PrimaLuna Dialogue Seven Tube Amp Review

[ahofer]

Drapes? What drapes? The amplifier chasses have bottom plates on them and there is nothing on top of the amp that could burn, what with all transformers encased in steel end covers. If a transformer or something in the bottom of the amplifier were to burn, the fire would be completely encased in steel. The tubes have vented covers over them for fire & electrical safety as well, should a tube shatter for some reason. I've done my work to make them safe, and they use a UL/CE approved fused power entry module & cord. The only thing that could set fire to the drapes would be me doing something stupid, not the amps.

Jeez, it was a joke.

My old tube amps were less protected-

 

[beefkabob]

Nothing's too good for my little Fi-fi; do you understand? N-n-n-nothing. Of course, a tube amp will not beat a Benchmark S.S. one, but the sound can be pleasing, and distortion, with good design, can be kept below audible levels. Why bother with tubes in the first place? I enjoy my DYI circlotrons because of the 'designed & made it muhself' feel, and they do measure well and sound good as well. Plus, they're fiddly, what with bias adjustment pots to be adjusted every so often. If you have a set it & forget it approach to audio or require many zeroes to the right of the decimal point before you see the first non-zero digit in the distortion reading, then such amplifiers are definitely not recommended.

'Circlotron' refers to the output stage design in which tubes & floating power supplies are arranged in a bridge configuration with the OPT across the center of the bridge. As a result, the tubes are all in parallel with the OPT, rather in series with it as would be the case in an ordinary push-pull design, allowing for a 4x reduction in turns ratio in the OPT. This allows for an OPT with excellent performance due to the low turns ratio, and this transformer is patented. So in short, tubes are fun and I learned a bit about coming up with a new OPT as well. And, it was fun. So I'll go pet my hound and crank some tubes--oops!--tunes now. I also have the excellent Bryston 4Bst bipolar transistor amp, and rotate that with the tube ones every so often. Only real difference is the bottomless base of the Bryston, which is only noticeable with music that has that. Of course, the Bryston has near bottomless power compared to the tube ones as well, but I never need all of what just the tube amp can deliver, which is about 80W per side at about 0.15% THD. Plenty for me. "Circlotron" was the brand name given to a tube amp pioneered by I think it was General Electric, which has that topology in the 1950's. The advertisers took the diamond-shaped bridge look of the output stage diagram, rounded it into a circle, and dubbed it 'circlotron'. So, bottom line is, enjoy whatever tickles your nun-handles.

If you accept that your technical fetish is a technical fetish, I haven't a problem with that. More power to you. If you believe your fetish is somehow purer audio, well, ummm...
But it does sound like you accept the truth and enjoy the fiddling, so that's cool.

 

[gorb]

Cheap shot considering Mr. Dudley passed away a couple of years ago from cancer.

My condolences to his family. Cancer sucks.

 

[egellings]

If you accept that your technical fetish is a technical fetish, I haven't a problem with that. More power to you. If you believe your fetish is somehow purer audio, well, ummm...
But it does sound like you accept the truth and enjoy the fiddling, so that's cool.

It's not a fetish--it's merely a hobby. I don't bash any particular amplifier tech. Home audio listening is not a precision experiment done in a laboratory setting. If that were the case, a vacuum tube approach to amplification would be silly. I simply enjoy tubes for what they are. I make no claim about any kind of superiority, sonic or otherwise.

 

[beefkabob]

It's not a fetish--it's merely a hobby. I don't bash any particular amplifier tech. Home audio listening is not a precision experiment done in a laboratory setting. If that were the case, a vacuum tube approach to amplification would be silly. I simply enjoy tubes for what they are. I make no claim about any kind of superiority, sonic or otherwise.

I use "fetish" less judgmentally than perhaps I come across. Like people who enjoy RWD in cars are fetishists like me.

 

[gorb]

Really nice. Dudled died a few years ago from cancer. Classy.

Condolences to his family. Cancer sucks.

 

[Purité Audio]

Any death is sad, an example of his subjective writing,

Listening #206: Shindo Cortese amplifier Page 2

But note also, irrespective of the loudspeaker in use: In every listening session I've enjoyed so far, the Cortese has taken at least an hour to warm upand even then its sound continues to improve over at least another hour. I don't recall another Shindo that has taken as long to perform at its...

www.stereophile.com

For me this is typical of the subjective pap that has brought us to the situation we find ourselves in today.
Keith

 

[WillB]

I get the impression that many of the people who express "their" opinions of tube based equipment are completely uninformed about modern high quality tube equipment and therefore fall back on stating gross generalizations of tube equipment sound quality from decades past.

If tubes are so "distorted" and band-width limited then ask yourself why, at audio shows, do many of the high quality speaker manufacturers currently use tube electronics to promote their products?

That is my gross generalization I've gotten after reading through this and many of the other posts on this website.
I'll post the same on the preamp postings.

 

[amirm]

That is my gross generalization I've gotten after reading through this and many of the other posts on this website.

What you should have learned is the difference between what people believe, and the reality. The latter shines right through with measurements. What then happens is folks looking for ways to still keep the head in the proverbial sand. It doesn't get more illogical than this. But such is this hobby.

 

[BDWoody]

I'll post the same on the preamp postings.

Let's keep the discussion to one thread please. The other one

 

[Geert]

I get the impression that many of the people who express "their" opinions of tube based equipment are completely uninformed about modern high quality tube equipment and therefore fall back on stating gross generalizations of tube equipment sound quality from decades past.

Of the 273 posts this topics counts only 4 argue tube amps are generally inferior. Actually, one of the arguments is that amps from the past performed better than this device.

One of the critiques about tube amp performance is from an EE who designs and builds amps. He stated facts, not opinions, unless you can prove otherwise. Lots of tube amplifier measurements on Stereophile.com you can choose from to make your point.

 

[Purité Audio]

I get the impression that many of the people who express "their" opinions of tube based equipment are completely uninformed about modern high quality tube equipment and therefore fall back on stating gross generalizations of tube equipment sound quality from decades past.

If tubes are so "distorted" and band-width limited then ask yourself why, at audio shows, do many of the high quality speaker manufacturers currently use tube electronics to promote their products?

That is my gross generalization I've gotten after reading through this and many of the other posts on this website.
I'll post the same on the preamp postings.

Hi-Fi shows are expensive to attend a room at Munich must be now Euros 20k, manufacturers look for partners to share the cost, sound quality or even comparability are of minor importance.
The room I helped out in used a variety of amps over the years including some really poor designs, I remember one manufacturer pulled out and this didn’t cough up just a week before the show.
Keith

 

[egellings]

I use "fetish" less judgmentally than perhaps I come across. Like people who enjoy RWD in cars are fetishists like me.

I like RWD too, except in snowy, icy conditions, where front wheel drive has less of a tendency to cause loss of steering control.

 

[MattHooper]

Thanks for the fascinating review Amir!

Another lousy measuring tube amp. More grist for the "WTF would anyone use tube amps?" crowd...

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.

Isn't it possible, at least in principle, that if the distortion is audible someone could perceive it as pushing more detail? Seems like that definitely wasn't the case
for you. I wonder if someone else might have had a different reaction.

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

That was very interesting. I wonder if the difference was audible. I've sometimes had the impression that something changes in the sound of my tube amps. It starts off, for lack of better word, more "dark" and rolled off sounding, but somewhere around 20 minutes or so it's like the frequency response suddenly "snaps in" and everything sounds more vivid. Since I've never believed in things like burn in or audible changes in equipment warm up, I figured it was most likely my imagination. But it was quite a strong impression. Now I wonder if there was something to it (?)

I love tube amps. I play all of my guitars through tube amps (e.g. Marshall, Fender, Music Man, etc.). However, I cannot for the life of me figure out why anyone would want a tube amp driving their hi-fi system.

I wish you could hear my system. Not that it's the best system in the world or anything, and not that there is any guarantee you'd like it. But I've had a few "why would anyone use tube amps?" audiophiles hear my system and then they say "ok...I get it." Even if it were the case we couldn't tell the tube amps apart from an SS amp in blind tests, in either case the sound is terrific. I don't think I've heard sound as spectacular in any audio shop with speakers driven by SS. But it's not that of course "because SS amps aren't as good." Rather, much of a good home set up gets done in having a good room and careful speaker set up. But the tube amps certainly don't seem to be holding the system back (and I have used various SS amps in the system too).

The point is that IM and Harmonic Distortion, FR deviations from linearity (and colored glasses and lights) are additional “Maya’s veil” in relation to the experience of a live instrument, voice, orchestra or bird’s song, therefore changing in perceptible way our overall experience of the Musical Art Event.

As someone else pointed out: In a way that assumes that the recording/reproduction system is relatively accurate to live sound. I find that generally speaking music reproduction suffers quite a bit compared to live sound, even excellent recordings on accurate systems. For me most reproduced sound, at least on the type of gear most normal audiophiles can afford, tends to sound threadbare and reductive, both in body and harmonic complexity, relative to real voices and instruments. Therefore if something addes some of that back in, even if artificial, in principle it can sound a bit more like the real thing. Now...I *think* that's what my tube amps do, but I could be wrong and can't prove it. (Though I did do a blind test of my tube preamp against a SS preamp, and was able to reliably hear the differences I just described).

The thing is, it's still far away enough from the real thing that it's all a compromise, and if there is audible distortion with the tubes, I can also see someone thinking the lack of tube distortion is more natural.

For me, even if the particular sonic characteristics I seem to hear with my tube amps are all expecation effect, it is so remarkably persistant - something like 25 years going on strong - that I am happy to live with the effect.

I do not buy audio gear for its physical presence. I buy it for the sound it makes. SMH.

Since audio gear will necessarily be a physical presence in the home (especially loudspeakers), I buy both for sound and aesthetics. I find good aesthetics (and a tactile sense of good quality, e.g. to volume knobs etc) to enhance the overall pleasure of owning and using the gear.

 

[AndreaT]

Thanks for the fascinating review Amir!

Another lousy measuring tube amp. More grist for the "WTF would anyone use tube amps?" crowd...



Isn't it possible, at least in principle, that if the distortion is audible someone could perceive it as pushing more detail? Seems like that definitely wasn't the case
for you. I wonder if someone else might have had a different reaction.



That was very interesting. I wonder if the difference was audible. I've sometimes had the impression that something changes in the sound of my tube amps. It starts off, for lack of better word, more "dark" and rolled off sounding, but somewhere around 20 minutes or so it's like the frequency response suddenly "snaps in" and everything sounds more vivid. Since I've never believed in things like burn in or audible changes in equipment warm up, I figured it was most likely my imagination. But it was quite a strong impression. Now I wonder if there was something to it (?)




I wish you could hear my system. Not that it's the best system in the world or anything, and not that there is any guarantee you'd like it. But I've had a few "why would anyone use tube amps?" audiophiles hear my system and then they say "ok...I get it." Even if it were the case we couldn't tell the tube amps apart from an SS amp in blind tests, in either case the sound is terrific. I don't think I've heard sound as spectacular in any audio shop with speakers driven by SS. But it's not that of course "because SS amps aren't as good." Rather, much of a good home set up gets done in having a good room and careful speaker set up. But the tube amps certainly don't seem to be holding the system back (and I have used various SS amps in the system too).



As someone else pointed out: In a way that assumes that the recording/reproduction system is relatively accurate to live sound. I find that generally speaking music reproduction suffers quite a bit compared to live sound, even excellent recordings on accurate systems. For me most reproduced sound, at least on the type of gear most normal audiophiles can afford, tends to sound threadbare and reductive, both in body and harmonic complexity, relative to real voices and instruments. Therefore if something addes some of that back in, even if artificial, in principle it can sound a bit more like the real thing. Now...I *think* that's what my tube amps do, but I could be wrong and can't prove it. (Though I did do a blind test of my tube preamp against a SS preamp, and was able to reliably hear the differences I just described).

The thing is, it's still far away enough from the real thing that it's all a compromise, and if there is audible distortion with the tubes, I can also see someone thinking the lack of tube distortion is more natural.

For me, even if the particular sonic characteristics I seem to hear with my tube amps are all expecation effect, it is so remarkably persistant - something like 25 years going on strong - that I am happy to live with the effect.



Since audio gear will necessarily be a physical presence in the home (especially loudspeakers), I buy both for sound and aesthetics. I find good aesthetics (and a tactile sense of good quality, e.g. to volume knobs etc) to enhance the overall pleasure of owning and using the gear.

Well recorded Music with well placed microphones and good mastering do minimize the deviation from personal experience in a symphony hall in an ideal seating position with well behaved listeners (no clanging wrist bracelet, no chronic bronchitis behind you, no turning pages of the program behind you). Yes, it is correct: no microphone is perfect, no array of microphones is behind reproach, and we are victims of the choice made by sound engineers. However, it does not make any sense to hope that adding electronic noise, deviations of frequency response, addition of extra harmonics and beats of IM distortion along the audio reproduction chain do add value to my listening experience. When a painting is observed with dirty eyeglasses, it does not help to improve imperfect Museum lights with a white balance different from the (unknown) average WB when the painter originally created the masterpiece.

 

[MattHooper]

However, it does not make any sense to hope that adding electronic noise, deviations of frequency response, addition of extra harmonics and beats of IM distortion along the audio reproduction chain do add value to my listening experience.

That's cool. For me, I don't have to hope: I experience it. I have two sets of speaker cables I can run to my L/R speakers, one a solid state amp, the other from my tube amps.
Whenever I use the SS amp it's not long before I go running back to the tube amps. It's not that it sounds "bad" but driven by the tube amps my system practically hits my platonic ideal for stereo sound. (All caveats assumed...)

 

[Purité Audio]

One does tend to imagine one is experiencing the ‘best’ possible sound until you hear something better.
I remember taking a pair of 8Cs to a Kii/8C shoot out conducted at a proper studio ( room within a room masses of passive absorption behind every surface) the 8C always sound really good that is their strength ‘working’ in every room but in this studio they were sublime such an even sound.
I would have liked to measure them just to see their in-room.
Keith

 

[DSJR]

As for warm up - this definitely happens with some amps - with hindsight (isn't that a wonderful thing after the event) amps with slight flaws in their design or realisation. One more internationally known one was the Nakamichi PA7 at least in mk1 form, where I remember the sound changing noticably (into a three ohm average speaker load) for two hours after switch-on before settling down. Turns out there was a mix-up on the bias circuit or something in the translation of the original Stasis design drawings and this caused eventual bias-drift issues anyway over the years. Once fixed (I believe the mk2 version did this from the get go), it was a really nice powerful amp, although lord knows how it'd perform today on the bench in good working order - a pal in the US had his serviced and I believe the service ($1700 or so) cost rather more than the amp did to buy used. All stable now I gather and he loves it.

Other more stable amp designs just 'work' straight from switch on with no 'personality' to them at all

 

[mhardy6647]

It's not a fetish--it's merely a hobby.

+1
No fetish here!



Not shown: My lucky 2A3 necklace.

 

[fpitas]

Of the 273 posts this topics counts only 4 argue tube amps are generally inferior. Actually, one of the arguments is that amps from the past performed better than this device.

One of the critiques about tube amp performance is from an EE who designs and builds amps. He stated facts, not opinions, unless you can prove otherwise. Lots of tube amplifier measurements on Stereophile.com you can choose from to make your point.

I'm sure there's some guy here who just hates tubes but has no real knowledge. So, we'll pretend WillB meant him.