PrimaLuna DiaLogue Two Integrated Tube Amplifier
A Strong Case for Tubes
                                   

 

 

       

               

Changing my speaker wire to the 4-ohm terminals allowed the amplifier to sound sweeter and much more like a very good tube amplifier. So, since my 8-ohm Preludes seemed to prefer the 4-ohm setting (I know I did!) I used the 4-ohm taps for the remainder of my evaluation. My advice is not to assume anything and to try both impedance settings to determine which sounds best to you.

The Chinese KT-88 Genalex knock-offs performed very well in my system. The midrange was a bit forward, but the bass extension and articulation was quite healthy and the high frequencies were airy, non-fatiguing, and extended, without any obvious roll off. What I’m saying is that the stock KT-88s provide very respectable performance in the DiaLogue Two, which will satisfy many. Buyers should not feel that they need to run right out and buy some expensive NOS tube set.

But since I simply had to try out that Adaptive AutoBias circuit, I pulled a quad of JJ EL34 tubes from my Antique Sound Lab AQ1003 DT (ASL) amp and plugged them into the DiaLogue Two.

I powered up the DiaLogue Two with the EL34s and began listening. Now this was truly a sweet sound. The JJ EL34s sounded both sweet and natural in the ASL amp, and also gave a nice sense of depth projection. The highs were natural and extended, though not as extended as the new KT88s, but nonetheless, they provided quite a bit of detail and shimmer on cymbals and other high-frequency instruments. The midrange was, in a word, “gorgeous,” and in my room, the EL34s provided bass that was fairly equal to that of the KT88s, and perhaps it was even a bit more articulate.

Moving on to a quad of vintage Genalex KT66 gray-plate tubes, the sound became very detailed, but also very forward, and lost a bit of bass extension and punch. This was my least favorite tube match for this particular system.

So it is true that you can plug virtually any type of output tube into the DiaLogue Two and it will play just fine. It is also true (as with all tube amps) that each different tube type will have its own distinct character. Which one will sound the best to you will depend on your associated gear and your listening biases.

As for me, I was very impressed with the overall sound of the EL34 tubes in my system and consequently went on to use that tube set for the rest of my evaluation. They provided a bit more harmonic richness than the KT88s in the crucial midrange, and were just a touch more laid-back sounding.

Let the Games Begin
I began listening to the DiaLogue Two with some familiar CDs. I was quite impressed with the amplifier, which offered more bass extension and punch and certainly more extended high frequencies than my ASL tube amplifier. But what impressed me the most about the DiaLogue Two was its near solid-state control of the bass combined with an uncanny ability to reproduce midrange notes, such as guitar chords, with a bit more power and dynamic flair than I had experienced with most other amplifiers. It quickly became apparent that this was going to be a thoroughly enjoyable evaluation. Indeed, the DiaLogue Two sounds more dynamic and actually has better bass control than some solid-state amplifiers I’ve had in my system

A Shocking Revelation!
PrimaLuna’s USA Distributor Kevin Deal offered to install the optional phono board in my DiaLogue Two, and being an analogue man from way back, how could I refuse? The MM Phono was installed on the AUX2 input, which was as good a choice as any.

Kevin had enticed me by telling me that this phono board, which is made in Holland, works particularly well in the DiaLogue Two. It boasts a very high-quality op-amp, minimelf resistors, and a very short signal path. Although it is a solid-state circuit, my personal philosophy supports this approach (solid-state phono into a tube line stage). In my view, it keeps noise levels very low and provides better detail and articulation in the high and low frequency registers.

Keep in mind that I had my Michell Orbe SE with the Wilson Benesch ACT 0.1 arm, Benz Ebony L MC cartridge, and Musical Surroundings Nova Phonomena phono stage hooked up on the DiaLogue Two’s direct HT input. At first, the only turntable I had set up for MM playback was an old Sony PS-LX2 with a Grado ZC+ cartridge. Shamelessly, I just plunked it on the carpet near enough to the amp to hook up its cables to the AUX2 input.

I cued up a Laura Brannigan’s Brannigan 2 LP (Atlantic 7 80052-1) and was flabbergasted when the needle hit the record and began playing “Solitaire.” I must say that Laura’s vocal and the backing instruments sounded jaw-droppingly musical and natural through the DiaLogue Two’s phono section. And when we got to “Squeezebox,” and the “squeezebox” made its entrance, the reproduction was smoother and more holographic than it had any right to be. With respect to the critical midrange reproduction, the DiaLogue Two phono was strutting its stuff big time. Even the lows and highs were as good as I’d ever heard them with this particular cartridge (though the midrange is its strength).

A few days later, I bought a used Luxman P-405 automatic belt-drive turntable from Craig’s List, and installed my mighty vintage Audio-Technica PB-12S cartridge with its Shibata stylus. As I recall, it received a good write up from TAS back in the day.

This time, I had my music-friend Mike and his lovely wife Kyle over to check out the system. Mike had brought some premium quality MFSL records and we played Boston’s original LP as well as one by Stevie Nicks. To me, the sound was decent, maybe a touch on the bright side, but really nothing too special.

So I said to Mike and Kyle, “How about if I put something on that’ll rip your heads off?” They looked at each other suspiciously, and then turned and said, “Uh, okay.” “Sweet,” said I.

I then dove into my 80’s 12-inch-single dance music collection and pulled out Jody Watley’s Real Love (MCA 23928). I cranked the volume a bit and then pressed the Start button on the Luxman. The song began with Jody talking, then some loud cymbals after which the bombastic bass line kicked in. I looked at Mike and he said, “I think the bass may be overloading the room a little.” I considered his veiled request for a volume reduction momentarily, then retorted, “That’s right bitch—Take that!” “Oh-Oh-Aaaah,” Watley wailed! It really was surprising how LOUD the DiaLogue Two could play the Preludes in my 11’x14’ room. And not only was the sound loud, it was clean and controlled.

My point is that the DiaLogue Two’s phono is a surprisingly great sounding addition. It provides a wealth of detail, impressive dynamic contrasts, and a wonderfully musical and dimensional midrange. I would expect it to equal or surpass outboard units up to $1000.

The real truth (if I must tell it) is that the seductive sound of the PrimaLuna’s phono stage had me checking and double-checking all the settings and adjustments on my much more expensive Nova Phonomena and Michell Orbe. I mean hell; the Orbe had to sound better than the Sony or the Luxman, right? And it did—after resetting the VTA, the tracking force, and the loading value.

Once I had recalibrated the Orbe, it sounded truly inspirational. Playing Stravinsky’s L’ Histoire du Soldat, performed by the Columbia Symphony Orchestra from Stravinsky Conducts, 1961 (Columbia MS 6272) the coronet and the trombone had a richness and texture that I’ve rarely experienced. And the tympani, cymbals, and other drums sounded very poignant and convincing. I could easily hear the tuning of the skins on the various drums. In one movement there is a drum roll that just comes out of nowhere and is shocking in its level of transparency.

When I put the record back, I noticed that I had an Everest-labeled copy of the same piece (Everest SDBR - 3017) performed by the London Symphony Orchestra. The Everest recordings are renowned for being among the world’s best. This particular recording was mastered at the Belock Recording Studio using Ampex 300 stereo tape machines recording on half-inch tape via microphones from AGK, Telefunken, and Neumann.

I played the same movements of L’ Histoire that I had just listened to on the other recording and it was very evident that as good as the first recording was, the Everest recording was a considerable step up. The brass, woodwinds, and violins were so immediate and detailed, and the drums so palpable that I had to suspend disbelief in order to believe that I was not witnessing the actual concert. In truth, the quality of the reproduction was about as good as it gets.

I realize that I was listening to two different orchestras recorded in two different venues, but still, the difference in recording quality was unmistakable. It seemed that the Everest recording likely used a different microphone configuration with better quality microphones, resulting in more apparent detail and intimacy.

Caveats
The DiaLogue Two is a very hard product to fault, but I wouldn’t be a reviewer if I couldn’t find some small things to complain about, so here goes.

First, I would prefer to have a pair of volume-controlled preamp outputs instead of the fixed-volume tape outputs.

Second, I wish that the source selector defaulted to the last selected source at turn-on instead of automatically reverting back to the CD input.

Although the tube cage is uniquely styled, modern, and very functional, it’s just not my idea of eye-candy. Luckily it pulls up and off quite easily.

Summary
My hat is off to the folks at PrimaLuna. What impresses me most about the DiaLogue Two amplifier is how well though out and executed this product truly is. It seems that the designer left no stone unturned when it came to considering what modern users would desire and look for in a tube integrated. From the Adaptive AutoBias circuit, to the verily useful remote control with on-the-fly UL/triode switching; then last, but far from least, the provision for an excellent low-cost onboard MM phono stage, the DiaLogue Two is a bona fide home run all the way.

As if all of the above are insufficient reasons to make a semi-expensive purchase, the clincher is the gorgeous musical presentation that this amplifier provides all day long. Its dynamic contrasts are among the best I’ve encountered; and although its midrange is beauteous, its superb articulation and command of the frequency extremes is what puts it ahead of the competition. Accordingly, I’ve committed to purchase the PrimaLuna Dialogue Two. I will surely enjoy it as my prime tube reference amplifier.


                             



Specifications
Output: 38 watts x 2 ultralinear, 21 watts x 2 triode
Freq. Response: 10Hz-30kHz +/- .5dB
THD: Less than 1% at full power
S/N Ratio: 89dB
Input Sensitivity: 270mV
Power Consumption : 250 watts
Dimensions: 15.2" x 8.3 " x 16 " (WxHxD)
Weight: 63.8 lbs
Inputs: 5 pair RCA / 1 pair HT bypass
Outputs: 4 & 8 Ohm speaker taps / 1 pair RCA fixed tape output
Tube Compliment: 2 - 12AX7, 2 - 12AU7, 4 - KT88
Price: $2,625 USD; Phono adds $199

US Distributor:
Kevin Deal
PrimaLuna USA
2504 Spring Terrace
Upland, CA. 91784
USA
Phone: 909-931-9686
FAX: 909-985-6968
Web: www.primaluna-usa.com