back to article Fatman iTube amplifier

The iTube is a valve amplifier - yes valves, those old-fashioned glowing things that TVs used to have - with an iPod dock unit, all encased in chrome and black metal. It's really two separate systems: a power amplifier, which is the analogue bit, and the dock. Fatman iTube amplifier The amplifier has two sets of RCA/phono …

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I don't understand

Valve amps are for audiophiles who appreciate a softer sound than that produced by a transistor amp.

I don't see how an amp made for appreciating the subtle qualities of analogue recordings (e.g. well kept vinyl) would be of any use for playing compressed digital sound. Surely all the audio nuance is well lost in the compression of the format. And for £300 - I don't get it.

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Anonymous Coward

it's perfectly simple....

It's got analogue inputs too, so you can ALSO use it for your well-kept vinyl. And perhaps audiophiles put lossless FLAC music on their ipods....

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It *is* perfectly simple

Even FLAC - or any form of 16-bit digital audio for that matter - won't sound as good as a well-kept vinyl LP.

A well-produced LP with a good pickup can offer a dynamic range in excess of 120dB over the standard 20Hz-20KHz frequency range. With 16-bit digital audio, the dynamic range - ie: the amplitude of the largest possible signal divided by that of the smallest possible signal - is 65.536, or 96dB [20×log(65536)]. This mathematically inevitable difference *is* perceptible to the human ear.

While a CDDA beats the socks off a vinyl record for durability, which is why it's so popular nowadays, the vinyl LP can puree a CD (or any other form of 16-bit digital audio) as far as sound quality is concerned.

Of course, the SACD and DVD-A are a whole new kettle of fish but that's no longer 16-bit audio sampled at 44.1KHz.

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Anonymous Coward

So the valves *DO* something in this then?

Unlike:

http://www.reghardware.co.uk/2006/07/11/review_isteroid2_amp/

That works before the valve warms up or even (amazingly) if it is unplugged. Hmmm.

The reviewer rather charmingly assumes this is because of some "twin amplification" system. A cynic may suggest that the valve is simply there as eye candy to please the stupids.

Suggestions that plugging it back in change the sound are a bit too close to Peter Belt woo-woo for me.

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Don't forget...

... to buy the OFC polarised 'monster' cables with gold plated connectors and certified goat-free.

This is a fluff product, then again 90% of "audiophile" equipment is. Seriously people, next we'll be selling iPod headphones with "reduced skin effect"*.

Still, it looks good, if you've £300 to waste. But because virtually no one has the right listening environment and audio sources they are never going to hear it anyway.

* Note to those interested: 'Skin effect' has no appreciable effect anywhere near the frequencies used in audio.

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Real life dynamic range of LP vs. CD

The previous poster brought up the old vinyl/CD discussion, which is really a very difficult and subjective topic to discuss about. It's much to do what kind of sound you personally prefer.

Yeah, maybe vinyl theoretical dynamic range is in tune of 120 dB but in reality, according to some randomly selected web pages below, the range is somewhere between 60 and 80 dB:

http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/iandm/part12/page2.html

http://wiki.hydrogenaudio.org/index.php?title=Vinyl_Myths

http://history.sandiego.edu/gen/recording/dynamic.html

About valve amps: They are thought to sound musical compared to transistor amplifiers as they add harmonic distortion (normally measured as THD) to the sound, sometimes in the tune of several percent. The distortion is the reason why e.g. violins are made of wood as opposed to concrete.

The added distortion by e.g. valve amplifier, in my opinion, makes the sound less realistic, i.e. LoFi :-) This is especially true when a tube amp is overloaded, which is pretty easy to do as their output power is normally lower than transistor ones. However, human ear finds harmonic distortion pleasant, hence the tube amps sound more "musical". Even badly recored harsh material sounds bearable through tube amp as opposed to a real HiFi amp :-) However, if you material is recorded right you get way more resolution with (a well designed) transistor amp.

There are also other stuff that matters like (normally) less than straight frequency response characteristics etc. but I think this is enough for now.

Tube amps do not care if the incoming signal is digital or analog. They add distortion in both cases. If you like the sound of them I can't see any reason not to connect a iPod to one.

Here's my humble opionion.

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Bronze badge
Anonymous Coward

Some common sense, please!

Thank you, Sami Hentunen, for that measured response. I had composed something similar but rather less polite. The only thing being "pureed" in the earlier comment is common sense.

As to the comment that another product worked with the valve unplugged, well that got me thinking. I had assumed, as no doubt one is supposed to, that the output stages of this amplifier used valves. If they did, there would be two output transformers (as it's stereo) but there is only one transformer lump, which will therefore be a mains transformer. The valves look like small signal devices, too. So, we are conned into thinking that this is a valve amplifier when it's a transistor amplifier which might possibly have a valve in the pre-amplifier stage. (Output transformers and power amplifier valves are expensive, after all!) Maybe the reviewer can confirm whether the amplifier works instantly on switch-on (before the tubular cathodes of the valves start to glow orange), or if it works with the valves unplugged.

The middle valve is just an EM84 or similar "magic eye" indicator - it does no more to affect the sound than would a VU meter. But at least the reviewer confirms that this one is actually doing something!

The photos look like Photoshopped publicity shots. Valves do not glow like that unless they are being seriously overdriven, and there's no sign of the green phosphorescence from the indicator valve (which is there to a certain extent even if there is no signal, if the indicator is of the EM84 type).

In short: why does El Reg stoop to reviewing such rubbish?

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Gold badge

Vinyl?

Quote "A well-produced LP with a good pickup can offer a dynamic range in excess of 120dB over the standard 20Hz-20KHz frequency range."

Unfortunately a well produced LP doesn't produce these ranges, RIAA equalisation is applied:

http://en.wikipedia.org/wiki/RIAA_equalization

Which is preemphasis and deemphasis, such audio processing is a no-no if you are an audio purist and are trying to achieve a sound as close to the original source material as possible.

Most studios use digital recording now, so there's little point in claiming analog technology produces a better sound when there's so few people recording with reel to reel tape. Modern mastering of recordings allows recordings to be dithered and converted to 16-bit 44100 without any intermediate analog stages and so the noise levels are almost non-existant.

Dynamic range counts for nothing if you have a poor signal to noise ratio. The noise floor will be such that the effective dynamic range will be lower.

Nobody is claiming CD is the best digital audio format, it's just the current "standard". People are reluctant to move from CD as they know the next generation of digital disc media will be full of restrictions and DRM.

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Deliberate distortion

Speaking as an electronic engineer, and as an audiophile, valves add EVEN harmonic distortion.

This distortion is great in a guitar amplifier - it adds the colouration that guitarists want. It can also be pleasant in a microphone preamplifier in a recording studio - it can enhance vocal sounds.

However, it's NOT appropriate for high quality audio reproduction. Do you really want distortion added to the entire content of the material? I don't think so!

There is NO valve amplifier at ANY price that can compete with a simple, cheap semiconductor design. My semiconductor-based amplifier will win on noise, hum, transient response, power output, price, reliability, frequency response, distortion, and any other parameter you want to throw at it except weight!

The only remaining use for valves is in high power TV transmitters - they are largely redundant for all other functions!

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Manufacturer's site confirms this is a hybrid amp!

Look at:

<http://www.fat-man.co.uk/docs/product/itube_spec.htm>

for confirmation that the valves are used only as pre-amps. Two ECC85s cannot be used to produce 13W per channel! This device must have a solid state (likely an IC or two) power amplifier stage.

This is a little bit of a con, even if there are some audiophile merits to using valves for the pre-amp stage - they could be a little more "honest"!

Still, I gotta say, I loooove the iPod dock they've produced! As the reviewer says, true geek retro.....

Nigel

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