Record and playback calibration

[frpe12]

Hi Mampfi,

Still waiting for my level test tape.
In the meantime, could you explain the role of R1/R3/R5 and R2/R4/R6 trimmers on board Y for recording ?
Thanks in advance.
Regards.
François

[mampfi]

First of all you have to adjust the recording azimuth to the playback head. In hope the playback azimuth is correct.
Because you need a azimuth testtape to adjust it. Give a 10kHz -20dB signal to the machine and measure it with oszillograph.
Set the sinus curves on top of each other on the screen, so you can see if the sinus curves matches each other.

If you do so, you can adjust the recording level and the pre magnetisation for 19cm and 4,75cm speed.

Choose a type of recording material that you like. LPR35 or something like that.
Put a 1kHz Signal to the machine and record it with 19cm @ 0dB ---> approx. 1,3V at the output from the monitor socket.
Turn the prerecording/recording switch to record and adjust R1/R2 that you have the same level in prerecording and in recording position.

Don't move the recording slider/controller. Put a -20db Signal with 10kHz into the machine and switch also from prerecording to recording.
Adjust R5/R6 so that you have the same level between prerecording and recording.

Do the same with R3/R4 @ 4,75cm

Note:
The recording level @0dB will be adjusted only once @ 19cm or 9,5cm/sec
Grundig wrote to do so @9,5cm. I do this @ 19cm/sec. and optimate the frequency response for 19cm/sec
There is only one adjustment for 9,5 and 19cm/sec
You can use R5/R6 and R3/R4 to optimate the frequency response