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Needledrop - skip phono pre-amp?

I'm in the process of researching what I will need to try to get quality recordings from vinyl source.

It just dawned on me, there's an RIAA filter with sox.

Can I just skip the phono pre-amp, do my de-click and noise reduction etc. working on the 24-bit depth needledrop and then use the riaa filter in sox when I do my final downsample to 16/48 kHz?

Or is it really better to apply RIAA curve when it is still analog?

I'm really tempted to just do that curve digital, removing the need for another possible source of noise in the analog chain between the turntable and the ADC. Thoughts?

Needledrop - skip phono pre-amp?

Reply #1

Phono preamps are optimized for the EQ and dealing with the rather low level of a magnetic cartridge. If you can get the S/N ratio out of your method it will be OK but I'm old and old school. I try to get the best signal processing throughout the entire chain. Good mic preamps. Good phono preamps.

In theory your RIAA curves should be better as they're digital constants without component tolerances. Flip side, check the performance of 24 bit A-D converters and you'll find they really don't get to 24 bits - from the standpoint of running low levels and boosting them later in digital.

Good luck but they're still only LPs.


Needledrop - skip phono pre-amp?

Reply #2
You still need a preamp to get the signal up to line-level for your soundcard (or interface, ADC, etc.).    And, the preamp should have a 47K Ohm input impedance to properly "load" the phono cartridge.    A good "pro" microphone preamp has a balanced input with an impedance somewhere around 1K.    The mic input on regular soundcard has different issues but is no better of a match.

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do my de-click and noise reduction etc.
Of course, what you hear (or what your noise-reduction software "hears") is going be different before/after EQ.    The exaggerated high frequencies may make it easier to hear click-transients, but overall I think you'd end-up fixing things that don't need to be fixed (and possibly causing more damage) and missing things that need to be fixed.

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working on the 24-bit depth needledrop and then use the riaa filter in sox when I do my final downsample to 16/48 kHz?
Either way, you can record & edit/process at 24-bits if you wish...  If you've got a 24-bit ADC, go ahead and use it.  But due to the noise floor, vinyl has less than 16-bits of resolution/accuracy anyway.

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I'm really tempted to just do that curve digital, removing the need for another possible source of noise in the analog chain between the turntable and the ADC.
Like I said, you're going to need amplification either way, and  amplifiers always add some noise.  It shouldn't make any difference if you amplify first and apply the RIAA filter later, or build the RIAA curve into the amplifier circuit.

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to try to get quality recordings from vinyl source.
Hopefully, you have well-produced and well-manufactured records in excellent condition.      Older records may not sound that great even if they are in like-new condition.  In fact, with the older records RIAA curve accuracy may not be that important...  Older records (maybe from the early 70's or older?) often sound a little "dull" and seem to need a little extra high-end boost.

Needledrop - skip phono pre-amp?

Reply #3
The noise from my phono preamp is so far below what comes out of an unmodulated groove (i.e. between tracks or from a test LP) that it is a total non-issue for recording LPs.

For example, the unmodulated tracks on two of my test LP run about -55dBfs, The two channels on an old LP I recently recorded are -51 and -53 dBfs, possibly due to wear and damage. It came from a thrift store so I have no information about its history. My phono preamp (in a Kenwood receiver) is down more than 80dBfs.

Actual numbers will depend on the signal output of your cartridge and the amplification of your phono preamp and the front end of your ADC, but they should have similar relationships.


Needledrop - skip phono pre-amp?

Reply #5
You still need a preamp to get the signal up to line-level for your soundcard (or interface, ADC, etc.).    And, the preamp should have a 47K Ohm input impedance to properly "load" the phono cartridge.    A good "pro" microphone preamp has a balanced input with an impedance somewhere around 1K.    The mic input on regular soundcard has different issues but is no better of a match.


Yes, the pre-amplification before sound card is needed to get the best results.

As an addition for suitable load resistance, proper load capacitance has a meaning as well.

Needledrop - skip phono pre-amp?

Reply #6
With respect to vinyl quality, yes. I have only been buying vinyl that looks in really good condition and they will be washed in a pro-machine first, found a local place that does it and the owner is an older guy who has been into vinyl since before CDs exiisted and knows what he is doing.

For pops and clicks, I don't plan to completely remove them. What I will do is attenuate them to just below the amplitude of the surrounding audio. I have listened to several needledrops and I seem to prefer the ones with far less aggressive de-clicking, I'd rather have the flaws still there but attenuated than have the audio modified.

Before CDs pops and clicks were part of the experience, and people enjoyed the music. I don't have to completely remove them to enjoy it, I just don't want them to interfere with peak normalization.

With respect to recording at 24-bit, the reason behind that is so that I can use a test LP and target say -12 dB peak and just use that as the input volume w/o needing to try to get close to peak. That way if some records are a little louder than the test LP they still are not likely to clip.

After whatever clean-up I do, I can then peak normalize and resample to 16-bits vis SoX as the last step. My target is 48 kHz (not burning to CD) 16 bit - which is what I use for everything, even the few hdaudiotracks I've bought (archive the ridiculously high sample rate because it's what I bought but downsample to reasonable for my listening library)

The vinyl I'm interested in doing this with are titles like Sheila Walsh Future Eyes or Steve Taylor Limelight - they simply never were digitally mastered so I have no source for studio digital. This isn't about trying to capture the flaws of vinyl that many enjoy on CD. It's about getting music never released on CD. I do have a few thrift store finds that were released on CD - e.g. I have a Decca US release of Jesus Christ Superstar that looks like it is brand new (I'm sure its not, the booklet was missing and it wasn't wrapped in plastic, but it is extremely good looking) and I may try to needledrop those as well but my primary concern are the niche records that never were and likely never will be released as digital.

-=-

So it looks like amplification designed for phonograph is going to be needed anyway, and there probably is no point in looking for one that doesn't do RIAA curve.

Needledrop - skip phono pre-amp?

Reply #7
For pops and clicks, I don't plan to completely remove them. What I will do is attenuate them to just below the amplitude of the surrounding audio.

I take it that you haven't yet started your vinyl transfer project. Once you do, you'll discover that quite offensive clicks and pops are typically *way* below the amplitude level of the surrounding audio. Your intended strategy of attenuating them to just below the surrounding audio will: (a) fail to adequately reduce their annoyance value; and (b) only tackle the most extreme clicks. You need to re-think how you plan to tackle de-clicking.

Needledrop - skip phono pre-amp?

Reply #8
Well no I haven't, I'm still doing a lot of research into the hardware I want. Especially the cartridge, it can be hard to determine what is audiphile mumbo jumbo and what is meaningful to a good recording.

But to honest I'm not that concerned with pops and clicks that aren't loud. I think sometimes people let them ruin the music because they know it is vinyl and their mind focuses on them rather than focusing on the music itself like everyone did when they enjoyed played records because CDs did not exist.

I don't understand how a medium that brought so much joy and happiness even on mediocre turntables with lots of pops and clicks now seems unsuitable to many because of the same pops and clicks that didn't matter before, I think it is psychological and if you don't let them ruin the music, the music will be enjoyed.

The loud ones need to be taken care of because they impact the peak normalization but the quiet ones, if the record is clean then they will sound better than any record I ever played growing up on our Sears record player, and I enjoyed the music then.

Needledrop - skip phono pre-amp?

Reply #9
Once LPs were the only medium available, so better than nothing, but the clicks and pops were ALWAYS quite annoying.

Declicking can be destructive but most of the buggers can be removed totally with no hint that anything was ever there. The music is not damaged. Overly aggressive settings, to try to do it all automatically, will remove many transients which had nothing to do with clicks. Then the music is noticeably damaged. Thus the problem is not removing the clicks and pops but removing too much other material.

The main complaint I've had with many declicking programs I tried is that they reduced the clicks but did not completely remove them. The sound was thus different but no less noticeable.

Needledrop - skip phono pre-amp?

Reply #10
I don't understand how a medium that brought so much joy and happiness even on mediocre turntables with lots of pops and clicks now seems unsuitable to many because of the same pops and clicks that didn't matter before, I think it is psychological and if you don't let them ruin the music, the music will be enjoyed.

You make a fair point. Back in the days before CD, I enjoyed listening to vinyl and it was only big clicks that really bothered me, even though the smaller ones were still noticeable. I think the fact that this was as good as it got meant we were all willing to compromise. But once CD became widespread, our expectations changed to the extent that even minor ticks on vinyl now bother me.

I appreciate that the annoyance value of vinyl surface noise varies from person to person. I vividly recall an open day at Naim's factory when they proudly demo'd their new SBL speakers. They played an LP on a Linn LP12 and I was horrified by the crackle-fest that emerged. I just couldn't understand how they could possibly be using such a hopelessly noisy LP for the demo. And yet many in the audience seemed oblivious to it.

Needledrop - skip phono pre-amp?

Reply #11
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For pops and clicks, I don't plan to completely remove them. What I will do is attenuate them to just below the amplitude of the surrounding audio. I have listened to several needledrops and I seem to prefer the ones with far less aggressive de-clicking, I'd rather have the flaws still there but attenuated than have the audio modified.
If you are going to take the time to find and attenuate individual clicks, I strongly recommend that you try Wave Repair (Developed by cliveb, $30 USD after 30-day free trial).  In the manual mode it only "touches" the audio where you've identified a defect.    It has a few different repair methods that you can try to get the best repair of each defect and with most clicks it does a perfect job...  The click is just gone with no side effects!  (But with hundreds of defects on a "typical" record, some are not perfectly repairable and I rarely get a "perfect digital-sounding" result.) 

The downside is that I usually spend a full-weekend cleaning-up a digitized LP.    I've used Wave Repair several times over the past few years, but next time I'm probably gong to try Wave Corrector or Click Repair, maybe in combination with Wave Repair to save some time & effort.  These are more automated (and like Wave Repair they are affordable).  Clive also has a web page with more software recommendations and TONS of information about digitizing vinyl.

Needledrop - skip phono pre-amp?

Reply #12
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Once LPs were the only medium available, so better than nothing, but the clicks and pops were ALWAYS quite annoying.
I'm with you, Andy!  I grew-up with vinyl and the "snap", "crackle", and "pop", ALWAYS drove me nuts too!    Especially when it was my record and I knew just when that nasty click was coming, I'd be gritting my teeth waiting for the click instead of enjoying the music.  But, most people didn't seem bothered by it unless the record actually "skipped" or "got stuck".

I tried to take care of my records, buy somehow they got damaged & deteriorated.    I didn't like the tape hiss on cassettes either, and records had better frequency response.  So, I never actually bought any cassettes although I transferred LPs to cassette for the car.

I didn't buy a CD player when they were first introduced, but prices were falling and I decided I'd buy one when they came down to $200.    I think I ended up paying closer to $100, the dead-silent background was wonderful and I never bought another record.

 
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