Integrated Tube Amp Demo Follow-up


On November 20 of last year, I posted a thread about my plans to conduct an in-home comparison of different integrated tube amplifiers. At that time, I asked for recommendations from Audiogoners for different integrated amps to try. For what it’s worth, thought I’d report back on my experience and thoughts on the comparison.

 

I eventually auditioned three integrated tube amplifiers (in addition to an existing McIntosh MA252 hybrid integrated):

1.     PrimaLuna EVO 300 (https://www.primaluna-usa.com/primaluna-evo-300-tube-integrated)

2.     Raven Osprey MK 3.1 (https://www.ravenaudio.com/product/osprey-mk3/), and

3.     Octave V 40 SE (https://www.octave.de/en/htdocs/verstaerker/v40se.php)

 

For the comparison, the other components in the system were:

1.     Analog - VPI Classic Signature turntable with three belt drive and VPI Analog Drive System speed controller, Soundsmith Sussurro cartridge, and Herron VTPH-1A phono preamplifier (stock tubes).

2.     Digital - Melco N1A server/streamer, and Benchmark DAC3.

3.     Power - dedicated 20 amp circuit and Furman PST-8 DIG.

4.     Speakers - Bowers and Wilkins 805 D3 on B&W stands (filled with sand) and bi-wired, REL 5i subwoofer connected to high level outputs via REL Arrow transmitter.

5.     Power cords, interconnects, and speaker wires are all Audioquest.

 

All four amps easily drove my B&W 805 D3 speakers which have a tested sensitivity of only 88 dB (https://www.stereophile.com/content/bowers-wilkins-805-d3-loudspeaker-measurements). When I say easily, normal listening levels were at only one quarter volume on the three tube amps. At half volume, the sound level in the room became uncomfortable.

 

When comparing components, I like to concentrate on very well recorded vocal music on digital, and equally well recorded jazz on vinyl. The digital music included large doses of Diana Krall, Chris Webster, Jamie Cullum, Jonatha Brooke, Amy Winehouse, and newer Van Morrison. On the vinyl side, mostly 50’s, 60’s, and some 70’s recordings of west coast giants Art Pepper, Chet Baker, Bill Evans, Bud Shank, Shelly Manne, and Gerry Mulligan.

 

When listening, I try to follow Robert Harley’s advice in the “The Complete Guide to High-End Audio” and concentrate on tonal balance, sound staging, dynamics, detail, and timing. However, my personal bias is to seek a sound quality with a very full tonal balance while still delivering great detail and transparency.

 

All four of these integrated amps are well built, quality pieces of equipment. Based on sound quality, I could be quite happy with any one of the amps. It is only when listening “side-by-side” that one can really hear the differences in sound quality between them. 

 

Each of the integrated amps were run-in for about 100 hours before doing any critical listening.

 

McIntosh MA 252 - this amp uses a four tube preamplifier and a solid state amplifier which delivers 100 watts per channel. The stock preamp tubes have been changed to two Amperex Bugle Boys followed by two Mullard 6201’s. This is my existing integrated amp. The sound is very transparent with very good detail. The soundstage is well defined. The dynamics and timing are good. The tonal balance, though, is just a little lean. The overall sound is clear, airy, and detailed.

 

PrimaLuna EVO 300 - uses a six tube preamplifier, and an amplifier with four EL-34 power tubes supplying 42 watts per channel. Compared to the McIntosh, the tonal balance is definitely “warmer”, more mid-range and bass (somewhat surprising given tubes here versus solid state in the MA 252). A much fuller tonal balance. Sound staging, dynamics, and timing are all good. Detail, however, is certainly lost compared to the McIntosh.

 

Octave V 40 SE - uses only a two tube preamplifier section with an amplifier section utilizing four 6550 tubes to deliver 40 watts per channel. The sound here is almost exactly the same as the McIntosh, but perhaps just a half step up in all respects. Detail and sound staging are superb. Timing and dynamics good. But, the tonal balance lacks some mid-range and bass.

 

Raven Osprey MK 3.1 - uses six tubes in the preamplifier section, and four 7581A tubes in the amplifier section to deliver 30 watts per channel. Raven does something very unique by supplying NOS tubes for the preamplifier sections of their amps. In this case, 1940’s era Phillips, and 1950’s era Brimar and RCA tubes. The sound combines the best attributes of the other three amps. The tonal balance is near perfect between treble, mid-range, and bass, while also delivering impressive detail. The soundstage is clearly delineated. Great timing and dynamics. Overall, I am hearing even more music details not heard before, and the other three amps are no slouches is this area. Vocals and instruments sound amazingly real, even piano which I always find particularly difficult to reproduce well. Impressive integrated amplifier.  

In conclusion, I decided to keep the Raven. I will also keep the McIntosh to use in my main system at another house.
gareents
Good read. You can’t go wrong with 7581A. And those NOS tubes. I’d be curious how they would alter the tonal/detail characteristics of the other amps if some rolling and biasing were done.
Nice write up - thanks for the follow up!!  The Raven sounds really interesting!
Thank you for fair and balanced reporting.
Finally, someone who has tested multiple amps at the same time.  Great Writr-up.  I was really interested in your outcome.  I had the The Raven Reflection MK2 amp and loved it.  Dave T is an awesome guy with some of the best vintage tubes out there.  Enjoy your music and congrats on your final selection.  
Thanks for your report. I am interested in a tube integrated and have considered Octave and Raven. 

Just a comment to @gareents.  You said: "When I say easily, normal listening levels were at only one quarter volume on the three tube amps. At half volume, the sound level in the room became uncomfortable

Just a technical note -- the position of the volume knob on a preamp or amp tells you next to nothing about how much power the amp is putting out nor now close you are to clipping. 

Some amps might only need an input of 1 volt to achieve full power output, while another might need 2 volts or more to achieve the same full output. That then gets combined with the voltage output capabilities of the source component -- many have had the experience of needing to adjust the volume knon when switching from, say, a tuner to a CD player. Those two sources had different output voltages. 

The final item in the equation is the linearity -- or lack thereof -- of the potentiometer or resistor network used in the volume control itself. Turning the knob up halfway may deliver half of the potential voltage, or something different. I've heard stories in years past that some manufacturers used potentiometers that allowed 3/4ths of the voltage thru at the halfway setting, thus making the amp appear more powerful than others to the casual user. 

Thus, the only way to know for sure how much power you are sending to a speaker to achieve a particular listening volume is to use a meter on the amp's output to see what voltage is being delivered.

Having done this for my own system (which also has 88 dB sensitive speakers), I find it takes about 3 volts to achieve an average listening volume of 85 dB, with peaks running to 5 or 6 volts. That translates to under 2 watts average with peaks of 4 or 5 watts. For me this is as loud as I want or enjoy. However, if you listen louder than that, the power need escalates rapidly since volume has a logarithmic relation to watts.


Listening in your room is the only way to go. Smart way to make a final choice instead of relying on reading endless puffery by everyone in forums.

Raven doesn't show any pics of the build quality. What is the build quality like inside?  Comparable to PL? If better, how?
tablejockey
You should watch Raven vids.
He claims to be the only amp mfger. to use Nasa spec thick boards which he insists will outlast Chinese point to point.
There's that.
@noromance - I'm sure tube rolling would affect the PrimaLuna and Octave, but didn't have the necessary supplies to try. Plus, wasn't prepared to go down that particular rabbit hole. Since Raven supplies different NOS tubes and encourages one to try them in different positions (row 1 versus row 2), I did switch the Brimar and Phillips tubes around. Significantly different sound. Brimars in row 1 had stronger bass and mid-range with backup instruments more forward. Too forward for me, I preferred the more vocal/lead instrument forward sound of the Phillips in row 1.

@mlsstl - appreciate and understand your edification. What I was trying to convey (poorly) is that ALL three amps had the exact same one quarter and half volume control to speaker response. Found that interesting.


The sound combines the best attributes of the other three amps. The tonal balance is near perfect between treble, mid-range, and bass, while also delivering impressive detail. The soundstage is clearly delineated. Great timing and dynamics. Overall, I am hearing even more music details not heard before, and the other three amps are no slouches is this area. Vocals and instruments sound amazingly real, even piano which I always find particularly difficult to reproduce well. Impressive integrated amplifier.  

In conclusion, I decided to keep the Raven. 

I am shocked, shocked, etc.