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Anyone use the NAB curve over the RIAA?

dewdude

dewdude

High on resolution.
Hey all,

This is probably a very bizarre question, but has anyone out there used the NAB de-emphasis curve as opposed to the RIAA for playback?

I bought a Korg MR-1 recorder for digitizing my vinyl, it'd been a device I'd been wanting to get for a number of years and I finally had the playback hardware on my end to fully take advantage of it (1-bit DSD recording). The most recent version of Korg's audio conversion software has this nifty feature called "DSD Phono EQ", from what I can tell it's a DSD-domain equalizer with deemphasis curves. The microphone preamp in the unit will amplify a direct cart feed...which means there's a chance I can "simplify" my attempts at digitizing my LPs by bypassing an external preamp entirely and just letting software do the work.

But here's where I'm starting to get confused.

The EQ has the standard RIAA curve as well as the RIAA + IEC modification, but it also has NAB, Columbia, AES, and FFRR. This LP I digitized and playback sounds MUCH better with NAB vs RIAA; the sound seems fuller and better equalized.

I realize most everyone probably uses preamps with RIAA pretty much forced in the feedback loop; but is anyone out there not using such a device and ever used a different playback curve? If there hadn't been some wood-glue stuck in the last few grooves I'd be very temped to just run NAB on this recording and call it done.
 
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I won't pretend to understand the "ins and outs" of RIAA, NAB, IEC, or XYZ, but owning several older tube amps, I often experiment with different settings. Recently I was listening to a box set of Miles Davis reissues on 10" LP's, Mono, of course. The sound was not very engaging so for fun I hooked the turntable up to the Tape Head input of the amp. What a difference. The recording sounded much more natural and enjoyable than when fed thru the phono stage.
 
Below are the input specifications for your unit. Note that the input impedance is only 10K Ohms. This is considerably less than the standard 47K Ohms that most phono cartridges like to see in order to produce there published specifications. Changing the resistive loading may result in a change in the frequency response of the phono cartridge.

Phono cartridges also like a range of load capacitance (this can vary from phono cartridge to phono cartridge) to produce their published frequency response characteristics.

This is achieved by capacitance of the cables used to connected the turntable to the phono preamp and the amount of capacitive loading supplied by the phono preamp. Some consider this to be critical for achieving the best sound quality.

In a quick look, I do not see any specification for capacitive loading for your device.

upload_2017-7-23_21-20-16.png

Below is a basic comparison of the specifications for RIAA, NAB and others.


bnc.JPG

How much any of this (changes in the playback frequency response which is the response that you will be recording) will impact your enjoyment of the music is up to you to determine.
 
Yeah. It was something I'd always wanted to experiment with and this was an easy way to do it.

I did after some critical listening of a couple LPs found out NAB only seemed to sound fine on that one LP...which indicates just a difference in mastering. When comparing with the lousy CD release I found it doesn't have as much midrange as I thought it should.

I have decided Im going to build a simple flat preamp with proper loading for the cartridge.
 
dewdude said:
Hey all,

This is probably a very bizarre question, but has anyone out there used the NAB de-emphasis curve as opposed to the RIAA for playback?

I bought a Korg MR-1 recorder for digitizing my vinyl, it'd been a device I'd been wanting to get for a number of years and I finally had the playback hardware on my end to fully take advantage of it (1-bit DSD recording). The most recent version of Korg's audio conversion software has this nifty feature called "DSD Phono EQ", from what I can tell it's a DSD-domain equalizer with deemphasis curves. The microphone preamp in the unit will amplify a direct cart feed...which means there's a chance I can "simplify" my attempts at digitizing my LPs by bypassing an external preamp entirely and just letting software do the work.

But here's where I'm starting to get confused.

The EQ has the standard RIAA curve as well as the RIAA + IEC modification, but it also has NAB, Columbia, AES, and FFRR. This LP I digitized and playback sounds MUCH better with NAB vs RIAA; the sound seems fuller and better equalized.

I realize most everyone probably uses preamps with RIAA pretty much forced in the feedback loop; but is anyone out there not using such a device and ever used a different playback curve? If there hadn't been some wood-glue stuck in the last few grooves I'd be very temped to just run NAB on this recording and call it done.
Click to expand...


I also found that different records sound better with some variation of equalization curve. I cannot change what phono stage is doing, but use tone control in preamp for adjustment. Commonly for records made before 1970 - I raise base and reduce treble one or two notches. For newer records I do just opposite - reduce bass and raise treble. Records made in 1980 and newer, usually do not need need adjustment (I assume they were made with digital master).
 
tnsilver said:
Call me crazy but in this explanation the sample audio without the RIAA curve sounds much better to me than the one with the RIAA curve applied. Way better! What's going on?
Click to expand...

The first track, without the RIAA curve, is what the audio should sound like from the master tape, CD, file, or what-have-you, before going through pre-emphasis. It is unmodified. The second track has been run through the RIAA pre-emphasis as it would be before the amplifiers driving the lacquer cutting head. This is the sound that as it is encoded on the record and similar to what it would sound like if you play a record without using the necessary de-emphasis.

Another thing. Many people seem to assume that the master tape already has the RIAA pre-emphasis encoded and that this would have to be removed to make anything other than an Lp from the tape. This is not true. The master tape is playable in full range fidelity just as it is and can be used to make any other media. The RIAA pre-emphasis curve is done "on-the-fly" by an electronic circuit as lacquer is being cut, just the same way as the de-emphasis is done by an electronic circuit as we are playing the record.

Also, the RIAA characteristic is very well defined and is applied to all records and is not something that one cutting lacquers can "use a little more or a little less of it". Someone might monkey with some other equalisation if he feels it's necessary but the RIAA curve is set in stone (by the little circuit right before the cutter head amplifiers).
 
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Thanks @tubewade for the info, but I went through the comments in that blog and someone (the author?) mentioned they swapped the samples by mistake. That would explain it too.
 
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