BALANCED v. UNBALANCED

pingu · Jul 20, 2013

Where does the majority come down on the virtues of balanced v. unbalanced amplification and cabling? I have a pair of Nestorovic NA-1's that have an old school balanced input. No Neutrik connectors just 2 "live" rca inputs and one ground rca per side. To use balanced would require a special cable with either a floating ground or one connected to the amplifier chassis, I think. But, the amp was clearly designed with balanced in mind. Although, in 1981, Neutrik was pretty much studio only gear. Only a couple of pre-amps had two rca outputs per side in inverse and regular phase so the real life application was probably not balanced for most people.

Anyway, I am interested in a very high end line stage that has no balanced output. I asked the manufacturer why not and he advised that balanced has the effect of canceling out even order distortion but leaving the odd order harmonics. More gain of course, but a thinner, less bloomy sound. This is, I am told, the result of electrical theory well beyond my pay grade. For that reason, he opted for single ended only.

Is there any consensus on this issue? Is balanced properly left to long microphone runs with single ended the right choice for home stereo?

Steve Williams · Jul 20, 2013

It's easy to get RCA terminated balanced cable. I just did it

garylkoh · Jul 20, 2013

How a balanced design can cancel out even order distortion but still leave in odd order distortion is beyond my pay grade too. I still prefer balanced all things considered.

Here is a very high quality single-ended to true differential balanced (and vice versa) converter that I've used very successfully a number of times:

http://smcaudio.nfshost.com/product_flex-connect.php

pingu · Jul 20, 2013

garylkoh said:
How a balanced design can cancel out even order distortion but still leave in odd order distortion is beyond my pay grade too. I still prefer balanced all things considered.

Here is a very high quality single-ended to true differential balanced (and vice versa) converter that I've used very successfully a number of times:

http://smcaudio.nfshost.com/product_flex-connect.php

Thank you Gary. Basically solves my problem!

Speedskater · Jul 21, 2013

Wow. I had to read that twice. So you have a balanced cable, but at one end the two center signal conductors are connected to a pair of RCA connector center pins? Does it still work with nothing connected to either of the RCA shields? As it should.

Steve Williams · Jul 21, 2013

Speedskater said:
Wow. I had to read that twice. So you have a balanced cable, but at one end the two center signal conductors are connected to a pair of RCA connector center pins? Does it still work with nothing connected to either of the RCA shields? As it should.

Not sure how the connections are made but I even have a fully balanced Valhalla cable that is RCA on one end and XLR on the other

mep · Jul 21, 2013

pingu said:
Anyway, I am interested in a very high end line stage that has no balanced output. I asked the manufacturer why not and he advised that balanced has the effect of canceling out even order distortion but leaving the odd order harmonics. More gain of course, but a thinner, less bloomy sound. This is, I am told, the result of electrical theory well beyond my pay grade. For that reason, he opted for single ended only.

Is there any consensus on this issue? Is balanced properly left to long microphone runs with single ended the right choice for home stereo?

I have heard lots of reasons why some companies choose to not make balanced amps or preamps, but the above claim about balanced circuits cancelling out even order harmonics and only leaving odd order harmonics is way out there in voodoo land. Most companies that don't use balanced circuits usually talk about the added complexity is not worth the cost for what they feel is little to no sonic gains.

jfrech · Jul 21, 2013

pingu said:
Where does the majority come down on the virtues of balanced v. unbalanced amplification and cabling? I have a pair of Nestorovic NA-1's that have an old school balanced input. No Neutrik connectors just 2 "live" rca inputs and one ground rca per side. To use balanced would require a special cable with either a floating ground or one connected to the amplifier chassis, I think. But, the amp was clearly designed with balanced in mind. Although, in 1981, Neutrik was pretty much studio only gear. Only a couple of pre-amps had two rca outputs per side in inverse and regular phase so the real life application was probably not balanced for most people.

Anyway, I am interested in a very high end line stage that has no balanced output. I asked the manufacturer why not and he advised that balanced has the effect of canceling out even order distortion but leaving the odd order harmonics. More gain of course, but a thinner, less bloomy sound. This is, I am told, the result of electrical theory well beyond my pay grade. For that reason, he opted for single ended only.

Is there any consensus on this issue? Is balanced properly left to long microphone runs with single ended the right choice for home stereo?

Hi, when you say you're interested in a "very high end line stage" can you give a little more criteria and what it might be matching up with? price ranges always help guide our recommendations also...

garylkoh · Jul 21, 2013

Steve Williams said:
Not sure how the connections are made but I even have a fully balanced Valhalla cable that is RCA on one end and XLR on the other

Depending on whether the RCA is input or output there are various constructions.

RCA in, XLR out:

1) generally the center pin of the RCA is connected to Pin 2 of the XLR, and the ground of RCA connected to both Pins 1 and 3.

2) sometimes, ground of RCA connected to Pin 3 and center pin of RCA connected to Pin 2 - this is useful in some preamps like the output-transformer coupled SMc Audio VRE-1.

3) for some European equipment (Burmester and FM Acoustics for example), pins 2 and 3 are reversed.

XLR in, RCA out:

1) generally Pin 1 and pin 3 of XLR shorted and then connected to ground of RCA, center pin of RCA connected to Pin 2 of XLR.

2) again, for some European equipment, center pin of RCA connected to pin 3 and then pin 1 and pin 2 shorted.

Steve Williams · Jul 21, 2013

Thanks Gary

when Nick was here setting up his tape head preamp he made me a balanced RCA out to a balanced XLR in, in under 10 minutes

MylesBAstor · Jul 21, 2013

garylkoh said:
Depending on whether the RCA is input or output there are various constructions.

RCA in, XLR out:

1) generally the center pin of the RCA is connected to Pin 2 of the XLR, and the ground of RCA connected to both Pins 1 and 3.

2) sometimes, ground of RCA connected to Pin 3 and center pin of RCA connected to Pin 2 - this is useful in some preamps like the output-transformer coupled SMc Audio VRE-1.

3) for some European equipment (Burmester and FM Acoustics for example), pins 2 and 3 are reversed.

XLR in, RCA out:

1) generally Pin 1 and pin 3 of XLR shorted and then connected to ground of RCA, center pin of RCA connected to Pin 2 of XLR.

2) again, for some European equipment, center pin of RCA connected to pin 3 and then pin 1 and pin 2 shorted.

Gary is saying what I was going to say. In short (NPI), always check with the manufacturer about how to wire the balanced/SE connection! Not all companies follow the same formula and I think I ran into that years ago with Rowland and more recently with Bottlehead.

garylkoh · Jul 21, 2013

Steve Williams said:
Thanks Gary

when Nick was here setting up his tape head preamp he made me a balanced RCA out to a balanced XLR in, in under 10 minutes

Yes - it isn't difficult if you know what you are doing - he probably made it the correct configuration for his tape head preamp. You need to know the equipment to build the right one.

microstrip · Jul 21, 2013

mep said:
I have heard lots of reasons why some companies choose to not make balanced amps or preamps, but the above claim about balanced circuits cancelling out even order harmonics and only leaving odd order harmonics is way out there in voodoo land.

Mep,

Sorry it is not voodoo land, as any one having studied differential amplifiers will tell you. Reduced Even-Order Harmonic Distortion is one of the intrinsic basic properties of differential amplifiers. You just have to expand the transfer functions of circuits into a power series to quantify the distortion products and note that the in a differential amplifier, the odd-order terms retain their polarity, while the even-order terms are always positive. See Texas Instruments Application Report SLOA054D by James Karki or any non elementary text book on differential amplifiers for a complete explanation.

http://www.google.com/url?sa=t&rct=j&q=&source=web&cd=5&cad=rja&ved=0CEIQFjAE&url=http%3A%2F%2Fwww.ti.com%2Fgeneral%2Fdocs%2Flit%2Fgetliterature.tsp%3FbaseLiteratureNumber%3DSLOA054%26track%3Dno&ei=XCfsUeDGH-ip7QaIyICQAw&usg=AFQjCNE3N9Slo42CtJOJlrGg-xaXlZMXyA&bvm=bv.49478099,d.ZGU

microstrip · Jul 21, 2013

garylkoh said:
How a balanced design can cancel out even order distortion but still leave in odd order distortion is beyond my pay grade too. I still prefer balanced all things considered.

Here is a very high quality single-ended to true differential balanced (and vice versa) converter that I've used very successfully a number of times:

http://smcaudio.nfshost.com/product_flex-connect.php

I can second Gary advice - I got the Flex connect and it is a great unit! Besides it also attenuates level - something great in most systems!

mep · Jul 21, 2013

microstrip said:
Mep,

Sorry it is not voodoo land, as any one having studied differential amplifiers will tell you. Reduced Even-Order Harmonic Distortion is one of the intrinsic basic properties of differential amplifiers. You just have to expand the transfer functions of circuits into a power series to quantify the distortion products and note that the in a differential amplifier, the odd-order terms retain their polarity, while the even-order terms are always positive. See Texas Instruments Application Report SLOA054D by James Karki or any non elementary text book on differential amplifiers for a complete explanation.

http://www.google.com/url?sa=t&rct=j&q=&source=web&cd=5&cad=rja&ved=0CEIQFjAE&url=http%3A%2F%2Fwww.ti.com%2Fgeneral%2Fdocs%2Flit%2Fgetliterature.tsp%3FbaseLiteratureNumber%3DSLOA054%26track%3Dno&ei=XCfsUeDGH-ip7QaIyICQAw&usg=AFQjCNE3N9Slo42CtJOJlrGg-xaXlZMXyA&bvm=bv.49478099,d.ZGU

Do you have measurements of balanced preamps or amps which show they don't have any even order THD and only have odd order THD?

microstrip · Jul 21, 2013

mep said:
Do you have measurements of balanced preamps or amps which show they don't have any even order THD and only have odd order THD?

Although I do not have analysis of distortion spectra or measurements showing it, it should not be difficult to look for them if someone is really interested in them. But I only have pointed to technical literature showing that differential amplifiers handle even and odd harmonics in theory. Real life depends on the implementation of the circuits!

mep · Jul 21, 2013

There are lots of balanced products in the marketplace and I don't ever remember reading a review that contained measurements which indicated all even order harmonics had been cancelled out and only odd order harmonics remained. Seems like this would really be an issue if true depending on the level of harmonics contained in the signal.

microstrip · Jul 21, 2013

mep said:
There are lots of balanced products in the marketplace and I don't ever remember reading a review that contained measurements which indicated all even order harmonics had been cancelled out and only odd order harmonics remained. Seems like this would really be an issue if true depending on the level of harmonics contained in the signal.

Mep,
Not difficult to remember or find

Many balanced solid state preamplifiers from the 90's had distortion spectra similar to the ML 380s http://www.stereophile.com/content/mark-levinson-no38s-preamplifier-measurements

Bruce B · Jul 21, 2013

I know for folks with Otari tape decks, pin 3 is hot, whereas normally it would be pin 2 on an XLR

Steve Williams · Jul 21, 2013

Bruce B said:
I know for folks with Otari tape decks, pin 3 is hot, whereas normally it would be pin 2 on an XLR

Nick base my cable based on my balanced switch circuitry coming off the heads. IOW it is a true balanced switch. He redid my switch based on the need for SE outputs. Lack of space beside the existing XLR outs. So I need a balanced pair of cables coming RCA out of my Studer and XLR into his tape head preamp. Hence the need for such a cable. I have since sent back a pair of my balanced Valhalla cables for R A on one side and XLR on the other. Works beautifully. Dead quiet.

BALANCED v. UNBALANCED

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