Review: Denon AU-S1 step up transformer

 

Moving back to a low output moving coil has been a real eye-opener.  Yes I had experience with the venerable Denon DL-103R mounted on a rather sketchy VPI HW19 Mark III with a Rega RB300.  But, at least with that system from long ago, I never quite cottoned to the sound I was getting.  I wanted more.  Luckily I found it (some time later!) with the Rega Planar 8 with a Rega Ania Pro MC cartridge.  This combination has quickly become my favorite analog reproducer so far.

My MC step-up transformer is the popular Cinemag 1254 which did its job quite admirably.  Nonetheless I had a nagging thought I could do better here.  Would a passive device, especially something made of wound wire actually make a difference?  I had to find out.  So I read and read some more, trying to find an affordable venue to follow.  I thought of buying some Lundahl transformers and DIYing my own case.  Or I could have gotten anything else, including an active device to give me that additional gain needed for the low 350 micro volt output of the Ania Pro.

Several searches on Ebay and I saw a Denon AU-S1 unit for sale.  It looked extremely well built, more so than my Cinemag "transformers on a box" look.  But finding information on the Denon was, to be blunt, extremely difficult.  It was designed for Denon's once top-of-the-line cartridge, the DL-S1 that cost a princely $1000 way back in 1996.  The transformers themselves are mounted horizontally in the case with padding to reduce vibration.  How much this would work in real life is questionable.

After several audio philosophical discussions a friend, I decided to take the risk on purchasing the AU-S1.  It was the idea that something like this would be of the highest quality given the amount of time and research that a company like Denon can do.  There was only way to find out.  Thankfully the Japanese seller was very quick and I received the transformer(s) in only three days.  The AU-S1 weighs _alot_ for such a small thing.  Build quality was extremely good with gold-plated RCA jacks and (oddly enough) separate grounding lugs for each channel.

 I took out the Cinemags and put the Denon in its place.  Turning the volume up I was immediately taken aback by the amount of hum I was getting out of the speakers.  Moving the AU-S1 around and I was able to get some reduction in noise but still I wasn't happy about it.  It wasn't until I touched my fingers to the left RCA outside jack and then to the ground lug that the hum completely disappeared.  It's the nature of the Rega turntable output connection which doesnt have a separate ground wire.   To circumvent this grounding issue I took a length of solid-core bare wire and wrapped it several times around the left RCA outside lug with one end plugged into the ground lug of the AU-S1.  After that I was hum free!

Well, dear readers, that was a lot of introduction for something that was ultimately bought as an experiment.  How does it sound?  Read on.

Initial impressions were good - solid bass, a "cleaner" view of the soundstage, and just better air. Several records later and a listening session with my audiophile friend and I can say the Denon AU-S1 was a worthwhile upgrade.   

Does it surpass the Cinemags?  Yes.

The Denon reproduces the space around instruments better - such as the horns on Lonnie Liston Smith's Visions of a New World.  This gives the impression of more body and weight.  

And speaking of body, the bass is terrific.  It feels like an extra octave is being recovered - not bloated - but detailed with depth and slap.  Something that was really apparent on Brian Bennet's Voyage album as the excellent bass player provides the space age groove.

Soundstaging is deeper and wider than before.  An example of this is the beautiful Dead Can Dance album Into the Labyrinth.  The second song, "The Ubiquitous Mr Lovegrove," has a moment where the drum shifts left and right, now well detailed beyond the edges of my KEF speakers.  A true demo disc moment.

Overall there seems to be less grain than before.  Why?  I have no idea.  The purity of the copper?  The padding reducing microphonics?  The quality of the transformer windings?  Your guess is as good as mine but the clarity is higher than before and that's all that matters.  Finesse would be a fine word to discuss these SUTs, and given their roughly $700USD price they are a good bang for the buck.  Perhaps, when funds permit, I'll try something more expensive.

Denon AU-S1 Step-up Transformer Specifications
- Ratio: 1:13
- Frequency range: 10Hz-80kHz
- Size: W150 x H70 x D175mm
- Weight: 7.1 pounds

Review: Sovtek 12AX7WA

 I have a love and hate relationship with Russian tubes.  Some of them - like the ECC99 - rival some of the best vintage American and European tubes, while others, like much of the Electro-Harmonix line sounds like solid-state in a bottle.  Yes these tubes can be transparent but they are often lacking in detail or suffer from an aggressive treble and upper midrange.

The early Russian tubes, that first were available in the 1990s to the Western World, were godsend to the tube-o-phile community.  They were cheap and rugged.  An example of this is the 5881WXT which could take the current hungry bias of the Harmon-Kardon Citation V.  Even a RCA blackplate of the era would start to glow on the seams.  But not these Russian mil-spec tubes.

It's been my belief - shared by some friends too - that Russian tubes have good metallurgy but not the best cathode chemistry.  Yes they are rugged, but many of them have the already mentioned issues with the higher frequencies.

As for the Sovtek 12AX7WA, it has a pair of very small coated plates and what I would call a primitive looking spacer that should be made out of mica.  The pins ends are sharp but overall construction looks quite good.  I plugged it into my Frankenstein EICO ST70, which provides the initial gain before the 6SN7 phase-splitter.

The Sound:  Initially I was surprised how much I like the Sovtek.  The sound was very transparent and, at first listen, very modern sounding.  I was reminded of a really good JFET preamplifier or MOSFET amplifier - big, dynamic and smooth.  But, like the aforementioned solid-state gear, lacking in inner detail.  The soundstage was also smeared a bit, removing the space around individual instruments and the big front-to-back sound of a vintage Mullard.  Dynamics in the upper part of the spectrum became a little rough/forced sounding with the Sovtek.

What I'm really finding - at least so far - is that modern tubes often has a good tonal presentation but lack in inner detail and making a big soundstage.  I'm curious to the reason why this is true.  Is this linearity or an artificial presentation brought on by - an unknown variable?  We shall have to continue and have some vintage comparisons.  More later!

Review: Rega Planar 8 turntable

 

I've owned a half-dozen turntables in my time.  Starting with an old Technics direct driver with a p-mount cartridge and working through two VPIs, a long running Dual CS5000, and two Thorens of varying vintages.  Except for some experimentation with the Denon DL-103R MC, it has mostly been MM cartridges of different expenses.  I thought, for example that the Thorens TD309 and Ortofon Bronze cartridge was very good - especially for the price - combination.

Well the past few months living with a new Rega RP8 and Ania Pro MC cartridge has been a real eye-opener.  Gone is the fuzziness and opaqueness of the MM sound, replaced by more detail and a bigger soundstage.  The experience has changed my mind about the moving magnet.  Though the Rega Ania Pro MC needs a step-up transformer  - in my case Cinemag 1254s - the speed and transparency has brought everything up to a much higher level of refinement.

Since there are already several reviews of the 'table I will keep it short.

The biggest surprise with the Rega combination is the bass and dynamics.  It was always my belief that a "real" turntable required a gagillion pound platter and base.  Instead the RP8 is decidedly unimpressive - at least visually - compared to something like a VPI Aries.  How did Rega do it?  I have no idea about the mechanical engineering behind this table, but, to my ears, is just works.  Perhaps it is the turntable acting as a whole system with a cartridge, arm, and everything else like the included speed controller working together.

Soundstaging, like on several original Dead Can Dance LPs, is superlative.  We are talking a rounded arc left-to-right that goes beyond the edges of the speaker, along with exceptional depth.  The coloration and clarity of something like Lonnie Liston Smith's Visions of a New World comes through much better than my now-departed Thorens TD309/Ortofon 2M Bronze.  This is also a big sound turntable with excellent resolution and separation of instruments; exceeding any front end I've ever had before.

Yes the Rega RP8 is much more expensive than my previous turntable but, at least in this case, the cost was worth the sonic upgrade.  Not only does my whole system sound that much better, but everything from the preamp to the amplifier and even the speakers sound way better than their price point. 

Very, very recommended.

System:

• Audio Research SP8
• modified Eico ST70 with 6AR6 tubes
• Cardas Neutral Reference interconnects
• KEF R500 speakers with Mogami stranded wiring
  
• Dual CS5000 turntable with an Ortofon OM20 cart, aftermarket Shibata Stylus

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.

Review: Psvane 12AX7

 

The Psvane T-12AX7, apparently the base version, is a Chinese design that looks much like a vintage one with gray ribbed plates, quality construction, and steel pins.  The triple-layed mica also looks good.  Bulb size, like so many other new tubes, is slightly larger than my collection of old stock, a mm or two difference in height and circumference..

Break-in was approximately fifty hours as the driver tube in my Frankenstein Eico ST70.  This is basically the classic Mullard 5-20 circuit.  It's been my general experience that the driver tube - before the phase splitter - has a high impact on the overall amplifier sound, more so than the phase-splitter or even the output tubes.

Listening was initially done while reading a book.  There were several times where I had to look up from the pages to truly appreciate what I was hearing.  Like the TJ FullMusic, the Psvane has a great almost vintage tone.  I was hearing little details - an example is Lonnie Liston Smith's Vision of a New World - that I thought weren't apparent to my standard vintage Mullard.  I was beginning to feel some really high hopes for this Psvane.

However some further, more detailed listening, some of it shared with an old audiophile friend with an extensive knowledge of 12AX7s both new and old, began to show some weaknesses.  Though the sound was never muffled, the Psvane, like the TJ, also lacked inner detail and bloom around the instruments.  But wait a minute, you say, where did that extra detail you mentioned go?  It is a strange effect of the Psvane: suppression of reverberation both artificial or natural, pushed some information forward.

Keep in mind this is still the best new production 12AX7 I've heard and I could see use for it in gear or speakers that aren't the most transparent.  The bass was excellent, there was a distinct lack of glare unlike some lesser "solid-state in a bottle" new production tubes.  The midrange was also even as was the treble.  It was just the lack of detail that stopped the Pvane running with the best of the vintage 12AX7s.

Disclaimers: No tube is 100% perfect for all gear.  The only way to be sure how a tube will sound in _your_ system is to hear it.  Also a tube in a phono stage, for example, may have different audio characteristics than say line, input, or phase-splitter use.

 Negative feedback - several dB in this circuit - also reduces the sonic signature of the tube.  An example of this came apparent to me when I built a triode-connected EF86 linestage.  The tube selection - GEC CV4085 and the Mullard "long mesh" were the best - played a big role in the sound quality.  However the EF86 in my Eico HF60 monoblocks were less important, most likely due to the loop negative feedback or perhaps the total number of tubes in play with a more complicated circuit.

 It should also be noted that I am not biased towards vintage tubes.  I really do want a new tube that can compete with the old.

So take this review as a general guideline, not as hard fact.