Note: you are free to quote and reference this review, in part or in its entirety. It is and remains © 2007, by George Flanagin. Return to the homepage.
The iTube is a chip amp with two 6N1 pre-amp driver tubes and a built in dock for the Apple iPod. It has two other line level inputs. The only audio outputs are the speaker terminals, but it has S-Video and composite video outputs that come off the iPod.
The 6N1 is a dual triode tube, so one is used per channel. There is also a 6E2 tube used as a rough order of magnitude power indicator. I have to say that I loved this little visual aid --- it reminds me so much of the first radio of my life, a radio that my parents kept in full view of almost everything in the house. I suspect it had two of these tubes: one was used to convey the sense of room filling mono sound, and the other was used as a tuning indicator. This was the very early 1960s, so the radio had to be retuned a couple of times per hour as the stations drifted in an out.
There is a flimsy little remote that doesn't seem to work very well, and it ought to be delivered with gun sights and a scope to get the aim correct. There is no balance control.
The unit will work with either common mains voltage, 115V or 230V.
This product is described "in full" on the manufacturer's web site.
The retail price is $US900, and like most electronics it is made in China.
The expression Joshing comes from 1883 when a man named Joshua gold plated the new five cent pieces and passed them as five dollar gold pieces, buying something for five cents or less, and receiving $4.95 in change. The first run of these new coins did not have the word cents, and just had a big V, the Roman numberal for five. Because he was a deaf mute, the courts ruled that the merchants deceived themselves, and he was not prosecuted.
If you go to the Fatman website, you encounter a bit of joshing. On the page describing the product it is said to be a Vacuum Tube Amplifier, which is completely true if you understand the statement to mean that it is an amplifier (true) and that has at least one vacuum tube in it (also true).
There are several clues that it is not a tube output stage, the most obvious being that the 6N1 is not a power tube. And then there are the missing output transformers. Throw in the prominently placed, multiple winding mains transformer, and the visual appearance of the unit strongly suggests to the casual observer that it is a miniature tube amplifier.
Whether or not it is related to the problems described below, let me mention that this unit, Serial Number 00209, arrived with the left channel's 6N1 tube out of the socket. The tubes are reversed in orientation, so the tube on the right is part of the left channel's circuit. The loose tube was one motivation for taking a peek inside, the admonition that the warranty would be voided if I did so being the second motivation.
In the above picture, the layout is relatively clear: On the left side we find an iPod interface; in the center is the mains transformer; then we come to the chip amp (mounted on the aluminum heat-sink, and shown in the picture to the right), and the high voltage power supply for the tubes at the far right.
Despite its small size and low output, the iTube needs five minutes or so to warm up. I can't imagine why, but it does.
Let me confess up front that I have been unable to find a use for this thing. The coolness is offset by a number of design compromises that are very hard to work around, and to some extent this review is a catalog of those weaknesses.
I have had it for about two weeks, and I have used it in the usual places here --- driving the Mission M71s, the Celestion SL700SEs, and the Quad 988 ESLs. I have listened to iPod source material and SACDs.
A careful look at the web page (click here to see a 4 December 2007 screen capture of the fat-man.co.uk site) reveals that the actual spec is 18w/ch not 25w/ch. Using my Kill-a-Watt, I have been unable to see it consume even 30 watts from the wall, which leads you to believe that 50w of output for even a second is considerably beyond its abilities. Compared with the similarly rated Naim NAIT-2 (15w/channel) this unit is an anemic joke.
Keep in mind that the audio level from the interface plug on the iPod is both known and fixed. I am just guessing here, but it appears that someone has made the choice to calibrate the gain in the unit so that full output from the iPod will not clip the output stages of the iTube. However, if you consider that you might well be listening to a podcast in which the maximum signal level is -6dB then you have cut your maximum output by that same amount, further limiting what the chip amp is able to do.
The sensitivity of the line level inputs is similarly low, which means that you will experience some of the same behavior on the line level inputs as well as the iPod dock. I used a Squeezebox v3 to listen to Classic FM in London some of the time, and I found that there was no recovery from the low sensitivity.
If you are inclined to build your own low powered amplifier, headphone amplifier, or phono preamp, you may want to consider that the absolute noise level becomes a factor, not just the signal to noise ratio of the final stage. Low powered amplifiers are likely [1] to be paired with rather efficient speakers, or [2] used with less efficient speakers in smaller rooms, or [3] used with headphones. If the signal to noise ratio of the amplifier is poor, or the absolute noise level is high, everyone is going to know about it through one of the three methods.
The noise from the Fatman is no smooth hiss of tube heaven. This is gritty, dirty, grinding noise that has a 120Hz component to it, as well as some higher order harmonics. I tried the usual methods to rid the unit of the noise, but I was unable to succeed. I am 100% convinced that the noise is inherent in the unit:
The volume knob may be rotated freely, although after a certain amount of both left and right rotation it ceases to change the volume level. The useful range is necessarily limited, and within that range the steps are unsatisfactorily large. Additionally, every click of the knob causes the tubes to ring briefly.
The Fatman iTube Carbon is exceptionally "cute." The fit and finish are good, and unlike a number of lower end tube products I have seen, the iTube doesn't seem like it is going to fall apart shortly after plugging it in.
To speak honestly, this is an overpriced ornament, which may well be exactly what it is supposed to be. I had hoped to have a more visually interesting yet sonically reliable version of the old Naim NAIT. I regret to report that this item is not it.
