I am taking the liberty of crossposting from rec.antiques.radio+phono, in case there are any collectors who monitor comp.dsp: On Mon, 02 May 2005 12:54:33 -0500, Greg Berchin <76145.2455@compuswerve.com> wrote:>>I am looking for every bit of information that I can find >>about EQ curves used before RIAA EQ was adopted.A followup to my previous message: I have been able to identify the following EQ curves. If anyone knows of additional curves, or finds any errors, please post. (See http://www.rfwilmut.clara.net/repro78/repro.html for definitions of "Turnover" and "Tip" frequencies.) I have a digital filter implementation for each of these, at 192 kHz sampling rate, that matches the ideal analog filter �0.025 dB amplitude and �0.25� phase from DC to over 75 kHz. - Greg Berchin Bass Tip/Bass Turnover/Treble Turnover combinations --------------------------------------------------- / 150/ 3.4k Decca / 150/ 5.8k early Decca / 200/ flat Westrex / 200/ 5.8k Columbia 1925 40/ 200/ 6.36k American 1025, Victor 1925 (some) 50/ 250/ flat Blumlein, HMV / 250/ flat Columbia (Eng.), EMI 1931 40/ 250/ 6.36k London FFRR 1949, FFRR 78 / 300/ 1.6k Columbia 1938 / 300/ 2k FFRR 1951 50/ 353/ 3.18k BSI / 375/ 2.5k Decca 1934 / 375/ 5.8k Decca FFRR 1949, EMI / 375/ 6.36k Decca FFRR 1949, EMI, Victor 1925 (some) 70/ 400/ flat early 78 (mid-'30s), US mid 30 / 400/ 2.5k old AES, Decca 1934, Mercury 100/ 450/ 3k FFRR 1953 / 500/ flat early 78, Brunswick, Parlophone 100/ 500/ 1590 Columbia LP / 500/ 1590 early LP / 500/ 1.6k early LP, NAB, NARTB 70/ 500/ 2.5k EMI / 500/ 2.5k Capitol 1942, MGM, Victor 1947-1952 100/ 500/ 3k FFRR 50/ 500/ 3.18k CCIR / 500/ 3.18k London FFRR / 500/ 3.4k Concert Hall until 1952, Oiseau-Lyre until 1954 / 500/ 5.8k Victor 1938-1947 50.05/500.5/2.122k RIAA / 629/ flat "629" / 800/ 2.5k early RCA
Phono EQ
Started by ●May 21, 2005
Reply by ●May 21, 20052005-05-21
in article nd2v819hjk68l1ng06mqm0k5aof3hars7o@4ax.com, Greg Berchin at 76145.2455@compuswerve.com wrote on 05/21/2005 15:24:> I have a digital filter implementation for each of these, at 192 kHz > sampling rate, that matches the ideal analog filter �0.025 dB amplitude > and �0.25� phase from DC to over 75 kHz.gee, Greg, i just don't think that's good enough. i think you need to tighten those specs a bit. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge." :-)
Reply by ●May 21, 20052005-05-21
On Sat, 21 May 2005 17:39:14 -0400, robert bristow-johnson <rbj@audioimagination.com> wrote:>>gee, Greg, i just don't think that's good enough. i think you need to >>tighten those specs a bit.The impossible just takes a little longer ... Greg
Reply by ●May 21, 20052005-05-21
"Greg Berchin" <76145.2455@compuswerve.com> wrote in message news:d0mv811h67kv081te0tv9jv3o5sg50knes@4ax.com...> On Sat, 21 May 2005 17:39:14 -0400, robert bristow-johnson > <rbj@audioimagination.com> wrote: > >>>gee, Greg, i just don't think that's good enough. i think you need to >>>tighten those specs a bit. > > The impossible just takes a little longer ... > > GregHello Greg, I have a feeling, your specs are a lot tighter than the sample to sample variations that exist in the original equipment. Any guesses as to the variance in the production units? Clay
Reply by ●May 22, 20052005-05-22
On Sat, 21 May 2005 22:15:11 -0400, "Clay S. Turner" <Physics@Bellsouth.net> wrote:>>I have a feeling, your specs are a lot tighter than the sample to sample >>variations that exist in the original equipment. Any guesses as to the >>variance in the production units?You mean the original analog signal conditioning, cutting, playback, and associated equipment? The variances were HUGE. (The speed for nominally "78 RPM" disks, for example, could actually range from about 71 RPM to over 80 RPM.) But at least I can all but eliminate one extra source of variation, if I can build digital filters that match how the analog filters SHOULD HAVE performed. And now that I have nailed-down the technique for creating these filters, I can also fine-tune them to specific situations, if those situations can be characterized in the form of a transfer function. Greg
Reply by ●May 22, 20052005-05-22
Greg Berchin wrote:> I am taking the liberty of crossposting from > rec.antiques.radio+phono, in case there are > any collectors who monitor comp.dsp:You have not crossposted but multiposted. Crossposting means posting the same message to more than one group, just like you would send an email to a number of people at once, and should entail setting followups to the most appropriate one -- comp.dsp in this case. The way you've done it, folks in rar+p don't know something may be going on here since you haven't told them so in the otherwise identical post there; you've basically presumed to decide for them that they aren't interested in DSP. That is one reason multiposts are bad. Martin -- Teach a man to make fire, and he will be warm for a day. Set a man on fire, and he will be warm for the rest of his life. --John A. Hrastar
Reply by ●May 22, 20052005-05-22
On 22 May 2005 13:45:45 GMT, Martin Eisenberg <martin.eisenberg@udo.edu> wrote:>>You have not crossposted but multiposted.Thank you. I stand corrected. Greg
Reply by ●May 22, 20052005-05-22
robert bristow-johnson wrote:> in article nd2v819hjk68l1ng06mqm0k5aof3hars7o@4ax.com, Greg Berchin at > 76145.2455@compuswerve.com wrote on 05/21/2005 15:24:>>I have a digital filter implementation for each of these, at 192 kHz >>sampling rate, that matches the ideal analog filter �0.025 dB amplitude >>and �0.25� phase from DC to over 75 kHz.> gee, Greg, i just don't think that's good enough. i think you need to > tighten those specs a bit.Maybe he has some CD4 albums. Didn't they go pretty high with a subcarrier in each channel? Otherwise, it is a little high for a phono cartridge. -- glen
Reply by ●May 22, 20052005-05-22
On Sun, 22 May 2005 14:47:14 -0700, glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:>>Maybe he has some CD4 albums. Didn't they go pretty high with a >>subcarrier in each channel? >> >>Otherwise, it is a little high for a phono cartridge.I'm ignoring the capabilities of the medium, and just attempting to approximate the analog signal conditioning (which could easily go past the 96 kHz Nyquist limit associated with 192 kHz sampling) in the digital domain. Any adjustments to accommodate the limitations of the medium can be applied separately, if desired. Greg Berchin
Reply by ●May 22, 20052005-05-22
Greg Berchin wrote:> I am taking the liberty of crossposting from rec.antiques.radio+phono, > in case there are any collectors who monitor comp.dsp:> On Mon, 02 May 2005 12:54:33 -0500, Greg Berchin > <76145.2455@compuswerve.com> wrote:>>>I am looking for every bit of information that I can find >>>about EQ curves used before RIAA EQ was adopted.> A followup to my previous message:> I have been able to identify the following EQ curves. If anyone knows > of additional curves, or finds any errors, please post. (See > http://www.rfwilmut.clara.net/repro78/repro.html for definitions of > "Turnover" and "Tip" frequencies.)When I was younger, my father had a preamp with knobs to select the various frequencies. It might be that turnover sounds familiar. At some age I would turn the knobs, not knowing what they did. When I was a little older, I knew to always keep them in the RIAA position, though I did wonder what the others were for. I believe it was a Heathkit from about 1958, just before I was born. -- glen
