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Review: Audio Note Kits Interstage Mono Block Amplifier

Posted by DougE (A) on October 25, 2007 at 14:25:07

Every kit builder knows what it feels like to get it working. I don’t mean “buttoned-up” and polished, but to get your new baby wired to the point where you can install tubes, put the plug in the socket, and--hold your breath--flip the switch! Yes! It works!

Only one thing is more exciting. The first listen. You pick up your newly assembled object of joy and carefully, oh so carefully bring it in from the cold workshop to your listening altar. You place her gently on the rack and wire her into the big rig. You already know she works—or at least lights up. Now, the big test. Will it be worth it? You cue up the first track…

But what does it sound like, man?! Well, with just one mono built and inserted into my main system, I literally listened to a full album in mono. It was that good. More than that: it was that engaging. And so it is X 2 (at least) in stereo. Now, with about 200 hours on the pair, I’ve got some thoughts on these great amps I’d like to share.

Let me get some housekeeping out first. I’ve built the AN Kits Kit1 amp and L3 linestage, along with kits from other manufacturers. My experience with SET amps and Audio Note goes back years, and I’ve played with systems and components both in my main and secondary rigs. My main rig is all AN: as above plus AN factory CDT II/2 and DAC 2.1x Sig. Speakers are Cain & Cain single BEN. At the office I have a simple SET system with Omega hemp XRS. The Kit1 will now be living at the office, as the Monos have taken over at home!

The Monos are a fantastic product, and Brian should be applauded for bringing this new offering to us. Quality of the chassis and all parts is similar to the other kits, and rivals the factory products. Instructions are superb, with excellent photos included on a disc if you want a closer look than the already clear color photos in the printed manual. The build is straightforward, and in many ways more manageable than the kit1, a great benefit of the increased chassis size of the Monos which gives you more room to work.

I ordered my Monos from Brian with the Double C core output and interstage transformers. Along with this arsenal of iron, the mains transformer and choke are substantially larger than the ones on the Kit1 I built a couple of years ago. And all this for just one channel! These things have serious power supplies. My kit also included Black Gates for the 300Bs and on the power supply, and 2 watt Tantalums. The power supply caps are JJ and Jensen, with the 2 cap configuration. Brian has thought the amp out extraordinarily well, and with different plates, you can choose a 2 or 3 cap configuration for the power supply. I started with the 2, but may move to the 3 later. The caps are physically huge, and stand proud on the chassis. Did I mention that this is a fantastic looking kit? The chassis is long, low and well proportioned with the huge iron and tubes mounted on top. The faceplates are a nice touch of class in deep, black gloss. With the insert plates for the caps and power tubes in contrasting silver to the black chassis, the overall look takes kit built products to a new level.

Background covered, here’s what it sounds like. Bold, colorful, fast, deeply textured, extended, strong, sweet, dense and a whole slew of other adjectives that I will use in actual sentences in a moment. It’s easiest for me to describe the sound by comparing it to the Kit1, and since you probably either have one or have heard one, this should give a good point of reference. Where the Kit1 is beautiful sounding, with an ethereal tone and harmonics that never end, the Monos are much more firmly planted and decided in their portrayal of music.

When listening to well recorded rock or jazz, the Kit1 creates a wash of wonderful shimmer with every cymbal strike. The room literally lights up as this shimmer reaches up out of the speakers, and in space drifts toward the ceiling. Beautiful! Through the Monos, this same music is portrayed differently. It honors beauty, but with a stronger sense that reality has taken over. The cymbal strike is still there, but before the harmonics ring out, you feel the instrument and sense it’s physicality. Then, the strike is both heard and felt before the harmonics develop. Unlike on the Kit1, the harmonics have more densely woven content so that there appear to be literal waves in the outpouring of sound as opposed to the light and airy mist that the Kit1 portrays.

It’s so easy to not think about what I just said while you’re listening. Like all of the systems I have enjoyed the most, with the Monos you can choose if you want to do the audiophile thang, or just listen. The beauty is there. Not laid bare, but there. As in, maybe you never noticed it before. Not in a hey-I-never-noticed-that-little-sound-and-I’ve-heard-this-song-a-million-times, kind of way. My experience is that people that get their rocks off over stuff like that are after something different than me. Rather, the emotion of the music is simply so much easier to connect with, that you realize the meaning far more readily. This can get hammy, so let me just leave it at that.

The presentation is less laid back and amorphous than the Kit1. It’s more up front, though not in your face or razor edged. The images created are more structured and there is an astounding sense of space. Space exists both for the instrument and musician, and also for the place in which the recording was made. The sense of depth does seem diminished compared to the Kit1, and yet sometimes I’m shocked at how deep the Monos place a musician in my room. Separation of right-left information is for obvious reasons superior on the Monos to any stereo amp. I will need to play around a bit with speaker positioning, and maybe speaker cables, too, to get the most out of the Monos.

How much of what I’m hearing is attributable to the interstage transformers is impossible to know without a rewire of some caps in place of them. Since I don’t plan to do this, I’ll draw a generalization. Every cap sounds like something. The iron probably does, too. What this sounds like that is different than the caps is that it seems to have less of a distinct flavor. Every cap I’ve tried brings a flavor, and I get the “feeling” that with this interstage there just isn’t the same type of flavor being added. It seems faster, less bloated, less constipated, less veiled than what I’ve heard from caps. I’ve never heard another interstage transformer coupled amp at home, but I have heard interstage factory AN products including both the Ongaku and Kageki, and there is a similarity in this regard.

I know the Double C cores play a big role in the improvement I have in the bass department. Big iron is known for controlling woofers. But that big iron includes the stuff in the power supply, and it’s my understanding that the same mains and choke are used for the IE core models as well. So, you can expect a stronger bass response than from the Kit1 or other SET that has a less robust power supply. Where I am used to bass that’s got good flow, but not good definition, now I have both. The pitch and control on a single bass guitar is startlingly better than with the Kit1.

A huge improvement in my system comes from the fact that the Monos don’t congeal in complex passages. Listening to music like Wilco, Tool, Joanna Newsom, and others that go from simple to complex has always been an edge of my seat experience. I luxuriate in the tone and texture as a single instrument plays, but I start to hold my breath as the music gets louder. Not so with the Monos. They sail through transitions and the music sails as well. The whole presentation isn’t subdued, it’s exciting! But where there used to be a limit, the bar has been raised much higher. I can listen to The Who at near deafening levels and not want to lower it just because “I Can’t Explain” is about to open up with an onslaught of electric guitars. Of course, there are limits. There are always limits, and much of my systems’ limits have to do with my choice of single driver speakers. These just don’t do complex at loud volumes well. The AN-E does a much better job than my speakers in this area. However, now I don’t feel like this weakness is really too bad anymore. Did I mention that I really like these amps?!

My room is a real pain. 2 stories tall, and only 13 feet wide, but 20 feet long. The speakers are six feet into the room. There’s minimal midbass reinforcement. That’s probably why I’m planning to convert my amps to the parallel version. My bet would be that if you’re good with the amount of power you have now from your 300b amp, you’re going to be more than satisfied with what the monos do with a single 300b. If I do build the parallel, you can be sure I will let you know what I find.

Thanks again to everyone on the forum. You are a great source of inspiration for continued building and discovery. And to Brian: thank you again for bringing such an accomplished product to us!

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

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