Hi everyone,
Just sharing an interesting experience.
While calibrating my Revox B77, I couldn’t find the usual bias peak, making the standard bias adjustment impossible.
Instead, I monitored the frequency response in real time with the QA403 and alternately adjusted the bias and EQ trimmers until I obtained the flattest response.
The result was excellent: by ear, I could no longer distinguish the tape from the source, which is more than good enough for my personal use.
One interesting point: during the measurements, the QA403 Exposhirp output was connected to the recorder input, and the playback head output was returned to the QA403. At 3¾ ips, the tape path introduces a delay of about 340 ms.
I initially thought this delay had to be entered into the QA403 software, but it only worked with the default settings. The QA403 appears to recognize its own test signal automatically, even after such a long delay.
Very impressive! 