Elekit's TU-873KEII tube amplifier for DIYers who can
By Thomas Ricker 
posted Feb 8th 2008 3:51AM
posted Feb 8th 2008 3:51AM
[Via Impress]
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I would if the frequency response was more than 40 Hz... :)
Yeh, I'm thinking that upper limit should be 50kHz, rather than the 50Hz it currently says.
that is freaking badass awesome
Bottlehead.com is the place for tube amp kits. Great product photos as well.
I guess I´ll just have to tune my ear's upper frequency limit to 50 kHz to get full use of the amplifier.... and my speakers...and my source.
Actually, any freq below 20Hz or above 20kHz is going to be for harmonics. Those freqs taken out will produce a washy flat sound, this is why all mp3's suck. Those upper freqs interact with the freqs that are within the human range and create certain harmonics that are necessary to reproduce an accurate to source sound. I would love to hear this on a well recorded drum track. Probably sounds like pure aural sex.
Bob, I do not believe that what you say is accurate.
First of all, harmonics can not be generated below the operating frequency (which in this case you have indicated to be 20 Hz). Harmonics are even and odd order multiples of the operating frequency, for example 9 kHz would be a 3. order harmonic of 3 kHz as well as 2. order harmonic of 4.5 kHz.
If what you say is true, then all kinds of harmonics inside the audio band would interfere with each other in the amplifier and mix to be a bad quality audio.
The truth is that the source (CD's f.x.) only contain frequencies up to 20 kHz, which explains why the sampling frequency of the CD's is 44.1 kHz, which fulfills Nyquist sampling theorem. It states that the sampling frequency must be at least 2x higher than the highest tone in the signal (44.1 kHz > 2x20 kHz).
The function of a decent audio amplifier is to amplify audio signals as linearly as possible over the whole frequency band without changing anything of the input signal. Therefore it makes no sense to create an amplifier which changes the audio(file).
Thor, it's called Super Audio CD and DVD Audio.
Many users of this amp will have vinyl as a source, so CD sampling is irrelevant.
Michael, vinyls are irrelevant since it does not help to have sounds above 20 kHz to increase the quality. Your speakers and your ears will filter the upper limit frequency tones out anyways.
What's the point of being 10Hz-50kHz when most headphones and speakers only do 15Hz-22kHz or so? Why not just build a Millet Hybrid Max? Much cheaper and probably sounds better.
Most decent headphones do much better than that- my Sennheiser HD-595s, for example, can handle 12Hz-38.5kHz. Not like you can hear that anyways...
dang, this thing is worth it just for the 300Bs
Thor is correct in his description of the Nyquist Theorum. Your ear will not hear higher than 20-22 kHz, plan and simple. In fact, most people in their 20s and 30s (and older) can't hear higher than about 16 kHz. As people age, their ability to hear high frequencies diminishes.
Through the process of sampling and conversion (coding and decoding), most digital audio is low pass filtered at the Nyquist Frequency to prevent aliasing. SACD and DVD-A use higher sampling rates and/or more bits per sample to enhance transient response and/or overall resolution, but in the end you're still not gonna hear higher than ~20 kHz -- it's just physically impossible because of the size, shape and physical makeup of the human ear.
44.1kHz comes from the lowest common denominator (above a Nyquist Freq of 40kHz) between the video formats they were using for CD mastering in the early days of digital audio production.
"Compliment" and "complement" are different words. As a vacuum tube adds distortion to sound, imprecise grammar add distortion - not warmth - to writing.