Tecnical details LCR Cortese.

The LCR Cortese uses 6688 and 6H23 tubes in its phono stage, and 6SN7/6H8C tubes for the linestage.

The phono only LCR preamp (no linestage) uses 6688, 6688 and 6E6P tubes.

These tubes were designed and built towards the end of the tube era, and are perfect devices for audio preamplifiers.

The LCR Cortese is suitable for any moving coil cartridge, but not moving magnet.
Impedance switching allows for loading of 10,100,1000 and 47,000 ohms (or whatever values are required.

To ensure enough gain with even the lowest voltage MC cartridges (0.1mV) the phono section has nearly 80dB of gain - that's an enormous amount of gain  and its a real task to ensure quiet operation with no hum and hiss below the vinyl floor level.

The input stage of the phono uses a cascode circuit with J-fet and 6688 (E180F) tubes.

With nearly 30 years of development this cascode circuit negates the need for a passive step up transformer and has all the advantages of active operation- greater dynamic range , more linear frequency response and suitability for all MC cartridges.

To ensure it is quiet , a special earthing arrangement is needed, along with extremely quiet power supplies - more on that later.

The next stage (6H23 tube) is another gain stage with transformer output, which provides the low impedance and drive necessary to drive the L coils for the RIAA equalisation.

These are specially built by Lundahl and are finest quality.  They are precisely measured and the required CR values are matched within very fine tolerances.

The last stage (6H23 tube) provides some more gain and the drive needed to couple with the line stage.

Polyprop caps are used throughout, but kept to a minimum.

In line with Supratek design goals, electrolytic capacitors are only used when absolutely necessary - there are only 2 in the phono stage,  and none in the linestage.

Compare this to a typical phono preamp which can have dozens of strident sounding electrolytic caps.

The line-stage is another multi- year development that is designed to be as transparent as possible , in order for the astounding sound of the LCR circuit to come through unaltered and rich in dynamics.
It has extremely low output impedance and will drive any, and multiple power amps.

I've also concentrated on making both the phono and linestage as robust and reliable as they can possibly be.

They only use design circuits and components that will have an almost indefinite lifetime - I'm sure that like other Supratek products it will become a classic that will be performing flawlessly and at the highest level many years from now.

The heart and soul of any audio electronic component is the power supply, and the PSU for the LCR phono preamp is an example of clever and uncompromising engineering focused on sound quality and robustness.

The tube shunt regulated supply for the high voltages is responsible for the Supratek sound- precise imaging and sound-staging , and rock solid stability .

Seperate heater supplies for both phono stage and line-stage ensure super quiet noise levels, even with 80dB of phono gain .

The Supratek LCR phono is the only MC cartridge capable LCR tube preamp in the world.

How did it come to this?

I think this is going to be the most difficult article/blog to write.
I'm preferably a man of few words, and prose does not come easily to me.

But I'm very passionate about sound , and derive enormous satisfaction and pleasure from listening to fine music, so when something comes along that provides even more satisfaction I want to tell all the world about it and provide some clue to what I'm feeling.
I'm not so good at that- but here goes anyway.

How does a tiny pointed rock on the end of a equally tiny piece of metal, swinging between microscopic ridges imprinted into black plastic vinyl provide a sound that is so textured, vivid, and alive with a stereo soundstage that is so wide and dynamic, yet equally seamless with its images of right and left channels.

I have some very good dacs here , I'm up to date in the computer audio world, have a very nice CDP , and am reasonably competent in building and understanding digital.

It doesn't compete in any way in equaling the sound of vinyl playback, in particular the sound of a LCR phono preamp with a high quality moving coil cartridge.

Over the years I've been tempted to sell off my record collection, its bulky, is a pain in the arse whenever I've moved house , and just like digital , not all of the recordings are first rate.

But I never have , because when I take the record out of its cover, place it on the platter, clean it, and then drop that rock into the groove, I'm then always grateful that I never succumbed to the temptation.

LCR phono playback has made me even more grateful- LCR phono is the ultimate playback of any recording system, whether its analouge or digital,  nothing else compares . (Except maybe master tapes)

Its superiority is mostly in dynamics , which is rather perverse as digital has an overall greater dynamic range , but within a LCR phonos dynamic range its faster, cleaner, simply more alive and exciting.

And this force of dynamics is also audible at lower listening levels, if your restricted in the volume levels you can use, the LCR phono is very worthwhile.

In comparison, digital sounds veiled and choked- yes it can sound very good , but the difference between a digital recording and a LCR reproduced recording is night and day.

Digital has its place, it's convenience cannot be denied , and it can sound very good, but for the ultimate listening experience LCR phono , and even very good standard CR phono (both with tubes of course) will let you hear angels.

Its taken me 30 years to build a moving coil LCR tube phono that doesn't require a step up transformer, is quiet and will work with all moving coil cartridges.

In the next article I will go into the technical details of this design.

Moving coil cartridges. Denon DL103, Ortofon SPU, Accuphase AC-3, Dynavector DV30.
All with Expert Stylus cantilvers and diamonds- highly recommended.
The SPU is superb, amazing with tube LCR.