Review: JJ ECC83S short plate 12AX7

 

To be honest my expectations for this 12AX7 was low.  I haven't had a JJ tube in any of my gear for well over a decade.  Nothing personal, mind you, but back then I was all about more exotic tubes like the C3m, 5687s, EL156s, and whatnot.  JJ has been around since 1994, built on the ashes of Tesla and Ei.  Their small signal tubes aren't mentioned all that much on the forums I visit, or at least I missed the posts.

This particular version of the 12AX7 looks to be based on the famed Telefunken ECC803S, which also had a Tesla copy.  The architecture has small plates that are very similar to a 6DJ8.  This should translate to low microphonics.

As for the sound, at least as the gain tube for a power amplifier, the JJ ECC83S was better than I expected.  There is an overall darkness, making this a good match for some zingier MC cartridges or digital front ends.  This is a "chocolate" expression of the music, with solid and tuneful bass, warm mids, and a high end (to my older ears) that is even less detailed than a Mullard. 

Inner detail with the JJ is less than the long plate Mullard; a slight smearing of instrument and vocal space along with soundstage depth.  Nonetheless at least the JJ sounds like an vacuum tube unlike some of the inexpensive Russian offerings I've heard.  So, much like the TJ and the Psvane, a solid offering but, and your mileage will vary, not exceeding the better old stock versions of the 12AX7 I've heard.

Project: Building a Pass Aleph J Amplifier

After the success of the ACA amplifiers, I decided to tackle something a little more difficult: the Aleph J, which is yet another Nelson Pass design that he released to the community at DIY Audio. Like the ACA, the Aleph J is single-ended design but instead uses two output devices in parallel, along with a current source. Power output is in the 25W range, which is good enough for my small listening area, even with 86dB efficient speakers. Except for the input capacitor on the negative leg of the input, the entire amplifier is also DC coupled which means the output offset must be nulled out.

Nelson Pass has a manual on the Aleph J here.

DIY Audio Build - with better pictures than mine - is here. Also includes a schematic.

I first stuffed the circuit boards, including the power supply PCB, with the passive parts:

And next was the installation of the Jfets and FETS, along with the placement of the circuit board on the heatsink. I ran into some problems that the DIY Audio community graciously helped me with. Turns out that I have too much of a soft touch with the soldering iron and had a few cold solder joints. It's that fear of burning up those rare 2SJ74 jfets that make me nervous. Also note the Keratherm output transistor insulators which are a lot easier to install than the old "white goop" thermal grease, and also make removing the board easier for troubleshooting. 

  

I'm obviously skipping a lot of the build steps - power transformer installation, power switch, and the wiring. So with the magic of my time machine, here is the end result of most of my labor: some magic glowing blue LEDs. I do have to say that the DIY Audio Store supplied chassis and circuit boards made this project a lot easier - everything, with the exception of the power transformer, just fits without having to drill holes or battle with placement.

Here is a picture of the completed amplifier :

Note on playing the Aleph for the first time in the main system: I'm quite impressed - lots of little detail on records that I hadn't heard before, super fast but delicate sounding - ie, not aggressive. Excellent bass control. Some actual depth and wide imaging. They would make excellent mastering/studio monitoring amps.

The sound is a tad "clean" - lacking some of that bloom that I hear with the best tube amps. So like digital television versus 70mm film. Perhaps not the best analogy but the only one I can think of. It does need some more break-in time so I'll be patient. But - at least in this system - it is the best solids state amplification I've heard. I think a really good SE tube amp would be preferable but at half the cost, the Aleph is certainly in the running.​

01/04/19 Update: The Aleph J is one of the more interesting amplifiers that I've ever experienced.  It has such a lack of apparent "character" that it just blends into the background.  I'm not trying to say it is boring, quite the contrary; you can hear the differences between recordings.  That is to say every record sounds different, as to be expected.  And, for a solid-state amplifier, it has some of the best body and definition I've heard.  I'm really beginning to hear the limitations of my front end now!  The bottom end is also tightly controlled too, giving quite a bit of boogie factor even with the small woofers of the Denton speakers.

Now the Aleph still doesn't sound like a tube amp - but it also doesn't have that upper-midrange glare or treble edginess I hear with lesser solid-state amps.  Highly recommended for its neutral character and dynamic ability.  This amp will be running in my system for a long time while I start to explore different turntable and speaker upgrades.  Stay tuned!

The Most Important Amplifier In the World: The Dynaco 70

 

The Dynaco 70 is the most important tube amplifier ever made.  Sure, some may quibble at that characterization, but I can’t think of any other amplifier – at least within North America – that has turned on more audiophiles to the possibilities of tube amplification.  Like countless others, it was the amplifier that turned me on to an alternative way of listening to music. 

Back in the late 1950s, the stereo wars were heating up.  Many audiophiles had invested in the expensive monoblocks or stereo amplifiers from Marantz, McIntosh, and Fisher.  The smaller players – Heath, Dynaco, EICO, and Pilot were nipping on the heels of their more upscale brethren.   David Hafler made the right move at the right time by introducing a $99 stereo wonder – the Dynaco 70.

Sure, this little budget amplifier couldn’t compete with the big boys at a performance level, but it was such a bargain that no one seemed to mind.  The sales numbers certainly back this up.  Yes, the power transformer was woefully underrated for supplying the current to four EL34s, and yes, the 7199 tube is not an ideal driver/phase-splitter, but whatever failings the Dynaco 70 has is ameliorated by the warm forgiving sound that throws a big wide soundstage.  This is an amplifier made for playing music, and if paired with good tubes, the performance is damn well good enough to have made me a tube convert for life.

I bought my first Dynaco 70 at the tender age of nineteen.  I was heading off to college and needed a stereo system.  At the time I didn’t know anything about tube amplifiers but came enamored with them after hearing a McIntosh 240 over at a friend’s house.  I loved the black transformer and chrome chassis look and lusted after the glowing tubes.  When he asked if I wanted a tube amp, I readily agreed.  However, I will admit that I had to hide my disappointment when he brought out the brown caged Dynaco 70.  It certainly couldn’t compare to the McIntosh in the looks department.  But little did I know how this little tube amplifier would change my life.

The amplifier started stock with Siemens EL34s, a Mullard 5AR4, and RCA 7199s.  After a few weeks of that, the same friend suggested running an outboard tubed regulator to supply the front end.  With the shortage of 7199 tubes – this was before the Internet, mind you – I converted the PCB, through the use of a RCA manual and my first soldering iron, to use 6GH8As.  After that, it was modified to run the EL34s in triode.  After that, it was sadly sold to another friend who began his own audio journey with tubes.  At that point I was running modified Scott or EICO integrated amps, a small step before my DIY journey.

A few years ago, I exchanged emails with the fellow who bought the Dynaco 70.  He still had it!  We did a swap and I had my very first amplifier back in my possession.  The original circuit board was long gone, the tube sockets were shot, and the can cap had been replaced by a giant oil power supply capacitor.  This old amplifier was due for a rebuild.

In order to stay true with the spirit of the Dynaco house sound, my restoration was fairly limited in scope.  The input circuitry was replaced with a PCB from Triode Electronics that utilizes a pair of EF86 tubes and a single 12AU7.  The power supply can-cap was replaced with a SDS circuit board that fitted underneath one of the output transformers.  A bit of wire and solder, some new output tube sockets, and the amplifier was ready to sing again.  

For tube selection, I went with some budget Russian valves – EH EL34s, Sovtek EF86s and a 5AR4.  The sole American tube was a late production Phillips 12AU7.  The sound, as to be expected, was a little on the harsh side.  This was due to the “solid-state in a bottle sound” that afflicts many of the lower-end Russian tubes.  So it was time for a spate of rolling.  In the end, the amplifier finished with Matsushita EL34s, Dutch EF86s, a Hitachi 5AR4, and a 1950s-era RCA blackplate 12AU7.  This change made for a much smoother and cohesive amplifier that was quite enjoyable to listen to.

But, I’m not the sort of chap who wears rose-colored glasses.  The Dynaco, even with an improved power supply and new input circuit, suffers from several flaws that stop it from being a truly great amplifier.  

First of all, the power transformer is helpless underrated in the current department which will cause the voltage to sag at higher output powers.  Another issue is the use of a single 5AR4 rectifier to handle all four output tubes.  Sure, it’s within the specification of that tube, but still it is hitting the top of the envelope.  Of course these two problems can be rectified (ha! – editor) by an aftermarket power transformer and a different rectifier or even the use of solid-state diodes (which have their own issues).

However, even with those changes, I believe the fatal flaw of the Dynaco 70 rests with the A-470 output transformers.  Like many things Dynaco – especially on their budget gear – this output transformer was built to a price point.  At higher output levels, the amplifier sounds like the core is saturating, giving that pleasant “tube-like” compression.  It sounds like the images are on springs, causing the soundstage to shrink in size as large dynamic swings occur.  Why do I pin the blame on the output transformers?  I’ve heard the same effect on the Dynaco Mark IV, the monoblock version of the Dynaco 70 that have a much beefier supply that isn’t shared between two channels.

So yes, the Dynaco 70 – and all the new kit versions now available – is still a great introduction to the world of tubes, but it isn’t the end game.  There are much better - and admittedly more expensive – amplifiers that really lift the veil over the music and provide the sort of output that an audiophile wants to hear.

Review: Quicksilver full function preamplifier

Introduction
Quicksilver has been around for quite some time, but their products are often overlooked for the more flashy Conrad-Johnson, Audio Research, or whatnot.  However, much like VTL, Quicksilver instead concentrates on simple but solid tube circuitry, robust old-school construction, and moderate - at least for audiophile gear - prices.  The full function preamplifier in question is the earliest incarnation of the product having first hit the street in 1988.  Price back then was a princely $1995, making it roughly in the same price range as the famed Audio Research SP-8 or the slightly later Conrad-Johnson PV11.

I bought mine from a seller on Audiogon.  Shipping was prompt and I received a very heavy duty preamplifier that doesn't quite have the same ooze of quality that ARC or McIntosh has, but certainly is no slouch in fit 'n' finish.  Cracking open the top plate grills, you will see that the power supply and signal path are separated by a thick steel wall.  Very nice.  Component quality is also good though hardly esoteric.

Circuit and Controls
A quick look over the tube complement and circuitry:  Some of this is based on guesswork since no schematic could be found.  The power supply uses a large power transformer, a pair of 6X4s which are still widely available NOS, a small choke and a number of large Mallory capacitors to provide the DC smoothing, along with some regulation for what I assume are the tube filaments.  The line stage uses one 12AX7, one 12AU7, and one 12FQ7.  Since the reported output impedance is so low, I'm assuming the 12FQ7 is being used as a cathode-follower with some negative feedback wrapped around the entire circuit.  The last bit is the phono stage which only uses a single 12AX7 and a 12FQ7 with some sort of green LED biasing.  Coupling capacitor quality is in the meh range, but hardly out of place for the era.  The big 2uF capacitors on the output stage are some REL Polyesters (ughh).  The smaller signal caps are branded Quicksilver though also look to be REL made.

Front controls are fairly standard though a little dated: No remote here!  Lighted power, AC rear receptacle switch, and a mute button make up the left hand of the faceplate.  The right side has a tape monitor switches, a reduced (20dB) gain switch, a selector switch, and a stereo/mono/etc switch.  Volume control is dual mono with one stepped Blue Alps per channel.  These actually work better than expected - with the numbered volume steps it's very easy to match levels between channels.

Rear panel is the usual assortment of nice gold-plated RCA jacks and a grounding post for the phono stage.  Power cord is captive.  Fuse Holder holds a 1A unit.  AC receptacles are a nice throwback to the days when the user would power up his amp and sources with one flick of the on button.

The Sound
Okay, enough introductions - how does it sound?  Well, since this is an older unit, the stock tubes are long gone.  For the purposes of this review I used some really nice NOS tubes from my stash, so results will vary to a certain degree depending on what is plugged into the sockets.  In my case I used early 1960s short plate Mullard 12AX7s, a late 1940s black-plate RCA 12AU7, and 1960s-era side-getter RCA 12FQ7s.  Rectifier tubes were Tungsol 6X4s.  Some generic tube damping rings came with the unit, so I kept those in place.

It's been my experience that ultra-regulated, current-sourced, current-sinked, and whatnot circuits are very detailed, but also suffer from sounding slightly unnatural.  Note that tube regulators are usually better than solid-state, while shunt suffers from less sterile sound than series.  My own DIY experiments with a simple linestage showed that pulling regulation out of the circuit actually improved overall musicality and enjoyment.  Sure, some of the last bits of inner-detail are missing, but the music usually sounds more relaxed with a looser power supply.  This type of sound was very evident with the Quicksilver preamplifier which just uses chokes and caps to provide a clean source of DC.

Compared to my old Threshold FET-10/HL linestage and Audio Sector Phono Stage, the Quicksilver (with Cinemag step-up transformers) has a relaxed presentation that draws you into the deep soundstage.  It's almost like unclenching your teeth after a roller-coaster ride, or taking a good solid gulp of your favorite adult beverage: the muscles relax and you sit back with enjoyment, washed away by the sonic swirl of the music.  A good stereo should be a psychedelic experience - an unregulated and legal high - that lets you forget the troubles of the world.  With the Quicksilver preamplifier, I feel as if my entire audio experience has been improved.


Listening Notes:
I used my turntable exclusively for this review, but the linstage by itself is no slouch either.  The Audio Sector phono stage combined with the Quicksilver was a pleasant surprise, but the Cinemag and native phono section got the nod in sound quality.

The Who - Tommy (W. German Polydor):  The Quicksilver has very excellent detail and speed, keeping up with Keith Moon's manic drumming without breaking a sweat.  Small individual instruments - like a small bell - maintained their place in the soundstage while still being audible in the wash of thundering bass and guitars.  Depth was deeeeep, making my room seem bigger than reality.

The Beatles - Rubber Soul (Japanese Parlophone): This particular cut of this famed album has been described as bright and bass heavy compared to the original British pressings, but to my ears it sounds like it was eq'd flat.  With the Quicksilver, treble is extended and detailed with out any forwardness or grit.  There is lots of nice detail with John's wonderful voice cutting through the primitive stereo mix.  It's harder to get closer to the Beatles than this.

Tom Waits - Closing Time (80s Asylum): Perhaps I'm a sentimental slob, but I love this album.  However, the Quicksilver revealed the limitations of this later pressing.  Some detail, compared to some better versions, was missing, as if the music was hiding behind a thin gauze.  Tom Waits voice, however, was still wonderful, leading to some near tears while listening to the bittersweet song Martha.

Record after record revealed a preamplifier - and stereo system - that was very analog sounding.  Perhaps somewhat lacking in some of the hyperdetailed / transparency of more modern pieces, the Quicksilver was still no slouch.  When it came to musical enjoyment, I give it an extremely high ranking since it never sounds bleached out or unnatural, even with less-than-perfect recorded music.  If you want a preamplifier that speaks to the mind instead of the heart, you may want to look elsewhere.  I've gone down that road with my foray into solid-state gear, but I'll take naturalness over artificial effects any day of the week.


Overall:
Soundstaging:  Deep and Wide, imaging goes beyond the boundaries of the speakers and even the walls of my listening room.

Treble: Airy and extended, but also pure and detailed.  Compared to the darker Threshold/Audio Sector, it seems there is even more overall treble, but yet it never is harsh or unfaithful to the record.  A strange effect and not at all what I expected from tubes and a step-up transformer.

Midrange: Glorious, but not overly slow or "tubey" in the classic sense.  The Quicksilver certainly doesn't sound like a soggy Dynaco PAS.

Bass: The 12FQ7 output tubes can swing some current while delivering a low output impedance.  This translated into control.  I certainly didn't miss the solid-state drive of my last preamplifier combination.

Speed: (or PRAT) Good tube gear isn't supposed to be sloggy 'n' slow.  The Quicksilver preamplifier and Yaqin amplifier combination certainly doesn't sound like an aged tube integrated or a Dynaco 70 in need of a rebuild.  Instead, the music transients started and stopped on a dime with no overhang.  With the UREI loudspeakers, this led to a very dynamic, exciting, but yet unfatiguing sound.

Detail: As mentioned above, the Quicksilver is no king at wringing out the very last drop of detail from the music.  No, it isn't flat or uninvolving, but the very last bits of information are perhaps less apparent than some other units I've heard.  Some of this may be due to the large Polyster output capacitors.  An upgrade is due for some of the parts - notably some new polypropolene capacitors - so it will be interesting to see what effect this has on the sound.  But really, I'm not complaining because I'll take all of the positive attributes over hearing the squeaky chair of the violinist in the third row.of the orchestra pit.


Conclusion
For a going used price of $850-$1000, the Quicksilver full function preamplifier is highly recommended.  It's extremely well-made and is very natural sounding.  Errors - and I mean minor - are ones of omission with a high scale of musicality.  The simple circuitry will minimize future troubles since there are less "moving parts" once you get rid of the solid-state and regulation support circuitry often found in modern tube preamplifiers.  I expect to increase the audio grade of this unit with some coupling and electrolytic capacitor replacement, so stay tuned!


Main System:
VPI HW19 Mark III with SDS Power Supply
aluminum rebodied Denon DL-103R
Rega RB300 with Cardas wiring
Cinemag CMQEE-3440A in custom aluminum box
Cardas Cross 1M interconnects
Quicksilver preamplifier with (real) Mullard 12AX7s, RCA 12FQ7s, and a RCA 12AU7
Cardas Quadlink 5C 1M interconnects
Yaqin MC-10T amplifier with black-plate RCA 12AT7s and (real) Mullard XF2 EL34s
Cardas Hexlink 2M speaker cables
UREI 813A speakers
VTI BL503 equipment rack