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

Using the Cinemag CMQEE-3440A step-up transformer

Ah, the moving-coil phono cartridge is famous for it's speed, detail, and audiophile street-cred.  Ranging from the lowly Denon line, up to multi-kilobuck units, the low output moving-coil (LOMC) requires more gain than your average phono stage delivers.  Since I recently bought a Quicksilver full-function preamplifier (review forthcoming), I needed a way to boost the lowly voltage of my Denon DL-103R before hitting the tubed phono section.  I could continue to use my Audio Sector Phono Stage into a line input, but if you're going to run a tube preamp, what's the point of letting the phono section lay fallow?

Enter the Cinemag 3440A step-up transformers.  Cinemag, once a division of the famed Altec-Lansing, has been making this inexpensive step-up transformer for some time.  Word is, coupled to the Denon Cartridge, this step-up makes beautiful music.  Since I already had an aluminum chassis, RCA jacks, switch, and ground post from a previous DIY project, this was an easy decision to make.

Here's a list of what you would need:
Solder
four RCA jacks
DPDT switch (optional)
ground post
wire cutter/stripper that can handle 26awg wire
a few nuts/bolts to hold down the transformers to the chassis
some sort of chassis, metal or plastic will work
a drill press
two Cinemag CMQEE-3440A transformers

Since I didn't want to wait the few weeks for Cinemag, I ordered at a slightly higher price from an Ebay seller.  A few days later and I received a small package with two dinky transformers, two L brackets and two screws.  With both transformers, I screwed on the L brackets, using the longest piece against the bottom of the transformer.  The other end of the bracket was fastened to the chassis into some holes that I drilled with my press.

I put in new RCA jacks and a binding post.  I was lucky enough to already have a DIY phono project that already had holes for these.  If you're not steady with a drill, Front Panel Express or some other company can do the work with a professional fit and finish.

Now comes the wiring.  I used Cinemag's wiring diagram:

Input: Brown and Yellow wire RCA input lug
To Position 1 of switch: Red and Green Wire
To Position 2 of switch: Orange and Blue Wire
From Switch, solder a single wire to the RCA ground lug

Output: Purple wire to RCA input lug
Black, White, and Great wire to RCA ground lug

Note: The switch is optional if you know you are going to just use one of the taps.  With the the Denon DL-103R, the 37.5 ohm input seems to work the best.  At least in my system.  But having the switch does allow one to try both settings.

Another Note:  This wire is thin and fragile.  I use a GB-branded wire stripper from Home Depot.  When stripping off the insulation, make sure not to pull hard on the wire.  I use a needle-nose pliers to hold a section of wire downstream, giving some support.  I would hate to yank a wire off from inside the transformer.


Okay, here comes the moment of truth:  So how does the Cinemag/Quicksilver combination stack up against the Audio Sector Phono Stage?  Well, I will save the nitty gritty for my review of the tubed Quicksliver, but for now I will say that I was pleasantly surprised by the Cinemag.  My presumption was that running the small output of the Denon DL-103R through several lengths of wire would give less detail and dynamics.  But the real world shows great performance: deep bass, good 'slam', extended treble and, as the transformer broke in, plenty of detail.

I may give the nod to the Audio Sector Phono Stage for hi-fi pyrotechnics - attributes like detail and speed.  But the Cinemag/Quicksilver has a more relaxed presentation that makes it easier to enjoy music.  Stay tuned!