Icon Audio or PrimaLuna?

Gentlemen I am new to tube amps, and wondered which would be your choice and why.
Prima Luna.  I have owned two PL amps for the past 14 years (PL2 integrated and PL5 power amp).  Zero and I cannot stress enough, zero issues.  The amplifiers are also self biasing, so outside of changing tubes, zero maintenance.

Sound wise, a very fluid, organic tube sound.  

Admittedly, I am not wild about the looks.  But most tend to be very similar in that department.

The answer could very well depend on which specific model you were to choose, especially among the PrimaLunas.

I see in another thread that you are using Klipsch Cornwall III speakers, and you are presently driving them with a solid state McIntosh MC-7106 amp, which I see has a damping factor of "greater than 100."

As can be seen in the measurements John Atkinson has provided in conjunction with Stereophile reviews of various PrimaLuna amps, some (but not all) of them have extremely high output impedances, even for tube amps. More than 8 ohms in some cases, as I recall, which corresponds to damping factors of less than 1!

Although various versions of the Cornwall III have been produced over the years I would expect that the impedance curve of your speaker is generally similar to the one shown near the bottom of this page:


It can be seen that the impedance varies from a low of about 5 ohms at about 100 Hz to a high of around 75 ohms at about 2.5 kHz. That very wide variation will cause the tonal balance of the speaker to vary considerably as a function of differences in amplifier output impedance (which is inversely proportional to damping factor), and in contrast to solid state amps (which like your MC-7106 almost always have output impedances that are a tiny fraction of an ohm) the output impedance of tube amps varies widely among different amps.

I took a quick look at the specs of a few Icon Audio models. One model had a specified damping factor of 10, which is fairly high for a tube amp and signifies a relatively low output impedance (less than 1 ohm). No spec was provided for the other models I looked at.

The bottom line, IMO, is that if an audition with your particular speakers is not possible, I would suggest that at the very least you try to find reports of which specific amplifier models others have used with your specific speakers, rather than relying on generalities about the two brands.

Good luck. Regards,

-- Al

P.S: Here are examples of what I was referring to, about the output impedances of some PrimaLuna amps:

From Stereophile’s review of the DiaLogue Premium power amp:

The output impedance varied widely, from an extraordinarily high 15 ohms with EL34s and 14 ohms with KT120s from the 16 ohm tap, both tubes in Ultralinear mode, to 2.4 ohms with EL34s and 2.15 ohms with KT120s, both tubes in Triode mode, from the 4 ohm tap. The output impedance from the 8 ohm tap was lowest with both tubes in Triode mode, at 4.6 ohms (EL34s) and 3.9 ohms (KT120s). Changing to Ultralinear mode raised these impedances to 7.9 and 7.4 ohms, respectively.

With these high output impedances, the DiaLogue Premium’s frequency response will be altered to a significant extent by the Ohm’s law interaction between these impedances and the manner in which the loudspeaker’s impedance changes with frequency.

From their review of the ProLogue Premium power amp:

The output impedance from both output taps was significantly higher than that of the ProLogue Premium integrated amplifier. From the 8 ohm tap, I measured 9.2 ohms at 20Hz, 8.75 ohms at 1kHz, and 8.45 ohms at 20kHz; from the 4 ohm tap, the respective impedances were 4.7, 4.5, and 4.35 ohms. As result, the variations in frequency response with our standard simulated loudspeaker were extreme, reaching ±3.1dB from the 8 ohm tap (fig.1, gray trace), and with a large drop in level each time the load impedance was halved (cyan, magenta, and green traces). As expected, these variations were smaller from the 4 ohm tap (fig.2), but the matching between channels was excellent from both taps.

But on the other hand, from their review of the DiaLogue Premium HP integrated amp:

The output impedance depended on frequency, the transformer tap, and the mode of operation. The lowest impedance was from the 4 ohm tap in triode mode, at 1.1 ohms from 20Hz to 1kHz, rising to 1.33 ohms at 20kHz. Ultralinear mode slightly increased both of these impedances, by 0.1 ohm, while the 8 ohm tap almost doubled them. Even so, these impedances are significantly lower than with other PrimaLuna amplifiers I have measured, and the modulation of the amplifier’s frequency response by the interaction of its output impedance with that of the loudspeaker was relatively mild.

I can't say which of these models would sound best with your Cornwall IIIs.  But what I can say is that given the very wide variation of the speaker's impedance over the frequency range these three amps will sound significantly different with those speakers.


-- Al

I own a Prima Luna Dialogue integrated. I couldn't be happier, it interacts beautifully with my Von Schweikert loudspeakers. I have never listened to Icon gear.
I would just like to say thanks to you for all of that valuable information. You certainly went above and beyond in kindness, which is another reason I love this hobby so much. 

At the risk of sounding corny,

People such as yourself have such a passion for this hobby that you (and we) almost can’t help ourselves from telling another all of the information gathered throughout the years. 

Thank you so so very much, Al!

- Nick 
Thanks for the very nice words, Nick.

When I respond to a question I try to focus as much as possible on the specifics of the questioner’s situation, and sometimes that necessitates getting into considerable detail.  In the process, I sometimes learn things myself.

Thanks again. Best regards,

-- Al
Can't thank you all enough, great response to my question.
I can’t say anything about PL as I have never owned any of their products.

I have had several IA components over the last 5 years.  Stereo 40 Integrated and PS1 Phono Pre most recently.  My experience with IA has been very positive.  Zero issues, great support from the people at Icon (my first venture into tube gear so I had lots of questions), sound quality that exceeded my expectation and beautiful build.    The bias adjustments on the Stereo 40 were extremely easy and quick so for me the auto bias feature didn’t sway my decision.  I’m not a rapid fire tube swapper either.  

If you have the ability, I’d suggest that you demo both in your home.  My purchases were from Music Direct which does offer a 30 or 60 day in home demo.  Needless to say, none of the IA stuff went back.  
I have a PrimaLuna DiaLogue Premier HP amp and couldn't be happier with it, driving either Focal Utopia Diablo III's or Joseph Audio Pulsars.  It has fantastic soundstage and imaging, and is probably the most hassle-free way to own a tube amp, with auto-biasing, tube failure indicator lights, and a host of other great features such as point to point wiring.  Hits way above its price point and if you really want to go nuts, buy two and switch to mono and get 140 watts per channel!
For my two cents, you cannot go wrong with the Prima Luna Dialogue Premiums. I have both the Pre-amp and two HPs as mono blocks. I'm a big fan. I have tried a few others, that shall remain unnamed, and none sound as good as what I am listening to now. You can spend a lot more and not get as satisfying results; if you spend less you will not get the build quality and high end components. Jus' sayin'.

The Prima Luna’s are fine products and have heard, along with auditioned them several times. I do own a set of Icon Audio MB90 MkII KT150 MonoBlock Power Amps and without a doubt they are excellent performers and exceed the Prima Luna’s from my standpoint. I also have an Icon Audio PS3 Mk2 MM/MC Phono Preamp that adds value to vinyl listening which off the charts. With the Icon Audio components paired up with some Acoustic Zen speakers (have both Cresendo’s and Adagio’s) sounds superb. My recommendation would be to go with the Icon Audio’s and don’t look back!
The Icon Audio group in the UK are great to corrispond and work with. They have been very helpful timely in answering questions and helping out. The guy's at Music Direct (the US distributors) are tremendous in their support too.