Not frequency, levels. In most professional tape machines, including the ATR-102, there are three (3) trim pots in the record side, and another 3 for the playback side. Each channel has: a Recording circuit card, a playback circuit card, and a "sync" circuit card, for overdubbing in sync with previously recorded material. All 3 have the 3 frequency level adjusting trim pots.Mustang Martigan wrote: ↑Wed Jan 13, 2021 3:58 amThanks for a that info. So you send each of those sine wave freq to the ATR and then adjust it's internal eq so it outputs the same freq?
I was reading UA's Tips and Tricks for the Studer and I guess you can do the same with that one. They suggest putting it as the first plugin on every track.
I'm really interested in trying that and then sending the Master to a new track that has the ATR loaded. So it'd be mimicking boucing the final 2" mix down to a 1/2" Master Reel.
You send 50Hz, 100Hz, 1,000 Hz, and 10,000 Hz at a "zero VU" level, in order to see what each circuit card is leveled at. On the 50Hz, you do NOT adjust anything, you just see where the machine is at. This is because the ATR-102 has a slight BUMP around 52Hz or so, it varies ever so slightly between machines. These older solid state circuits do not keep their settings for too long, maybe a couple of weeks before it bonkers out of calibration, if you do not abuse the machine. Playback is first, with a known calibrated tape, like an MRL labs one, or the test tones from something you did prior, and know the calibration is 100% accurate. Second, the record circuits, and last the sync head.
Depending on the tape formulation, you send a known level of 1K, for which 0 = 1.677 volts, or something like that. A known exact voltage (I forgot what it is, but it is an industry standard), and then set your middle trim pot to ZERO on your VU. And then go from there. If your tape formulation says 250 NanoWebers (the amount of energy to change the direction of the tiny iron filings on the tape), then you calibrate your tape machine to ZERO at the VU with a certain voltage. More nanowebers = more voltage equaling that same ZERO point. You are calibrating to the tape formulation. This is called the tape BIAS. You have to set this first, when using new tape. But you have to first calibrate the playback side, otherwise your signal through will not be accurate. LOL.
Studers, of which I had experience with a few of, had the same three sets of three frequency trim pots, for each channel. I got to be able to calibrate a 24 track Studer in 10 minutes. Takes precision aiming of the tiny trim screwdriver to do that LOL.
Someone on the net has the "how to do this" manual somewhere. Oh, like, WELCOME TO 1979 Studios. They have tape camps where they teach all this to engineers. I highly recommend that, if you ever get into recording onto tape.