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Equalization With Speed Change ?

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  • Equalization With Speed Change ?


    I have a 78 RPM recording (Pistol Packing Momma) that I am restoring. The method is :

    1. Play the record at 45 RPM.
    2. Use a RIAA style preamp (Dynaco) to feed into the sound card.
    3. Change the speed to 78 RPM with the change speed tool.
    4. Apply the conversion tool for EQ. with Preamp RIAA and record 78.

    Question is, Since the record was played back at a lower speed than normal, did the frequencies of the record get shifted lower and hence the RIAA in the preamp boost the "wrong frequencies"? If so, then the software didn't correct the record properly, since the software thought that the recording was played back at the correct speed and the RIAA EQ in the preamp was thought to be correct.

    I know that the best way is to use a "flat" preamp, but I don't have one at this time.


  • #2
    The method that you used does shift the corner frequencies of the system. It is further complicated by the fact that you used an RIAA preamplifier to play a 78, and then add into that the fact that it was fed through your Dynaco RIAA preamplifer at the wrong speed. You are getting the wrong result using the described method. I would say that the resultant EQ that you are getting is an "EQ Hodge Podge" and not easy to correct.

    So, yes, indeed the right way to perform fractional speed transferring is via a flat preamp.
    Last edited by Craig Maier; 06-19-2008, 09:57 AM.
    "Who put orange juice in my orange juice?" - - - William Claude Dukenfield


    • #3

      Thanks for your comments.

      I made an error in my message. I used only one RIAA circuit, that in the Dynaco premap. Guess that I had "preamp" on the mind....

      With the speed change resulting in a change in the corner frequencies....can you in-vision a possible software filter that would correct properly ?

      I'm sure that many people have only a turntable with 33 or 45 RPM available with the standard RIAA playback. These people would then need a new software tool to both fix the speed to 78 and correctly "un-do" the incorrect EQ.



      • #4
        Try doing it in three steps - - - first, remove the RIAA curve that the pre-amp imparted. That should be done before performing the speed change operation. That should leave you with a flat transfer, but at the wrong speed. Use the Speed Change filter to correct the speed. Then, you need to look up in the Diamond Cut users guide what turnover frequency was used by the 78 record manufacturer and apply that after the correct speed change has been applied.
        Last edited by Craig Maier; 06-19-2008, 11:48 AM.
        "Who put orange juice in my orange juice?" - - - William Claude Dukenfield


        • #5
          Thanks Craig,

          I'll give it a try.After all, with a record like "Pistol Packing Mamma" (Al Dexter) you just have to have the right sound.



          • #6
            Yeah! You ain't kiddin'. Gotta get that one right, or watch out! Let us know how you make out with it.
            "Who put orange juice in my orange juice?" - - - William Claude Dukenfield


            • #7

              While there is more than one way to reverse RIAA with Diamond Cut version 7, the best (most accurate) way is to use the VPA with the following settings:

              Preamp Hardware: Set for Standard RIAA Preamp

              Record Type: Set for Acoustical

              Run the filter and you have it.
              "Who put orange juice in my orange juice?" - - - William Claude Dukenfield


              • #8
                Multiple Functions

                Originally posted by Craig Maier

                While there is more than one way to reverse RIAA with Diamond Cut version 7, the best (most accurate) way is.......
                I am still getting to grips with Millennium, but is it not the case that, with much software, there are several ways to achieve the same (or a similar) objective? I recall, when I first bought my present digital camera (not a point-and-shoot model!), spending ages trying which way would work best, in spite of a very well-written and well referenced manual. Eventually the helpline confirmed that there were indeed often several combinations of settings which would achieve precisely the same result.

                It would be very helpful, if anyone has the time, to be able to refer to a glossary of different functions in DC which achieve the same or similar result, with perhaps notes, where appropriate, of when one method should be preferred to another. Perhaps such a resource is already available?


                • #9
                  Hi WGCman

                  Another way to reverse the RIAA curve imparted on a recording is via a preset in the Paragraphic EQ. This method, while slightly less accurate than the VPA method, will reverse the curve. The DC7 Users guide includes a "Filter Finder" chart which can be helpful in determining what does what.
                  "Who put orange juice in my orange juice?" - - - William Claude Dukenfield


                  • #10
                    Thanks, Craig

                    This is not exactly what I meant, but it's very a useful resource. I 'll try the Audio Mentor demo, which looks as though it might help. Getting started with Audio restoration is not a quick process!


                    • #11
                      WGC -
                      There are multiple ways to do many of the things you might want to do, but the VPA that Craig mentions is the most exact way of doing it.

                      Anything else is an approximation to what the VPA achieves. So, the other ways of doing something like this will have varying success, depending on your tolerance for error and the ability of your ears to notice the difference.

                      It's the same with interpolating all the clicks. You can run some of the expert impulse filters with various presets, but not all the clicks will be caught, and if you are too aggressive, you will get distortion. On the other hand, you could manually declick them using the "I" key and highlighting them, but that may take quite a bit of time, and you may make some mistakes in over- or under- interpolating by highlighting larger or smaller areas than you need. In the end, your ears are the judge there as well. Most of us have gone to the EZ impulse filter for much of the work in that area because it's "EZ-er" than the other ways, but most of us (I think) all still use the other techniques as well, because every situation and every restoration is a little different.

                      I imagine that you might find some transfers where the sound is more pleasing if it is not an exact reverse of the RIAA eq. That is, you may find that your ears don't really like what was on the original recording, and you may need to fix it up a bit to make it sound more pleasing to your ears. In that case, you can use the paragraphic eq instead of the VPA, and no one is likely to know the difference; it's just that the VPA is mathematically correct, so you get a better (i.e., more faithful and accurate) "restoration," but that might not mean a better (i.e. more pleasing) transfer.

                      Take your time and you'll learn how to use enough to get excellent results; experiment every time you make a new transfer and you'll learn fairly quicky.
                      Dan McDonald


                      • #12
                        Thanks for this, Dan

                        I'm a little surprised that an experienced user (as I assume a Senior Member to be) uses the EZ filter much of the time, as I had thought it was for beginners. However, it's good news as the learning curve won't be quite so long as I feared.

                        Best Wishes


                        • #13

                          I also use the EZ impulse filter unless I am trapped with a very unusual impulse noise problem. The EZ impulse filter does the job beautifully 99% of the time.

                          I think that the Expert Impulse filter is probably used more in Forensics applications rather than High Fidelity audio clean-up.
                          "Who put orange juice in my orange juice?" - - - William Claude Dukenfield


                          • #14
                            I use almost all of the filters over the course of a year. I think that what happened with the software was that so many improvements have been made over the years that sometimes a new filter comes out that does a very complicated thing very easily and with little adjustment needed, so us "old-timers" get the benefit. When I got the software at first, there weren't any "EZ" anythings, if I recall. It was great, but a really steep learning curve. These days, Craig and Rick have incorporated all the things they've learned into new algorithms, etc., so most of the EZ things are pretty nice.

                            The one thing I don't use much is the EZ clean. I'm not sure why. I used to use it as a pseudo-cnf, but with the changes in the cnf over the last couple of years, I've just gone back to it.

                            Dan McDonald


                            • #15
                              EZ Filter

                              I think Craig originally was going to name it "Very Complex and Sophisiticated Impulse Filter That Also Happens to be Easy to Use", but it seemed a tad long.

                              I think my middle name should be "Water", because I like to travel the path of least resistance. I leave the heavy lifting to the EZ Filter and invoke Expert and manual interpolation only when absolutely necessary.

                              Also, with 78's, my target isn't necessarily a completely clean restoration. They run the risk of sounding overprocessed.