From My Stash

I've built so many preamps and power amps over the years , but some have been my favourites as they suited my taste, system I was using then and curiosity for technical prowess at the time.

I've kept some of them and will do a story on one or two over time.

I was reminded of this one when I did the article on impedance matching and put up a graph of a SE amp driving a simulated speaker load.

It showed that SE amps dont have low enough output impedance for linear response and the resultant coloured response.

If the output impedance of the amp can be lowered the result will be better, and the way to get low output impedance is to use a low plate resistance tube.

 The Russian 6C33C-B tube is one of the lowest Rp tubes available and with a good transformer can give quite good results with a broader range of speakers.

I built quite a few of the MERLOT amps with the 6C33C-B tube with 6SN7 input tube and 300B driving the 6C33C-B .

                                                              Merlot amps at front

The best ones used Plitron output transformers and they were awesome amps, unfortunately you cant get this transformer any more , mores the pity.

This amp I built for myself  about 10 years ago- it has Sowter transformers , and uses 6SN7 driving 300B , driving the 6C33C-B tubes.  The other tubes are a rectifier tube and a 6AS7G used as regulator for the power supply.

Monoblocks , so two for stereo.

Very nice amp , puts out a solid 18 watts and can drive most speakers .

It can be configured as cathode follower , which lowers the output impedance even more, but the consequent feedback generated does take some of the sweetness from it.

Its sitting in my collection , and unused for a few years now, but will be used again when I get a horn system going again.

LCR Phonos

L(Inductance)C(Capacitance)R(resistive) phonos have been around for a long time.

They are simply a different method of getting the EQ required in a phono preamp to change the signal from a record into flat frequency response.
Instead of using C&R , as is usually used an inductor L is added.

Tango, the famous Japanese transformer company, made a unit that had multiple inductors plus the necessary caps and resistors in it, quite a few years ago .
It was the inspiration for many diy LCR phono stages but rarely available commercially as they are expensive and tricky to implement .

Tango Circuit

I built quite a few LCR's 15 years ago but always found them a little inaccurate  and prone to hum, with the inductors picking up any stray AC fields.
A good tube CR phono can also sound very good so why make it harder.

In conjunction with Kevin Covi I also built a lot of LR phono prototypes, which I think is a better approach, as this eliminates the C , which is mostly a good thing.
These are tricky though, just a slightly wrong value of L or R and frequency deviations are more than what is tolerable.

And building an active tube phono that can give enough gain for a 0.2mV moving coil cartridge is tricky enough without complicating it with noisy inductors.

Which is why commercial LCR phonos released over the last few years are for MM cartridges only or require a step up for MC cartridges.

Michael Fremer , the influential analogue reviewer has a LCR phono in his system, and his acclaim
of its sound has introduced LCR phonos into the audiophile mainstream.

The unit he uses is very expensive, and is confined to MM use or MC with an overly expensive step up.

Its a very nice design and very well made, but I have no love for step ups , and I decided to re-investigate the LCR approach.

Fortunately , all the ground work was done years ago , and our hybrid LCR phono , using CR and LCR stages , with a few innovations and Lundahl inductors works and sounds perfectly.
And it is capable of gain for the lowest output MC cartridges, with no step up,  so dynamics - micro and macro are stunning.

As Fremer says, a good tube LCR phono doesn't sound "tubey" , their forte is revealing micro-dynamics . I dont think CR tube phonos are shamed by them, but there is something inherently nice about them.

Now I need to go back and do some work on a LR phono , which could be even better again!

Listening levels

I had a request to do a blog about listening levels and how they relate to speaker types and efficiency.

Fortunately I have a listening room that's quite isolated and I dont have to worry about how loud I listen to music.

And I do prefer listening at slightly elevated levels rather than at background levels, its just a bit more involving and interesting.

However, many are constrained by having to share their stereo system with family, neighbours etc and turning the wick up isn't always possible.

So what are the best speakers for listening at lower levels and obtaining the maximum resolution , detail and enjoyment?

I suppose 80% of speakers are moving coil box speakers with efficiency around 80-90dB.

Typical of this design are my Lipinski studio monitors.

When I finish a preamp build I always test them on the Lipinskis, primarily because they are very accurate , and because they closely resemble what 80% of my customers will be using themselves.

The Lipinskis will quickly tell me if a preamp is operating at 100% quality ; its a very capable tool that is also very engaging and nice to listen to.

But its not so good at low listening levels , which is typical for all medium efficiency box speakers.

They sound a little "veiled" , hindered in dynamics and detail.

Higher efficiency speakers however have an ease , a directness that does make them more listenable at lower levels.

Not always the most accurate of speakers, which is perhaps a compromise they make for dynamics , but always interesting.

My Supravox field coil drivers are up in the high 90's for dB and while I wouldn't call them the most accurate drivers they certainly are fun to listen to, at any level.

Horns are of course the highest efficiency speakers and dynamics are unriviled , the softest sounds come through loud and clear, although they can be coloured and take up room, and perhaps not the prettiest speakers. I've always had a pair of horns, and although I dont have these anymore I have another pair waiting to be configured.

Similarly,big panel speakers which have a driver surface area many times higher than a box driver , can throw a much larger soundstage even at lower sound levels.

Some of the really low efficiency panel speakers are exceptions as they struggle to use power, but get a good medium efficiency panel and you are enveloped in sound.

My Acoustat 2+2 are each 8 feet tall and 2-1/2 Feet wide - with high power amps they fill the room with a vast soundstage and are just as exciting at low sound levels.

What to do if you are confined to box speakers and lowish listening levels?

A good dynamic pre, usually with high gain,will help greatly, the more dynamics you can get the better and a good pre with a highish power solid state or tube power amp will sound alive and interesting.

Any topics you would like covered ? Email me at supraATsupratek.com.au

But please no gurus who want to argue, these posts are intended for the average audiophile and are deliberately  basic in  concept.

Impedance matching

Impedance matching between different devices can be confusing, so here is a very simplified analogy.

A loaded truck driving up a mountain has to downshift gears to enable the engines torque(power) to be used.

Its  a difficult task (load) and more driving power is needed.

Once the truck gets over the hill and is coasting down the hill very little power is needed as the load is lightened by gravity.

With a preamp, power is related to low output impedance , but its relative to the load (power amp) it has to drive.

If a power amp has an input impedance of 10,000 ohms, then an ideal ratio of 10:1 would mean a preamp impedance of 1000 ohms.

10,000 ohms is a typical figure for a solid state amp, but a typical figure for a tube power amp is 100,000 ohms, so applying the 10:1 ratio the preamp could have an output impedance of 10,000 ohms.

10:1 is like the ideal gearing in our truck analogy, the power can be transmitted cleanly and without strain.

There's no loss of gain and frequency remains linear .

Its possible to get the output impedance of a tube preamp down to 100 ohms or less, which would drive the most difficult solid state preamp, but there can be sonic compromises to this .

An output impedance of around 1000 ohms is ideal for a tube preamp, as it can be feedback free and still capable of driving 95% of solid state power amps.

Things get a bit more complicated when we look at the impedance issue with power amps driving loudspeakers.

If a speaker has an impedance of 8 ohms then applying the 10:1 rule we need a power amp with impedance of 0.8 ohms.

No problem for a solid state power amp, but a tube power amp which, without feedback , will have a higher output impedance will not be able to achieve this ratio.

The problem is compounded in that a loudspeaker doesn't have a constant impedance - it varies with frequency and can shift from less than an ohm to a 100 ohms, which is worse case, but they all have varying impedances.

Use a Single Ended , no feedback,  tube amp which will have a high output impedance and the resulting frequency response will be far from linear.

Which is why many people like Single Ended amps, they act more like a tone control, accentuating the mid range and sounding "romantic" .

Single Ended amps are best with easy loads, like crossover less full range drivers, or used in bi/tri amp systems, driving the midrange or treble drivers.

Push Pull tube amps, with a little feedback,are much more capable, but still need a loudspeaker suited to their capabilities.

Fortunately the preamp/poweramp impedance issue is a lot more straight-forward , and you really can't get better sound than combining a capable tube preamp with a tube or solid state power amp.

Here's a measurement of a single ended tube power amp with output impedance of around 2 ohms - the black line is frequency response into a simulated speaker. Its actually not too bad for a SE amp, but it's far from linear, and will sound coloured.

Vinyl phono stages.

The Supratek phono stages are designed for moving coil cartridges only.

Why no provision for moving magnet?

Well I'm sorry but if you are going to spend considerable money on a phono preamp then you may as well buy a quality cartridge, and in my experience moving coil cartridge always gives a better result.
Yes there are some good MM's but even a good quality budget MC will always sound better.

Its my opinion, and some will disagree, but I build the preamps to what I consider the highest standard ,  so MC it is.

In some ways I'm making it harder for myself- as I've pointed out MC have tiny voltages and need enormous gain , and to achieve that gain with tubes, and no feedback is difficult.

There's two ways to get the extra required gain for MC compared to MM. Passive and Active.

Passive is a step up transformer , and its the method most manufacturers of phono stages use.

They are quiet, reliable , and I'm a big fan of transformers in audio, but not for phono stage inputs, phono step ups always sound limited in dynamics and "choked" to me, they just bore me , its as though someone turned the excitement down.

Actives use electronic methods to get the gain, either more tubes (too noisy) or with FET transistors in front of the first tube.

They are very dynamic sounding and handle the tiny voltages perfectly, I dont think there is any comparism in sound quality, and its not a small difference, active is alive and exciting.

So why are most tube phonos designed to use passive step-ups?

Tubes are wonderfully linear devices that dont require feedback to give very accurate preformance, but they are not as quiet as solid state devices , or passive transformers - they have a noise floor that is louder than solid state or passives and when you amplify thousands of times the noise floor can become  audible as hum or hiss.

So you cant simply add more tube stages to get the required gain as noise will become a problem.

If one is determined to use an active method, for the most realistic sound ,then fet's are the ideal solution, these little guys work more like a miniature tube than a transistor and are quiet.

In combination with very quiet and substantial power supplies, very well designed and implemented grounds and good circuit layout, the gain for low output moving coil cartridges with outputs of 0.2mV can be realized .

Its not easy, which is why very few manufacturers even attempt it, but the noise can be down below the noise floor of a vinyl record, which is all that is required.

Still not as quiet as a passive , its true, but the combination of a low output MC cartridge and an active tube phono stage easily surpasses any passive method, even the ultra expensive passive phono devices struggle to come close to the excitement of active vinyl.

Tomorrow, LCR and LR phonostages.

Recording Quality

Is DSD audibly superior to MP3?

Yes of course it is, provided the recording process and equipment is of equal quality.

I have MP3's in my hard drives that sound quite wonderful, because the recording equipment and process , the mastering etc were first class.

I also have DSD recordings that are terrible, because they were made from a bad recording.

Sound quality is determined primarily by the recording quality- you cant turn a poor recording into a good one by increasing the bit rate or converting mp3 into flac or dsd.

Years ago I built a tube based microphone preamp for a pair of ribbon microphones, which are consider to be the most "analogue" sounding by musicians- they like the sound compared to cardoid , omnis etc.

We taped a small guitar/banjo combo at a local pub , ribbon mics straight into the tube preamp , then into a reel to reel tape deck.

Minimal mastering and then converted to CD. The recording was exceptional , did a really good job of recreating the performance.

Unfortunately someone brought a little kid who cried all the way through, and it came through just as well!

Tube Microphone Preamp. 6SJ7/ECC88 tubes. Balanced/Unbalanced in and out.
Has matching regulated power supply.
Ribbon mics.
Would consider selling this, makes very nice class A recordings.

Vinyl

What they say about vinyl being more tangible , of more substance, relates not only to the musical quality.

Back in the day, buying a new vinyl record meant more than just the presentation of a new recording.
It was something that you held in your hands, something that was a source of interest, of information, and stimulation, more than just the pretty woman on the cover.

Playing a vinyl record involved unpacking, placing it on turntable and placing cartridge needle in the groove, and in 20 minutes you did it all over again.

The 60's, 70's and 80's were also when music broke fresh ground, the time was ripe for a brand new sound , and a plethora of songwriters and musicians wrote groundbreaking new forms of music and song. Its no coincidence the golden age of songwriting happened along with the golden age of vinyl.

I've been listening to vinyl for nearly 50 years now - these days its not my main source of music.
I listen to music while I'm working and its simply easier to turn the computer on and listen to a whole album or leave the music on shuffle.

And its true that digital audio is very good these days, there's still a lot of bad digital around, but when its good its very good.

I actually believe good digital is more accurate than vinyl, and with a good recording, which is the actual quality determining factor of any source, digital can be closer to the recording than vinyl.

Vinyl has a lot of potential for coloration,  mostly on playback in our systems , whereas digital software and hardware is very constant and uniform.

BUT, there is something about vinyl, its totally immersive , and its seems to be far easier to sink into the music listening to vinyl than digital.

Vinyl washes over you, it makes you forget what you were doing, and the 20 minutes goes far quicker than you thought.

Being a tube guy, I naturally think the only way to listen to vinyl is through a tube preamp, with a tube phono stage.

There's good technical reasons for this , vinyl playback through a cartridge tip is feedback free, its a perfectly physical process , that converts magnetic movement into electrical signals.

The resulting frequency response is far from linear , and massive amounts of EQ are needed to get it back to flat.

Combine this with the fact that the signal from the cartridge will be as low as half of a thousandth of a volt for a moving coil cartridge and 5 thousandths of a volt for moving magnet.

To get it up to typical line stage input levels we need to amplify it by at least 5000 times, not an easy task.

Well it is an easier task if you use lots of feedback , which simplifies a lot of problems.

Feedback can be very useful, and it can be the devil, the amount of feedback that is typically used in a solid state phono stage chokes all the life and soul out of vinyl playback.

Its very hard to build a solid state phono stage without a lot of feedback , it can be done, but the royalty of phono stages is the zero feedback tube phono stage.

There are compromises , when you are using tubes for gains of between 5000 and 10000 you are also amplifying the noise floor,  so its hard to get a tube phono stage dead quiet.

However it is possible to get them quieter than the noise floor of a vinyl record , so its really not a big issue.

The massive EQ required of a phono stage is always almost done with large amounts of negative feedback with solid state devices , but can be done with zero feedback with tubes.

Feedback with vinyl is bad m'k , something so expressive and free, just doesn't deserve to be castrated and chained.

Vinyl can be beautiful, impressive, strong, expansive and simply great fun.

A good bottle of red or a fine craft beer, give me vinyl!

In other blogs I will explain virtues and compromises of the 300+ tube phono circuits I have designed and built (in conjunction with Kevin Covi)

                                 One of my turntables , the mighty Micro Seiki RX-5000

Exotic components-2

Bob pointed out I didn't mention volume controls.

Its the obvious DIY approach for many as its relatively easy to do (and also pretty easy to get wrong)

There's ladder resistor pots, and variations on them, transformer volume controls, autotransformer controls, electronic stepper pots.

Some of them can sound good, some of them are more properly called tone controls , and some are terrible.

I tried to get along with some of the more exotic VTC, ATC's  but long term they are nothing but trouble.

Like exotic caps, they just sound different, not necesarily better . Its very important to use the right values of pot in a preamp circuit, as just putting anything in can cause serious frequency inaccuracies. 

Like wise, impedance matching is critical when using VTC, ATC's.

In my opinion, the best pot is what's been the standard for a very long time- the carbon resistive pot.

I use high quality Alps pots in my preamps, but to be truthful even a cheap carbon pot will always sound pretty good, and I doubt anyone could hear the difference in a double blind test.

The Alps have better channel to channel specs, but its minimal, and any good preamp will have a balance control to enable pin point imaging and sound-staging.

The old faithful carbon pot is transparent, accurate and reliable.

And they can be easily configured for remote operation, which just makes relaxing and listening to good music more enjoyable and fun.

Nothing worse than having shuffle on and the next track 3dB louder than the last, at least with a remote volume its nothing to adjust from listening position.

                                                        Alps Blue Pot, motorized.

Exotic Components

Another contentious issue perhaps.

You can spend a lot of money on exotic capacitors, resistors, switches etc.
Gold/Silver paper in oil capacitor?
Pure Silver wound transformer?
How much money do you have sir?

I recently had a preamp returned for a modification upgrade.

It had been filled with expensive capacitors , silver plated switches and ridiculous amount of cap bypassing, along with some questionable soldering skills.

Unfortunately the "technician" who did the work had also made the preamp un-operational and it was returned to me for a repair and upgrade to latest circuit.

Over the years I've tried lots of premium parts in my preamps, and there is definitely a place for the best quality possible, some components are very critical - transformers for example, and my distaste for electrolytic capacitors doesnt have to be repeated again- Supratek preamps have about half a dozen electros at most while most preamps have hundreds of the nasty devices.

For signal capacitors I use polypropylene film or good quality paper in oil caps, yes there is a difference in quality between a cheap and nasty polyprop , but once you get to a certain level of quality , differences become just differences, not significant steps in quality.

                                           Just some of the caps tested over the years.

And these differences are quite minimal, mostly inaudible, although the cost of some of these items requires the brain to justify some audible "improvement".

I left the expensive caps in the preamp when I rebuilt it, at the customers request, but on listening to it I had to take one expensive pair out, as they were just horrible sounding.

This preamp did sound different, albeit it was minor, compared to the stock preamp built with my choice of high quality, but non exotic components.

It certainly wasn't "better" in terms of sound quality, it had a slightly different tone, very minor, but probably enough for a zealot to proclaim as significant.

The fact is changing the current running through a tube, like the 6SN7 for example, from 4 to 8 milliamps will make an audible difference, changing the operating voltages, or the type of plate loading  will make a difference, as will an output transformer designed and optimised for the application.

Most of the time these changes can be measured (not all the time) - the role of the circuit design is paramount to sound quality, not the level of exotic components.

Good circuit design, over engineered and high quality components ( not necessarily overly  expensive) are far more important than filling a chassis with so called exotica which has profit for the vendor as its main purpose.

As an aside, I do like a Russian military teflon paper in oil cap I use in my preamps as it seems to have a nice synergy with the circuit and other poly caps in preamp.

Its not cheap, but a fraction of the cost of an exotic Teflon capacitor that frankly sounds brittle and nasty.

Music

This hobby/passion is all about music, so occasionally I will post some music I'm enjoying
.
I've liked Bruce Cockburn for years, although some of his work can be a bit "different".
I really like this one, not bad for an old geeezer 72yo.



It's been six years since Bruce Cockburn delivered a studio offering. His daughter was born in 2012, he assembled a career-spanning box set, and wrote a candid memoir, Rumours of Glory. When he was finally free of his writing and curatorial chores, he wondered if there was anything left to say. A book of poems by Canada's greatest 20th century poet, Al Purdy, provided inspiration. The song "3 Al Purdys," in which Cockburn sings and speaks the yarn of a homeless wanderer under the spell of the poet (and weds his words to Purdy's) is one of the finest tracks here (and one of four to feature jazz cornetist Ron Miles). Cockburn's less concerned with perfection, particularly when it comes to his vocals. In his seventies, his instrument is gruffer, but via Colin Linden's immediate production, it proves a benefit. "States I'm In" is a searing, insightful, rearview look at what Cockburn's witnessed – beautiful and horrible – in his global travels as a musician and an Amnesty International observer.

He transforms the song from reverie to a meditation on the present realities and in his own life and society. There's a more overt engagement with Christianity on this record, balanced by a sense of "growing tenser with the times" while living in a country led by Donald Trump. The bumping rockabilly shuffle "Stab at Mater" (a wonderful wordplay on the Latin "Stabat Mater") illustrates the experiential grind between spiritual insight and everyday life that deepens them both. Members of his local San Francisco church were recruited as a chorus here and elsewhere, including on the folk-inflected, poetic, yet urgent "Forty Years in the Wilderness." ("…getting to the know the beasts….") "Looking & Waiting" is wafting acoustic reggae. Buoyed by the chorus, it's a hymn to knowing full well that waiting is indeed the hardest part of faith. The title track is a gorgeous instrumental acoustic guitar workout, while "Mon Chemin" is a jazzy, Latinized folk song buoyed by charango and dulcimer, with Miles' cornet, accordionist nephew John Aaron Cockburn, bassist John Dymond, and drummer Gary Craig. The final two tracks also use blues as jumping-off points. On "Jesus Train," Cockburn delivers them through fingerpopping, house-rocking 21st century gospel. It's followed by the traditional "Twelve Gates to the City" (so closely associated with the Rev. Gary Davis). Cockburn makes it his own by adding some new lyrics and a radical NOLA-styled R&B arrangement – Miles' Louis Armstrong-esque fills and the chorus add soulful weight to the proposition. Bone on Bone is a fine, deep return. This somewhat grimier and edgier Cockburn is clearly inspired, his lyrics are both jagged and elegant; they dovetail in songs that question and reveal the rough-hewn beauty of a life guided by spiritual principles. He continues to question these principles while affirming their primacy as a witness to the world's brutality. They also struggle with the next right thing and how to accomplish it, even when it seems pointless to try, and that kind of struggle is the kind of hope we need more of.





Eilen Jewell's country-blues flavored folk on Boundary County will remind listeners of many new, talented women singer/songwriters without ever seeming like a copy. Like Jolie Holland, she slurs her muffled vocals on a series of original songs and accomplishes the neat trick of evoking tradition. Like the Be Good Tanyas, Jewell relies on fairly eclectic arrangements, though she's more progressive in her marriage of electric and acoustic elements. The slow, sad "So Long Blues" ventures toward pure country with Jerry Miller's lap steel underpinning Jewell's lonesome vocal, while the spunky "Gotta Get Right" captures a more folksy feel with banjo and mandolin.

On both, Johnny Sciascia's upright bass is heavy in the mix and sounds more like an electric bass. Jewell is also frequently joined on the choruses by drummer Jason Beek's deeper, raspier voice, an intriguing combination in which both voices intertwine while keeping their identities. A couple of the songs – "The Flood" and "Blow It All Away" – seem a bit long, and it's easy, especially with the latter, to allow Jewell's lazy, bluesy vocal to fade into the background. These tracks, along with the two that follow and bring the album to a close, lack the vim and vigor of the album's earlier tracks. The first two-thirds of Jewell's Boundary County, however, is well-written, well-sung, and well performed, and will please fans progressive traditional-flavored music.

Balanced V Unbalanced

Ok this is going to upset a few people.

I don't like balanced operation and only use it when I have to.

I do supply balanced inputs and outputs on some of my preamps, but only because people want them, and because sometimes you have no choice.

Balanced operation comes from the pro-audio world, music venues etc, and is used to cancel out noise that is caused by very long cables, and less than ideal electronic applications.

It doesn't cancel all the noise but does a pretty good job of making it inaudible.

But balanced operation doesn't do a better job than a properly designed and implemented unbalanced design in normal hi fi home situation, if you are using 200 metre long cables you need another house!

Balanced operation in hi fi situations is a clever marketing ploy based on fashion.

Below is a simplified circuit of a cascaded tube preamp.

The round circles are tubes, the squiggly lines are resistors and the parallel lines are capacitors.

It's very simple and very effective, has nice harmonics , good phase response, all you need really.

If it has a good power supply, is designed and constructed properly it will be very quiet with very little, if any, hum and noise.

Below is the same circuit in balanced mode.

Note how there are double the components , two different phases and operating in differential or push pull operation.

It wont be audibly quieter than the above unbalanced circuit, unless you want to drive 200 metre long cables. Harmonics aren't as nice as single ended and there's no guarantee it will be perfectly balanced between tubes and components.

After many years of building both balanced and unbalanced preamps, I've still to hear a balanced circuit sound better than a simpler unbalanced circuit.

To my ears there's always a slight veiling, a lack of cohesion and clarity with balanced operation.

Yes there are plenty of good sounding balanced power amps , but I've never heard a  good balanced preamp.

The perfect place to use a balanced circuit would appear to be with moving coil phono cartridges. The voltages from MC cartridges are minuscule , around 0.5 mV , that's half of a thousandth of 1V!

Using tubes to get the required gain of 5000 is tricky , as the noise floor is also amplified, so balanced operation makes sense in this situation.

I built hundreds of differential balanced phono-stages and never heard one that sounded as good as a really well built single ended phono stage.

Yes they are quieter but a well built single ended phono will be quieter than the noise floor of a vinyl record anyway, so there's really no point.

Below is how Supratek preamps provide balanced operation.

The Single ended circuit remains but I use transformers to accept the balanced input and provide balanced outputs.

Good quality transformers, brands like Lundahl , Jensen and Magnequest provide perfect phase splitting and combining- without any of the complications of a doubled-up balanced circuit.

Nice even harmonics are maintained throughout the circuit , and it can be easily switched for balanced or non balanced operation.

Its a win-win, gives true balanced output, there's no price to pay, no compromises and sounds as good as balanced gets.

New Year New Models

Happy new year to everyone. Sorry for lack of blogs lately, I had some commitments I had to take care of, but all done now and from Jan 2nd I can devote all my time and effort towards Supratek.

I'll try to do a blog every day, and should be able to find some  interesting audio topic each day.

Also this year I'll be bringing out some new models, an entry level preamp and a stand alone phono stage.

Also will finish off Bob's field coil PSU!

Tomorrow I will do an article on balanced v unbalanced operation and why I generally don't like balanced .  It will be a bit contentious, so have a read and decide for yourselves.

Here's a pix of what I got up to over the holiday period, the most fun you can have with clothes on (as they say)