Two Stage Amplifer

[marcbarker]

An electric guitar would sound awful with frequencies above 8 kHz. It's supposed to be limited bandwidth, what made the 'valve sound' (in guitars that is) was the transformer was limited in bandwidth, and had partly burned out valves driving it (to soften the edges), and a speakers that were almost crafted like a Stradavarius violin. People tried replacing speakers with modern technology ones and it messed the sound, those amps you could buy cheap because they were beyond repair without the original speakers.

Funny thing is, that guitar sound is now messed up badly by MP3 in P2P filesharing, because MP3 can't handle the complex tonality. It sounds like it's underwater or someone is fiddling around with the 'tone controls' while you listen.

 

[Hero999]

Valves mess the sound up more than MP3s.

The quality of the MP3 depends on the bit rate but if you want good quality then use FLAC which is completely lossless.

probably an over-reacting unstable opamap with a feedback loop resonating, that didn't show up in pspice.

Try building an inverting amplifier with a gain of 10, using the 741, and applying a 1.2Vp-p 12kHz sinewave to the input and see what you get at the output. Hint you do not get a 12Vp-p sine wave out.

 

[marcbarker]

Valves mess the sound up more than MP3s.

The quality of the MP3 depends on the bit rate but if you want good quality then use FLAC which is completely lossless.

Try building an inverting amplifier with a gain of 10, using the 741, and applying a 1.2Vp-p 12kHz sinewave to the input and see what you get at the output. Hint you do not get a 12Vp-p sine wave out.

The whole point of music is the colouration of sound by the instrumentation.
Saying 'valves mess up sound more than mp3'. That's like saying a "Stradovarius violin messes up the tonality of the vibrating strings more than an electric violin does". It displays it little bit of ignorance!

The whole point of popular music is 'messing up the sound', but doing so, so it sounds NICE not nasty. Then, to prove it.. people buy your record MORE than the competitor, it's as simple as that, and nothing has changed today.

In 60's a typical beatles song, a vocal part would be fed into a spinning Leslie Speaker, and recorded. Or a cabinet speaker would be used as a microphone. It was done creatively, and the record sales proved it worked.

If you heard the mp3 sound quality in p2p filesharing, you can hear a similar rotating leslie speaker effect, on just about ALL the tracks you hear.

Commonly used MP3 (the one that just about everyone uses), cannot deal with the tonality of most guitar music, especially if there are fuzz and phasing effects together at same time. Because the complex sound demanded a 'photographic' recording, not the fourier transform analysed spectral-taking-the-sound-to-bits, converting the time and frequency domain analysis into text-based instructions for later recreating the 'orginal sound' (ha ha) according to a low-rate bitstream set of instructions. Did you know that inside a digital cellphone (highest rate of compression) there is a simulated human vocal tract that is virtually operated text-to-speech? People doing filesharing often don't use 'lossless' mpwhatever encoding. The choice of professionals is 'Wav files', because that records the shape of the sound, just like CD-digital audio by philips does. This all happens in realtime, in exactly the same way that the eardrum picks out the shape of the vibrations, in real time. Not 'near instantaneous'. (have you ever seen the lip-sync out on someone else's HDTV?). Of course now days, there are less Stradovarius's being recorded, instead are MIDI-sequenced wavetable sounds, each sounding the same each time played, so MP3 helps, common mp3 does the colouration 'automatically'.

And anyway who's talking about 12 v p-p signal @ 12 kHz ? 741's are not used like that, if I remember rightly they are used at low level circuits, discrete transistors are used for 12V levels, not a 741. You'd be silly if you expected a 741 to do that.

 

[Hero999]

Nobody makes a 50 ohm speaker.

Yes they do.
**broken link removed**

 

[audioguru]

The tiny 50 ohm speaker is only 2" in diameter.
It resonates sharply at 300Hz so it will sound like a little bongo drum.

 

[Hero999]

I never said they made good 50Ω speakers.

741's are not used like that, if I remember rightly they are used at low level circuits, discrete transistors are used for 12V levels, not a 741. You'd be silly if you expected a 741 to do that.

The 741 only has a gain of 40db at 10kHz and it's as noisy as hell. You're better off with discrete transistors.