no rec eq on tascam 32?

FALKEN

FALKEN

*************************
i haven't calibrated my 32 in a while and it looks off, so I am going through the steps again.

i calibrated input, meter, repro,

i am on to biasing...tried gp9 and now 456, same issue. 1 khz input at 0, output at 0. 10khz input at 0, output at +3. On the GP9 I even tried biasing it down further to get it flat, it did nothing though. the rec eq also does nothing. what is going on ? i am looking at the manual, there is no 10k adjustment. huhwha? i dont remember that....
 
You should be doing biasing at a lot lower than 0VU. The book probably recommends -20VU or -10VU.
Also, adjust bias using the 10khz overbias method, not just for flat output, and again, not around 0VU which is too high generally and you might get a false reading.

Then use the rec eq (high) to get a flat response.

Is it possible your test tape is worn out, causing you to boost the highs in your repro amp? That might explain having too many highs when you make a recording. Generally the repro high eq should be somewhere in the middle of the trimpot's range, not at an extreme end of the range.

Tim
 
I'll take a look but the rec eq pot is having absolutely zero effect for me. that is why i started messing with bias, I started thinking the 10k is fixed. now i can't figure this thing out...
 
FALKEN said:
I'll take a look but the rec eq pot is having absolutely zero effect for me. that is why i started messing with bias, I started thinking the 10k is fixed. now i can't figure this thing out...
Click to expand...

Try this:

1. Recheck your playback calibration.
2. before doing anything on the record side, place the eq trimmer at it's mid point.
3. Set bias with a 10khz tone @ -10 for 3db over-bias
4. Set eq pot for flattest response @ 10khz @0vu.
 
Gp9 .....

I'm going to assume that you have a working machine with no failed electronics. It there are failures then all bets are off.

The bias circuitry on a 32 will not produce enough bias to bias GP9 correctly. Machines like the MS-16 and 58/52 need a mod to be able to bias GP9. Even they cannot do it stock.

Bias should be set before doing an EQ adjustment. Changing the bias will change the frequency response and thus alter the EQ settings.

You can set the line in and meter cal then bias then EQ. The service manual has a specific order to avoid interaction. I have used 0 VU before but as Tim notes you could get invalid readings due to either tape or head saturation at 10 kHz. The actual level you use to get a 3 dB or so overbias is not important if you are not in saturation and if the tape gives a sharp peak.

You can try the "ROCKS" method of setting bias. Set you oscillator for 20 Hz or so (some use 12 Hz others 7 Hz, use a low frequency that works for you) and record it.

While recording listen to the repro head output. Because 20 Hz is too low to be recorded well you should not hear it. But you should be able to hear any distortion that mis-bias is causing. This distortion often sounds like crushing or rolling rocks together. Adjust the bias to min then start increasing the bias level until the distortion is minimized. Poof (orange smoke dissipates) you are now at the best bias level.

Then you are ready to adjust HF EQ for a nice flat frequency response.

Regards, Ethan
 
interesting....

no this is what i mean,

i sent in as per the manual a 700 hz .3V tone, with in and out knobs at 7, adjusted the input so that the output read .3V, then adjusted the meter to read 0.

I then loaded the test tape, played the 1khz tone, adjusted that to read 0 at .3V. played the 10khz tone, adjusted the hi to read 0. (this is all at high speed, i didn't bother with 7.5 ips for now)

I then loaded the blank tape, played the 10 khz tone, adjusted for 3.5 db bias drop, played in a 1khz tone where the input reads zero, adjust record level so that repro reads 0.

play in a 10khz tone so that input reads 0, repro reads +3. rec eq has no effect.
 
Gabriel,

I haven't done it in a while, but If I remember I just overbiased 3 more db to get the response flat, and set the eq pots to be centered.
 
You must log in or register to reply here.
Back
Top