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August 24, 2019, 07:28:21 AM

Author Topic: Tape Calibration Issue with RS-1500/Eros  (Read 566 times)

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Offline kevemaher

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Tape Calibration Issue with RS-1500/Eros
« on: May 20, 2017, 09:39:33 PM »
I've just received my Eros kit (Thanks!!!). I've been doing a bit of thinking about use with my RS-1500. I am pretty sure about how to extract the signals from the 4T/2T switch. However, I'm not so sure about tape calibration. I have already calibrated my stock 1500 for LPR35 at 355nW/m (MRL tape). Yes this is higher than the factory setting of 185nW/m but well within the capabilities of the preamps. Full calibration of repro/record was done. But if I now disconnect the repro amp to use the Eros, I won't be able to monitor the tape from the machine - no VU meter. And no calibrated repro amp. I used a scope and AC voltmeter to set repro/rec levels. Playback with Eros will be alright  (no VU meter). I can still set record input level using the calibrated VU meter (input monitoring). So I'm OK as long as I stick to recording with LPR35. But what if I recal for SM900 at 520nW/m? Do I need to re-connect to the internal repro preamps and perform the cal? Can I use an external AC votmeter?
Maybe I've overthought this and I will understand once I start using the Eros with the 1500. Or maybe I am missing some key point.
Any help will be greatly appreciated.
Kevin

Offline Doc B.

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Re: Tape Calibration Issue with RS-1500/Eros
« Reply #1 on: May 21, 2017, 05:56:37 PM »
520 is just 3dB hotter than 355, so you can just use your 355 tape and offset your meters 3dB. You can see what the level is from your 355 tape at 1kHz with the Eros outputs plugged into the line inputs on the deck and monitoring the line ins with the deck's meters. Since you know 520 is 3db hotter you can just calibrate to a 3dB offset. I'm not sure this would happen, but depending upon how hot your peak record levels are at 520 you might run into issues with overloading the Eros or something past it and increasing distortion.
Dan "Doc B." Schmalle
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Bottlehead Corp.