Thursday, June 14, 2012

Review: Quicksilver full function preamplifier

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.

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.

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

Monday, June 4, 2012

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:
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!

Friday, June 1, 2012

Revisiting the UREI 813A loudspeakers

In my previous review of the UREI loudspeaker, I claimed:
Weaknesses? Maybe because of the large baffle area, these are not soundstaging champions. Most mixes never go beyond the sides of the speakers. Another downside is that the sound never truly opens up until these are playing very loud. This makes them unsuitable for apartment and condo dwellers. Because of this, they don't quite work with baroque music either. They are also a touch dry and unrelenting - a bad recording is well, a bad recording and they will certainly show you the weaknesses of your favorite not-so-well-mixed music.
After some extended listening with a new front end and different amplification chain, I'll take most of those words back.  With an EL34 based amplifier and my improved analog front end, I am now getting excellent left-to-right imaging that goes beyond the boundaries of the speakers.  Depth has also improved.  The EL34 coupled to the Altec 604 driver has also resulted in a smoother, more coherent sound than either the Threshold S/500 or my old Dynaco Mark IIIs using SED 6550c.  Now hearing inner-detail doesn't require the volume level to be cranked to the max which makes me happier.

Lessons learned?  The front end is the most important part of your system; concentrate on that part before casting blame downstream.  Also the UREIs are in fact very neutral speakers only revealing the flaws of your signal chain.  That is to say that modern production tubes just can't hold a candle to the old stuff, especially in the treble department.

Main System:
VPI HW19 Mark III with SDS Power Supply
Rega RB300 with Cardas wiring
aluminum rebodied Denon DL-103R
Audio Sector Phono Stage with OPA627s
Cardas Cross interconnects
Quicksilver preamplifier with (real) Mullard 12AX7s, RCA 12FQ7s, and a black-plate Raytheon 5814
Cardas Quadlink 5C interconnects
Yaqin MC-10T amplifier with black-plate RCA 12AT7s and (real) Mullard XF2 EL34s
Cardas Hexlink speaker cables
UREI 813A speakers