Well, it’s been a rather long time since my last post on the Audio Note Kit 1 Single-Ended 300B amplifier. I’m happy to get you caught up on what’s been going on!
My early days with the newly built Kit 1 were exhilarating. Gorgeous music was filling the room with holographic imaging, midrange magic and stunning vocals. I was quite thrilled. However…
You may remember that in this post I mentioned that the Kit 1 had a tendency to exhibit clipping distortion on CDs featuring very low, “hip-hop” style bass lines, such as several tracks from Lorde’s “Pure Heroine” and Sade’s “Soldier Of Love.” I attributed this to a mismatch between the amp and my not super-efficient Reference 3A De Capo speakers. I was convinced that there was nothing wrong with the amp itself.
I’d begun considering switching out my De Capo’s for other, more efficient, easier to drive speaker choices.
Then, as an experiment, I took my amp to the home of local audiophile and Audiogon regular “sebrof.” He offered to let me try my amp paired with his 96 db efficient Tekton Katz Meow’s. No longer in production, the Katz Meow featured a Fostex main driver coupled with a super tweeter. Shockingly, the same tracks that were distorting on my De Capo’s at home were showing the same distortion on sebrof’s far more efficient Katz Meow’s. More shocking still, sebrof’s 3 watt per channel DIY 2A3 amp played the same tracks on the Katz Meow’s with no trouble at all!
Dictionary.com defines “gremlin” as “an imaginary imp jokingly said to be responsible for malfunctions in machinery.” (Apparently this term was coined by RAF pilots during WW II to describe mysterious malfunctions in British military aircraft.)
Okay, a gremlin had taken up residence in my amp. But where was it hiding?
Heroic Service From Audio Note Kits
Thus began a month-long (more or less) series of phone calls, Skype debugging sessions and emails with Audio Note Kits owner Brian Smith. (If you’re really interested in all the twists and turns in the troubleshooting process – and if so you have way too much time on your hands – you can follow this thread on Audiogon.) Suffice it to say that this was one very elusive gremlin who was not eager to show himself too easily.
Brian has a deep knowledge of the kits he sells and was incredibly generous with his time in walking me though various tests and measurements in a valiant attempt to get the amp working properly.
Once we figured out that the amp was having an issue, Brian said, “I’m going to make you happy, don’t worry.” And truly, Brian and Pete Fulton (see below) took every possible step to make this right, including sending me a replacement, finished Driver Board (when we thought that was the problem) and sending a set of replacement tubes to eliminate a bum tube possibility.
Through our long-distance troubleshooting sessions, we’d managed to eliminate a number of possible causes for the distortion I was hearing. In the end, though, we decided that someone who really knew this amp inside-out and was in the same room with the actual unit was going to have to get their hands (and test equipment) on it to smoke out that pesky gremlin. So Brian and I decided to ship the amp to Pete (“digitalpete”) Fulton down in Naples, Florida.
Pete both builds and services ANK Kits for ANK. In fact, some of the kits sold by ANK (including the various flavors of the Kit 1) can be purchased prebuilt by digitalpete at an extra charge through ANK. Pete is a real artist with this stuff – his builds are over-the-top gorgeous. Although I was disappointed not to have conquered the issue on my own, I was ready to entrust the amp to Pete.
In the end, the problem turned out to be an issue with the output transformers. They were not putting out full power to the speakers. In other words, the amp was not producing anything near its rated 8 watts per channel, which is why taxing musical passages were driving it to distortion. (It also explains why I had to turn the volume knob on the Kit 1 just as high on sebrof’s 96 db efficient Katz Meow’s as I did with my 92 db De Capo’s to get any decent volume out of the system!)
In all the many Kit 1 kits that have shipped over the years, Brian and Pete have NEVER seen this weird Output Transformer issue before. In fact, my original transformers have shipped back to Brian so he and his transformer folks can do an autopsy on them to see what caused the problem.
Digitalpete: Artist With Solder and PCB…
I thought it would be fun to show you some of the things that Pete Fulton did while replacing the output transformers of my Kit 1.
Let’s take a look at some of the “cleaning up” of my build that Pete’s done, shall we?
You’ll notice throughout the build that Pete has used cable ties to bundle some of the wires together and eliminate the “rat’s nest” aspects of my build. Looking carefully at the volume potentiometer near the lower left corner of the chassis, you’ll see that Pete has eliminated the little volume pot PCB and soldered the connections right to the pot. Note also the twisting of the red Mains Transformer leads leading to the rectifier valve base. He’s also bundled and shrink-tubed the wires from the pot to the Driver PCB. Nice!
Here’s a close-up of the wires running from one of the output transformers to the speaker binding posts. Pete has braided them. Sweet!
The blue/white and brown/white and black ground wires have been finished with a lug connector and screwed down to one of the screws attaching the Power Supply PCB. Pete explained that he did this so as not to run quite so many wires under the board.
Happy Endings: Listening Impressions
I have been playing the heck out of the Kit 1 since receiving it via UPS (superbly boxed) from Pete a week or so ago. And…
It sounds fantastic!
Since tracking down the problem with the output transformers, it’s amazing how much more powerful the Kit 1 feels. Whereas previously, I was turning up the volume knob to 11 o’clock or 12 o’clock to get normal listening volumes out of the amp, I’m now getting plenty of punch and volume from a 9 o’clock or 10 o’clock position.
This amp sounds much more powerful than its rated 8 watts. Tracks with deep bass sound punchy and powerful as they should, and the clipping distortion has vanished entirely! The top end of the musical spectrum sounds, if this is even possible, more sweet and extended than before. As one early reviewer of the Kit 1 suggested, this is a thoroughly modern sounding amplifier. There is nothing rolled off or “romantic” sounding (in the sense of “syrupy” or “slow”) about this amp. It just sounds clean and “right.”
Tracks with deep bass sound punchy and powerful as they should, and the clipping distortion has vanished entirely!
Again, I will use the word “pure:” there is a clarity and purity to the presentation that is intoxicating – you just want to keep listening and listening. And what about imaging and soundstage? If, like me, you are a devotee of this aspect of the home listening experience let me just say that the ANK Kit 1 may just be your ticket to bliss.
The Reference 3A De Capo is something of an imaging monster, too, but the Kit 1 takes the De Capo’s to an entirely different level in this regard. I am getting wall-to-wall soundstage spreads and a stunning sense of ambience on recordings that have this information buried in their analog grooves (or zeros and ones, as the case may be). What about the low end? There is plenty of power there, as well. I’m thinking this is where those massive transformers come into play. This amplifier seems to have plenty of power reserves to go quite deep. Orchestral kettle drums have the requisite impact and rock ‘n roll is appropriately raucous when called for.
So, I am going to retract my earlier opinion – from the time before getting the amp sorted out – that the Reference 3A De Capo is a “borderline” match with the Audio Note Kit 1. I think it’s a fine match… That said, I’m not only a music lover but also an audiophile which makes me susceptible to the inevitable “I wonder…”
I wonder what a super efficient speaker with a sensitivity somewhere in the high 90s decibel range would do for this amp. What would it be like to pair the Kit one with a speaker so efficient that it could play loudly without the amp breaking so much as a sweat? Also, if there is one shortcoming of the De Capo with the Kit 1, it’s that this combination does not exhibit the last word in low end definition. So, yes, I am toying with the idea of moving on to a very high efficiency design. I’m curious to hear what you, my readers, think of this idea. In any event, I may talk about some of the possible speaker candidates in a future post.
Again, I will use the word “pure:” there is a clarity and purity to the presentation that is intoxicating – you just want to keep listening and listening. And what about imaging and soundstage? If, like me, you are a devotee of this aspect of the home listening experience let me just say that the Audio Note Kit’s Kit 1 may just be your ticket to bliss.
POSTSCRIPT: A List of Reasons Why You Can and Should Build An ANK Kit 1 300B Single Ended Amplifier:
- The Kit 1 isn’t “cheap,” but it is a bargain in terms of what you get: ultra high-quality parts and a beautiful finished product. Sold assembled, through a normal retail channel, I’m guessing this would be a US $4000 amp, at least.
- You’ll learn so much during the build process and feel confident that you can later upgrade the amp all by yourself if you choose.
- The finished amp is rock solid, beautiful and sounds great.
- The finished project doesn’t scream “DIY” – it looks like a beautiful, boutique, high-end audio component.
- Brian Smith and Pete Fulton have your back if you run into problems with your build. Trust me, I know.
- Building things with your hands is great therapy.
- Building things with your hands is fun.
- There’s a world of difference between “I bought it” and “I built it.” The pride of ownership and emotional satisfaction are enormous.
I look forward to posting again soon! Thanks for following Steve’s Audio Blog.
Until next time…