Youngklip Posted October 29, 2002 Share Posted October 29, 2002 why do people still use Phono-amps I can understand because of old records but is it still used on dvd-audio and SACD? WHy is it used? Quote Link to comment Share on other sites More sharing options...
lynnm Posted October 29, 2002 Share Posted October 29, 2002 Youngklip Phono preamplifiers are used to raise the signal from a phonograph cartridge to a high enough level for a modern amplifier to use. CD's , DVD's , tuners etc. produce a signal that is large enough and therefore do not require the extra amplification that is needed by a phono cartridge. In addition a phono preamp provides RIAA equalisation to the signal received from a cartridge. RIAA equalisation is required to match the frequency characteristics of older recordings to the amplifier. It is a standard introduced by the Recording Industry Association of America a time when there were no real standards as to what comprised proper frequency response curves, (or even recording/playback speeds for that matter ) , in order to make records produced throughout the industry compatible. Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 29, 2002 Share Posted October 29, 2002 If I may expand a bit on what Lynnm was saying. The long play 33 rpm LP vinyl record was/is played with a magnetic pickup cartridge. The needle rested in the groove. So it was like a magnetic microphone fed by the vibrations of the record groove, rather than a diaphragm. One thing was that the magnetic pick up acted like a hand cranked generator. Crank it faster, and it put out more voltage. So, at higher frequecies, it had a higher output. None the less, the output of the cartridge is very low. So you need a pre-amp before the main amplifier. A related issue is/was that surface noise on the record platter was higher, at higher frequencies. The 78 rpm recording typically show this. Therefore, there was a solution in the 33 rpm record of emphasis or equalizing. The actual sound put down on the record had boosted levels of treble. This got it above the surface noise. Then the play back pre amp cut down the treble. As you can imagine, the treble boost in making the vinyl had to match the roll off in the pre amp. This was somewhat standardized by the RIAA spec. However, vinyl fans will tell you that there were different schemes being used. In later years we had tape machines and CD player and VCRs and then DVD. The outputs of the playback devices are theoretically "flat" and at a high level. So there are no pre-amps in a strict sense and no equalization, at least not comparable to the RIAA preamp / equalizer. Gil Quote Link to comment Share on other sites More sharing options...
lynnm Posted October 29, 2002 Share Posted October 29, 2002 Yah - Uhhh Duhhh - Like he said !! Thanks William your post reminded me of some details that I had known many moons ago and had forgotten - especially the tendency for the o/p levels varying with the frequency. Quote Link to comment Share on other sites More sharing options...
Lone Palm Posted October 29, 2002 Share Posted October 29, 2002 youngklip don't use the phono jacks for anything other than a phonograph. It'll really sound AWFUL! Quote Link to comment Share on other sites More sharing options...
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