March 2006

Delta Studio 6s33s
A Super Duper Amplifier
Review By A. Colin Flood
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  The Delta Studio 6s33s is a new, 100-pound dead weight, stereo tube power amplifier (with volume control), wrapped in a semi-circle of sumptuous wood. With transformers as big as coffee cans, it push-pulls 72-watts in class AB, with the first 20-watts in Class A. Although expensive (priced at 5,000€, currently about $5,931), with some prototype nits, the 6s33s is gorgeous in sound and appearance. It is flat-out one of the best amplifiers I have seriously auditioned, in my own home, with my own equipment, for Enjoy the Music.com.

As far as I know, I am the only reviewer to consistently review equipment with big ole horns as reference loudspeakers. By virtue of a new mate, new job, 3 moves and a handful of hurricanes, I listened to the 6s33s amplifier extensively in 3 locations, on 3 loudspeakers - and was always impressed by its golden sound. I listened not only to my big ole horns, but also to their large baby brothers, the two-foot square Klipsch LaScala horns, and a smattering of vintage solid-state and new age, digital class "T" amplifiers. Each offered some capabilities (sometimes for a price) that the others didn’t.

Let’s get right to it; how did this voluptuous looking babe sound?

Comparisons

First impressions on a Jack Johnson CD were of warmth, smoothness, quickness, a delicate nature and excellent imaging typical of tube amplifiers on big ole horns… but with firmness in the mid-bass. The hard notes lost their edge. The vocals are very forward. They are among the best I recall, as realistic as Joule OTL on Nearfield Pipedreams (See my "Deprecating the G-ds" article) and Avant-garde horns.

The naturalness of the 6s33s midrange on his recordings is peerless, convincing, detailed, coherent and physically present. Johnson’s voice appears with a tumbrel and textural reality. The sonic illusion of a 3D holographic image is as good as any system I have heard.

Warm on the top end, a bit boomy perhaps down below, the Delta Studio 6s33s plays the mid-range with a loving, gentle sound that unites the bandwidth into a coherent and rich whole. Other amplifiers are more extended on the top, better damped on the deep bass, more punchy and dynamic, but this one delivers the joyful effervescence and palatable presence of live music.

Roksan Caspian

One of the smoothest sounding solid-state amplifiers I have auditioned on big ole horns, the Caspian cast gray notes in burnished silver, while the 6s33s amplifier rendered them as delicate pewter. It was almost as if a single-driver loudspeaker, like the eminently listenable Omega TS1s, slipped into the line.

On the 6s33s, the voice is cohesive sounding, but I sometimes wished for a sparklingly treble and hard-hitting subwoofer. While the sharp edge of the treble is subdued compared to the Caspian, the tone was enticing and engaging. It sounded a lot less like a recording. The 6s33s amplifier is not a luscious sound, like the Pope’s new robes. It is more accurate than that, without being bloated or ostentatious. It catches nuances of Johnson’s voice the Caspian never revealed. You do quickly miss the Caspian’s remote control however.

Perhaps the root of the 6s33s amplifier’s superior performance is that it brings vocals to the foreground. It excels at vocals like few other amplifiers I have seriously auditioned for Enjoy the Music.com^®. This is also an easy amplifier to play hard – it sounds good at low and loud volumes.

I have yet to hear a tube amplifier that has the cement solid feel of even a modest solid-state amplifier, and the 6s33s amplifier doesn’t change that. Yet its music is more like the live event, except without the background sound effects playing on the same horizontal plane. While the 6s33s sounds like the mic is down Johnson’s throat, it relegates other instruments to the background. Where the 6s33s subdued Johnson’s rim shots with concert-hall reverb, the Caspian exhibits space around the notes.

harmon kardon 330B Receiver

This single-transformer cousin to the classic vintage receivers is all the power one needs to make big ole horns dance around the room. Compared to the 6s33s though, it is not richly textured. Sonic effects are sharp, bass is bold, almost boomy, but capable of some rumble. The harmon kardon slides up the scale quickly. It is easy to play it loud.

Sonic Impact 5066

This gentler, softer, class "T" digital amplifier fits into the palm of your hand for only $35. It is like the traditional size solid-state receiver in many respects, but without the sharper high end. It has better balance between the vocals, but strumming a guitar has less zing. The 6s33s amplifier impresses images on your brain.

Red Wine Clari

This digital class "T" amplifier is powered by a rechargeable battery the size of a pound of cheese; about half the size of just one of the 6s33s amplifier’s transformer. It is more substantial sound than the SI 5066, more like a stoic linebacker than fleet receiver. And yet, it is still more similar in quality to the 5066 than it is to the 6s33s amplifier. It finds the ringing rim shots of Jackson’s "On and On" and almost captures the lusciousness of the 6S33s. Steeliness in Norah Jones’ mid-range is instantly gone with the 6s33s, as is the edgy treble and hard bass. Coherence and imaging is excellent: the magnificent monster projects the singer and instruments out into the room. Like the female voice, the sensuous breath of the flute is a litmus test for audio ecstasy. Here the 6s33s surpasses any amplifier I’ve heard. It breathes "flute" like none other.

With solid-state amplifiers, if any adjustment is made to the volume, it is most often higher, one needs more of the sound. With tubes amplifiers, if any volume adjustment is made, it is most often lower. Neither is completely 100 percent satisfactory to tweaking audiophiles for all movies and music. 

Bottlehead 2A3 Paramours

Vocals with my Bottlehead 2A3 tube Paramour amplifiers on big ole horns are in the same league as the best amplifiers. Comparing my reference stack of not too challenging soft jazz (see my bio) on conventional cone loudspeakers, incredibly controlled singers like Diana Krall come off smooth and gently, but with less bass control.

The Paramours are lighter and leaner than the 6s33s amplifier. Their quickness makes percussion enjoyable and lends sheen to cymbal ring. The piano tinkles, but does not crash. Where the Paramours render pianos as delicate, the 6s33s amplifier plays them as strident – with energy. It fills in songs, rounds off the treble and makes luscious bass.

The bass booms on Paramours, but does not thunk. While easy to listen to, the Paramours certainly need subwoofer support. You hear the low bass, but with the 6s33s amplifier, you feel it. Bass on the 6s33s amplifier is like a bulky American muscle car. On the Paramours, it is a tight Japanese compact.

The 6s33s amplifier brings out the intelligence of the sound engineer’s design: oh, that is why they juxtaposition those rasping notes on Patricia Barber’s "Café Blue." The logic of tonal contrasts appears as they are meant to. It not only seems to get what music is about, as other tube amplifiers do, but it also has the capabilities to get what the engineer -- probably on solid-state equipment -- was trying to accomplish.

In the past, I gloried in Tracy Chapman’ snappy folk-rock dynamics, but the 6s33s amplifier subdues these effects. It is said amplifier and loudspeaker combinations influence music choices. That is certainly true of the 6s33s on both conventional cones and big ole horns. Although perfectly adept at movies, I gravitated away from slamming rock sessions and yet could not get enough of female vocals (my favorite anyway).

Pass Laboratories Supersymmetry™X250

The 6s33s amplifier should be compared to amplifiers in this league. The league of first-class, heavy-weight, does everything right, as long as you don’t let beauty queens up to their hotel rooms, power-punchers. The league of champion amplifiers. I loved this amplifier, but did not get a chance to race it down the same streets with the 6s33s. My impression however is that the 6s33s amplifier would deliver an gorgeous edge in the mid-range, while the silver Pass mountain would dominate in the bass and treble trials. See my review of this incomparable monster within our archives.

Preamplifiers

A good pre-amplifier can certainly be the icing that makes the audio cake. I tried my classic Dynaco PAS 3, but liked the CD player best when piped directly to the 6s33s amplifier. The soundstage was better, the treble smoother, with less of a hard or leading edge.

The Manufacturer

Delta Studio’s office is located in Wroclaw, the biggest city in the southwest part of Poland. The company is owned by Witold Jaskulowski (pronounced Vi-told Ias-koo-lov-ski), who designed the amplifiers’ semi-circle shape. The amplifiers’ electronics are designed by Marek Kochanski (pronounced Mark Ko-han-ski).

Jaskulowski is a big music fan with a large vinyl collection. He was always looking for perfection in music. For years he was buying, testing and collecting audio equipment around Europe. During his search, he met Kochanski, great amps and transformers constructor also a music fan. Kochanski knows perfectly power tubes construction. They joined together in 1999. After 2 years of search for the best components, such as German capacitors and hand made output transformers, in 2002, the 6s33se was produced. This is the most powerful integrated amplifier in the Delta Studio family.

Enter The Third Man

Tomasz Szylar does business in the US as Hi End Studio. He is the US distributor for Delta Studio. This review introduces his product to the US market. "It is really hard to break into the market with an unknown product," he writes in halting English, "from middle Europe. I was looking for amp kit for me and searching web all over USA, read hundreds of reviews, I can't really decide which should I buy. Then I found the Delta Studio web site."

"I went to Poland to see Witold and his amps. He built kt88 and 6s33se amplifiers for me. Today I'm very happy with my choice. They play wonderful, no problem at all! Any time I can contact Witold - ask him for advice and help. They provide wonderful service and great products. Then I decide that this is the product what customers will be very proud to have, so I start to sell this product in the USA. Thus Hi End studio was born."

Now Szylar offers three Delta Studio models:

Delta 845/GM70, Single Ended Triode, integrated amp with separated power supply.

Delta 6s33s SET, Single Ended Triode, dual monoblock (stereo channels, but on a single chassis)

Delta 6s33s Push-Pull, integrated, 2 power tubes per channel

All models are made for Europe with 230-volts and for USA with 115-volts.

The Tubes

The output tubes for the amplifier are four squat, powerful looking 6s33 bottles, about the size of a small fist, with a crown of dimples on top, like a meringue pie. Although there was no manual, the tubes are numbered with a tiny Sharpie dots – and so are the white sockets. The 3 three dots on one tube match the 3 dots on a socket. A thoughtful consideration. At night, most tube amplifiers resemble a small town, lit by the beckoning lights of dance clubs. The burly 6s33s lights look more like industrial refineries on the plains.

The chunky tubes are produced in Russia for the military use. The tubes require a looooong time to power-up. Turn on the amplifier and then go get your beverage. Szylar says the tubes need about 2 hours to sound their best, but I did not notice any appreciable difference. No tube covers provide safety, but the amplifiers do meet ISO 2002 standards. Specs from Russia say the power tubes should last about 2000 hours. Szylar says they will they last much longer. Replacement tubes are $150 each, from Russia. Play this baby hard and the tubes throw as much heat as a stovetop.

He says their most popular model is KT88 tube because of its high sound quality and high power. Yet it looks like this one will be the most popular. He says after presenting both KT88 and 6s33s, most hi-end customers prefer the 6s33s amplifier.

The Cans

The black power transformer cans dominate the 6s33s amplifier horizon, like gas storage tanks at the edge of the city. They are made from heated metal sheet (silicon) 0.27mm, shape EL-120. Depth and width are 100/120 mm and the height of the metal sheet is 75mm. The cans are suitable for 600-watt units. They transfer 70-watt per channel without distortion or negative feedback. They are hand made by Delta Studio constructor Kochanski. Production models will have Delta Studio logos on the top of transformer covers.

The amps work without negative feedback – which might help explain their never-ending listening pleasure. There is no fatigue with extended music sessions on this monster. Szylar says maximum induction level on the transformer core is about 0.6 Tesla. The size of the transformers, he says, is the compromise between a good quality of high tone and losses resulting from the transformer core, winding and etc.

The amps are made for 8-Ohm load. Szylar says "you can put 4-Ohm load, but the sound quality will be a little bit worse, and you have to be very careful with volume control. We believe that this class amps should match the speakers for the best sound quality." With such large power draw, Szylar does recommend 20-Ampere electrical service.

The Construction

He says the burnished beauties should be placed on a free space, away from heat source or sun. "Should stay away from anything what can catch the fire." Moving the massive machine required rearranging my home movie and music reproduction system: this beast was not going to slide easily in and out of the audio rack. Be sure to protect the surface of fine furniture it is located upon: once planted, the 6s33s amplifier grows roots and stays there.

The gold binding posts are the best possible. Easy to reach and use, as big as a walnut, they fasten any style of cable like an ocean liner to the dock. The posts feel so good, the volume knob should also be gold and beefy.

When you turn on the 6s33s there is a red LED light, which means the amplifier is not ready. Szylar calls this a soft start. At this point you can't play; there is no output power. The only power is to the power tubes. When the LED turns green, it means the tubes are warm enough to enjoy the music. The soft start "prevents to listen music with cold tubes."

Szylar does not recommend power line conditioners. He says the power lines in US are in the good condition, given the some level of power. While a power conditioner is not recommended, he says don't put the massive device on the some circuit with heavy load equipment like a microwave or fridge.

The 6s33s top plate gets hot enough to make toast. Szylar says the top and bottom plates have small holes, but the amplifier’s cooling is by the natural air circulation. "It sucks cold air in the bottom and give the hot air on the top." The amplifier, he says, was tested in the very hot environment and was working great, "so we don't worry about the top temperature. What we worry about is to keep [it] out from children."

The Nits

In his defense, Szylar says the massive amplifier "should not lay on a floor, optimal height is around 25 inches, to minimize sucking in dirt and dust. Perfect [position] would be to stand on a table with a hole in it’s deck to allow free air flow. In this position, [the] LED on a bottom side is visible enough and nicely reflects in table’s deck. That was the point." Also, he says, you don’t reach power switch over tubes, but from side around the amplifier ("that’s why the switch is close to a side, not central").

The Product Details

Szylar says they believe in, and stand behind, high quality and do not want to compromise quality with lowering the production costs. Therefore, he won’t build the amplifiers in China. He says he has seen China amps with beautiful frame, nice shape, but the sound quality just wasn't there. Best example, he says, is Jolida brand. "When their production moved to China, the quality of their product was also compromised."

A few stores around Poland showcase their amps, but the final order is placed directly with Delta Studio office. Each amp is made on customer order. They match the frame to customer’s environment and quality of sound to customer preferences. Price varies with customer specifications.

Shipping is handled by PolTravel company to the USA. Szylar says they provide good and fast service. In the USA, they use FedEx, "but if it is possible, we are going personally with the product to the customer. Customer pays for shipping in the USA, he says, and for the warranty repair if customer is shipping amps to us. "If the damage occurs on our fault, we repair it or give all the cost back."

Fulfillment time on orders depends on model. Usually the 6s33s manufacture time is about 4 to 6 weeks. "This includes not only putting all the components together, "he says, "but also amps must be checked, warmed up and adjusted before they are shipped."

He does not recommend upgrading or modifying their amps. "All elements and parameters are chosen very carefully, passing a lot of tests for the best sound. So whatever is going out of Delta Studio is ultimate best of what you can get from the unit. As I said before, all our amps are custom made according to customer's preferences. Sky is the limit. We can build output transformers with perm alloy core with silver wire clean class 9999, but the price is also affected."

Szylar concentrates on the direct sales. He plans on a showroom in New York city, but right now visits are by appointment only. "We would like to develop a relationship with the group of people, he says, "who are interested and appreciative of a product of this class. In Poland we have a listening/ showroom when potential customers can listen to and pick his/hers favorite model. Sometimes customers come with their own speakers and CD players to make sure they got what they want. Sometimes we are going to the customer’s homes, if it's more convenient for them."

I suggest he hook up with the Uptown Horns of Bob Visintainer's Avantgarde Music & Cinema. An upscale audio emporium is the perfect venue for amplifiers of immense quality.

The Summary

Apparently, the miserly grader is gone for a while. Once again, I lavish 4 and 5 Blue Notes on the Enjoy the Music.com categories. I am surprisingly quite pleased with the last few components I seriously auditioned. I think Delta Studio’s 6s33s amplifier was above average in Tonality, with no Self Noise. The 6s33s amplifier affected many other categories, but such influence is expected at this level. My own Enjoyment category is higher than most other products: this one simply excels – as it should - another 5 Blue Notes. With two dozen dress pants in my closet, I still do not have enough pockets to afford this beast. Despite a high-end price tag, I award four Blue Notes, above average, for Value.

A massively solid, attractive and powerful performer, the Delta Studio 6s33s amplifier’s blatant appearance and obvious charms, despite newbie glitches, make it a very enjoyable companion! For those who drive nothing but the best, this is a beautiful looking and gorgeous sounding amplifier any tweaking audiophile would be proud to own.

Specifications

Type: stereo amplifier

Power Output: 72 watts per channel

Operation: Triode AB (20W in Class A), Push-Pull 

Tube Compliment: two 6S33S per channel

Frequency Response: 4Hz to 82kHz (-3dB)

Distortion: < at 1W/1kHz

Intermodulation: <0.05%

THD: <0.04%

Signal To Noise: >95dB

Line Input: RCA

Output impedance: 8 Ohm (4 Ohm optional)

Weight: 100 lbs.

Dimension: 17.5 x 14.6 x 9 (WxDxH in inches)

Price: €5,000

Company Information

Delta Studio s.c.
al. Jaworowa 6a
53-123 Wroclaw, Poland

Voice: +48 602 72 38 31
Fax: +48 71 367 96 99
E-mail: delta@amplifiers.pl
Website: www.amplifiers.pl

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