Unbalanced to Balanced Conversion

Does anyone have experience with this? Pitfalls? Advice? Recommendations on gear to do the conversion?

I'm contemplating a move to a new preamp and some of the units on my short list are Balanced Only. The only place where I'm slightly hung up is the turntable. My turntable does not have Balanced Outs and my phonostage does not have Balanced Ins or Outs. So I was considering conversion. I find everything from $4.50 adapter plugs to $355 single conversion boxes. It's just not my nature to go the cheapest way possible and I don't mind spending some cash if there is value there. Need some help here.

 

Not what you would want to pay, but what I would consider in your shoes:

http://www.decware.com/newsite/ZBIT.html

 

Thanks Lon. I'm not totally put off by the price, they seem like a good company and the build quality looks pretty good. But unless I'm missing something I think it's going the wrong way. I need Unbalanced to Balanced and this says it's Balanced to Unbalanced. Right?

 

You can simply use these:

http://www.neutrik.com/en/accessories/circular-adapters/na2fpmf

I use them when ripping vinyl, as my external ADC has balanced inputs. Neutrik is top quality, been using them for decades. Beware Japanese XLR's have a different pin configuration than western.

 

That's good to know! Thanks for the link. Geez, can it really be that simple?

 

Yes, that simple

I've had a few fully balanced preamps myself before in time. But not wanting to mess with my XLR cables, I modified the balanced output on my Sony X777ES CD player instead. Today I use XLR between my Linn Akurate and Oppo HA-1 headphone amp.

 

Good to know, thank you very much.

 

Um.. . yeah. I'm embarrassed to say yes, that's right. I was thinking backwards. . . sorry.

I'm intrigued by the Decware transformer as I could use balanced to unbalanced, though I don't think I need to do so (have both balanced and single-ended on two of my sources, and a single-ended preamp and amp with gain control).

 

No worries, you jumped in and tried to help. I appreciate that.

 

Balanced inputs are normally in studios for long distance and balanced inputs need more input voltage . Passive cables (no transformer or circuit ) will introduce -3db loss plus the unbalanced signal is -10db low compared to the regular 0db needed for balance input. Also you lose the Common-mode rejection benefits of the balanced input but for short distance this coul be not a problem. The problem with passive adaptor or cable is the low level.

 

Yes, the level could be a problem. I get around it because I can adjust the input level on my ADC. If the OP's setup was mine, I would have been looking for more expensive solutions, or build it myself. I built a balanced input once, with two excellent Burr-Brown operational amplifiers, because I had a four meter run of cables betwen my preamp and power amp. Maybe overdone, but a funny little project.

 

I had that issue with my Legacy Aries, which have balanced inputs and outputs to a equalizer-like device that goes between the preamp and my tube mono amps. (The Aries have a built in solid state amps to drive the woofers and there is a separate run of balanced cables from the "equalizer" to the speakers.) I just bought adapters (or rather the Legacy rep did). It seems to work fine. I have thought about trying to upgrade them, maybe with something from Cardas, but have not done so to date.

 

I looked into this pretty extensively a while ago but never pulled the trigger. The Rane Balance Buddy seemed to be the best one for doing a true conversion from unbalanced to balanced. The output is compatible with consumer balanced inputs too, which is important because some units are designed to go into the mic inputs on a mixing board.

 

Should the Shield only be connected on the XLR/Balanced end, not both? Otherwise it's a potential ground loop (hum)?

 

I would personally just scratch those few units off of your "short" list in that case. If you don't have everything else fully balanced and don't have long runs, all it does is create additional costs and hassles. When you are in a situation where you do need to connect an unbalanced input to a balanced amplifier and the cable run length is not the issue, then you just use a simple adapter or you can make a custom cable as illustrated here for that one connection. In a hi-fi rig, there is not much of a voltage difference if you are not introducing pro gear into the chain. Only if you are making a connection where you really want the cable to be balanced do you use a transformer instead. Jensen makes these but you would buy them already incorporated into an adapter box. The transformer converts SE to true balanced and vice-versa. That isn't needed for your application and just introduces more components. If the turntable and phono stage is the only issue, you would connect the table SE as always to the phono stage and then make a custom SE to XLR cable to run to the line stage. Better to just get a linestage with SE in and out to avoid all of that. The balanced has no advantage here.
-Bill

 

No.

 

Many thanks for your comments Bill. I'm in a better position now to be less cryptic in my description of the issue(s). Ultimately I did do as you suggested and did not chose a preamp with only balanced connections. I ended up going with an Allnic L-3000 Mk 2 preamp with both balanced and SE inputs. So now I don't have to wonder/worry what to do about SE connections from the TT/phonostage. But I will take this opportunity to ask you a different question. I'm already running long balanced connections between the preamp and amp. In addition to the Allnic I'm adding a Playback Designs MPS-5 Reference SACD/CD player. It also has both balanced and SE outputs. These two pieces will be close to each other so length of cable is not a consideration. But what are your thoughts on this connection type? Balanced or SE? And while I almost HATE to bring up the subject, your recommendations on cable manufacturer for your preferred connection type.

 

I agree with Bill.

But...even for short runs, if I have balanced in/out, I would for shure use balanced cables. If any noise is introduced in the cable, it will be cancelled at the preamp input. Some may say this is overkill, but what's wrong with that? Makes me feel better. I tailor-made XLR cables 0.7 meters just for short runs, and these cables are now used between my Linn Akurate media player and my Oppo HA-1 headphone amp.

Regarding manufacturer, I have found that good'ol professional Belden cables are good enough, even with many high-end rigs I have had. The pro's (musicians and studios) use them all the time.

 

The amplifier is either SE and just using transformers or op amps for balancing, or it is a balanced amplifier with summing to SE input and output in SE mode. I believe it is the latter but I cannot be sure. In that case, if it is a balanced amplifier design, then using a balanced input would be best as it eliminates some connectivity. Basically, you have to add some sort of coupler to go from one form or the other, so without any regard to any benefit of being balanced (many sound basically the same either way), you have a shorter signal path by not adding additional connections as you have to use the circuit supplied in either case. This addresses only the preamp and assumes the CD player is also fully balanced at its output. If the CD player uses a transformer coupling to create a balanced output from a SE output stage design, then it is adding that extra step there and its balanced outs would likely only be for the benefit of long cable runs. So both components have to be considered to make sense of it. Ultimately, any transformers or circuits used to create a balanced design will have a sonic impact and coloration, so it will come down to listening to both for a difference. I would get a pair of simple balanced and SE cables using the exact same conductors and configurations other than one being terminated in a fully balanced connection and the other in RCA to make the comparison. That way, you are comparing amplifier topologies / transformer colorations and not cables. Once you find which method of coupling is best, then you can change cables if you find that makes any improvement. I'll leave the choice of cables to the wire sniffers.
-Bill

 

Good stuff Bill. Thanks.

 

Good listening!

 

NO. IT IS NOT.

That is an adapter. That does NOT move between balanced and unbalanced, it simply moves between RCA and XLR.

This may be fine if you plug this in at the input of the pre-amp, but it is NOT a transformer that moves to a balanced line. As such, you would NOT want to use this at an output of something and then use an XLR cable. XLR cables are twisted-pair, and generally unshielded, and they depend on balanced transmission to reject noise. If you simply use an RCA-> XLR adapter, you are just making an antenna for noise out of your interconnect.

I would agree with what Bill said above, you'd either want to move to a phono preamp with balanced outs, or avoid a preamp that ONLY had balanced inputs most likely.

A proper transformer will be a minimum of $100, many options available generally sold as DI boxes of various kinds. The size of the transformer is the expense, and the little (and cheap) ones do not perform well and you lose a lot of bass. To maintain bass throughput you need a bigger brick, and those are usually $100+.

Something like this would do the trick, and well:

http://www.bhphotovideo.com/bnh/con...kCFU9hfgodSV8K7g&is=REG&ap=y&m=Y&Q=&A=details

Or:

http://www.bhphotovideo.com/bnh/con...NWWh-rbrMkCFYhffgodsvgI8g&is=REG&A=details&Q=

 

Good stuff, thank you Captain.