There was an old Rodriguez cartoon in Stereo Review a long time ago that is a apropos of my recent audio purchase. It showed a sales person talking to a customer in an audio store. The sales person says something like this:
“You say you have a powerful transistor amplifier with very low levels of distortion and you want to ‘upgrade’ to a low-powered tube amp with much higher levels of distortion?” At the time I thought that cartoon was very funny and audiophiles who made that “upgrade” were crazy.
Well I recently made that “upgrade” to the PrimaLuna Prologue Seven Monoblocks. My solid state amp is the Coda Model 11, 100 watts class A. The Coda has been in my system for about 18 years now. I thought it had no limitations, until now.
I got the bug for a tube amp after I bought the Decware ZSTAGE tube preamp (see my review this section) that replaced my solid state Aragon preamp. That really is an upgrade. If a tube preamp can make so big an improvement I thought, what about a tube power amp. I hesitated because my Coda 11 left nothing to be desired (or so I thought). In addition, I had lots of worries. I worried that the highs would be rolled off which is deal killer for me. Would it be powerful enough to drive my Thiels sufficiently loud and absent strain. Would it be so “warm” so as to obscure detail and lack sparkle (another deal killer) I worried that the amp itself would be somewhat problematic; intrusive idle-level hiss and/or transformer buzz or hum. Well ……never mind.
I believe the best way I can describe the Sevens is to borrow a phrase from Robert Deutsch’s s review in Stereophile. They are an optimal combination of accuracy and musicality. The overall presentation is generally smoother than the Coda. String tone for example on the Living Stereo SACD reissues (or any Shostakovich’s 5th symphony recording) is no longer just short of making my ears bleed. Mahler’s 1st Symphony and Francesca Da Rimini are real work-outs for any amp, especially the very loud fanfares. The Sevens remain musical and coherent even when all manner of musical hell breaks out. They are no less dynamic than the Coda. Jazz at the Pawnshop has never been better…sparkling and smooth throughout.
Then there is their bass response which is simply revelatory. They are far more satisfying than the Coda in the lowest octave. Telarc’s classic bass drum whacks are rendered with satisfying impact and fullness. Eugene Wright’s bass in Brubeck’s Time Out is the best I’ve ever heard. The Sevens provide a foundation for the music that has been a no-show with my Coda. As a matter of fact, the bass reproduction is the best I have ever had in my system. What is most remarkable is I thought the bass response would be a weakness. Robert Harley says in his book on high performance audio systems that “Tubes have less control in the bass, making the presentation less paunchy, taut, and extended.”… just the opposite with the Sevens in my system. When I asked Kevin Deal of Upscale Audio what would be the difference between the Sevens and my Coda, he said immediately “Better bass”. So great is the improvement that I’m beginning to think that there may be something wrong with my Coda.
The Prologue Sevens themselves contribute no noise of their own of any kind; no hiss, no hum no buzz. They drive my Thiels CS 3.6s just as loud as my Coda. I have them connected to the 2 ohm taps. The setting on my preamp is either the same or one or two notches higher than with the Coda. I find this somewhat surprising since the 3.6s have a reputation of needing lots of power and current.
I should point out that I have replaced the stock 12AU7s in both my preamp and the Sevens with the 1956 Radiotechniques. I believe these tubes are absent the classic “warmth” frequently associated with tube sound and their signature sound is great depth of image, separation of instruments, and inner detail. Even quiet, instrumental sound images deep in the mix are highly articulated and palpable. Consequently my setup may not reflect the classic tube sound. It may be closer to an exceptionally musical solid state sound with exceptional bass.
I anticipated switching back and forth between my Coda and the Sevens. Well, that won’t happen any time soon
Sony SCD-XA5400ES or NAD M5, Kimber KCAG, Decware ZSTAGE, Nordost Red Dawn, PrimaLuna Prologue Seven Monoblocks, Nordost Red Dawn, Thiel 3.6s/ Paradigm Servo 15, PS Audio Power Plant Premier.
Graduating through the years to better and better equipment, I thought I had what I wanted with Musical Fidelity A3cr dual mono amp, Sunfire Classic Tube pre-amp (with fab NOS Tungsram 6922s from Upscale Audio), MF A324 DAC hooked up with Sony SACD all flowing through Ohm Walsh F5 speakers. A sense of being in the performing space, gobs of detail but not harsh, etc. etc. And an almost complete lack of stridency on even the worst recorded classical disks (e.g., early digital like DGG). I had been reading about the benefits of tube amplification, and was originally captured by tube sound with an Ah!Tjoeb 4000 with Anthem 2 hybrid integrated in my office system. I hesitated because the Ohm Walsh F5s require a lot of juice to sound right, and I wasn't quite prepared to shell out $6,000-$10,000 for an appropriately powerful tube amp. I had also gotten accustomed to the MF's very high resolution in addition to the "you are there" imaging and knew that to approach that performance with tube amplification required serious $$$. So when the Musical Fidelity Superchargers came out a few years back, I got the idea of one day, maybe, if I was lucky, acquiring a decent tube amp and backing it up for the Ohm Walsh's power appetite with the MF Superchargers. I was able to pick up a pair of the MF Superchargers 18 months ago at a deep discount, and put them aside until I could find a good tube amp. Being a fan of Upscale Audio and Kevin Deal's personalized service and vast knowledge of audiogear, I visited Upscale's site with some regularity, and was slowly seduced by the Prima Luna Prologue monoblocks and impressed with what I read about them in Stereophile and in customer reviews. I was able to purchase a pair last summer, but before hooking them up, I first replaced the MF A3cr with the twice as powerful Superchargers (since you can run them as monoblocks, too), to see how my Ohms would like them. After some break-in I was very pleased. Super sweet but detailed sound, with all the umph the Ohms required for the biggest classical disc passages I could throw at it. Very nice on jazz, too. I thought the Stereophile Class A recommended A3cr amp was wonderful, but the Supercharges was a definite step up the scale. Then I hooked up the Prima Luna Prologue 7s. I was immediately blown away by a sense of the presence of the musicians in the room that came with the deep sound stage and palpable imaging. Truly three-dimensional is the only way I can describe it. I was also gratified to see that these tube amps didn't give up much if anything in the way of detail and resolution to high dollar solid state. Needless to say I was very glad I made the jump to the PL monoblocks, and then proceeded to work my way through my CD collection to see how all my old favorites sounded (wonderful). I also tried some NOS tubes to see what they could add. Well, as good as the PL monoblocks were with the stock tubes, they got to a whole different level with NOS Siemens EL34s and NOS Mullard signal tubes (from Upscale, and also with cryogenic treatment). Added to the deep soundstage and life-like imaging heard with the stock PL tubes was now even more detail, plus a smoothness and richnesss of sound that told me I was really in the high end. On the first cut of MIles Davis' Kind of Blue, I never really noticed that Bill Evans' comping in the intro was doubled by Paul Chambers bass notes. Not only that, but I could clearly hear each instrument at different points in space. Then when Miles came in, he was standing in the room, to the front and just to the right of center between the speakers. Joe Jones was behind Miles and slightly to the right opposite Evans and Chambers. Lots of space between the instruments. Amazingly life-like. Another really impressive recording through the PL's is Serge Prokofiev's soundtrack to Serge Eisenstein's classic 1930s film Ivan the Terrible, re-recorded in the early 90s by Yuri Temirkanov leading the St. Petersburg Philharmonic on RCA (the score was later reduced by Prokofiev to a cantata by which it primarily known). It was recorded in Philharmonia Hall, St. Petersburg, which is, judging by this disc, one of the acoustically very finest concert halls in the world. There are some huge climaxes with full orchestra, chorus, and a battery of percussion instruments whacking away (lots of battle scenes), and it all came through with amazing clarity and depth. In sum, I'd consider my move to the Prima Luna monoblocks a system improvement only equaled in my audiophile memory by my purchase 25 years ago of my first pair of Ohm Walsh speakers (which are truly amazing speakers).
Strengths: Soundstage, imaging, autobiasing (which made it possible for a tube neophyte like me to get the courage to go with an all tube amp).
Similar products used: Musical Fidelity (various amps), Vincent hybrid integrated, Anthem 2 hybrid Integrated, Adcom separates, Cambridge Audio, Carver Receiver.
This has been a long time coming. I've had alot of amplifiers in my time The last two amps I had was a Classe Omega Stereo 500 watts per channel .And a Plinius SA100MK3. Both great amps but really expensive. I have enjoyed the sevens more than any amp I have ever owned period! I wont get into all the audiophile babel but they simply do everything better and with the money I saved I bought a ton of records. I bought these amps from Upscale Aaudio from Kevin. The customer service is incredible he always has time to talk. And he just flat out loves to listen to music. I have sold audio for many years and he is truley one of the best retailers I have ever worked with. So if you are looking for amps at any price you would be a fool not to put the sevens on your list
Just what the Dr. ordered ProLogue Sevens, we let them burn for 48 hours before we even sat down for a listen and was I ever happy we bought them.
Same smooth, detailed sound we were used to with the ProLogue 5 stereo amp, only seemed to have a larger sound stage with better separation. These are hands down the best amps you can buy anywhere at this price or even twice the price I researched different tube amps for almost a year before I decided on the sevens. If you want a tube amp that you do not HAVE to mess with all the time or worry about a tube failing and damaging something else on the amp THESE ARE FOR YOU!!!!
We have had the ProLogue for a little over two months now with around 75 hours on them and they continue to improve every time we listen. My wife and I started with a ProLogue 5 over a year ago because they were not making a monobloc amplifier at that time, as soon as I noticed the sevens I knew it was only a matter of time before they would be in our system, boy was it worth the wait they seem to have opened up the soundstage with our system and are very dynamic! Plus if you are new to tubes these are very user friendly you will never have to bias a tube or worry aboout buying matched power tubes EVER due to the adaptive auto bias circuit and the Sevens look very nice. The Prima products seem to be very accurate, that is they do not add any colorations to the sound. We love them!!!!!!