Capture tape bias settings

Blue Jinn

Rider of the ARPocalypse
I didn't want to post in this old thread which has specs for a bunch of tapes.

https://homerecording.com/bbs/gener...d-35-coercivity-beck-235554/?referrerid=84801

It's my understanding that Coercivity relates to bias, and Retentivity to the level a tape can take.

The new Capture 9xx is billed as a "Standard bias (+2.5) high output, low distortion, low noise, backcoated, for studio and archive use." tape, which I'd assume means Ampex 406 and most tapes like that but it is

360 Oe
1300 G

406 is

330 Oe
1300 G

and 456 is

320 Oe
1500 G

I've always heard that SM900, and SM468 all require higher bias,

but e.g.

SM900:

370 Oe
1540 G

If I bias for 406, it still seems farther off. ????

Capture is the right price, and it's from a small company in Oregon, which is kinda cool. Word has it that it is made by a company in Australia, or maybe the people who made Zonal. Don't know about that. So is it bias compatible on a machine aligned for 456, or would it be better to align for 406?
 
I've never really been able to link the MOL to the physical parameters of the tape, but if I remember correctly, 406 is nominally +3, 456 is +6 and 499/SM900 is +9. I understood Capture to be a 406-alike so +2.5 makes sense, especially since some people like to slam 406 to make it saturate.

A lot of it depends what you're trying to do. For a consumer machine that simply can't bias up to +6 without modification, Capture would seem to be your best bet. I might see if I can get some for my Akai, actually.
If you're trying to get as good a recording as you can, line the machine up for 406. However, people have been known to line the machine up for 456 and then put 406 on it, to deliberately overload it and get lots of tape saturation.
 
As I understand it, the bias requirements for 406 and 456 were the same - it is just the maximum output level that was different.

RTM also make SM911 which is closer to 456 than SM900 (which was more like 499).
 
I totally misread the thread title..."Capture tape bias settings" ...I thought it was about documenting/copying your bias settings.
I had no idea there was a new tape brand called "Capture". :D
 
The bias of any tape is not obtained from charts or over bias methods which are usually only ball park settings.
I have adjusted the 900 series Capture tape from Splicit to a few machines and it does work OK for what it cost.
I would not call it equal to 406 as the record sensitivity is higher on 406.
The reason the cost is lower is less slurry is used on the tape making it lower bias and less print level. Yes tape like AM900 and ATR Master with almost 2mil of thickness will need more bias as there is a lot more oxide to magnetize under the head.

Bias set up is best done at 1KHz and then equal level at 10KHz to start the process and then some refinements depending on speed of tape and the track width we are dealing with. It also depends on machines and the type of heads on them. The Teac heads are capable of over 20KHz usually where as the Otari, Pioneer and Technics heads roll off at 18KHz at 0 Vu levels. This is because these heads are optimized for higher speeds and have deep longer lasting gaps. We in Chicago are having 1/4 track heads made again but the supplies are real limited.

15 IPS tape machines usually can go 30Hz to 28KHz inside plus or minus 2 dB at 0 Vu.
7.5 IPS deck can in some cases do 25Hz to 26KHz and most can do 20KHz at 0 Vu level.
Most 3.75 IPS deck can not usually do more than 13-14KHz at o Vu but can gpo way up to 20KHz at -20dB. But then who records at that level?
I had a Tascam 42 record 30Hz to 50KHz with SM900 tape at 0 Vu with 15 IPS speed, The heads were not new. Just as a figure of merit.
 
Well, it's good there's a new tape available. Much better than tape brands folding up and going away.

Edit: Just looked it up. Seems they only make 1/4 inch. Bummer
 
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