written by
Ziga Rezar

Telefunken M15 Tape Machine Tutorial

3 min read
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You don't have a plugin for that.

Yes, there is more plugins out there that take a shot at simulating what a first class tape machine sounds like. Some actually come pretty close. But none of them takes on the Telefunken M15 in particular.

It's weird actually! Everyone that googled "tape machine" knows about the Studer A80, but the German answer to that legendary machine was none other than Telefunken M15! It's a fully discrete, mastering grade unit that came in two flavours - 1/4" stereo and 1/2" 4-channel version.

The one at mix:analog is the 1/4" variant, lent to us by a private collector in great shape (it was used as a "hot spare", so the heads are as good as new!).

Telefunken M15 magnetophon tape machine at mix:analog
Telefunken M15 "magnetophon" at mix:analog

Ok, so enough history already, how do I make it sing?

It's gain staging

Yup, that topic again. But with a processor like a tape machine, the level that hits the preamp cards and the tape means everything! But in this case, it's very simple, as there are literally only two places that you need to be mindful of the level. Ok, maybe three if you count the AD converter.

The IO unit

The IO unit has two knobs and the upper one - OUTPUT LEVEL - controls the (still digital) level that gets sent to the DA. If you exported your stem or mix at a safe level, but want to hit the tape hard at this stage, use this knob to use all the level possible from the DA output.

The standard way is to play the loudest part of the file and adjust the OUTPUT LEVEL so the peaks reach approximately -1dB (or even closer to 0dBFS clipping point if you feel like a daredevil at the moment). The reference level of the AD/DA converters is +18dBu = 0dBFS.

mix:analog IO unit
mix:analog IO unit - adjust digital gain here

The next unit in the chain is the Analog Volume Control (AVC from now on). This is a buffered passive attenuator with the output line driver stage providing 6dB of gain. This unit has an internal headroom (clipping point) somewhere around 22dBu.

This means that if you max out the digital level and the AVC dials, the maximum level adds up to +24dBu and that can be trouble for the AVC, as it's slightly over its headroom. You can usually get away with it, but be careful and back of a little bit if you start to hear clipping noises and it's not the converters fault!

The total range of the AVC is split into left and right trims and the master level. This allows for fine adjustments of the stereo balance if need be.

mix:analog Analog Volume Unit and Telefunken M15 GUI
Analog Volume Control unit and the Telefunken M15 GUI

The Telefunken M15 GUI

There isn't much to do with it, but there's useful into there. The display on the right shows the approximation of how much tape is left on the reel and when it gets close to zero, it will eventually stop and initiate automatic rewinding. The whole procedure takes around one-and-a-half minute, and you're back in business.

The reference level for the tape machine for 0VU at calibration procedure was set to +6dBu, which might seem low compared to the +18dBu for the AD/DA converters. But the devil is in the details - not all dBu are created equal!

The tape machine calibrates to RMS level and the converters to peak level! With that in mind and the fact that for most musical material the RMS level is al least 10dB below the peaks, this brings us in a very healthy territory.

With such level settings, you're in the sweet spot when operating with all the levels set to zero and still able to drive the tape over the nominal level for up to 6dB if you want to.

End of tape

I hope this answers a good portion of the most frequently asked questions about our tape machine setup. But if you still find anything unclear, don't hesitate to open the support chat on our site and ask away - we're always happy to help!

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