Alright!

  • Thread starter Thread starter antispatula
  • Start date Start date
Wow, this thread has an intimidating feel to it for someone that is doing this for the first time... not that it's a bad thing, but there's just a lot of information here that are all pieces of a relatively involved, albeit rewarding process.

From a purely non-technical perspective, I would suggest you take a step back from all of this and just go have some fun with your deck recording music for a while. Once you feel like you are enjoying yourself again, then maybe you'll want to dig back into calibrating your deck a step at a time... when you get to that point, try to have fun with it keeping the end results in mind: 1) You'll gain some great knowledge on how to calibrate your deck, and 2) You'll be 100% certain that your deck is operating up to it's full potential.

Take a step back and enjoy yourself for a while -- I know I always do a much better job of something when I'm enjoying it, and not frustrated by it.

So long as there is nothing obviously wrong with your deck, 'don't fix what isn't broken for now.' Just record some music; 'a great performance on recording is far more important than the recording itself.' 'If it sounds good it is good.' 'Rome wasn't conquered in a day.' Insert other applicable cliches HERE. :p
 
hey thanks guys. Yeah, I'm taking this all a little too seriously I think, it's not as if I'm hooking it up with 10,000 dollars worth of equipment and will make much of a difference anyways. But I am going to try and do the simple things since I just spent 140 bucks on tape.

A few questions: My manual says that I should hook up a voltmeter that reads DB instead of using my onboard VUs for all the tests.

A. Anyone know how to hook up the two meter leads to an unbalanced XLR connector?

B. But maybe that isn't important, since I THINK I may have already adjusted the VU's to read correctly, does this sound right?:

I sent a 1kh tone into the machine via an oscillator, the VUs were at the standard reference level, and all the VUs read pretty darn close to 0db. There were a few that were SLIGHTLY off, and I adjusted the VU meter level pots accordingly so now they all read 0VU when I send a 1kh tone.

Since that SEEMS to make sense, and they all were already close to 0db, and the deck was calibrated years and years ago then placed in storage and never really used, I THINK I did that kind of right.

So if I did do that right, do you think I could use the onboard VUs to further adjust the machine?
Any help would be great.
 
alright sweet, so you think I did that right?

So now I just reproduced the 1kh tone from my mrl tape, and most meters were around +2 db. I know that the last time the machine was calibrated, it was calibrated for scotch 226. I'm not sure what level 226 can take, and wether or not it was previously calibrated to set the VU's to the MOL or gave it a few db's headroom, but do you think this sounds right? Do you think it's safe to adjust the repro levels to 0 (or -3 if I wanted headroom)? I'm worried that I'm actaully only scewing up my machine :D
 
FALKEN said:
yo dude.

I just got my MRL test tapes today too. I think you are going to need the service manual. I will be awaiting the responses that you will receive because I too am interested. My guess so far is that you will need an oscilloscope to test azimuth and phase. You will also need a tone generator (you can use your pc) and a level meter that can read millivolts. I think the general idea is that you play a tone into the inputs at a certain voltage that will correspond to zero on your meters (which you will adjust to match zero for that voltage). Then you will make another adjustment so that you are getting the same voltage readings on the outputs as you are on the inputs. that is before you load the tape even. Then you test the playback by using your test tape and testing the millivolts on the outputs and make another adjustment. Finally you record the test tone onto a blank tape and test the playback (separate head if you have it) to be the right output level, and adjust as necessary. You want to get each adjustment to within 1 db, however many millivolts that is.... I haven't done this and this is just what I got from a brief perusal of my 1/2"'s service manual. hopefully someone more knowledgeable can help us both.
Click to expand...

You can adlust azimuth without an O-scope. The test tape is used to calibrate playback alignment. Test tones will allow aligning recording circuitry. If you have real VU meters, it is all you need otherwise you will have to measure output using a multimeter with a "db" scale (or AC voltage, lo scale if you know the conversion to db)
 
in the immortal words of you-know-who:

how do I do this?
 
MCI2424 said:
You can adlust azimuth without an O-scope. The test tape is used to calibrate playback alignment. Test tones will allow aligning recording circuitry. If you have real VU meters, it is all you need otherwise you will have to measure output using a multimeter with a "db" scale (or AC voltage, lo scale if you know the conversion to db)
Click to expand...

Ok thanks, but my VU meters themselves are adjustable too, and I'm not sure I adjusted them right :D They go to 0 VU when I run a 1kh tone through an oscillator though......
 
FALKEN said:
in the immortal words of you-know-who:

how do I do this?
Click to expand...

First patch the tape recorder's 'outside' tracks
(track 1 and 16 or 24) to 2 different input channels of
your board, making sure that the board's eq is out, and that there are
no Echo Sends or Aux Sends on.

Then select just ONE channel (say Track #1)
and send it to any one buss (say "Buss 1" out of the console).
Set this one track's channel's fader level on the console so that
your 'Buss 1' output VU meter reads -6 VU.

Then turn OFF that channel.

Next turn on your other channel, (it would be Track 16 for a 16 track,
track 24 for a 24 track and so on...) send it to the SAME buss as the
other channel you just setup, again set that track's console fader level
so the Buss 1 output meter AGAIN reads -6 VU.

Now both channels are set to read individaally at -6 VU on the SAME buss Meter
where either one is turned on alone and the tape is reproducing tones.

Then turn BOTH channels on. Since two in-phase VOLTAGE signals should add
together by 6 db, you now should be reading 0VU on the meter.

If the meter is very near 0 VU and is stable (not moving around much), you're ok.

ALWAYS check another frequency!!! Use 1khz and 10khz and 16khz if possible.

If the meter reads less than 0 VU, adjust azimuth
until the meter reads as close to 0VU as possible, with as little meter
movement as possible.

Make sure re-set your -6 vu levels on each channel
after making any azimuth adjustments !!! You MUST check azimuth with more
than just one tone.... use 10khz and 15khz if you can as well as 1khz.

Check that each frequency is at the correct individual track -6db VU level,
and that they add together about 6 db, reading about '0VU' when summed.

Once you have correctly set azimuth, all tones should read close to 0 VU and be stable.

Of course this assumes that your tape machine is properly aligned, and that
all tones reproduce at '0 VU".

Note that often tones will not quite get to the full 6 db increase -
often you'll get only about a 5.5db increase which will show up as a
-1/2 db on your VU meter. this is OK if all the tones are stable and
right around this level.

Also you MUST use a GOOD ANALOG VU METER!!! Most LED vu meters don't
have the resolution to show small increments, so you cannot use
LED meters!!!
 
MCI2424,

the system won't let me give you any more rep, or else I would.

Antispatula,

check out this thread. it might clear up some things. especially this post.

it sounds like your machine is doing ok so far. at least your playback seems right. try threading a blank tape and see if it records the tone and plays back and at what levles. I would also be curious to know what voltage reading you get on the onboard 1k.
 
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okay;

my manual says to have a 250 nwb/m test tape; calibrated tp 0 db on the VU meters, and .3 V on the output.

but the USR website said for 456 to get a 355 nwb/m tape. so if you have a 355 nwb/m tape, according to the thread I referenced above, you want the vu meters to say +3.

what should the volt reading be on the output?

I think I need a refresher on how to add dBs and convert to voltage.
 
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also some good info in this pdf http://www.flash.net/~mrltapes/choo&u.pdf

this is my first calibration also so all the info i am spreading is ifo i have just learned myself. I'm calibrating an A-6100 and a 3340s

If anyone has a service manual for the 3340 can i have gander* please? :D




*gander = goosy gander = a look/peruse/brouse etc.
 
You'll have to check your manual for the specs.


it get's better...

wait till you try and figure out the in and out levels of the thing your testing with

ok i've got an idea why don't we start from the beginning and we can all calibrate each step at a time together and we can all post our findings and wories and stuff. wadya recon?

we should start with playback head alignment
 
If I have this correct, you are using dbu because your machine is +4. I am using dbv because my machine is -10.

my one question is;

if my machine is spec'd out to 250 nwb/m = 0 on the VU's and .316 volts on the output;

and I have a 355 nwb/m tape, which should = +3 on the VU's, what should the voltage reading be?

and say I set it up to distort more easily, so I want the 355 nwb/m to = +1 on the VU's, what should the voltage reading be then?

and how would you calc this out?

how can antispatula convert these figures to the +4 realm?
 
If I have this correct, you are using dbu because your machine is +4. I am using dbv because my machine is -10

desn't work like that -10 dbV = about -8 dbu (-7.781512501 to be exact)

use the calculator in the above link
Click to expand...
 
i think if you calibrate using a 200nw/m tone but you will be using 250nwb/m tape, then you set your machine to put out -2db and the meters reading -2db when playing the cal. tone.

i think anyway. If i'm wrong please say coz this has been fucking with my head
 
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