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I was thinking of the Audio Fidelity records that claimed recorded frequencies up to 24k or 27k, I forget which, (not at full level, of course), and although you couldn't hear these frequencies, you were invited to check with a microscope. 

db 

Sent from my iPhone

> On Mar 12, 2015, at 3:28 PM, Tom Fine <[log in to unmask]> wrote:
> 
> Yes, that would be a smart use of half-speed mastering. That would be for CD4 records only (mostly RCA and Elektra titles). SQ and QS did not have a high-frequency carrier, rather they were matrixed systems.
> 
> -- Tom Fine
> 
> ----- Original Message ----- From: "Randy A. Riddle" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, March 12, 2015 3:21 PM
> Subject: Re: [ARSCLIST] Decca FFRR "backwards" disk-cutting -- likely a MYTH
> 
> 
>> Wasn't there "super-sonic" frequencies on Quadradiscs?  I was thinking
>> those had to be cut at half speed because they included a 30 kHz carrier -
>> if you put one on a turntable and slow it down, the carrier tone is clearly
>> audible.
>> 
>> On Thu, Mar 12, 2015 at 3:10 PM, Tom Fine <[log in to unmask]>
>> wrote:
>> 
>>> I don't think very many LPs contained "super-sonic" frequencies, because
>>> everyone rolled off at some point to avoid blowing out the cutterhead. You
>>> are very correct, though, that it's easier to cut 10kHz than 20kHz at a
>>> high level, but what music has high levels of 20kHz in the first place? I
>>> just don't see any big advantage to half-speed cutting, but I should call
>>> up my friend Stan Ricker and discuss this in-depth before saying more.
>>> 
>>> For what it's worth, among the major classical LP labels cutting records
>>> in NY in the first decade of stereophony, it was typical to low-pass around
>>> 15K, meaning there was a decrease in level down to about 10K. No one tended
>>> to complain that there's not enough treble on Mercury, RCA and Columbia
>>> albums of the time. If you didn't low-pass, you used something like a
>>> Fairchild Conax, which was a relatively fast limiter for high-frequency
>>> (above 10K) signals. The reason was, it was expensive to blow out Westrex
>>> cutterheads and they were easily blown out with intense high-frequency
>>> information. One thing that mystifies me about half-speed cutting is that
>>> it came into vogue later on, when most people were using Neumann lathes and
>>> cutterheads. I thought one of the big advantages of Neumann cutterheads was
>>> that they pretty much solved the problem of blowing up with intense
>>> high-frequency information. I know that George Piros, who could cut a LOT
>>> of HF into an LP using a Scully/Westrex system in the early 60's, said he
>>> could cut even more HF and level "if I turn off the computer" using his
>>> Neumann lathe at Atlantic Records.
>>> 
>>> A major test of how much HF you could cut with a circa 1958 Westrex
>>> cutterhead came with "Persuasive Percussion" by Terry Snyder and Enoch
>>> Light, the all-time best seller among "Stereo Spectacular" pop records. My
>>> father told Enoch Light's biographer that he and George blew out "about a
>>> dozen" cutterheads trying to get acceptable fidelity with the Chinese
>>> bells. They finally arrived on a compromise that kept the cutterhead from
>>> blowing up and ended up with a close approximation of Chinese Bells when
>>> played back with a good cartridge on a light-tracking turntable of the era
>>> (2g was very light tracking in those days). It was during that time that my
>>> father got Westrex to customize his cutterheads, making them mechanically
>>> stiffer (less compliant), so he could use much less electrical feedback and
>>> more net power from his 200W McIntosh amplifiers. George perfected cutting
>>> right on the edge of coming out with a trackable record and not blowing up
>>> too many cutters.
>>> 
>>> Ironically, now that I wrote that, I think half-speed cutting would have
>>> been really beneficial in the early stereo days. But not when it was en
>>> vogue.
>>> 
>>> -- Tom Fine
>>> 
>>> ----- Original Message ----- From: "Dave Burnham" <[log in to unmask]>
>>> To: <[log in to unmask]>
>>> Sent: Thursday, March 12, 2015 2:46 PM
>>> 
>>> Subject: Re: [ARSCLIST] Decca FFRR "backwards" disk-cutting -- likely a
>>> MYTH
>>> 
>>> 
>>> I always thought the advantages of half-speed mastering were in the high
>>>> frequencies, not the lows; super-sonic frequencies were brought down to
>>>> sonic frequencies and recorded more easily, but very low frequencies were
>>>> pushed down into a subsonic range and frequencies in the low teens can be
>>>> troublesome for tape heads. Also consider that direct to disc recordings
>>>> are better sounding than any half speed mastered disc and, of course, they
>>>> can only be recorded at normal speed.
>>>> 
>>>> db
>>>> 
>>>> Sent from my iPhone
>>>> 
>>>> On Mar 12, 2015, at 8:49 AM, Tom Fine <[log in to unmask]>
>>>>> wrote:
>>>>> 
>>>>> I do think they pioneered this, going back to SONAR training equipment
>>>>> in WWII.
>>>>> 
>>>>> Speaking of half-speed cutting, I have never understood how this is
>>>>> pulled off in a modern context, especially with Dolby-encoded master tapes.
>>>>> I guess it's possible to make the NAB or CCIR tape EQ de-emphasis work at
>>>>> half-speed, and the RIAA emphasis at the lathe, but doesn't Dolby get
>>>>> screwed up when frequency bands are lowered?
>>>>> 
>>>>> Today, I think one can listen to recent LP cuts by Bernie Grundman or
>>>>> Ryan Smith or Sean Magee and hear that there's no need for half-speed if
>>>>> the cutting engineer and his cutting chain are top-notch. I've heard
>>>>> arguments about fitting more bass energy on a disk at half-speed, but again
>>>>> I can't understand how that's true since the disk will be played back at
>>>>> full-speed and hence won't track on normal-priced systems if the grooves
>>>>> are too wide and deep.
>>>>> 
>>>>> -- Tom Fine
>>>>> 
>>>>> ----- Original Message ----- From: "Carl Pultz" <[log in to unmask]>
>>>>> To: <[log in to unmask]>
>>>>> Sent: Thursday, March 12, 2015 8:18 AM
>>>>> Subject: Re: [ARSCLIST] Decca FFRR "backwards" disk-cutting -- likely a
>>>>> MYTH
>>>>> 
>>>>> 
>>>>> Decca did do some half-speed cutting - am I remembering that right?
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: Association for Recorded Sound Discussion List
>>>>>> [mailto:[log in to unmask]] On Behalf Of Tom Fine
>>>>>> Sent: Thursday, March 12, 2015 7:57 AM
>>>>>> To: [log in to unmask]
>>>>>> Subject: [ARSCLIST] Decca FFRR "backwards" disk-cutting -- likely a MYTH
>>>>>> 
>>>>>> I asked the folks at Decca Classics, including the guys who just put
>>>>>> together the excellent new "Mono Years 1944-1956" box set. All of them
>>>>>> said,
>>>>>> in essence, no way. The technical guys said it's not possible to cut
>>>>>> 20-minute LP sides this way and there was no reason to do it, given
>>>>>> Decca's
>>>>>> advanced cutting techniques developed during WWII, many of which were
>>>>>> ported
>>>>>> over to microgrooves.
>>>>>> For 78's, they said again there was no reason to cut a disk backwards
>>>>>> since
>>>>>> they could easily accomodate FFRR cutting forward like everyone else.
>>>>>> Unless
>>>>>> someone can come up with some documentation saying otherwise, I would
>>>>>> say
>>>>>> this is a MYTH and should be nipped in the bud here.
>>>>>> 
>>>>>> -- Tom Fine
>>>>>> 
>>>>>> 
>>>> 
>>>> 
>>