[QuadList] Quad Head Life and environmental conditions (was [oldvtrs] Re: 1200B Restore, Part Four)

[Ted Langdell]

Hi, Terrance,

Thanks for the experiences and practices at Ampex.  This is valuable  
information for a number of reasons.

I've been searching for an article I ran across several years ago  
about how Nebraska ETV?? managed to get 1,000 hours or more from their  
Quad heads (on VR-1000's if I recall correctly.)

They had a very controlled environment for temperature, relative  
humidity, air flow to get particulate matter away from the machines  
such as you describe.

I'd think improving conditions to extend head life is likely more  
necessary today, due to the fact that only Video Magnetics in Colorado  
Springs still rebuilds Quad heads, and Lalo's the only guy doing it at  
this time.

If the sole source of rebuilding is lost, any facility depending on  
heads for content recovery will be up the creek without a paddle, and  
any useable heads will skyrocket in value to the point that the cost  
of transferring may become impractical.

I'd be curious to hear from Quad head users around the world about  
what they are getting in terms of head life, and what they're doing to  
extend the life of their heads.

The BBC set up a central facility to deal with Quad heads, outlined  
here:
http://www.vtoldboys.com/heads02.htm  which developed a standard  
reference tape for alignment, among other practices.

They also had an SOP for "constant chroma optimization
http://www.vtoldboys.com/pdf/Constant%20Chroma%20Optimisation.pdf

that "was made on current stock and more representative of machine/  
tape performance and could be used to set all machine parameters. The  
legacy benefits organisations like the BFI, who today still replay  
many quad recordings with little need for adjustment between tapes."

The page has data on head life and processes or practices developed to  
extend life.  On AVR-2's with Spin Physics Ferrite rebuilds, the BBC  
was routinely getting 1,000 hours with a record of some 2,500 hours.

Ted


On Jul 26, 2009, at 2:26 PM, eedesignpro wrote:

> I'm a bit new at this answering the question about Quad head life.
>
> Clean tape is a must.
> We when we were not concerned with interchange or banding, we would  
> run
> with as little tip penetration as possible.
> We would use tape that had a few passes more than 5 but less than 10.
> New tape nearly always had high head wear in the first few passes.
> Tall tips normally meant lower signal to noise, a condition that we  
> could live with while designing the next recorder. The high tips was  
> always the worse case operating condition for any recorder.
>
> In Redwood City the weather is always 50% HR.
> Where the HR is nearly 100% and with certain tape combinations the  
> head wear could be quite high. In parts of New York in the summer  
> time then weather is hot, the air can only be cooled with no added  
> clean outside air. This increases the HR as the day goes on this  
> water in the air with tape dust is combination adds up to high head  
> wear environment.
> The operational environment for VTR room should be room with  
> constant temp and HR. Clean outside air should be added to the cool  
> air, in Redwood City the outside air and the cool air were equal in  
> volume most of the time.
>
> If the recording and the playback were on the same machine, heads  
> could last a long time.
> The standard tape lab that made the setup tapes for head adjustment  
> would often last more than a year. The system was one of two or  
> three weeks of setup for the recorder and measurement of the record  
> tracks on the tape. Then the machine was put in auto mode which ran  
> for two to three weeks normally without a break. Then the tapes were  
> spooled into the 15min reels and shipped.
>
> Quad banding requires many things on the transport to be correct and  
> distant from the erase head to the head pole peaces to effectively  
> match the playback machine, very hard to do everyday all day.
>
> Not sure if it is any clearer.
> Terrance Smith

Ted Langdell
Secretary for the QuadVideotapeGroup

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