
LUNE
...a pieds joints
here's a little amateurish frequency analysis test I conducted on my machines and found interesting:

Hope you can see it ok.
ignore the volume level - unless noted they were hit to tape at 0db.
the Tascam decks are getting roughly the same VU level on input as playing from tape with the tapes I'm using.
>The darker blue line on top with the steady high end slope starting at 1.2k is the A2300 (at 7.5 ips)
>the yellow line is digital recorded white noise
>the white line is 0db on the 38 (Quantegy 456)
>the red line is 0db on the 388 (RMG LPR35)
>the lower lighter blue line is the 388 hit at -10db (same tape)
the 388 graphs were measured in 1 second intervals, whereas the others were longer times which accounts for the somewhat more erratic looking character of these 1 second graphs.
these are all decks that I have not calibrated and so I don't know how "in tune" they are - which is partly why this interests me - trying to find ways to check how far off they might be or how close to 'good' - though I still want to eventually make the calibration of course. I was pretty impressed though with the 38 curve, and the 388 curve doesn't look so bad - both 388 graphs seem pretty good, but you can see the -10db graph is slightly flatter in the high end as I understand would be expected.
if anyone has any thoughts on this or what a test like this can show with regards to how much the deck is 'in tune', why it might be deceiving, what its not showing etc., I'd be interested.
is this an ok way to make a basic frequency response test?

Hope you can see it ok.
ignore the volume level - unless noted they were hit to tape at 0db.
the Tascam decks are getting roughly the same VU level on input as playing from tape with the tapes I'm using.
>The darker blue line on top with the steady high end slope starting at 1.2k is the A2300 (at 7.5 ips)
>the yellow line is digital recorded white noise
>the white line is 0db on the 38 (Quantegy 456)
>the red line is 0db on the 388 (RMG LPR35)
>the lower lighter blue line is the 388 hit at -10db (same tape)
the 388 graphs were measured in 1 second intervals, whereas the others were longer times which accounts for the somewhat more erratic looking character of these 1 second graphs.
these are all decks that I have not calibrated and so I don't know how "in tune" they are - which is partly why this interests me - trying to find ways to check how far off they might be or how close to 'good' - though I still want to eventually make the calibration of course. I was pretty impressed though with the 38 curve, and the 388 curve doesn't look so bad - both 388 graphs seem pretty good, but you can see the -10db graph is slightly flatter in the high end as I understand would be expected.
if anyone has any thoughts on this or what a test like this can show with regards to how much the deck is 'in tune', why it might be deceiving, what its not showing etc., I'd be interested.
is this an ok way to make a basic frequency response test?