Did my own cal test...

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mamm7215

mamm7215

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So I downloaded some test tones from analogrules.com. They had a good small set of 30 sec tones of 1k, 10k, 15k, 100hz, and 50hz in one wav file I loaded into Sonar. I set the levels so that it would read 0dbvu on my TSR-8 (led's). Now on my system I had to set the output on Sonar at -15.5dbfs to get 0dbvu on the deck. That mean anything? Also, you need to bear in mind that the deck has NOT been demagnetized yet. My demag hasn't arrived so this is a preliminary "general" test. I recorded the tones to tape. All meters read 0dbvu on input/record. No wavering, rock solid. On playback, this is what I got:

1k Track 1 dropped about 2db (flickers between -1 to -3db) Tracks 2-8 solid at 0. Track 8 flickers above 0 1 db late in the tone

10k Track 1 goes to -5db, track 2 to -3, tracks 3,4,5,7 solid at 0, track 6 -1 and track 8 +1

15k Track 1 flickers between -5 to -7, track 2 at -3, tracks 3-7 at -1, track 8 at 0

100hz All tracks steady at +1

50hz All tracks steady at 0 except 2 flickers between 0 and +1, track 8 at +1, and 4 and 5 bump to +1 towards the end of the tone, but initially at 0.

I'll redo this test after I get it demagnetized, but any opinions? Seems track 1 and 2 take the biggest HF hit on playback. Could it also be the tape? It's not new. Quantegy 456, came with the deck.
Thanks.
 
You really have to set the tape decks output first in order to get any reliable readings. Good chance your deck is right on but to actually set it up you need an MRL tape.
 
You probably have a head alignment issue based on your results with the test tones but as Steve said, you really need an MRL and set the other stuff first for any reliable readings.
 
Yes but you really do need an MRL tape to do this correct.

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Here's some good info:
http://www.churchsoundcheck.com/tra.html

(scroll down a little to "Checking Azimuth")

Excerpt from the above:

Checking Azimuth

The azimuth alignment for the playback head is performed by playing back a high frequency tone on the laboratory test tape, connecting a dual trace oscilloscope to the outputs of the machine, and adjusting the azimuth set screw until the two traces lock closely together. If the machine is a two track machine, connect the outputs of the left and right channels to the oscilloscope inputs. If the machine is a multitrack machine, the most accurate alignment would theoretically be made by observing the two edge tracks (top and bottom, e.g., tracks 1 & 8 on an eight-track machine). Since the playback integrity on edge tracks is often inconsistent, you could choose the next two track in (e.g., 2 & 7), or you could bring tracks 1 through 4 up on the console and pan them all far left and send that signal to channel one of the scope, and then bring tracks 5 through 8 up on the console, panning them far right and sending that signal to channel two of the scope. This will provide a reasonable average of the head output.

You should first confirm a rough azimuth alignment at 1 kHz, and make a coarse adjustment at a medium high frequency like 8 kHz. Then follow through and make a fine azimuth adjustment at 16 kHz.

What if you don't have a scope? Here is a little less precise but nonetheless useful compromise. Take track 1 and track 8 (or tracks 2 & 7) and feed them to two separate channel inputs on your console, and pan both channels to the left. Play back a tone on the test tape and make sure that you are feeding equal levels through the console. For convenience, adjust the combined levels so that the meter reads at some convenient mark, like 0 VU or +2 VU. Now, play back the 8 kHz tone and then the 16 kHz tone, and watch the left output meter on the console. The meter will wag back and forth as the phase cancellations between these two tracks cause decreases and increases in the combined signal strength. Adjust the azimuth set screw so that there is a minimum of movement on the meter. The best you will probably see, playing back a 16 kHz sine wave, are fluctuations of about 1.5 dB.
Click to expand...
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Good info, my manual actually states to use tracks 2 and 7. I've got an MRL test tape coming, bought it online today. I've got a good portable Fluke scopemeter at work and a very good Fluke multi at home. Been studying the manual lots, it actually doesn't seem like too much of a job now. The manual is very good for this machine.
 
Looks like you're all setup. Yeah, those 'vintage' TASCAM manuals are true gold mines of information.

Good luck and keep us updated.:)

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If you’re using used tape with unknown history there isn’t much you can gather from the tests... nothing to hang your hat on at least until you start with an unopened tape.

You also have to set input/output line levels and do preliminary alignment with a calibration tape first. You can get an idea if the machine is working within ballpark, but you can’t nail down the source of any deviation without starting the calibration process from step 1.

:)
 
Yeah, and these tests were just to see if the unit was indeed "ballpark". It seems like it is, and of course mechanically doesn't skip a beat. I found a year old Apex sustain pedal (I bought from Long&McQaude) that I'd mothballed, wasn't right for what I wanted it for but it works great for a punch-in pedal now! Score! The MRL tape I bought is brand new so I should be starting from a fresh square 1. One more question. The tape I bought is MRL 1/2" tape 15 ips IEC +6 cal. The +6 means when I set the levels on the deck to 0 with the tape, because the tape is recorded at +6, my deck will be set up to +6? Is that how that works?
 
This thread is a good reminder... If you are new to analog recorders and want to start using them and intend to do your own calibration and basic maintenance, you will need access to a non-trivial amount of gear:

1) calibration tape for each tape width of machine, preferably using your preferred EQ setting, speed and reference fluxivity, (playback calibration)

2) an audio oscillator, (rec calibration)

3) an AC voltmeter (or something providing that function), preferably the kind with an analog (meter needle) display, (setting levels, gain, etc.)

4) a dual trace oscilloscope (20 Mhz should be fast enough), (azimuth)

5) a frequency counter, (bias)

6) small scales (for testing transport tension),

7) head demagnetizer,

8) supplies for cleaning heads and transport parts (cotton swabs & fluids for head cleaning and rubber pinch roller cleaning),

9) the service manual for each recorder,

10) necessary tools (small screwdrivers, other wrenches and tools needed for whatever adjustments your machine(s) require).

Cheers,

Otto
 
mamm7215 said:
Yeah, and these tests were just to see if the unit was indeed "ballpark". It seems like it is, and of course mechanically doesn't skip a beat. I found a year old Apex sustain pedal (I bought from Long&McQaude) that I'd mothballed, wasn't right for what I wanted it for but it works great for a punch-in pedal now! Score! The MRL tape I bought is brand new so I should be starting from a fresh square 1. One more question. The tape I bought is MRL 1/2" tape 15 ips IEC +6 cal. The +6 means when I set the levels on the deck to 0 with the tape, because the tape is recorded at +6, my deck will be set up to +6? Is that how that works?
Click to expand...

What is the model number of the MRL you bought? To set for 0VU without compensating the correct tape is 250 nWb/m, or +3 for the TSR-8. However, you can use a tape with any flux level as long as you compensate for the difference. If you have a 355 nWb/m test tape, you would set the meters to +3 while playing the 1kHz tone on the tape.

Good list from Otto in the previous post.

:)
 
Yes, it would be the 355 nWb/m tape. Thanks for the info. And great list as well.
 
Oh and 1 more question, when my MRL tape comes, exactly which level do I set to +3 (it's a +6 tape)? The reproduce level? All other levels seem to be set using the voltmeter. Just double checking. Thanks.
 
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