Multi tube preamp from the archive

This preamp belongs to the guy who makes the wooden cabinets for the Supratek preamp.
Its one of the older 300B designs, about 10 years old now .
I had it back to do a little mod on it, and it still sounds great, especially with the LCR phono design.
The little bit of DHT warmth sounds very nice in the right system.
This 300B design was the early type direct coupled from the 6SN7 driver tube.
Later on I went to a different design that enabled a little more definition , but the direct coupled designs had excellent phase performance which resulted in exemplary imaging.
In truth, even 10 years later the Supratek sound is one of a kind and all of the diferent versions have a very similar sonic signature. Accurate tone and superb soundstaging and imaging.
The beauty of this design is that it could use multiple output tubes- 300B, 45, or PX4.
It had a switch to set different filament voltages and a servo to set the required plate voltage.
Servos can be problematic sometimes, but this one was relatively simple , and has been reliable and problem free over its lifetime, and will continue to be. It ensures that the output tube always sees the correct plate voltage, even as tubes age, etc.

Here's a pix of the stock 300B preamp

and a pix of it with 45 output tubes and vintage 6F8G/VT-99 tubes.

Different sound, slightly more natural sounding,  more open and a bit more dynamic but still highly defined and very 3D like. Very expensive Emmission Lab 45's though, you'd expect a good result.

10 years on, a very capable and excellent sounding preamp, as good as the day it was made.

If you'd like a really nice high end equipment rack, or listening chair or anything in furniture grade wood,  handcrafted by an artisan , contact me and I'll put you in touch with Jon.

$45,000 for a 12AU7,12AX7 phono preamp.

Flabbergasted, thats what I am.

I just read a review on a just released phono preamp that retails for $US45,000 and it uses 12AU7,12AX7 tubes!!!

12AU7, 12AX7 tubes were designed for use in televisions , but became used in audio as similar replacements for 6SN7 and 6SL7 tubes, which were genuine audio tubes.

The 12 series were cheaper, but nowhere near the quality of the 6 series tubes.

Substitute a 6SN7 for a 12AU7 and the difference is day and night, but for reasons of economy and ease of supply the 12 series tubes caught on and became widely used in the audio industry.

I first used 12AU7 and 12AX7 in a phono circuit about 30 years ago- the popular RCA tubebook circuit.

It used feedback EQ and sounded ok, but couldn't drive a long cable let alone a power amp without the easiest of a load.

I wouldn't even use a 6SN7 and 6SL7 in a phono, although I have built a few phonos to prove it coudn't be done.

Well, actually  it can be done, and again they sound ok, but there were some fantastic tubes released at the end of the tube era which are near perfect for the needs of a phono preamp, and are high gain and have good drive -  these tubes give very high definition , accuracy and transparency.

The 12 series tubes are wimps in comparism and give a bloated ,warm "romantic"and "tube" sound , ok if you like that sort of ting but I guarantee you will soon tire of it.

My LCR and Standard Cortese use 6688 and 6H23 frame grid tubes in the phono section.

The soon to be released phono only LCR preamp uses 6688, 6688, and 6E6P tubes.

These are combined with the fantastic enveloping LCR circuit and state of the art circuit design to produce a circuit you will never tire of listening to and enjoying.

Classic cosmetic appearance, finest sound and $5500 for the LCR Cortese.

Against $45,000 for 30 year old technology ,  and another $10,000 for a SUT so you can use your MC cartridge  - flabbergasting!!!

Music

A couple of albums I've enjoyed this week- both female artists and both in an acoustic frame, and both at different points in their lives.



You never know what your going to get with Casey Chambers, but I'm really enjoying this, some great songs and very good acoustic guitar, uke playing.



Another great album from Joan Baez. You'd never know she was 77 from the singing, but the songs  come from a  voice aged with wisdom and retrospection.

Casey's songs come from someone in the prime of her life, her kids are growing up, she's in a safe place musically, lifes good, although she can sing a blues song with conviction.

Joans seen it all, and is at a stage of life when some things get a bit tiresome , how many times do we have to watch the same old shit - gun control in America , friends dying, being the last leaf on a tree.

Both good albums and recommended - good sound too.

One interesting thing- Casey doesn't have a great high voice, she gets a bit screechy at the higher notes, I think she had some problems with her voice some time back.

One way to soften this is to double track- the producer will put another identical vocal on top of the original, so you get a choir effect that sounds a bit more harmonic and agreeable.

Its very common and just about mandatory for those not blessed with a perfect voice. 
You'll find double tracking, or multi tracking on just about every album you own, but does your preamp enable you to discriminate it immediately ?

Its a sign of a good preamp with excellent definition - you should be able to hear two distinct, separate voices laid on top of each other.

The better the preamp, the better the distinction and the better the harmony will sound.

HighDefinition/High Enjoyment Preamp with LCR phono.

I've been very busy building preamps , so apologies for little blog activity.

This adaption of the Cortese preamplifier is very exciting and achieves some long held aspirations and goals for Supratek.

Firstly, it has an LCR RIAA circuit in it, and put simply, A LCR phono is the ultimate vinyl expression.  I've been building LCR and LR phonos for many years and this design is the result of many circuits tested and evaluated over the years.

LCR has an ease and liquidity which brings real life and vividness into vinyl playback.
In terms of actual objective performance its not much different than the standard Cortese phono stage, but the enjoyment factor is subjectively very obvious , it simply sounds even closer to real music .

LCR has amazing levels of texture and body, it really brings out the character and expression of artists and music- Leonard Cohen sounds more like Leonard Cohen, Dylan like Dylan, classical music surrounds you in sound, LCR really is a big deal, a real significant jump in sound quality.

All tube phono LCR circuits are rare and expensive, and they are not easy to build, they require very high quality iron chokes and interstage transformers.

This Supratek  LCR Cortese is the only tube phono stage in the world that is built solely for moving coil cartridges with output level as low as 0.1mV , and is designed for the majority of MC cartridges.

Why is the Supratek the only MC capable LCR phono, when the other tube LCR phonos are suitable only for MM cartridges. ( and cost up to 6 times more!)

With nearly 80dB of gain needed for low output MC cartridges, its very hard to get tubes quiet enough for MC use, as hiss and hum become audible with such a high gain.

The standard approach is to build a tube LCR phono with 40-60db of gain and use a step up transformer (SUT).

SUT's have limitations in adapting to every cartridge, frequency response and a lack of dynamics.

The active, high gain approach used by the Supratek achieves optimum dynamics and definition from every MC cartridge, reliably and consistently.

Only the Supratek Cortese LCR can achieve these gain levels and remain noise free , essential for the retrieval of micro and macro dynamics from your vinyl records.

A very complex earthing arrangement, over-engineered power supply, (big enough for a tube power amp) and regulated HT voltage , in a seperate matching power supply unit with state of the art componentry and copper chassis's, ensures quiet, efficient operation.

To match the phono stage the LCR Cortese has a line stage that is also especially quiet and capable of  the dynamics of the phono, a well as making all digital and other inputs sound amazingly real.

The line stage is a state of the art tube design, with very low output impedance that can drive any power amplifier, and even a combination of bi or tri-amped amplifiers.

It has the famous Supratek sound, and will carry on the Supratek reputation for reliability and ease of use.

I often hear from customers who have the original preamplifier I built for them 15-20 years ago, with no issues and the same tubes in them!

I've spent a lot of time and effort in ensuring that this preamplifier will perform at the highest level, and reliably over a very long term.

Just as the early Supratek Syrah and Chardonnay preamplifiers became respected "classic" pieces the Cortese LCR will become an item to appreciate and enjoy over a very long time.

With comparable tube LCR phono stages (without linestage) costing well over $20,000 the Cortese LCR is a handsome buy at $US5500.

The Standard Cortese with CR phono stage is $US4500 with 85-90% of the LCR sound quality.

Available in different finishes.