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Currently doing a few vinyl transfers for an archival project through a flat preamp... On some of the recordings, I'll need to apply the RIAA curve, but I've had a bit of a difficult time finding exact numbers for it. I know on playback it involves a pretty substantial bass boost and a high cut, but I don't know much else...

Thanks in advance...

--Ben

Comments

audiowkstation Mon, 12/12/2005 - 13:23

With vinyl, you will need the eq curve on all of them.

I will see if I can put together something for you. I am under the assumption these are LP33.33 and or 7" 45 from 1958 forward?

If they are LP51-58, another set of curves may be needed and the UK standard for the 50's period..yet another. For 78 RPM, 3 curves were used depending on date and mastering facility.

I know of NO.. post 1958 vinyl that did not use the eq.

Personally, I have not met a great argument as to why a flat eq is preferable. It will result in so much custom tayoring needed that "how do you know if you are really close?"

anonymous Mon, 12/26/2005 - 19:20

FifthCircle wrote: Thanks Bill

8-)

--Ben

There are several reasons why you should not do transfers like this!

The biggest is that you aren't loading the cartridge with the 47k and around 100pf needed for proper response.

You need to get a RIAA preamp and forget about tring to eq after the fact!

"RIAA curve" in Google will get you started, if you wan't to know the origins of the curve.

DC

anonymous Mon, 12/26/2005 - 22:06

audiowkstation wrote: Here is the resource for Phono cartirdge loading, depending on inductance, desired frequency response and a few other factors.

This of course is based on pre RIAA eq.

http://www.hagtech.com/loading.html

Do you catch the basic error in this site?

Other than that, the only factors are RLC, and if you are feeding your turntable into a mic pre, with an input impedance of like 2k, you are off by 50 times!

Let's forget digital eq for this one as well.....

DC

FifthCircle Tue, 12/27/2005 - 12:10

Yeah, I was trying to do what I knew I shouldn't do- take a shortcut and save a few bucks (my old vinyl setup was in need of help). I was actually going through a direct rather than just a mic pre so that the impedance would be a bit closer. Still not an ideal situation, though. The new turntable and preamp should be here within the next couple days.

--Ben

audiowkstation Tue, 12/27/2005 - 12:22

Look carefully when setting up your table. VTA can make quite a difference to overall traceability.

I tend to go toward the "higher side" with the tracking force issues as well.

Clean the albums very well. Many techniques are out there..you won't hurt the vinyl by doing some pretty major scrubbing if required. It does withstand a diamond..propped up by the groove walls, at tons per in sq!

audiowkstation Wed, 12/28/2005 - 22:30

dpd...I am afraid that technique would be futile with my arm/cart. Breaking a 1200 dollar cantilever is not in the plan for me. It would do nothing but give me a flat wallet and a boost of about 90dB at 7Hz..amongst other ills...

Never tried it. I might try it with my cheaper system...but I am interested in how you found this info out...hell..he may have something here.. (?)

dpd Fri, 12/30/2005 - 12:10

Bill:

Yeah, the thought of me 'dropping' my Monster Alpha II onto vinyl 20-some years ago brought shivers to my spine. You don't need to drop it much - obviously, one wouldn't want to damage the cantilever. A very slight amount should send a mechanical impulse into the system which will then cause it to exhibit its natural resonance; just like we do in electronics - excite an electrical system with an impulse reveals a system's complete response.

With the gear we have now, capturing the unequalized response and then spectral processing via FFTs is pretty easy. That required close to $50K of gear back in the 80's.

Never do anything that makes you feel uncomfortable, for certain. As you stated, you can always try it with a less expensive system to see how well you can acquire and process the data.

I like the PSpice model, too - assuming you can get all the information on the cartridge. The problem with that solution is that it totally ignores the mechanical resonance between the compliance of the cartridge, the equivalent mass of the cartridge and the arm and the damping in the arm. One can model all of that, too, if the tools are available and you can get accurate measurements to feed the mechanical model.

Sometimes, it's easier to obtain the information empirically. Caveat emptor.

anonymous Tue, 01/03/2006 - 21:53

dpd wrote:
I like the PSpice model, too - assuming you can get all the information on the cartridge. The problem with that solution is that it totally ignores the mechanical resonance between the compliance of the cartridge, the equivalent mass of the cartridge and the arm and the damping in the arm. One can model all of that, too, if the tools are available and you can get accurate measurements to feed the mechanical model.

You only have to drop it a few mm, it won't break anything! Even if you had the Spice model of the cartridge, I agree that giving it a "whack" is the best way to find the impulse response.

Was it Dick Heyser that wrote about this in the '70's? Somebody like that.

Otoh, if you had a good cartridge like a V15, and even a decent arm, the system resonance is well damped and below my cutoff freq.

DC

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