Subject:Vinyl Question: 78 RPM - (how many semitones) = 33 RPM

Posted by: Earle

Date:9/18/1999 8:07:00 PM

Dear anyone interested,

During a recent vinyl restoration project I came across
an old 78 RPM record (which also plays inside out). I'm
trying to avoid using an older phonograph player in order
to preserve quality. And of course, modern turntables do
not play at 78 RPM anymore (at least none that I'm aware
of).
Does anyone know how many semitones it takes to correct
the speed difference, assuming you're playing the 78 RPM
record at a speed of 45 RPM or 33.3 RPM? I'm guessing it would be
around half, or 12 semitones up, but I would like to
know for sure.
If you have had any experience with this, or have the
oppotunity to play with the problem, I would very much like
to hear your input.
(The inside out thing is solved, by the way.)

Jeff Earle, Engineer
Hideaway Audio Production, Kirkland, WA
hap@psnw.com

Subject:Re: Vinyl Question: 78 RPM - (how many semitones) = 33 RPM

Reply by: KPSchrage

Date:9/21/1999 2:18:00 PM

Dear Jeff,
when you try to record an old 78 RPM using a 33.3 RPM or 45 RPM
player, you have to shift the pitch up to compensate for the speed
difference. Just think of a player running at half speed, i. e. 39
RPM; you should have to shift the pitch up for excactly 12 semitones
or one octave.
Things aren't that simple with real players. Running your oldie at
33.3 RPM, you'll have to shift for exactly 14.72 semitones to get
a speed ratio of 78/33.3=2.34. In case of running at 45 RPM (which I
should prefer), the speed ratio is 78/45=1.733, which yields shifting
up for 9.52 semitones.
I won't give you the computations behind that, because things get
simpler using Sound Forge's pitch shift effect. In the pitch shift
dialog, you can enter any semitone/cent combination and Sound Forge
automatically calculates the corresponding transposition ratio; you
just have to try out until you get the desired ratio:
14 semitones/69.8 cents give a ratio of 2.34,
9 semitones/50.7 cents give a ratio of 1.7333.
I tried this procedure on an old 45 RPM record (I don't have an 78
available) which I recorded into Sound Forge, using 33 RPM on a
stabilized turntable, and I did this again at the correct speed of 45
RPM. The result was that the second sample and the first (after the
shift precedure) exactly matched in pitch!

I hope you could get what I meant dispite my English!

Klaus-Peter Schrage
kehl-schrage@telda.net




Jeffrey R Earle wrote:
>>Dear anyone interested,
>>
>> During a recent vinyl restoration project I came across
>>an old 78 RPM record (which also plays inside out). I'm
>>trying to avoid using an older phonograph player in order
>>to preserve quality. And of course, modern turntables do
>>not play at 78 RPM anymore (at least none that I'm aware
>>of).
>> Does anyone know how many semitones it takes to correct
>>the speed difference, assuming you're playing the 78 RPM
>>record at a speed of 45 RPM or 33.3 RPM? I'm guessing it would be
>>around half, or 12 semitones up, but I would like to
>>know for sure.
>> If you have had any experience with this, or have the
>>oppotunity to play with the problem, I would very much like
>>to hear your input.
>> (The inside out thing is solved, by the way.)
>>
>>Jeff Earle, Engineer
>>Hideaway Audio Production, Kirkland, WA
>>hap@psnw.com
>>
>>

Subject:RE: Re: Vinyl Question: 78 RPM - (how many semitones) = 33

Reply by: Dub King

Date:6/8/2012 4:43:07 PM

Mr. Schrage,

Its now 2012. I just read your post. IT WAS SO HELPFUL! THANKS!!!

Sound forge, bought by Sony, dropped pitch shift in the lite version. Its now pitch bend or something. Your formula worked perfect! Thanks. You were right on.

Big help for sure.

I hit a "b flat" on a recording from a record from the 1952. A B flat tone generator matched it spot on.

Take care.

Subject:RE: Re: Vinyl Question: 78 RPM - (how many semitones) = 33

Reply by: ChristoC

Date:6/8/2012 6:59:29 PM

Of course the pitch change is only half the story......
Modern microgroove stylus is different width to the original, & modern phono preamp very likely follows the RIAA playback compensation EQ curve which was not used on old 78s (and remember changing pitch changes the curve too!), therefore the overall result is likely to sound quite different to a proper transcription done at correct speed with correct stylus and appropriate playback compensation EQ curve, and have significantly more distortion due to the modern stylus being so narrow compared to the 78s groove.

Subject:RE: Re: Vinyl Question: 78 RPM - (how many semitones) = 33

Reply by: Larry Clifford

Date:6/22/2012 4:31:51 PM

78 rpm turntables can be purchased here. They are not inexpensive.

http://www.garage-a-records.com/categories.php?cat=98

http://www.needledoctor.com/Online-Store/78-Speed-Tables

I am curious, the latter has an option of MM or MC cartridge. The MC in $500 more. Can anyone tell me what the difference is?

Subject:RE: Re: Vinyl Question: 78 RPM - (how many semitones) = 33

Reply by: ChristoC

Date:6/22/2012 8:54:19 PM

here's the answer:
http://en.wikipedia.org/wiki/Magnetic_cartridge

Subject:RE: Vinyl Question: 78 RPM - (how many semitones) = 33 RPM

Reply by: Bob N

Date:2/21/2013 6:01:07 PM

"During a recent vinyl restoration project I came across
an old 78 RPM record (which also plays inside out). I'm
trying to avoid using an older phonograph player in order
to preserve quality. And of course, modern turntables do
not play at 78 RPM anymore (at least none that I'm aware
of). "

I had a Hitachi turntable that had a 78 RPM option. I gave it to a friend and occasionally borrow it for just such a purpose. Look for an older turntable.

Subject:RE: Vinyl Question: 78 RPM - (how many semitones) = 33 RPM

Reply by: UKharrie

Date:3/3/2013 8:38:47 PM

The old Leak/Lenco drive gives 78 (continuous variable 20-80rpm I guess) - as to MC/MM it's a cost thingy. MM is cheaper and for ghastly non-RIAA equalised records quite good enough. However, when I had some 78 tips fitted my siupplier used stiffer mounts, so the excursion was reduced as MM is only linear over a small needle movement.
There has been much discussion on 78 websites as to needles, but I recall there are three sizes - what you mustn't do is put the needle in the bottom of the groove where all the dirt goes.
I did some tests on MM pickups (in Britain, possibly Lenco cartridges,) and the OP is considerably higher for 78 compared with 45 - - and 33 is significantly less that "pop" 45's - although there are classical 45's whith lower op nearer 33's. This is to do with the groove movement (obviously) and the sound the Buyer needs . . . "Pop" being less fussy over quality since the whole chain of recording was distorted anyway.

However, if you are using RIAA correction, you are very wrong - so you'll need to rewire the preamp! 78's were recorded by manufacturers with crazy standards, since the repro was often an acoustic player . . it only mattered that it sounded loud.
Turnover frequencies (like RIAA) were not considered, although many believe there is some evidence they existed, but at different frequencies and with valves having low gain, you didn't get too fine a characteristic.

After all that, "Let your ears be the judge" - is probably the best advice, if any is needed. You may need to restrict the HF during quiet passages, then open it up when the signal is well above the noise. This could be done by an assistant turning the "tone" control during recording. Once digitised you can give it several treatments.

You might like to try a very light lubricant on the discs, but take care - try on a cracked one first- (but NOT with the needle).

Good luck, let us know how it pans out.

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