Matching preamp and power amp

Below a posting I made in Audioasylum concerning choosing a pre-amp for ML334 amp:

I used to drive my Mark Levinson 334 directly from ML 390S, speakers are Revel Studios. Some 6 months ago I tested at home Audio Research Reference 2 and frankly I was amazed how much better sound got. Consequently I placed an order for “little brother”, ARC 25LS mk2.

My opinion is that ML 390S analogue volume control equals in sound terms a good USD 2.500 – 3.000 transistors pre-amp. It also sounds very easy-going, quite detailed, and analogue. Volume control implementation (steps, channel separation) are superior to aforementioned USD USD 2.000 - 2.500 transistor pre-amps (which usually have ALPS Blue volume control). You also get a balanced control and cumulative gain of 390S and ML power amps is well matched.

In summary, look the following features in the pre-amp.

1) Decide if you prefer to go for hybrid solution, i.e. tube pre-amp & ML power amp. I can only say that in my case there is no looking back, tubes bring something special into music. If you prefer "transistor sound", pre-amps based on 6H30 tubes might be the right ticket, great clarity and detail over, lets say, 6922 tubes. i.e. seem to have less "tubey" quality (gross simplification, but shared by many industry experts). Or then look into new ML pre-amp 320S.

2) Pay attention to total gain, i.e. choose a pre-amp, which has gain selector. I drive my ML 334 with the lowest gain setting of ARC 25, highest setting gives way too much of total gain.

3) Pay attention to features and implementation of pre-amp; volume control (steps ...), remote control etc. Hard to find as comprehensive set of features as in ML products.

4) It seems to me that Levinson and Audio Research do have synergies, in other words ML & ARC combination provides super hybrid combination. Some other tube pre-amps might fit equally well.

5) Be ready to spend some USD 5.000 to get sonically worthwhile improvements. Generally my advice is to listen quality of bass, attack and decay - all areas where ARC brought significant improvements in to my system.

6) my experience is that ML gear sounds best driven with balanced connections, hence single-end only pre-amps might be no go ...

In summary, the key issues are system matching and functionalities your are looking for.

Stereophile's Recommended Components debate

"...some commentators have complained that almost all of the products reviewed by Stereophile find their way into "Recommended Components." "If everything is recommended," they grump, "what's the point of publishing the list? Or even reviews?"

"Given that we can only scratch the surface of the universe of products offered audiophiles, the goal of our reviews is not to try to review a representative selection of all the audio components that exist (footnote 2). Instead, we do our best to preselect components for coverage that have the best chance of performing well. (Once the review process is underway, however, a full description of a product's performance is published, warts and all.) If we do that job well, not only will everything we review eventually appear in "Recommended Components," but the listing will be skewed toward the higher grades, which it is."

These extracts are from John Atkinson "As We see It" in October 2004 Stereophile. If you are puzzled by number of recommended components, then I recommend that you read this particular this Stereophile article, available in their Web site.

Art Audio

Source: Art Audio Web site, Haute Fidelite January 2005, April/May 2004, 6moons.com

"Art Audio was created when Joe Fratus of Rhode Island encountered Tom Willis the British amp designer. Riccardo Kron, owner/operator of the Czech Republic's tube manufacturing plant KR Audio (then KR Enterprise) had charged Willis with the design of a custom SET circuit, to complement and maximally exploit his brand-new KR VV-32B power triode.

Instantly enamored with the sound of Tom's breakthrough amplifier, Joe was convinced. His search for the perfect audio opportunity was over. Between his own intimate knowledge of single-ended output transformers and sophisticated industrial design, Tom's amplifier design expertise and the ongoing support of Riccardo Kron, the engineering and marketing resources necessary to form a new company were in place.

One glance at any of today's Art Audio creations silences the common question. "What's in a name?" Sometimes, things do mean exactly what they imply. Art for the Eyes, Art for the Ears has been the company's guiding principle from inception. It simply insists that audio equipment dedicated to producing superior sound should embody superior aesthetics."

In January 2003, Kevin Carter, formerly of VAC and now heading his own firm K&K Audio, joined the company. Carter's K&K Audio is distributor of famous Lundahl transformers in the US. BTW, if you are in DIY, check out K&K Audio's kits. So, exiting team behind the products.

Art Audio Carissa 845 was reviewed in Haute Fidelite April/May issue. Carissa is 16wpc, single-ended, transformer-coupled, pure class "A", zero-feedback, stereo design with self-biasing circuitry using Valve Art 845 output tubes. The KR Audio 845 tubes and volume control are optional. The test unit demonstrated superior build quality (see below).



Did they like it? "...this low power amplifier tears apart the no. 1 prejudice of critics of tube amplifiers: incapacity to drive speakers with less than 90 dB/1M. To confirm this, we connected Carissa 845 with our Dynaudio Confidence 2. And, a miracle. Not only the system functioned, but moreover, it was joyful...it has fantastic transparency and purity...harmonic richness is staggering...timbre is sumptuous". You got the picture. For build quality, musicality and quality/price 5/5 stars. "...at this price Carissa...will perturb competitors." Price in France is quoted as €5.500.

Review in September 2003 in 6moons.com confirms. "This 16-watt amplifier drives like no other tube amplifier I've heard. Through the bass region, it reminds me of the push/pull Audio Research VS-55, a 50wpc amplifier utilizing the 6550 tube, well known for its bass prowess though less so for musical finesse and transparency. Not only does the Carissa do bass like the ARC but it sounds every bit as powerful. I never ran short of power."

6moons also tried optional KR tubes. "The optional KR Audio 845, said to be one of Dr. Riccardo Kron's last designs before his recent death, is, among other things, responsible for some difficulty organizing this review. I could easily have written an entirely separate review on the Carissa with the KR 845 installed - the difference between the Valve Art and KR tubes is that significant... Though the Carissa with the Valve Art tubes installed sounds very different from the Carissa with the KR tubes, both share the same traits, just to different degrees. Everything about the Carissa is intensified through the use of the KR tube. If you like what the Valve Art-equipped Carissa is all about, you may be ecstatic about what the KR does. Or, you may not. The intensified bass of the KR could be too much for your room or your tastes. I can't imagine why, but you may not enjoy the added saturation of tonal colors and harmonics that the KR brings to the table, nor its added drive."

Review concluded as "... I found the Art Audio Carissa to be one exceedingly fine amplifier. Her combination of muscular intensity and musical finesse puts her among the very best of amplifiers I've yet used in my system. Carissa has the transparency and intimacy I've come to expect from a good SET design and combines it with a spirited personality that's just plain fun to be around."

January 2005 Haute Fidelite reviewed Art Audio's Quartet, 50-watt, pure class "A", push-pull 845-based monoblock amplifiers. In order to assess specific charasteristics of Quartet they tested them with two, radically different pre-amps: Nagra PL-L and ATC SCA2. The Narga combination was all about finesse - "...this combination talks to your heart...". Introduction of ATC pre-amp utterly transformed the sound. "With considerable energy and impressive posture, ATC transformed ...into monsters of power and precision." Against Nagra some warmt and sweetness was missed, but control, dynamics, and balanced tonality were gained. Three dimensional soundstage was even better illustrated and illuminated that with Nagra, with super communication of small nuances and ambiance noises. "The passionate purchase which one will never regret." 5/5 stars for build quality, timbre, soundstaging, dynamics and quality/price. Price in France €8.800 a pair.

Viewpoint: None, have not heard Art Audio's product, but I've always fancied 845-based amplifiers since I heard Nagra VPAs some years back. Majestic was the world which came first in my mind.

EAT tubes

Euroaudioteam's KT88 tubes are the reason I'm seeking KT88 based amplifier powerful enough to drive my Revel Studios (88db sensitivity). Since my listening levels seldom exceed 105db, I'm confident I would manage with some 50w per channel amplifier. Idea is not to replace my ML334 amplifier, but have second, lust sounding tube amplifier for those wee hours jazz sessions.

So far I've looked into new McIntosh MC275, but it was no go as those old fashioned speaker cable hook-ups requires re-termination of speaker cables. I have narrowed my search now to two products: first is new PrimaLuna ProLogue Five with 40W per channel (SE only, but the price!); the second is Melody S88.

Back to EAT tubes. Story is fascinating. Company is a cooperative effort under the aegis of Jozefina Krahulcova. EAT combines top engineers from the UK, Switzerland and the original Tesla factory in Prague. All final testing of EAT tubes is done in Switzerland to assure the highest quality. The Hifi+ magazine tested the KT88 tubes in issue 34, and consequently gave them "Product of the Year 2004 Award" in issue 36. In short, they claim that performance of EAT KT88s exceeds of legendary (and very rare/expensive) NOS MO/GEC KT88s. The Hifi+ tested in Rogue Audio Model 90 KT88s from Electroharmonix, Svetlana and MO/GEC, and found EATs to be way superior - "..as if we were listening to an amplifier at three times the price ...". You can buy EAT valves at least from Tubedistinctions/UK, matched quad at £560. Or if you are visiting London, give a call to Pistol Music, +44 (0) 20 89 71 39 09 at 58 Durham Road, SW20 London.

6H30 tubes

Source: Audioasylum Tube section, some remarks made by Victor Khomenko, Mr. Balanced Audio Technology (BAT)

6H30 <> 6N30 confusion

"...It is the same tube, just the misinterpretation of the Cyrillic notation. The Russian lettering looks like 6H30n-DP, but its phonetic equivalent is 6N30P-DR, so some people "translate" it, other keep it original."

"...I guess I should take some blame for the confusion. When we launched the 6H30P-DR tube in the West, we simply shortened its name to 6H30. In the original Russian notation they all have the Pi at the end, indicating the miniature construction. So every 6H30 is the Pi tube, but some have additional letter after that."

And Conrad-Johnson's Lew Johnson said in March 2005 Stereophile: "actually, that's matter of some debate, since the tube is labeled in Cyrillic. It could be called a 6H30π (last character is Pi) or 6H30R just as accurately."

About DR versions

“… having compared the NOS ones (the -DR versions made in the late eighties and eary nineties) with current production ones, I can tell you the new ones are getting quite good - early ones, from 1999 and 2000, were crappy. Today if you compared the two kinds, your preference might go either way. I personally still prefer the NOS kind. The -EB is also quite good, they were just a notch below the -DR in ruggedness. The main difference between the NOS tubes, that went through the MOST stringent quality control in existence, and the lesse varieties is in quality.”

Viewpoint: Whole audiophile community should be grateful to BAT for introduction of 6H30 tubes in audio designs. Look the proof: beyond BAT 6H30 is now used in reference level pre-amps of Audio Research and Conrad Johnson, just to name a few.

AVTAC Pasiphae transformer attenuator

Source: UltraAudio.com

"The Line 3 and the Audio Research 2 Mk II are two of the best preamps ever made, and they do a lot of good things, but both veil the music, limiting transparency to some degree. I have, until now, run my amp direct from my dCS source for this reason. The Pasiphae VSR is the first component I have ever had the pleasure of hearing that is better than no preamp. Insultingly neutral? How about offensively transparent, debasingly detailed and revoltingly realistic…" — Ross Mantle, Senior Editor .

Technically, the AVTAC Pasiphae is a transformer based passive attenuator. Do not confuse this with inexpensive (or expensive) resistive attenuators. Transformer attenuation is in a league of its own. The Pasiphae uses transformers from Stevens & Billington to attenuate volume without loss of signal energy.

Mantle concludes: "... I’m talking about a quantum leap in speed, image definition, resolution, microdetail, dynamics, bass performance, and realism. It really works. I was so amazed I just sat there like an idiot.

Or like Tyrannosaurus rex seeing snow for the first time."



Viewpoint: Have personally never heard passive volume controls, which did not reduce dynamics. But this looks like interesting product: remote control, SE/XLR inputs/outputs, 110/240v etc.

There are audiophiles who maintain that the most important component in high-end system is active pre-amp, and that all other components should be matched synergically to pre-amp of choice. My own experience connecting Mark Levinson 390S cd-player directly to ML 334 power amp also ran in the face of "less is better / shorter the signal path the better" advocates. My system simply came alive with Audio Research LS25 mk2 tube pre-amp.

EMM Labs new SACD/CD transport

Source: The Absolute Sound 152

Harry Pearson avowed in HP's Workshop "You simple don't get this kind of improvement in part of the component chain of anything in audio more than once in a decade or so. Now that day has arrived."

Viewpoint: Unfortunately EMM's Web site is not updated, so details of this new transport are few and between.