A
Mid-bass (80Hz - 200Hz) N/A
Midrange (200Hz - 3,000Hz)
High-frequencies (3,000Hz on up)
Inner Resolution
Soundscape width front N/A
Soundscape width rear   N/A
Soundscape depth behind speakers N/A
Soundscape extension into the room N/A
Imaging N/A
Fit And Finish
Self Noise
Value for the Money



Type: Vinyl playback equalizer
Sixty-Four different record compensations
In "BYPASS" mode, signal is hard-wired input to output
In “IN” mode, left and right are combined to mono
Includes six pages of recommended compensation settings
Passive equalization design & film capacitors
High input impedance for use with either tube or solid-state amplifier
Connects to systems like any ordinary graphic equalizer
Price: $349


Company Information

Esoteric Sound
1608 Hemstock Ave. 
Wheaton, Illinois 60187

Voice/Fax: (630)-933-9801
E-mail: EsotericTT@aol.com
Website: www.esotericsound.com



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