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RIAA preamps

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LP's? You mean old fashioned vinyl records?????????
Hee, hee. You still play them?

In "the good old days" there were 78 RPM records, 45 RPM records and 33 RPM records.
The 33 RPM records used a magnetic pickup and the preamp had RIAA equalization.
The equalization allows the cutter to reduce its swing because the low frequency level was reduced by the equalization. Then the rqualizer increased the lows back to normal.
The cutter increased the highs and the equalization reduced them back to normal.
The signal will be extremely small from a pickup without a preamp.
 
erm yes I'm getting a preamp (if jaycars stupid website could just hang onto my cart while i look thru other goodies instead of dumping it) and I think it does need to be RIAA the desription says it has RIAA for 78's (yea dads still got some of them too !) and acts like you don't need it for LP's but i think you do
 
33 RPM LP records used RIAA equalization. I never had 78RPM records so I don't know what equalization (if any) they used.
 
right well i ordered the preamp hopefully it will end the exodus of amplifier trials each one of which has its own little fault (all old well used amps) so i decided once and for all cut the cackle and just get a preamp for playing records into the computer only and hopefully we'll have no more problems
 
I thought the equalization is to flatten the mag. cartridge freq. response, i.e., higher output at higher needle speed, just like a generator.
There's probably an equalization curve on the Internet; some dropped off at <10 Hz to avoid amplifying rumble.
A crystal cartridge, high output and found in cheap phonos, may not have needed any equalization.
 
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I thought the equalization is to flatten the mag. cartridge freq. response, i.e., higher output at higher freqs.
There's probably an equalization curve on the Internet; some dropped off at <10 Hz to avoid amplifying rumble.
No.
Simply look at RIAA Equalization in Google.
It has the same frequency response curve since 1954 except the very low frequencues have been cut off.
The cutter has its low frequencies reduced to reduce its swing and allow the record to play longer. The high frequencies are recorded with a boost so that hiss is reduced when the player reduces the highs down to normal.

The inductance of the magnetic cartrige resonates with the input capacitance of the preamp and connecting cable at about 18kHz and the 47k input impedance of the preamp damps the resonance a little so that the response is fairly flat to 20kHz.
 
yes thats what i was told the RIAA filter was specifically designed to make the record track of equal width over all frequencies else treble would get lost and bass would either erupt into neighboring tracks or the allowance for each track would have to be greater making the record shorter, so preamps need to reverse this to get back the original tone, although I have used a TDA2002 based power amp as a quikie for a preamp and it didn't sound too bad I'd rather have a proper RIAA preamp as we are transferring my dads LP (and some of the 78) collection into digital. and before people scoff and say why not just buy the CD's well lots of songs on CD are actually rerecorded in later years by the artists and sometimes "the original" of its day is hard to come by but for finding it on LP and all of my dads LP's are in pristine condition
 
Hope this link from National would help Thunderchild, to build his own, instead of paying more.

**broken link removed**
 
well thanks mate but i've already ordered one for 11 £ which is fairly good as i can't make PCB's the last RIAA preamp i tried making on matrix board being very careful to follow the pcb layout just resulted in being a radio of some kind I'd be damned if i could ge a rexord to play through it but it was piking something up from somewhere (UFO ?) so I thought time to just buy one, anyway its nice to know the theory behind it
 
well thanks mate but i've already ordered one for 11 £ which is fairly good as i can't make PCB's the last RIAA preamp i tried making on matrix board being very careful to follow the pcb layout just resulted in being a radio of some kind I'd be damned if i could ge a rexord to play through it but it was piking something up from somewhere (UFO ?) so I thought time to just buy one, anyway its nice to know the theory behind it
I assume that the present amplifier system used by you, will have the needed RIAA pre-amp, if it has the Phono input? How come you need to make one afresh?
 
I thought the equalization is to flatten the mag. cartridge freq. response, i.e., higher output at higher needle speed, just like a generator.
There's probably an equalization curve on the Internet; some dropped off at <10 Hz to avoid amplifying rumble.
A crystal cartridge, high output and found in cheap phonos, may not have needed any equalization.

You are quite right, crystal and ceramic cartridges need no equalisation - just a simple high impedance input.

Some crystal and ceramic cartridges are capable of VERY high quality reproduction as well - I always used ceramic for disco's, more than enough quality, and their higher tracking weight helped to prevent skipping.
 
No.
Simply look at RIAA Equalization in Google.

When the straight skinny is only a few mouse clicks away, and I don't do those clicks, I think I am being overtaken by terminal laziness!!!
:eek::(
 
You are quite right, crystal and ceramic cartridges need no equalisation - just a simple high impedance input.

Some crystal and ceramic cartridges are capable of VERY high quality reproduction as well - I always used ceramic for disco's, more than enough quality, and their higher tracking weight helped to prevent skipping.

Even Crystal Cartridges Require RIAA Compensation for phonographs.
This Compensation has nothing to do with the Type of Cartridge.

It is required because of the Reverse Frequency Curve that is used when making the Recording.
Without the RIAA Compensation the output will lose most of the recorderd BASS notes. Sound becomes really TINNY.

Excessive BASS Can't be recorded at the same levels as Higher frequencies as it causes the record material to Push Through to the adjacent grooves. So you will hear it as an overlapping sound.

And basically all 16 2/3, 33, 45 and 78 RPM records, all use RIAA.
Tapes use an NAB Curve for simular reasons.
 
yes I would have thought that as well unless crystal happens to have a responsive curve that is practically like the RIAA one,
 
Even Crystal Cartridges Require RIAA Compensation for phonographs.

They don't get it! :D

This Compensation has nothing to do with the Type of Cartridge.

Some of the top old amplifiers (like Quad) used plugin adaptors for various different cartridges, but it was more a change to match a specific cartridge rather than anything else. Only the magnetic ones used RIAA equalisation.

I've repaired, built, and modified many, many record systems over many years - if you don't use RIAA equalisation with a magnetic cartridge it sounds absolutely horrible (as does feeding a flat signal to an RIAA input). If you have a high impedance input preamp (I've used a simple 2N3819 drain follower many times) you can feed a crystal or ceramic pickup through it directly to any flat amplifier and it sounds perfectly fine.
 
Even Crystal Cartridges Require RIAA Compensation for phonographs.
This Compensation has nothing to do with the Type of Cartridge.
That's not correct. Crystal cartridges respond differently than magnetic cartridges. A crystal cartridge's output voltage is proportional to the amount of stylus movement but not frequency. A magnetic cartridge's output is proportional to both the amount of movement and the frequency of the movement. (A magnetic coil's output is proportional to the rate of change of the magnetic field, which goes up with frequency). Thus for a constant groove deviation amplitude, the magnetic cartridge output will increase with frequency, while the crystal cartridge output remains constant with frequency (assuming a perfect cartridge). The crystal cartridge thus has a relative rolloff of the high frequencies and a gain for the low frequencies as compared to the magnetic cartridge. Since this is the approximate response you need for the RIAA compensation, a crystal cartridge will sound reasonably good with no added equalization (as Nigel noted).

If you applied RIAA compensation to the crystal cartridge it will sound dull for the high frequencies and have excessive bass.
 
Has any manufacturer made a phono pickup in the last 30 years?
has a "crystal" phono cartridge been made in the last 40 or 50 years?

Has anybody played a vinyl record in the last 30 years?
 
Has anybody played a vinyl record in the last 30 years?

yes lots and recording them to digital is a very good idea if you have a pristine LP collection most stuff is not available now on CD its mostly remakes: not as good as original LPs
 
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