Otari MX5050-MKIII-2 XLR wiring

lo.fi.love

Functionally obsessed.
Hey folks,

I'm slowly getting my recording equipment set up in my new apartment, after having to redo a few of my snakes and otherwise getting things in order :)

I also finally got my Otari set up and I need to connect it to the patch bay. The signal going to the deck from the mixer will be +4dB (using the balance amp on my M-520), and the signal coming back to the mixer from the deck will be -8dB.

Two things:

1. Is it correct that the inputs are Pin 3 Hot? Does this mean that I need to short pins 2 & 3 on the xlr connector on the "Otari-end" of the cable?

2. The cables coming from the deck's outputs will be terminated on the other end with RCA connectors. So, 2a) Is pin three hot on the output jack? and 2b) How do you recommend I wire this connector? Can I just do pin 3 -> RCA Tip, pin 1 -> RCA Shield, and leave the third conductor in the cable hanging on both ends?

Thanks in advance for your help, guys!
Jeff
 

miroslav

Cosmic Cowboy
Yes Pin 3 is Hot + on the Otari (I simply reversed it on my 5050 to Pin 2)

NO...you don't short Pin 3+ to Pin 2-...if you must, short Pin 2 to Pin 1...
...or just float Pin 2 on the RCA end.

Yes...Pin 3 will go to the RCA tip...Pin 1 to the sleeve.

You might want to consider getting a 2-channel level converter...like this Ebtech LLS-2-XLR model.

http://www.ebtechaudio.com/llsdes.html

Then just get 1/4" to RCA conversion cables....
 

Blue Jinn

Rider of the ARPocalypse
I have the BII otari, are you going to be switching the level on the Otari each time? The M-520 is also pin 3 hot. so you should be able to use a straight xlr to xlr cable to the Otari. Coming back you could also get a Fostex 5030. They are pin 3 hot or pin selectable depedning on how old it is.

You could also if you wanted to get a couple of 4:1 transformers like Edcor or Jensen and make a passive balanced to unbalanced convertor yourself.

Here is some good gouge:

http://www.jensen-transformers.com/an/an003.pdf
 

lo.fi.love

Functionally obsessed.
The playback level from the deck to the mixer isn't an issue. The output is +4 or -8 switchable.
 

sweetbeats

Reel deep thoughts...
Jeff et al...is the Otari indeed balanced? I know some of the other 5050 series decks had XLR's but were unbalanced, pin 3 hot, pins 1 and 2 strapped.

In either case Jinn is right that you could use a straight XLR cable, but then there's no reason to waste channels on the M-520 balance amp...just set the Otari for -8dBu in and out, or set it to +4dBu and use the balance amp just to ge the hotter signal which may or may not make any difference depending on the self-noise of the balance amp.

If the 5050 is unbalanced I'd probably opt to set it at -8dBu and utilize the unbalanced -10dBv (same as -8dBu) ins and outs and avoid he balance amp altogether...you may get lower noise and better fidelity.
 

Blue Jinn

Rider of the ARPocalypse
Jeff et al...is the Otari indeed balanced? I know some of the other 5050 series decks had XLR's but were unbalanced, pin 3 hot, pins 1 and 2 strapped.

{snip}

If the 5050 is unbalanced I'd probably opt to set it at -8dBu and utilize the unbalanced -10dBv (same as -8dBu) ins and outs and avoid he balance amp altogether...you may get lower noise and better fidelity.

'beats, I'm pretty sure the Otari is unbalanced (I have the B2HD manual handy, but I don't think there are too many differences.) It doesn't *mind* an unbalanced or a balanced signal. There is a transformer option to make it fully balanced. I'll take a look at the schemo for the BII tonight. I don't have the BIII, but again I don't think there are too many differences between it and the BII as far as this aspect goes.

(I have a BII refab'd by Audio Village, that has some BIII parts in it, not sure which ones though....)
 

lo.fi.love

Functionally obsessed.
The BIII is balanced running at +4dBu on Input....switchable +4dBu/-16dBu on Output.

http://www.otari.com/download/files/mx5050_ad_e1.pdf

That's a different model. I have the MKIII-2, a desktop-style machine with a horizontally-oriented transport and the meter bridge sitting above. Looks sorta like the 8-channel MX5050 in that regard.

The input on the MKIII-2 is +4dB only. The output, however, is +4db/-8dB, switchable.

The input is unbalanced, but I have no idea if the output is unbalanced.

Regardless, the signal I'm feeding to the deck's inputs are sent out through the line amp on my M-520. I currently use two of the amp ports for my monitors, and using another two to boost the signal to the deck is not an issue for me. I doubt that there's any noise issues from using this intermediate step, since my experience in using the amp to feed into my monitors has shown me that there's no real added noise.

Does that help?
Thanks!!
 

Blue Jinn

Rider of the ARPocalypse
The output is probably unbalanced too. Check out the Jensen article, it should give you various options. Understanding that pin three is high rather than 2. They naturally advocate a transformer as the best option. You should be able to do as suggested above too. B/c pin 3 hot is an older standard, you may have to fashion your own cables.

Edit: I misread too....
 
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sweetbeats

Reel deep thoughts...
Miroslav that's funny...I read BIII too... :D

Jeff, okay. Otari input is +4dBu only with unbalanced XLR...I would wager that pins 1 and 2 are internally strapped on the Otari input so you can just run a standard XLR - XLR cable from the balance amp outs on the Tascam to the Otari inputs. Done. They are both pin 3 high (hot) and with pins 1 and 2 strapped at the Otari end it will unbalance the Tascam Balance Amp output but it will still be +4dBu nominal level. If you have hum problems with this then cut pin 2 from the XLR plug at the Otari end.

I concur that the output is likely unbalanced as well unless you open it up and see that the transformer balancing option has been installed. Set the outputs on the Otari to -8dBu and make up cables that go XLR to RCA and use your regular 2 track A or B inputs on the M-520. Connect pin 3 of the XLR cable to the tip of the RCA, and connect pin 1 to the shield of the RCA. Leave pin 2 disconnected in the XLR plug as I bet pins 1 and 2 are (like on the input side) strapped on the Otari outputs. To confirm you could get behind the jack panel on the Otari to double-check, but if they are already strapped in there you don't want to strap them again in the XLR plug because you can create a small loop there and I KNOW you are all kinds of done dealing with hums. :)
 

lo.fi.love

Functionally obsessed.
Quick update:

Turns out the output XLRs on the MKIII-2 have pins 1 & 3 strapped together. A little odd... so, Pin 2 is hot on the output, pin 3 is hot on the input. Maybe someone altered the wiring a little bit, or maybe not... it looks "Factory-done" in my opinion.
 

sweetbeats

Reel deep thoughts...
Otari would have followed a single convention for inputs and outputs and according to the manual its pin 3 hot.

Not bragging but much of my PCB solder work these days looks "factory" (or at least a dead-ringer as opposed to my early stuff whcih looked like burnt toast), so that isn't always a good way to tell if it has been modded.
 
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