Topic: I just got one of these (Marenius SMF-6 Mic preamp and ADconverter)What do need?

[Fisherking]

Hi guys and gals

I just got a Mic preamp/AD-converter in the mail. It is a Marenius SMF-6. A Swedish construction.

http://www.iberalp.es/Descripciones/Marenius/MRN_zmf6z.htm

http://www.marenius.se/smf6.htm

Is it even possible to run this in the field? Open taping isn´t allowed in Sweden but I guess I could convince a band or two to let me tape them.

What I have is a Sony D8 DAT player and a JB3. Microphones will come later (have a pair of SP-CMC4 for stealth). Attenuators is a given since the lowest gain is 30db.

The problem as I see it is to power it in the field since it runs on 2x15Volts. Is it even possible to find a battery for it ?

I don´t have much knowledge about connections. I run my JB3 from a AD-20 with a optical cable and i have a batterybox to power my mics with the D8.

The Marenius have a S/P DIF and a AES/EBU digital out. What do I need to connect it with the D8 or the JB3 ?

I only paid about $100 for it so if I can´t use it in the field there is no greater harm done. From what I have found on the net it did cost about $700 new.

Best wishes, A merry Christmas and offcourse a happy new year.

Stefan, Sweden

[hexyjones]

Wow - nice piece of gear..! And a sweet deal

I cant add anything but...have fun!!!

[Brian Skalinder]

Is it even possible to run this in the field?

I'm sure it's possible.  But is it desirable?  According to the specs it runs on AC.  Which means you'd either have to plug into AC, or run a DC > AC inverter.  Power inverters are generally inefficient and you'd likely need pretty BIG batteries to run this thing through an inverter.  But yeah, it can be done.  Depends on how much power gear you're willing to carry around in order to run the box.

Attenuators is a given since the lowest gain is 30db.

Attenuators are for reducing the strength of an analog signal.  Since the box is a preamp and ADC and therefore feeds your D8/JB3 a digital signal, you won't need / be able to run attenuators if you're using the ADC in the device - unless you want to open up the box and adjust its gain structure.

The problem as I see it is to power it in the field since it runs on 2x15Volts. Is it even possible to find a battery for it ?

See above re inverter.

The Marenius have a S/P DIF and a AES/EBU digital out. What do I need to connect it with the D8 or the JB3 ?

For your D8, you can run S/PDIF into a 7-pin cable.  Check the Archival Info for a thread on 7-pin cable options.  Most folks like the Oade or Pro Digital cables.

For the JB3, you need to convert the S/PDIF or AES/EBU to optical S/PDIF.  Two devices do this well:  Hosa ODL-312 (AES/EBU <-> optical S/PDIF) and Hosa ODL-276 (coax S/PDIF <-> optical S/PDIF).

[Todd R]

Attenuators are for reducing the strength of an analog signal.  Since the box is a preamp and ADC and therefore feeds your D8/JB3 a digital signal, you won't need / be able to run attenuators if you're using the ADC in the device - unless you want to open up the box and adjust its gain structure.

Not true -- you can just run attenuators on the incoming mic signal.  I had built some H-pad -10db XLR attenuator cables when I ran my Beyer MV100.  Just takes a few resistors for each cable.  Put them between your mic/mic cables and the inputs of the Marenius box and they will reduce the level of you mic output.  As they are made with resistors, some of the 48v phantom power will be chewed up by the resistors, but it is not too significant.  I can't remember now, but I think ~46v of the 48v phantom power will get to the mics.  Within the 48v+/-4v spec of phantom power.


All that said, it doesn't look like it is an issue.  The pdf of the Marenius unit you posted says it does 0-75 db of gain.  Selectable 0, 25, 50 db base gain + 0-25db additional trim gain.  Where did you see you'd have +30db gain minimum?

The bigger issue might be field powering.  If you don't have access to AC, it looks like you'd need a power inverter.

[Fisherking]

About the gain.
It has a switch 30 or 50dbs gain. The knobs start from zero and goes to 20. I figured since there isn´t a 0 on the switch you start at 30dbs gain.

Sort of like the AD-20 starts at 17dbs gain when the knobs are turned all the way down.

The pdf file is about SMF-7 which is abit more advanced than the SMF-6

My knowledge about these things are abit limited as you might have guessed. Anyway I think it is a very cool piece of equipment for that price even if I can´t power it in the field.

[Brian Skalinder]

Attenuators are for reducing the strength of an analog signal.  Since the box is a preamp and ADC and therefore feeds your D8/JB3 a digital signal, you won't need / be able to run attenuators if you're using the ADC in the device - unless you want to open up the box and adjust its gain structure.

Not true -- you can just run attenuators on the incoming mic signal.

Oops.  What Todd said.  Biffed that one pretty good, and I know better (well...apparently not)!  Must make sure I'm awake before posting next time...

[m.mouse]

It might not be easy to find batteries but surely the AC is converted to some DC voltage inside the smf-6?