Could the "hum" on the recordings not be connected with the line power, but
something mechanical or electrical generated by the recording machine
itself?

On Sat, Nov 1, 2014 at 10:03 AM, Tom Fine <[log in to unmask]>
wrote:

> Indeed, but as I said, Steve Lasker tuned to musical pitch and it happened
> to work out that the hum also sat at 120-121hz. Furthermore, to pitch it
> down to where those YouTube clips are, I think you're down below 100hz with
> the hum. I would call that unlikely but not impossible in 1937 Texas.
>
> -- Tom Fine
>
> ----- Original Message ----- From: "Parker Dinkins" <
> [log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, November 01, 2014 8:08 AM
> Subject: [ARSCLIST] Robert Johnson Wrong Speed?
>
>
>  Powerline frequencies in major cities in the US were not synchronized
>> until after World War II. At all. The citation for this statement can be
>> found in the archive. It came from a US military source.
>>
>> A much more detailed analysis of the vagaries of powerline frequency
>> pre-1965 was made by Mr. Brock-Nannestad on Nov. 3, 2009, with the subject
>> heading "power line frequency".
>>
>> Hum signatures are a valuable resource for speed correction when they
>> come from a synchronized source, such as the modern power grid.
>>
>> --
>> Parker Dinkins
>>
>>
>>  Date:    Fri, 31 Oct 2014 06:23:03 -0400
>>> From:    Tom Fine <[log in to unmask]>
>>> Subject: Re: Robert Johnson Wrong Speed?
>>>
>>> Hi Thomas:
>>>
>>> The 2011 reissue IS the correct speed, based on the 120hz hum from the
>>> original recording equipment.
>>> I was trying to stop this mythology, after talking with Seth. Let me say
>>> again -- the 2011 IS the
>>> correct speed, unless there was some freak power system present in Texas
>>> that operated at some
>>> frequency other than 120hz (just about zero chance of that). So, again,
>>> what you hear on that 2011
>>> edition IS the correct speed. All other discussion of "theories" of
>>> other speeds are not based on
>>> facts. To quote Seth Winner again, "the hum doesn't lie."
>>>
>>> -- Tom Fine
>>>
>>
>>
>>