PrimaLuna Dialogue Seven Tube Amp Review

[KEM]

I'm pretty sure that the design goal was to make this amp have a type of sound that a lot of listeners prefer. Creating an amp with good specs that is neutral was not important.
I am a very tech guy who strives for good performance. But I can understand the reasoning behind this design. Some tube based amps put a rosy glow around the sound, smooth out the highs and put a lot of blubber on the bass. somewhat similar to what the Koetsu MC cartridges provide for LPs. Is this bad? No. Just different. Tube amps of this type will never measure well.
There is a market for this type of gear. Buyers are not interested in the specs. They want that warm glow coming out of the speakers.
And I'm all for that. I am tired of systems (and especially phono cartridges) that have so much clean detail that the sound becomes tiring very quickly.

The goals of this website are the antithesis of the design goals for this amp. It is not truly fair to diss the measured performance. Some of the "obvious flaws" are not at all flaws, but means to achieve a type of sound that measures horribly but sounds great to some ears.

 

[maty]

I'm pretty sure that the design goal was to make this amp have a type of sound that a lot of listeners prefer. Creating an amp with good specs that is neutral was not important...

CARY AUDIO SLI-80HS
[Polish] https://audio.com.pl/testy/stereo/wzmacniacze-stereo/3420-cary-audio-sli-80hs

 

[EBrumbaugh]

Measure results aside, I run a PL EVO300 Tube Integrated, fed by a PL EVO100 Tube DAC ... they sound fantastic together. Speakers are the GoldenEar Triton One.R. Very enjoyable 2-channel setup.

 

[Descartes]

This is a review, listening test and detailed measurements of the PriamLUna Dialogue Seven tube monoblock power amplifier. It is on kind loan from a member and cost $2,747 when it came out in late 2000s.
View attachment 309754
Fit and finish seems excellent. My back unfortunately is not so situated and burdened under the load of 64 pounds that this amp weighs! Back panel shows high quality binding posts with a choice of impedance taps as is typical of tube amps with output transformers:
View attachment 309756

The amp has two modes of operation: Ultralinear (default) and Triode. Sadly the only way to select Triode mode is with the remote. You would think a hard button would also be provided. Since I didn't have the remote (and I didn't see a point anyway), I only tested the unit in its Ultralinear mode. Here are the specs and how that mode impacts the amp:

​

utput Power: Ultra-linear	70 watts x 2
Output Power: Triode	40 watts x 2
Inputs	1 each RCA
Outputs	2, 4, & 8 Ohm speaker taps
Freq. Response (+/- 3dB)	10Hz-100kHz
THD	< 0.25% @ 1 watt 2% at full power

S/N Ratio	84 dB
Input Sensitivity	1.1V
Power Consumption	232 watts (per amp)
Standard Tube Complement (per amp)	2 - 12AX7 2 - 12AU7 4 - KT88
Dimensions (WxHxD) (per amp)	15.2" x 8.3 " x 16"
Weight (per amp)	63.8 lbs

The unit has auto-bias and softstart which is nice.

Note: the amp has aftermarket 12AX7/12AU7 tubes. KT88s are PrimaLuna branded.

If you are not familiar with the tests that are about to follow, please watch my video on understanding amplifier measurements.

PrimaLUna Dialogue Seven Amplifier Measurements
I used the 4 ohm tap and ran our usual dashboard of 1 kHz at 5 watts:
View attachment 309757
There are ton of mains/power supply spurious tones which I could not at all impact with various grounding indicating that they are internally generated. They don't impact SINAD though as that is dominated by the sum of distortion products that have equal amounts of 2nd and 3rd harmonic plus higher ones mixed in for good measure. Notice the dual tones around our main 1 kHz tone due to power supply modulating it, i.e. kind of like digital jitter.

While not the worse we have measured, the Seven nevertheless lands in our "red" zone:
View attachment 309758

Noise performance is poor, likely due to power supply noise:
View attachment 309759
This is a problem as people tend to use sensitive speakers with tube amps so you want a low noise floor.

Multitone is disasterous showing rising distortion in low frequencies in addition to general intermodulation distortion:
View attachment 309760

As a result, 19+20 kHz doesn't look quite as bad:
View attachment 309761

Anyone thinking they are hearing more detail in music is going against the data here. And keep in mind that we are measuring the amplifier at just 5 watts.

Frequency response is highly tap sensitive and at a any rate, high enough to change the response (tonality) of any speaker you connect to it:

View attachment 309762

We see the typical gradual rise in distortion in power sweeps:
View attachment 309763

Distortion is so high that if we only allow 1% of it, the measured power goes way down, not up:
View attachment 309764

Here is the power with 8 ohm load (and tap):
View attachment 309765

Edit: forgot to post this initially:
View attachment 310824
As bad as 1 kHz distortion was, it gets even worse at higher frequencies.

I usually measure pop noise when the power on/off exceeds 1 millivolt. Here, the idle noise is at that level!
View attachment 309766
That is one messy response. Testing with my speaker (see below) I could hear a pop during power off although it was not too unpleasant.

The amp kept improving its performance as I left it on. I waited a half hour and it kept going:
View attachment 309767

I didn't like the spike patterns in there.

PrimaLuna Dialogue Seven Amplifier Listening Tests
I tested the amp using my lab Infinity Reference 253 tower speaker. As I have heard before (with high impedance tube amps), the bass was flabby and overloaded. It was quite annoying and obvious artifact. Whether your speaker will do the same depends on its impedance curve. Ignoring that, I cranked up the volume. Up to medium listening level if was "OK" but above that high frequency distortion started to increase proportional with volume control. This was a super annoying effect where at limit it sounded like the tweeter shouting at you.

To be sure I had not forgotten what my speaker/room sounded like, I swapped in the Topping L90 amplifier. Bass instantly tightened up and clarity improved in high frequencies. The sound was so solid and sure-footed in contrast to the Seven. There was no change in response as I turned up the volume.

Conclusions
There is nothing to hang one's hat on here other than the packaging. In every other respect, performance is cringeworthy whether we are talking measurements or listening tests. All of which makes stereophile reviewer Art Dudley's comments seem completely out of line:

"From my experience, the DiaLogue Seven succeeds at everything PrimaLuna set out to do: It's an apparently reliable, obviously wonderful-sounding amp that offers higher-than-average value—and a lovely opportunity for you to discover the playback approach that suits your ideas about recorded music while, at the same time, having fun. Very strongly recommended."

Fun is not what I had. Even within the context of tube amplifier architecture, there are design errors leading to artifacts that have no business being there (such as copious amount of noise and rising low frequency distortion).

I can't recommend the PrimaLuna Dialogue Seven amplifier. I implore you to get a proper solid state amplifier so that you can hear music without the limitations of the box in the middle.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Unfortunately, many years ago, I purchased an integrated tube amplifier from them based on the reviews from Stereophile! Never again!

 

[Descartes]

I wonder if this one measures better!

PrimaLuna DiaLogue Premium HP Integrated Amplifier

DiaLogue Premium HP Integrated — PrimaLuna USA

www.primaluna-usa.com

 

[Murray A]

+1
No fetish here!



Not shown: My lucky 2A3 necklace.

Almost every device pictured here, I've seen, evaluated and pondered the development of a product to emulate it in the current marketplace. In my not so humble opinion, audio technology has passed by this stuff big time!! The casual observer, myself included, experienced a warm feeling for a few milliseconds but let it pass into the past, and not rely on fond memories. Technology marches on!

 

[Ricwa]

Ooohhh! I see a Knight Star Roamer shortwave radio. Always wanted one when I was a kid.

 

[mhardy6647]

Ooohhh! I see a Knight Star Roamer shortwave radio. Always wanted one when I was a kid.

I need to replace the main P/S filter capacitor(s) in that one She's got a hummmmm. One of these days...

I had one in my college/grad school days (purchased for $5 from the guy who ran the electronics shop in the biophysics department at my alma mater). That one sadly succumbed to too many years in a damp basement (not my basement...). I picked up the one I have very inexpensively at a local antique electronics swapmeet. It is in very good condition. They're pretty mediocre radios, actually, but still kind of nice in a simple, elegant way.

source: https://www.alliedcatalogs.com/flipbook/1963_allied_radio_catalog.html
"New for '63"! They sold this kit for quite while. There was eventually a ss version (Star Roamer II) -- I've never encountered one in the "flesh", though.

 

[Descartes]

+1
No fetish here!



Not shown: My lucky 2A3 necklace.

So much stuff! I can’t imagine one could open a vintage audio store!

 

[mhardy6647]

So much stuff! I can’t imagine one could open a vintage audio store!

my heirs might want to consider that...