Teac Model 5B calibration

I

IainAndrew

New member
Hey guys, I recently bought a beautiful Teac 5B mixer and am a little confused by the calibration process suggested in the service manual. Here is the manual for reference - https://usermanual.wiki/Collections...am Series 5, 5A Mixer Service Manual.pdf.html

In the 'Level setting and operation check' section of the manual, it says to apply a -10dB signal to the line in, and a level meter to the direct out, then raise the trim pot so that the level meter reads -10dB. Shouldn't a -10dB input give me a -10dB output without adding gain?
I calibrated the mixer fully according to the manual, and the result is this - when I play back something I recorded to tape, the signal coming in is much lower than the signal going to tape. So I have to turn up the gain on the receiving channel in order to match the level (which is consistent with the way it was calibrated, but it doesn't seem right to me!). Maybe I'm missing something or misinterpreted the manual somehow? Any help would be greatly appreciated.
 
First of all, just a small ask, thanks for posting a link to the manual but it’s helpful to give a page or numerical section reference so the helpers don’t have paw through the document to find what they think is the same thing you’re looking at. I found it…Section 6 on page 15 of the pdf for those that want to follow along.

Don’t over-think this.

The TRIM control on the Model 5 series is not a gain control at all. It is a variable voltage divider shunting signal to ground over a 20dB range. It is exactly as it is labeled…”TRIM” not “GAIN”. The point of the calibration is not the same as you’re thinking with, like, a tape deck, where you’re lining all the channels up so they are exactly the same across all tracks with signals presented to the inputs. You can’t do this with the Model 5 consoles nor most budget to midrange consoles because they don’t have internal cal trimmers, just the external controls you use in normal operation. The point of the calibration then is to just verify you are able to get -10dB in to -10dB out. That’s all. It’s an operational check. If you can’t get -10dB out, there is something wrong in the guts.

Does that help? Yes you will indeed need to rotate the TRIM controls clockwise to level match your tracks on playback. Think of it this way…the TRIM controls are passive *attenuators*. At full CCW they attenuate 20dB of signal. At full CW there is no attenuation. If you need to turn them off (i.e. turn them full CW), then do that.
 
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As an additional comment, note Section 6 is not titled “calibration”. It is titled “Level Setting and Operation Check.”
 
sweetbeats said:
First of all, just a small ask, thanks for posting a link to the manual but it’s helpful to give a page or numerical section reference so the helpers don’t have paw through the document to find what they think is the same thing you’re looking at. I found it…Section 6 on page 15 of the pdf for those that want to follow along.

Don’t over-think this.

The TRIM control on the Model 5 series is not a gain control at all. It is a variable voltage divider shunting signal to ground over a 20dB range. It is exactly as it is labeled…”TRIM” not “GAIN”. The point of the calibration is not the same as you’re thinking with, like, a tape deck, where you’re lining all the channels up so they are exactly the same across all tracks with signals presented to the inputs. You can’t do this with the Model 5 consoles nor most budget to midrange consoles because they don’t have internal cal trimmers, just the external controls you use in normal operation. The point of the calibration then is to just verify you are able to get -10dB in to -10dB out. That’s all. It’s an operational check. If you can’t get -10dB out, there is something wrong in the guts.

Does that help? Yes you will indeed need to rotate the TRIM controls clockwise to level match your tracks on playback. Think of it this way…the TRIM controls are passive *attenuators*. At full CCW they attenuate 20dB of signal. At full CW there is no attenuation. If you need to turn them off (i.e. turn them full CW), then do that.
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Thank you for this, I understand now! Good to know it's all working as expected.
 
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