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PrimaLuna Dialogue Seven Tube Amp Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 209 88.6%
  • 2. Not terrible (postman panther)

    Votes: 9 3.8%
  • 3. Fine (happy panther)

    Votes: 6 2.5%
  • 4. Great (golfing panther)

    Votes: 12 5.1%

  • Total voters
    236

amirm

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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.
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Review.jpg

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:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear back panel transformer tap Review.jpg


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
Inputs1 each RCA
Outputs2, 4, & 8 Ohm speaker taps
Freq. Response (+/- 3dB)10Hz-100kHz
THD< 0.25% @ 1 watt
2% at full power

S/N Ratio84 dB
Input Sensitivity1.1V
Power Consumption232 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:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Measurement.png

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:
best tube amplifier review.png


Noise performance is poor, likely due to power supply noise:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear SNR Measurement.png

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:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Multitone Measurement.png


As a result, 19+20 kHz doesn't look quite as bad:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear 19 20 Measurement.png


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:

PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Frequency Response Measurement.png


We see the typical gradual rise in distortion in power sweeps:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear power 4 ohm Measurement.png


Distortion is so high that if we only allow 1% of it, the measured power goes way down, not up:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Max and Peak power 4 ohm Measurement.png


Here is the power with 8 ohm load (and tap):
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear power 8 ohm Measurement.png


Edit: forgot to post this initially:
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Power vs Frequency vs Distortion Meas...png

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!
PrimaLuna Dialogue Seven Monoblock Amplifier Ultralinear Power on off noise Measurement.png

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:
PrimaLuna Dialogue Seven Monoblock Amplifier Warm up Measurement.png


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.

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

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Last edited:

Blumlein 88

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So performance not quite equal to the Dynaco 70 you tested. Less SNR, less good FR and a few other things. A pair of bridged Dynaco 70s would have the same power more or less.
 

fpitas

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At least it's cheap. Oh, wait! :facepalm:
 

AdamG

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A complete shit show. Amir probably wants to take a shower after that train wreck. Tremendously awful. :rolleyes:
 

fpitas

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A complete shit show. Amir probably wants to take a shower after that train wreck. Tremendously awful. :rolleyes:
And it gives people more bogus ammunition to say tubes have to suck.
 

Dmitri

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I was actually thinking of building a Tubes4hifi Dynaco st-120 before I came across Amir and ASR.
Said project has since been removed from the bucket list. ; )

As always, thanks for the review AmIr!
 

dananski

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Cool. But it's so expensive, no control knobs and... RCA input?? Where am I supposed to plug in my electric guitar?
 

dfuller

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Amazing that it can't get 100W out of four KT88s in UL. GEC's KT88 datasheet shows 100W per pair at 3% THD. Meanwhile, this isn't even hitting half that per tube!

My guess here is that there's very little if any global feedback (not that you can have a particularly large amount of it with tubes), and the AC heater supply (again) is the source of the high 60hz noise. You could probably, with very little work, improve this amp dramatically. Change which tap the feedback is sourced from (my guess is it's probably on the 8R tap if present, so going to the 16R tap) and reducing the feedback resistor values should help dramatically on the distortion front, then floating the heaters up about 60V should help.
 

AdamG

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Nicely designed distortion generating machine.
Might come in handy if you’re in need of a poorly designed toaster or foot warmer. With enough creativity it can be repurposed for something useful but that won’t be for amplification. The vacuum tubes sucked the silence out of the music.
 

restorer-john

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There's no sensible reason in 2023 to have a tube powered hi-fi power amplifier, nor was there in the 2000s or even much after about 1970.

That said, having five different DACs, 4 headphone amplifiers and a pile of headphones for a desktop 'rig' is hardly sensible either, is it?

At some stage, all audiophiles/HiFi nuts decide they want 'to give tubes a go', just for fun. My time with tubes was short lived in the early-mid 2000s. No desire to return to them, even though I've had some nice tube gear across my lab bench.
 

Matias

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Pure 2nd harmonics awesomeness!
(Not!)
 

Glen20

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Might come in handy if you’re in need of a poorly designed toaster or foot warmer. With enough creativity it can be repurposed for something useful but that won’t be for amplification. The vacuum tubes sucked the silence out of the music.
My primaluna was great in the winter and unbearable in summer. All because of the heat. Mood lighting was also a highlight. You could use it to weigh down a body, but it would probably be your own body as it is so heavy it may kill you trying to move it.
ps primaluna for sale .buyer must pick up;) (not an ad, just a joke)
 
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