Tape machine alignment question

[ethyrvalve]

Hi all,

I had a tech set up Tascam 58ob to use sm900 tape a while back and finally attempted to check to see if it was still in alignment today.

I was able to set the overbias to -4db (as recommended in the manual and recommend by rmgi for .25mm head gap machines) and I was able to get the input and repro to match for 40hz and 1khz test tones.
However, for the 10khz the repro meter showed an extra 2db on all tracks. I have the record hi-freq eq trimmer all the way down.

Is this a big problem? If so is there a way to fix it?

Thanks in advance for any input!

[Beck]

It’s not a problem. It’s within spec for the 58... 30Hz – 24 kHz +/- 2dB. The specs are measured with Ampex 456, so you might be used to having it a bit tighter with the factory recommended tape, as Tascam specs are usually conservative.

On the other hand, I’d be interested in what 15k or 20k tones look like on repro. If they’re too high you might have to tweak the bias a little more. The 4dB down is the recommendation, but in practice you sometimes have to fiddle with it a half dB more or less.

[ethyrvalve]

Hey thanks so much for yr input. I just tried checking 15k and 20k as per your suggestion:
I got a 1db bump at 15k; 20k was right on the money.

BTW: I'm a longtime lurker on this forum, and I've learned quite a bit about tape from reading your posts. If you ever wrote a book on the topic, i'd buy it in a second.