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I have the following components in my studio:
*) Yamaha digital piano and various synth modules (unbalanced outs - RCA/phone jack)
*) Nakamichi tape deck (unbalanced ins/outs - RCA/phone jack)
*) MOTU 828mkII audio interface (balanced ins/outs - TRS - says to also accept unbalanced)

I will not need any connecting audio cable to be longer than 6-8 feet. Does this mean that I can make all connections unbalanced ? What do I need to consider ?

OJG

Comments

anonymous Sun, 01/15/2006 - 20:24

I am not sure how to make connection from unbalanced out to a balanced in and vise versa.
Some talk about just wiring, others about using transformers or DI boxes, but I've never done this before.

How should I connect my synth unbalanced out to the 828mkII balanced in. Also how should I connect the 828mkII balanced out to the Nakamichi unbalanced in ?
What about compensating between the -10db and +4db ?

OJG

ghellquist Sun, 01/15/2006 - 21:51

Unbalanced will be quite OK in most cases. If you get into large groundloop troubles you might want to go with transformers, otherwise cabling is OK.

There are probably different ways to do it, but here is my take:

First, connect all your equipment to the same power outlet strip. Used grounded connections for all equipment that has ground.

-- on instrument end, a standard unbalanced connection using a shielded cable.
-- on the MK828mkII end, a specially solded cable. Signal to tip, shield to ring and leave the sleeve (ground) unconnected.

-10/+4 can be set on a channel by channel basis on the 828mkII. Use whateverf works best.

Gunnar.

RemyRAD Sun, 01/15/2006 - 22:05

Ahhhh. The debate goes on whether to go balance or unbalanced.

Unless you're having problems with ground loop, humm and buzz, you don't need to go balanced. If you're having those kinds of problems, balanced makes more sense. The noise can still remain on the ground bus but is canceled out "differentially" on the 2 active audio lines. Another way to prevent humm and buzz in unbalanced equipment, is to attempt to make sure that all AC is plugged in together and not on separate outlets (that's where multi-outlet strips are so handy). I don't necessarily recommend the use of "3 to 2" ground cheater AC plug adapters, if avoidable. People have been killed by using those things.

Another reason to go balanced is if you are feeding your cables over long distances from 20 feet to 500 feet, or more as is the case in mobile recording as I have been doing.

One of the greatest mastering engineers in the business, has used all custom-made, unbalanced equipment (right now his name fails me. Arghh, I hate this over 40 stuff and I want my money back!) as he felt it had a cleaner sound. I agree. Unnecessary transformers and "Op-Amps" just contribute to distortion. You have to pay closer attention to your ground situations when going unbalanced. If you go balanced, the noise will appear on the ground bus and can still cause intermodulation distortion by modulating the ground bus and you may not notice that, since you cannot immediately hear it. (This article I'm speaking about, went back about 10 years ago, or more and mostly pertained to an analog oriented mastering facility, from an article in MIX magazine. Not Sterling Sound, or Doug Sax, ughhhh!) I have successfully intermixed both balance and unbalanced equipment throughout my career (longer than I want to admit to hear).

Generally, if you have a balanced circuit such as a tip, ring and sleeve, (such as the output from a Mackie) you can generally get away with shorting the ring to sleeve (in certain situations manufacturers tell you not to do that to their circuits but they are usually indicated). With an XLR connector, short pin 1 and pin 3. Pin 2 is hot. To unbalance a circuit.

To create a balanced circuit from an unbalanced output, (as from your keyboard output or Nakamichi) to your MOTU balanced inputs, you would need a "direct box", or matching transformer, which can be either step up, or step down, or, 1:1, which can be of the transformer type. As inexpensive from the ones at RadioShaft, to units costing in the three figures range. These transformer types can be run forward or backward, as there is no real polarity to Transformers. There are active circuit type direct boxes which can only be used in one direction as noted on the box. They too have their advantages since their inputs are usually of a much higher impedance than a transformer type. They are more well-suited to things like guitar pickups.

I have frequently used Whirlwind " Director" transformer direct boxes as they have a reasonable sounding transformer, provide electrical isolation, they can be used as step up or step down (which means you can use them for going from low impedance to high impedance or vice versa) and can be used in either direction and are extremely versatile. Transformers also provide us with "Electrical isolation" and is something I find very important in my professional sound duties. I find that professionally speaking, transformers are our friends! I even have a large electrical isolation/balance transformer to wire all of the AC in my remote truck. Yes you can get special balanced AC distribution boxes from companies like Furman, that further help to reduce electrically induced noise.

So coming from your unbalanced keyboard output to the MOTU input, you can get away with a good guitar cable. A simple Radio Shaft cable/adapter is adequate to get your Nakamichi output and/or input to and/or from the MOTU unit.

Again you should not have too many problems unless you are using a piece of equipment on one side of your room, where it is plugged in to the wall, to the other side of your room where your equipment resides, plugged into another outlet. That's asking for trouble and then you should go as balanced as possible.

I hope this helps?
Happy tracking!

The mostly unbalanced and balanced
Ms. Remy Ann David

Can I get off my motorcycle now?

JoeH Mon, 01/16/2006 - 12:30

That's a great link, Sanity; EVERYONE should read it, digest it, and incorporate all those tips. Once one has grasped the concept of "common mode rejection", it all becomes verrrrry clear.

I agree with RemyRad as well; many times it's not worth all the extra gain stages, op amps and/or transformers for the whole "Balancing act". (ouch- sorry for such a bad pun!) It can sometimes be counter-productive, or even overkill.

On live remotes with long runs, mic cables, interconnected professional gear (remote trucks, house PAs, racks, etc.) it's of course mandatory to be balanced everywhere except perhaps a guitar jack or bass pickup (going into a DI of course.)

But the line blurrs in my studio as well, depending on the gear; some of it is consumer, most of it is "Pro", and some is, well..."Pro-sumer." (You know what I'm talking about, I'm sure.) For anything unbalanced, I keep my runs short, use good cable, and keep the signal level fairly hot. For all the usual unbalanced ins and outs, inserts, etc. in my monitoring chain (I mix all the important stuff virtually "inside the box"), the Mackie line has always served me well, and taken a lot of the PIA aspect out of it all, with its bal/unbal. patches and routing.

I'm also fortunate in that my studio is technically below-ground; the walls are poured concret/cinderblock with another outer layer (for waterproofing), and the floors are "cured" concrete, 55 yrs old now - hard as diamond; I can't drill into them without a special bit. Hum is fairly non-existant here, unless I DELIBERATELY want to add it. ;-) Same with power distro: everything is on the same transformer leg and clean, so there's no worries of using the wrong outlet to add hum.

All that is to say: If it ain't broke.....wHen you have good gear and a good facility that works well at the git-go, you can be a little looser with balanced vs. unbalanced, if you need to.

anonymous Mon, 01/16/2006 - 13:27

Thanks everyone for your replies.
Remy, thank you for the detailed info.
The 828mkII has 1/4 inch phone jack type ins/outs. In the user's manual it reads:

These 8 analog inputs are gold-plated, balanced TRS quarter inch connectors, that can also accept an unbalanced plug.

Does that mean that it will accept a TS plug ?
If so, I will not need to solder a special cable connecting the ring to the sleeve.

OJG

anonymous Tue, 01/17/2006 - 20:02

RemyRAD wrote: One of the greatest mastering engineers in the business, has used all custom-made, unbalanced equipment (right now his name fails me. Arghh, I hate this over 40 stuff and I want my money back!)

[quote=RemyRAD]No, it's not Bill. It will come to me it's just that at 50 the signals to my synapses seem to be going on Sunday drives are the country??? I'll get there. He is on the tip of my tounge where he shouldn't be.

Ms. Remy Ann ..........David
at least I got my name..........right?

Didn't you just say over 40 a minute ago?
(Of course, I guess 50 would be "over 40") :-)

anonymous Wed, 01/18/2006 - 08:35

RemyRAD wrote: No, it's not Bill. It will come to me it's just that at 50 the signals to my synapses seem to be going on Sunday drives are the country??? I'll get there. He is on the tip of my tounge where he shouldn't be.

Ms. Remy Ann ..........David
at least I got my name..........right?

Whomever he is (some mornings I can't remember my own name, either... :-? ), he is not alone.

Electrical earthing as well as audio signal grounds, in controlled situations, can benefit greatly from a single-ended paths. The trouble, of course, happens when you start mixing the two...