|PrimaLuna DiaLogue Two Integrated
|A Strong Case for Tubes
Okay, I admit it—I read Jim Hannon’s review
of the PrimaLuna DiaLogue Two integrated
tube amplifier in the October 2007 issue of
The Absolute Sound magazine. And although I
don’t lend automatic credence to any review
I see in print, the review did get me
interested enough to request a review sample
and to see for myself whether or not all the
PrimaLuna hype is justified.
Make no mistake; the DiaLogue Two is a
thoroughly modern amplifier that includes a
very hefty anodized aluminum remote control.
It was designed in the Netherlands by Herman
van den Dungen and is manufactured to
stringent standards in China.
What we have here folks, is a 38-watt per
channel integrated tube amplifier, that uses
two Chinese KT88 per channel (patterned
after the British Genalex KT88s) to develop
its rated power into 8 ohms. One can switch
from the 38-watt ultralinear mode via a push
of the button on the remote, which cuts
power down to 21 watts per channel triode.
The input section uses two 12AX7 and two
From the get-go it was apparent that this
was a very solid and well-built amplifier.
Weighing in at a robust 64 pounds, with its
oversized power and output transformers and
thick aluminum faceplate, it certainly makes
an impression the first time you have to
lift it and carry it up a flight of stairs.
The heavy-gauge polished steel chassis is
coated in a 5-step process with an
automobile-grade dark blue paint. High
quality parts are used throughout from the
extra large half-speed wound output
transformers to the ceramic tube sockets,
Alps potentiometer, Nichicon and Solen
capacitors, and WBT-style speaker terminals.
Gold plated input jacks.
The DiaLogue Two is hand-made and point to point
wired although it does contain a couple of internal
printed circuit boards, one notably for the unique
“Adaptive AutoBias” circuit, which is claimed to
optimize valve performance and reduce distortion by
40 to 50%. It also extends tube life and makes the
unit more reliable and user-friendly.
Here’s the cool thing about the Adaptive AutoBias –
almost any output tube can be plugged in and played.
This unique biasing circuit will sense the tube type
and automatically set the bias for optimal
operation. You don’t need to do anything other than
install your favorite tubes, then sit back and
enjoy! In addition to KT88s, the amp can use 6550,
KT90, EL-34, KT77, 6CA7, 6L6GC, KT66, 7581, and
6V6GT tubes, or any of their equivalents. Talk about
a tube-roller’s paradise!
The DiaLogue Two has a rotary volume control and six
switched inputs, which include a HT input that
bypasses the volume control and the tube input
section. Therefore, when using the HT input, the
source must have its own volume control if you don’t
intend the DiaLogue Two to play into your speakers
and ears at FULL VOLUME!
One very nice extra cost option is the installation
of a very articulate and musical MM phono stage
(more on this later). The $199 extra was installed
on my review sample on AUX 2. The rocker off/on
switch is on the front left side of the chassis and
is not controlled by the remote control.
The rear panel contains 6 pairs of gold-plated RCA
inputs and one pair of RCA tape outputs plus a
grounding post. There are WBT style speaker posts
for 4 or 8 ohms, and an IEC AC receptacle to
facilitate after-market power cords (I found the
stock cord to sound very respectable). The DiaLogue
Two contains internal AC and plate fuses, and a few
spare fuses are included in the package, as are a
pair of white handling gloves.
The remote is an attractive black-anodized
heavy-metal unit that is quite useful. In addition
to the usual volume control, you can choose inputs,
mute and un-mute, and switch from ultralinear to
triode operation at the push of a button. It appears
to have other transport control buttons that will
conveniently operate the PrimaLuna CD player. The
remote has rubber rings installed at each end so
that it won’t scratch your furniture. Nice touch.
I did some experimenting with the ultralinear to
triode switching and found the triode mode to be
generally a bit warmer and slightly sweeter
sounding. It seemed to work well for low level
listening and for acoustic singer/songwriter music.
The ultralinear mode was used for most of my
evaluation because it provides greater power and
better articulation at the frequency extremes.
Impedance and Tube-Rolling:
The first thing one needs to determine when
installing the DiaLogue Two in a system, is whether
to use the 4-ohm or 8-ohm speaker posts. This would
seem perfectly straight forward, but in my
experience it was not exactly the case.
Since my Silverline Prelude speakers have a nominal
8-ohm rating, I started with the 8-ohm taps. In that
configuration, the DiaLogue Two sounded very
matter-of-fact and very similar to many solid-state
amplifiers. The sound was clean and extended at the
frequency extremes, but the harmonic sweetness I had
expected to hear from the DiaLogue Two was somehow
missing in action.