A better way to needledrop? (Using Voxengo Curve EQ)

This seems an obvious idea but I don’t hear it talked about much. Is anyone else using Voxengo Curve EQ to do their needledrops?

Voxengo Curve EQ is a plugin that allows you to capture the EQ of any piece of music and show it on screen in a nice EQ curve. But that’s just the start – the neat thing is, you can then capture the EQ curve of another piece of music and compare the two. Voxengo comes up with a curve showing the difference between them, and if you like you can then apply that “difference” curve to the second piece of music and give it the same EQ as the first. (Or vice versa,) It’s instant DIY remastering.

This opens up some interesting possibilities for needledropping. Let’s say there’s a much-loved old album that you want on your hard drive. You could just buy the CD or a hi-res download but you want the sound of the original album. The trouble is, your copy of the original LP is in poor condition and better quality ones, if they can be found at all, are very expensive.

You could try doing a digital restoration job on your old LP but it would be a lot of work and even then it would never be perfect. Bet here’s an alternative: why not rip the CD as well as the LP and then, using Voxengo Curve EQ, simply transfer the EQ of the LP rip to the CD rip? You’ll then have a perfect copy of the album in digital format with the original LP mastering – the best of both worlds.

If you want it in higher resolution, you can use a hi-res download instead of a CD, but obviously that involves a greater expense.

There are cases where this won’t work. For example, if the CD or high-res download is dynamically compressed, or from a poor quality source, you wouldn’t want to use that. But if the source is good, I think it will usually give you a better result than just needledropping the LP.

Anyone else think this is a good idea? Or not?

 

One thing I don't understand is how do these programs know what the EQ is for a flat transfer? I understand when you compare two sources, but how does it work if you only have one source?

 

I'm just going to bump this the once. This is a very different approach to needledropping and I think it has a lot of advantages over the existing approach. Doesn't anyone have an opinion on it at all, either for or against?

Conception, I'm not sure I understand your question. If you're asking how Voxengo Curve EQ works, it's simple - you give it a piece of music (typically, one track) and it measures the average amplitude of each frequency during the whole of that piece of music. It then shows you the result in the form of a chart.

For example, let's take the track "Take Me To The Pilot" from Elton John's LP Elton John. I have a really beat-up copy of this LP and I also have West German CD.

So I needleldrop the LP and rip the CD. I then open up Voxengo Curve EQ. I tell it to analyse the track "Take Me To The Pilot" from the LP and here's the result:



You can see the upper frequencies in particular are quite spiky and in practice it's often easier to use a smoothing tool to make it easier to see what's going on, like this:



Now, we run the same analsis on the same track from the CD. The CD analysis is in white and appears on top of the LP analysis, like this:


Now we tell Voxengo to compare the two and it comes with a "difference" EQ which is what you'd have to apply to the CD to make it sound the same as the LP. Here it is:



See that button at the bottom right-hand corner marked "Apply"? Assuming you've got the CD track open, you simply hit that button and Voxengo immediately applies that EQ curve to your CD track, so it now sounds the same as the LP - but without all the clicks and pops and rumble and surface noise and with better channel separation etc etc etc!

 

What if clicks/pops/scratches are skewing the EQ curve? Surely you must need to remove these imperfections first in order for the software to generate an accurate EQ curve?

 

Good question. If you were worried about this you could declick first but in fact it doesn't make a difference. Maybe it would if there were a constant hiss, and maybe a constant light crackle, but sporadic ticks, pops and scratches don't add up to enough over the course of an entire track to make a difference. For example, if you had a scratch that went across the whole track and made a click every time it passed under the needle, it would click about 132 times over the course of a 4-minute track (4 x 33rpm). If the clicks occurred at 1kHz and each one lasted a few milliseconds, by the end of the track the sum total of all these clicks would still be well under a second of sound at 1kHz, nowhere near enough to skew the EQ curve. To confirm this, while needledropping an LP, you can if you like use Voxengo Curve EQ to watch the EQ curve being formed in real time, and see what effect different sounds have on the curve.

One thing that definitely DOES show up however is low frequency rumble. When recording from vinyl, the curve often ends up with a big hump down in the low frequency zone and you find this especially when recording the outer edge of a dished LP or when recording lighter weight LPs - 180g LPs really are better! However this rumble is mainly below 20Hz so won't transfer to a CD file, which by definition has nothing below 20Hz. Also, it's very obvious and you can manually re-draw the EQ curve to eliminate it.

 

Hmmm, could be useful for those pre-emp cd's, interesting, thanks for the step by step, my next day off might try this with some bricked cd's

 

Have you actually tried your suggestion? Does it make the CD sound more like the LP? Do you prefer the sound of the CD before or after the re-EQ?

This is incorrect. There's nothing to stop sub-20 Hz info being present on a CD. For example, I have a test CD (a commercial one, not one I made myself) containing a frequency sweep that goes from 1 Hz to 200 Hz in 1 Hz steps (intended for finding bass resonances).

 

Quite true. Red Book is the standard for CD-Audio, but you can put anything you damn well please on a CD.

 

Interesting for sure.

On the example you used, I realize they are not aligned exactly level wise, but how do the Vinyl and CD compare to each other, actual sound quality. Oddly it looks like the CD is rolled off a bit more in the bass and treble, but that may also be not so true if the midrange was simply boosted a few db relative to the vinyl.

 

This seems somehow vaguely familiar.

I noted this post several days ago, and wanted to make a comment or two based on my own experience, but writing time has been at a real premium. Still, given the contents of your "bump" post, it seems like you have things well in hand. My hat is off to you.

And, let me make clear, I believe the full approach you are using to be entirely viable and correct.

Okay, now the ramble...

So far, I've only worked with completely digital representations of Joni Mitchell's "Blue" and "Blues for Thought" by Terry Evans in the fashion you describe. You know about "Blue", my first attempt at applying the EQ curve from one representation of an album to another (EQing on a track-by-track basis), but I can report that "Blues for Thought" gave even more worthwhile results. The "Blues for Thought" CD had terrific EQ, but was modestly compressed in dynamic range, while the 96K DAD version of the album had poor EQ (I have since learned that at the time the DADs were produced it was not possible to EQ at 96K), but had an excellent dynamic range. By applying the CD EQ to the individual DAD tracks, I was able to produce a 96K DAD that had both outstanding dynamic range and EQ. I downrezzed the resulting individual 96K/24 files to 44.1K/16 and burned a really terrific CD, also with excellent EQ and dynamic range that, to my ear, clearly exceeded the musical quality of the original CD. At the time of our original conversation, I mentioned the possibility of EQing the HDTracks 192K/24 "Blue" album to match the EQ curves of my original Reprise "Blue" vinyl, but at this time that is rather far down in my queue. However, I have every confidence it would produce fine results.

Now I never mentioned in our previous conversation what EQ tool I was using, primarily because what I found useful had little love for it amongst the internets. But I'll pass that on now, along with my thoughts. I did at that time also purchase CurveEQ, and I liked it, but somehow it seemed to me to be a bit too restrictive for my tastes. I used CurveEQ initially for a first pass filter, but soon redid everything from scratch, leaving CurveEQ out, cause I decided the way I was using it was introducing extra steps--and I thought maybe extra steps would somehow degrade the final processing/EQ matching result. Still, I loved that CurveEQ had as many as 60 sample points (and apparently does not position any of those points outside the "audible" spectrum), and had a fully automated result...I disliked that as a VST plug-in within Sony Vegas Pro, it lived in a very small window.

What I ended up purchasing and using is Har-Bal 3.0 (found here: http://www.har-bal.com/). While it has some level of automation, I found the automation feature frustrating and unsatisfying. But using the capability to piece-wise drag one EQ curve to match an imported EQ reference (e.g. using a file from our host's DCC CD release of Joni's "Blue" as a reference for modifying the EQ of the corresponding 192K HDTracks cut), was very satisfying if a bit time consuming. Har-Bal is a standalone application, so I can see EQ curves full screen and that works for me. It uses an 8198 point FIR filter for its EQ analysis of a given track or reference track, and I tend to like big numbers. (Though if, say, a 96k or 192k file is involved, most of the FIR points will reside outside of the audible spectrum...also, if the basic and reference files have different sample rates, the FIR filtering will not make sense till the basic and reference files are brought to the same sample rate.)

I hope you add a post to this thread speaking more fully of the sonics of your results.

 

I used to use an advanced digital RIAA filter, like PureVinyl's but for Windows. IMO, archiving vinyl to digital...one might as well do the digital RIAA method.

 

Yes, I recently adopted this method and much prefer this method to standard needledropping. Naturally I prefer the sound of the CD after the EQ otherwise I wouldn't be doing it!

Thanks for pointing that out. Surely it's the case, however, that normal pop and rock music CDs have no information below 20Hz? Therefore, as I said, no low frequency information will transfer to it using the method I've described. This is because Voxengo Curve EQ does not add or subtract sound from the existing CD file - it can only increase or decrease what's already there. If there's no rumble on the CD file in the first place, Voxengo Curve EQ cannot increase it - 100 per cent of nothing is nothing - so it cannot introduce rumble to the file. I don't think Voxengo Curve EQ works below 20Hz anyway.

In practice, I simply flatten the curve manually at the left-hand end so the question never arises.

I'm out of time at the moment but will reply to other posts later.

 

I think that's a safe assumption. The lowest I've ever seen was 16 Hz. (A Liquid Trio Experiment track.)

 

The LP has simply stupendous bass, the deepest and most powerful I've ever hear on a pop or rock LP, and quite a lot more than on the CD. The LP is also brighter through the vocals. The CD is much warmer - not as much deep bass as the LP but more upper bass and lower midrange, and quite a lot less top end, so the vocals are a bit recessed and dull.

It's good you mentioned level matching. One neat thing about Voxengo is that you don't need to level match at all, the reason being that the overall volume level doesn't affect EQ - the EQ of a piece of music remains the same whatever the volume level. But when those charts pop up showing you the EQ of the two tracks you're comparing, they won't be aligned vertically if they're at different volume levels, so if you want to compare them, you have to slide one or the other up or down in the frame till it lines up nicely with the other. That's what I did in the case above and it may be that, doing it in a hurry, I could have chosen a better alignment. But I repeat, this is purely cosmetic and for visual purposes only - aligning or not aligning the charts on the amplitude scale makes no difference at all to the EQ matching process.

 

Haha, yes, I well remember our conversation about Joni Mitchell's Blue when you were experimenting with this process and I was struggling to understand what you were doing. You can take a lot of the credit (or blame) for putting this idea into my head!

What happened is, I bought Voxengo Curve EQ for a completely different reason - purely to compare different masterings across formats. But once having discovered its capabilities, it wasn't long before I started thinking of other uses for it. It's an unfortunate fact of life that music is often available in very high quality formats, and often with very high quality masterings, but rarely both at the same time. So it's very tempting to find a way of transferring the best mastering to the best format.

I'll take a look at Har-Bal - thanks for the tip. Meanwhile, Blue is high on my list for treatment (Steve's mastering on the HDtracks download.) I'll let you know how it goes.

 

You seem to be making the assumption that EQ is the only difference between a CD and LP

 

Well, a CD is digital and an LP is analogue. But once you've needledropped the LP, the LP is digital too, so it seems to me that the only remaining differences would be in EQ and in the background noise/distortion on the LP file. Now, my aim in needledropping is to get rid of all that background noise/distortion. But some people like the sound of vinyl for its own sake and for them, this technique may not be suitable. Is that what you mean, or is there something else I haven't thought of?

 

The source material and the recording chain are 2 that kind of stand out to me righ off the bat. I highly doubt you can take a Beatles For Sale Stereo CD and Voxengo out a tube cut UK LP

 

How do you get it to analyse the track?

 

All due respect, but this is something I would NEVER want to do. Youre mixing apples and oranges here, Analog mastering vs. Digital. I dont think you can just mix and match EQs like that that and come up with anything thats "best" . Each source has to be taken on its own merits and flaws, and dealt with indvidually to get the best sound out of it.

This is one of the bugaboos I have with digital mastering...people are doing things like this JUST because the software "can".

 

It would be an interesting experiment! But that's not my goal. My goal is to get as close as possible to the sound the mastering engineer heard when he signed off on what was, to his ears, the best possible mastering of the source material. So I don't want the sound of a tube cut LP - I'm trying to eliminate the tube sounds introduced during the cutting process and the sounds introduced by the LP.

As I said before, lots of people DO want the sound of the tubes and the vinyl etc. Sometimes I do too, and when I do, I just play the LP. Other times, I'm curious to see how close I can get to the sound the mastering engineer heard, and this is what this technique's about.

 

What makes you think the CD used the same source as the LP?

 

It's rarely EQ choices that make a CD issue of a previously loved record sound bad to me. Most often it's added compression and unskilled use of anti-hiss software.

 

All criticisms welcome! Is it really such a problem, though, mixing analogue and digital? It's done all the time these days - everything before the 1980s was recorded in analogue but now most people want this stuff in digital so it's remastered again and again for digital. I do appreciate though that some people want either all-analogue or all-digital - that 's a position I respect and this technique's probably not for them.

 

Do you mean the Elton John example I used? Well, there's only one master tape so ultimately, the source is the same. If the CD was from a poor quality copy of the original master I wouldn't use it. I would only use this process in cases where I had a high quality digital source - it's on a case-by-case basis.

Yes, and that's a problem. You need a high quality digital source for this process. I would never use a CD that was more squashed than the LP or that had been subjected to to no-noise processes. Sometimes there simply isn't a good enough digital source available and then you just have to needledrop the LP the old-fashioned way!

In fact, Vinyldoneright mentioned The Beatles and this is a good example. The modern CDs, and the USB stick, have some added compression - not much, I don't think, but some - so in this case they're not really the best quality source. So I've been needledropping the reissued LPs the old-fashioned way. (The LPs don't have this added compression.)