December 2015

Margules SF220.15 20^th Anniversary Preamplifier
Margules U280sc 25^th Anniversary Power Amplifier
It's all about enjoying the music.
Review By Ron Nagle

  Being an audiophile can be tedious at times, as we may be easily diverted, and much perverted, by listening to all the latest 'buzz' technology. Why don't you try our Fantasaic Wonder Dots! Just place some on the rear wall and two on the ceiling and five more on the sides of your speakers. Or let's install our Incrediblicious Inaudible Subsonic Frequency Wave Generators that help your woofers woof with new and startling clarity. In a room at the end of the hall, listen to my Magnificentized Magnetized Steel Tubes that flux-fix your wiring. Imagine an entire exhibit hall of headphones with music inside your brain nerve or outside your head... depending on where your head is at. Our latest app allows you to change your music selection by accidentally butt dialing your smart device. Welcome to the 2015 edition of the Rocky Mountain Audio Fest within Denver, Colorado. I really need out to grab some mountain air.

Back Home
Let me take a moment to clear the little gray cells and put behind me that over-the-top braggadocio business buzz. Waiting for me back home in Brooklyn is my present reality. It is an upgraded special edition system from Margules that includes their SF220.15 vacuum tube preamplifier U280-SC 25th Anniversary vacuum tube stereo amplifier ($4599 and $5399 respectively). As a point of interest, the company was founded in Mexico by JacoboMargules and it has been family owned since 1926. There had just been enough time before the Rocky Mountain Audio Fest for me to unpack the SF 220.15 20^th Anniversary tube preamplifier and the U280sc 25th Anniversary vacuum tube power amplifier. My very first impression was that both of these components were made by someone who truly cares about quality. A very nice cosmetic feature is the inclusion of what looks to be Rosewood end caps. This is definitely my idea of attractive audio! Both audio components are built with an all-black chassis replete with gold badges that commemorates their special anniversary editions.

The U280sc Is One Solid Machine
The U280sc audio amplifier's front is unadorned, except for small gold lettering on the left side that reads Margules U280sc Amplifier. Just above this is the Margules logo outlined in gold. This logo is hard to describe, yet it looks to me like a stack of four black feathers. As supplied, the owner's manual is a bit thin and there are no diagrams inside that show were everything is located. So of necessity let me paint a picture in your head.

Atop, at the very front edge of the chassis, you will find five round black knobs. These knobs offer choices that I wish were included with every power amplifier. Beginning on the left side the first knob can switch the amplifier from stereo output to mono operation. To the right of that is the left channel impedance selector. It is marked for 2 Ohms, 4 Ohms or 8 Ohms. You can select speaker loading while the amplifier is playing and the resulting effects are not subtle. By switching the U280sc to the 8 Ohm position it markedly tightened the bass response of my Aurum Cantus Leisure 2SE monitors. Grouped at the center are the two left and right channel Gain controls. This adjustment allows you to shift the sound stage focus and move the sound stage image left or right to center it between stereo speakers. Of course this is like a balance function usually found on a preamplifier. But having this ability included with a power amplifier makes perfect sense to me. As you change a preamplifiers balance control by shifting either to the left or right you are actually shifting information in one channel relative to the other. (Trust Messrs Fletcher and Munsen) That is not exactly the same thing as a channel gain level adjustment.

Having power supply controls that provide independent right and left channel gain adjustment causes me to question why this is not a standard feature. The last control function is the right channel loudspeaker load adjustment. You can easily select 2, 4, or 8 Ohms on the fly. The amplifier uses a total of four 12AU7 dual triodes and it came with four KT88 beam power pentodes; that's two triodes and two pentodes per channel. Between the left and right bank of tubes there is a De Arsonval type meter calibrated to read in milliamps. At turn on there is a 60 or 70 second delay before the amplifier reaches its turn on threshold of 47mA. For each channel the input, phase splitter, and driver stages are configured using a pair of 12AU7 dual triodes. I confess a partiality for hollow state electronics. The warm glow of thoriated-tungsten cathodes reminds me of a warming fire on a cold night.

Margules' U280-SC 25th Anniversary amplifier incorporates an active servo biasing feature. Consequently, it is possible to interchange a variety of pentode output vacuum tubes. Compatible types include 6550, KT88, KT90, KT100, KT120, and KT150. There are two perforated tube covers protecting the left and right compliment of glass valves. These covers can get uncomfortably hot, yet not so hot as to cause harm. Margules states that the U280sc amplifier uses Class A for the output stage, has zero negative feedback, and has a regulated shunt power supply. The U280-SC amplifier can be configured to operate in ultralinear, triode or strapped mono modes. It is important to know that no matter how the output is configured the amplifier remains biased in Class A. There are two small toggle style switches on the top chassis surface next to the KT88 tubes; with these single pole double throw switches allowing you to quickly switch between triode and ultralinear modes of operation. This switching can be done while the unit is operating (I like this feature quite a bit). The rear of the power amplifier has two unbalanced gold plated RCA inputs, four copper Edison Price style speaker binding posts, two fuse holders (one for each channel), a power on/off switch and a switch style circuit breaker next to an IEC line cord socket.

Margules SF220.15 20^th Anniversary Preamplifier
This "Ultra Resolution" preamplifier functions like the old hardwired telephone center within a hotel. There is a large conventional volume control knob on the right side and the unit includes a remote control too. Julian Margules tells us this low output impedance preamplifier employs a shunt regulated power supply for better Q and fast transient response. This power supply is isolated within a separate internal enclosure. Additionally, the preamplifier uses five 12AU7 dual triodes operated with a DC filament that is sourced from an "actively damped" power supply. As far as the internal design of the SF220.15, that's all it says inside the owner's manual. I would like to know more, for instance how/why it uses five identical 12AU7 medium Mu tubes. If you just paid $4599 for a vacuum tube preamplifier they should provide more information on where you money went to, and why. By the way, both units use silver plated epoxy circuit boards and metal film resistors, so that helps us to better grasp the product's pricing.

Check Out The Back
Located on the rear panel are four unbalanced RCA inputs and outputs plus an RS232 input connection. The four RCA output jacks are stacked in pairs one above the other in this top down order. The first and second pair of RCA connections are simply labeled One and Two. The next two pairs just below them are labeled Direct Out and Direct In. The four RCA input connections are designated CD, Line 1, Line 2 and Line 3. All of the active/selected input devices have a corresponding red LED indication illuminated on the front panel. But with that I do have a question. The first or top set of inputs is labeled CD yet the remote control has no CD button. It does have a DVD and an SACD button, yet this is not relevant in a two channel stereo system. Also, the remote control has buttons labeled Aux.1, 2,and 3 though the rear inputs are not designated that way. The RS232 input connection "allows control by any automation system". Also, one of the preamplifiers inputs is direct and thus bypasses the SF220.15 volume control. This allows an external 5.1 channel processor to control system volume and integrate the preamplifier into an A/V surround system. Two of the outputs are in parallel so one can be used by another amplifier or a separate subwoofer. The last output is a direct output and thus is not pre-amplified. In other words, it bypasses the SF220.15 circuits so that the volume is set by the device connected to it. And lastly, there is a conventional AC socket for auxiliary power that can be switch on or off by a small switch located just above. Quoting, "This out let provides a high current source, 600 watts".

Switching Class
From ultralinear to triode operation, the most noticeable difference as you should expect is a drop in sound volume. Ranking second, there is a noticeable change in the sound of bass reproduction. It seems the bass is now warmer and more rounded as it losses some transient speed when telling us about things going on below 150Hz. However, the triode sound is very much better regarding one of my must haves and that is dimensionality. The soundscape is wide but still pinned at the corners. In triode mode the performance is played out on a deep convex bowl. I do not usually resort to citing artist's recordings because I know you probably do not own them, yet this time it might just serve some useful purpose. The cut is "A Case of You" sung by an older Joni Mitchell. This recording now sounds far more true-to-life by switching the amplifier to triode mode. It is an excerpt of one track from a CD demo compilation. As you listen the timber of her voice has changed by alcohol still somehow this has is made even more poignant. A rasping quality now exists in her voice that touches upon lost years past and hard times that we can only imagine. Still, our ears can bear witness to it as there is an enduring warm liquidity to her voice echoed by an accompaniment of bowed strings that soar a sonorous sigh. This is the stuff of lost longing, as it is the sound of flesh and blood that can touch us all.

The Sound Of Music
Fire in the filaments, and then after the first ten seconds something clicks in your little gray cells as one realizes you have been gone for far too long. You had forgotten the sound of vacuum tubes. The effect is poignant, and the contrast tells me why I burned out at the 2015 Rocky Mountain Audio Fest. It was simply sensory over load. Imagine trying to sleep near a busy street with the window wide open. Even if you get up and slam the window closed, still you stare into the dark. What is needed is the Class A tube effect. On a subjective level, imagine a purring kitten on pussy cat feet curls up in a ball just under your arm. Imagine then your tension slowly slipping away. That is my Glass Powered analogy. Vacuum tubes, and in this case Mr. Margules glowing globes, produce a very natural harmonic presence that you sense is part of the natural world. And so by this path I travel far away from an incessant stop and start world, pulsing like a digital Morse Code of one's and nothing.

Summation
It's all about enjoying the music. For music to have any real relevance it must reach out and touch inside something inside of us. It is better to follow a flowing stream of continuance that preserves the harmonic structure of music. This is what we respond to instinctively. The people at Margules have used a time tested technology and discovered a way to refine it. This newfound way is so that humanity can link to it. This has relevance that will not age. Thank you Mr. Margules for your music.

Semper Hi-Fi

Review System Components
Sangean Digital tuner, Marantz 8400 universal disc player.
Music Hall Up sampling DAC 25.3 and headphone amplifier.
Sanders ESL power Amplifier, Parasound Halo P5 Preamplifier.
Aurum Cantus Leisure 2 SE two-way ribbon tweeter monitors on 24-inch stands
Mark Daniels Omni Harmonizer panoramic tweeters
Onyx Rocket Strata Mini 3.5-way speakers
Kimber Kables
Monster Reference
Nordost cables
Chord cables
Wireworld power cables
Kaplan Cables
Islatrol Industrial AC line conditioner
Richard Gray 20 Ampere Sub Station
Alpha Core Balanced Transformer Power Supply
Audio Power power enhancer
APC Power Block
Triad  isolation transformer

Specifications
Margules SF220.15 20th Anniversary Preamplifier
Type: Vacuum tube stereo preamplifier
Frequency Response: 5 Hz to 400kHz
Total Harmonic Distortion: <0.014% max
Maximum Output Level: 30 Volts
Gain: 6dB
Raise/Fall Time: 6 micro seconds
Weight: 31 lbs.
Dimensions:16 cm x 45cm x 36cm (HxWxD)
Price: $4599

Margules U280sc 25th Anniversary Power Amplifier
Type: Vacuum tube stereo amplifier, monoblock capable
Frequency Response: 20Hz to 55kHz
Power Ultralinear: 80 wpc
Mono Power In Ultralinear: 135 watts
Triode: 40 wpc
Mono Power In Triode: 80 watts
Distortion: >0.1%
Signal To Noise Ratio: >88 dB
Weight: 70 lbs.
Price: $5399

Company Information
Margules
Uruapan #17-4
Col. Roma
Mexico City 06700
Mexico 
Voice: 52(55) 5514 7448
Website: www.Margules.com

United States Distributor
Integrity High Fidelity Solutions, Inc. 
3386 Harvest Ridge Lane 
Buford, Georgia 30519 
Voice / Fax: (404) 334-3242 
E-mail: info@integrityhf.com 
Website: www.IntegrityHF.com