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-   -   mixpre to sennheiser 100 (https://www.dvinfo.net/forum/all-things-audio/86572-mixpre-sennheiser-100-a.html)

Pietro Jona February 15th, 2007 09:00 AM

mixpre to sennheiser 100
hi all,
i'm feeding a sony z1 with a mixpre through a senn 100.
when connected by wire i set the reference tone at -20 and everything is fine. levels on the mixer meter run high up to +8/+12 and the audio is always good.
when connecting a sennheiser transmitter to the mixer out (line only) i set its sensitivity to -30 (lowest possible in this model). result: the af peak led start flashing when the mixer meter shows +4+8.
which way would you go, connect the transmitter to the mixpre's headphone out (mini jack to minijack cable, umbalanced and a few db lower) or get a -10 db pad and keep on using the xlr out? how would you set the limiters?
i hope i explaind myself well enough, thank you for you help


Pietro Jona February 15th, 2007 10:38 AM

sorry i wrote wrong, i'm talking about the tape output, not the headphone out.
i know that i could solve the problem by adjusting the camera input gain until the display shows -16 or -14 when sending the reference tone but i really feel unconfortable for having not so much headroom. besides, the display on the mixpre jumps from -15 to zero in one step, form there it is one more led only to get to +4db..

Jay Massengill February 15th, 2007 02:35 PM

First, confirm which version of the MixPre you have. The earliest version, which is recognized by the coaxial power connector, needs special attenuators on the XLR outputs. The newer version, with a small 4-pin power connector, can use standard attenuators. Investing in a pair of 10db attenuators would be a good idea, especially if you ever need to feed other sensitive line-level inputs like a DVX-100 camera in addition to your transmitter input. AT makes a -10,20,30db switchable model and Shure makes a -15,20,25db switchable model.
The wiring of your transmitter input cable will make a difference too since I think the Sennheiser uses different contact points for unbalanced line and mic input levels.
In addition, if you use only pins 2 and 1 from the newer MixPre XLR output, you get -6db attenuation immediately. If you have the older version of the MixPre, you don't get any attenuation by dropping the pin 3 connection. The earlier model uses an impedence balanced circuit, but the entire signal is carried on pin 2 rather than being split into positive and negative halves on pins 2 and 3 like a normal balanced XLR. So it's actually easier to build an unbalanced attenuator with the earlier circuit, you just have to recognize that it's not a standard output.

Pietro Jona February 16th, 2007 02:42 AM

thanks jay
the mixpre is brand new.
-6 db might be not enough, so i guess i'll go with the attenuator. i'm in sudan at the moment and i prefer not to mess with cutting/welding wires. i'll have the pad sent from home.

Gareth Watkins February 17th, 2007 02:34 PM

Hi Pietro,

I have the same gear as you (Z1, SD Premix and Sennheier wirelsess units) and am not quite sure of your problem... I have no problem hard wired either...but tend to set tone to -12db or -18db on camera, with no problem..

With the Sennie wireless... I leave the sensitivity at -10db.. but set the AF out to 0db.... The manual states that the mic AF out mic setting is -30 to -6db (I set at -12db) and the line setting 0db to +12db...With the Premix I set at 0db.

I've found a 0db setting lets me set a tone of -12 on camera... Not had a problem yet... It does mean that I have to reset my transmitters depending on the usage...

Is this your usage of the system?


Pietro Jona February 17th, 2007 11:25 PM

i'm not sure you are using the sennheiser for the same purpose i'm using it. i use it to send the signal from them mixer to the camera, not from a person to thee mixer.. my camera operator wants to move freely without wires.
given that the mixpre is line only it seems impossible to me thhat your transmitter could accept its signal when set to -10, mine shows overloading/clipping/saturation even at -30 when i reach +4db on the mixpre.
i like to set the reference tone at -20 or -18 because i like to have more headroom and run the average dialogue levels at about +8 +12.
i'm now using the tape output on the left side of the mixpre, waiting for a pad to be sent from home.
let me know what's the use you do of your transmitter and thanks


Oleg Kaizerman February 19th, 2007 01:50 PM

use the mix pre unbalance out to feed the the transmitter ( ring and ground)
, set the
calibrate the input so you have about -14 on the tx as you sending o dbu
calibrate the limiters around +12
work normally so the pics would fly +6 -10 , the mix pre limiter would work before the tx will limiting by it self
is better work this way and sacrifice abit of the headroom and get better sn to noise in the transmitter
establish your tone when you sending the signal to -16 dbs on the camera

i think with that setup you will be fine

Pietro Jona February 19th, 2007 10:59 PM

thanks oleg

tx means transmitter i guess?
what if i go the pad way? would i need about 40db attenuation?


Oleg Kaizerman February 20th, 2007 12:52 PM

15db go consumer line level -ring on the tx
40 db to mic level -tip on the tx input

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