Tape machine allignment/calibration - About +3, +6, +9

[8056]

I'm alligning/callibrating my 2-track machine. It's been a while. The machine's Been sitting idle for years.

I forgot something about calibrating and hope someone can help.

To calibrate a machine for +6/185, do I make adjustments just during record calibration or during both playback and record calibration?

I'm doing this:

1. Put on the MRL (0/250, so really +3/185)
2. Play 1k and set meters for 0 on the VU
3. Do high freq and low freq adjustments to hit 0 on the VU
4. Put on fresh tape
5. Record a 1k tone and make sure playback is -3 on the VU since I want +6/185
6. Adjust bias
7. Double-check a freshly recorded 1k tone is still playing back -3 on the VU
8. Record/playback high freq and get at -3 on the VU

So the question is for proper calibraton at +6/185: Should the meters in step 2 and 3 read 0 or -3 on the VU?

TIA.

[cjmnash]

um...you're close, but off a tad on a few points:

to get +6/185 w/a 250 test tape vu meters should read -3 db with the test tape. don't do low freq adjust w/test tape, fyi

vu meters should read zero in record.

i do 'over the phone' calibrations for people & can hip you to some better techniques regarding bias, etc.

-chris mara
615 476 6272
www.nobraineraudio.com
www.welcometo1979.com

[8056]

Thank you. I knew I was doing something wrong but couldn't figure out what.

I'll take you up on the phone consultation if I run into trouble.

Are you talking about doing bias via low-frequency instead of 10k? (don't answer if that's one of the secrets revealed during paid consultation! javascript:emoticon(':o'))

um...you're close, but off a tad on a few points:

to get +6/185 w/a 250 test tape vu meters should read -3 db with the test tape. don't do low freq adjust w/test tape, fyi

vu meters should read zero in record.

i do 'over the phone' calibrations for people & can hip you to some better techniques regarding bias, etc.

-chris mara
615 476 6272
www.nobraineraudio.com
www.welcometo1979.com

[nortstudio]

Agreed on the -3 if you want the +6 alignment (if your MRL is 250nwb). Also, I was always taught to bias before record alignment - because it is an intrinsic part of the record alignment. You want to make sure that is straight before you get to your mid/high.

Also remember that each type of tape and machine have their own specifications for bias alignment. That determines your actual setting for bias (my least favorite part of aligning a tape machine!).

Might be best to take last poster up on the offer for phone consultation, just so you have a sheet you can reference.

[@?,*???&?]

I've posted alot on this topic including posting a document on tape machine procedure. Search that.

[ofajen]

Are you talking about doing bias via low-frequency instead of 10k? (don't answer if that's one of the secrets revealed during paid consultation! javascript:emoticon(':o'))

Relax. Adjusting bias for minimum modulation noise is a common, well-knwon technique. So is adjusting bias at 1K.

Cheers,

Otto

[cjmnash]

Are you talking about doing bias via low-frequency instead of 10k? (don't answer if that's one of the secrets revealed during paid consultation! javascript:emoticon(':o'))

Relax. Adjusting bias for minimum modulation noise is a common, well-knwon technique. So is adjusting bias at 1K.

Cheers,

Otto

nope- that's not what i was talking about. biasing @ 10k is better for most decks/headstacks. i wasn't trying to be secretive, just didn't want to type a diatribe on alignment techniques. depending on what deck you have i most likely will be able to give you a couple deck-specific tips/personal preferences to try out....things that make alignments faster & more accurate-things of that nature...that's all i was saying.

-chris

[8056]

Ok, cool. Will get in touch if I need help. I'm trying to remember what I knew well enough many years ago. My web searches didn't find a clear answer because I was essentially asking the wrong question.

Thanks for your input.

nope- that's not what i was talking about. biasing @ 10k is better for most decks/headstacks. i wasn't trying to be secretive, just didn't want to type a diatribe on alignment techniques. depending on what deck you have i most likely will be able to give you a couple deck-specific tips/personal preferences to try out....things that make alignments faster & more accurate-things of that nature...that's all i was saying.

-chris

[cjmnash]

cool- feel free to call, or email to set up a time to walk you through the alignment. no reason to bang your head against the wall if you get stuck!

chris
cym@mindspring.com
615 476 6272