Single ended to balanced conversion....

[RothwellAudio]

That's exactly what I initially thought David. Live to pin 1, return to pin 2, and earth shield to pin 3. But having checked forums no one, it seems, is running it that way - all are using balanced preamps.

Who's David?
BTW, do you trust the people on forums?

[Barry]

Pin 1 on an XLR connector is always the ground or earth connection. Pins 2 and 3 are usually the +ve going and -ve going signal connection respectively, though it ought to mentioned that this convention is not always followed: on some equipment the polarity of pins 2 and 3 can be reversed. The latter will cause no harm but it will invert the polarity, which some claim to be audible.

http://theartofsound.net/forum/showt...dio-Connectors

I believe there are in-line balanced to unbalanced converters available which use transformers.



https://www.canford.co.uk/BALANCED-T...CED-CONVERTERS

They are expensive and are not really necessary: an XLR to RCA lead wired using shielded two-core cable as Andrew has described above ought to be quite sufficient. I use such when I need to connect an amplifier with an unbalanced input to my preamp which has a true dual-differential balanced output.

The only other thing to bear in mind when feeding a balanced amplifier from an unbalanced source (preamp), is the sensitivity of the amplifier will be halved.

[farflungstar]

Who's David?
BTW, do you trust the people on forums?

Why did I think your name was David? Dementia.

[farflungstar]

Pin 1 on an XLR connector is always the ground or earth connection. Pins 2 and 3 are usually the +ve going and -ve going signal connection respectively, though it ought to mentioned that this convention is not always followed: on some equipment the polarity of pins 2 and 3 can be reversed. The latter will cause no harm but it will invert the polarity, which some claim to be audible.

http://theartofsound.net/forum/showt...dio-Connectors

I believe there are in-line balanced to unbalanced converters available which use transformers.



https://www.canford.co.uk/BALANCED-T...CED-CONVERTERS

They are expensive and are not really necessary: an XLR to RCA lead wired using shielded two-core cable as Andrew has described above ought to be quite sufficient. I use such when I need to connect an amplifier with an unbalanced input to my preamp which has a true dual-differential balanced output.

The only other thing to bear in mind when feeding a balanced amplifier from an unbalanced source (preamp), is the sensitivity of the amplifier will be halved.

Yes you're right...
Technical specs from the maker
Output power: 75 watts
Frequency response: at full power 7Hz - 60kHz (-3 dB), at 1W -0.7Hz - 75kHz
Input sensitivity: 1.4V (25dB to 8Ω)
Input impedance: 300*
Absolute phase: not reversed (pin 2 = hot)
Negative feedback: approximately 15dB
Rise time: 10V/ms
Hum and noise: < 0.06 mV RMS (-112dB)
Dimensions: 483 x 222 x 495 (WxHxD)
Weight: 21.3 kg

[Pharos]

Generally, connecting an unbalanced O/P into a balanced I/P is never a problem, but the reverse can be.

ATCs are often fed from unbalanced preamp ccts, and without problems, I have done it with three pairs using Sumo and AVI preamps.

[RothwellAudio]

Actually, at the risk of putting the OP right off the idea of feeding a balanced power amp from an unbalanced preamp, there is one more complication, and it's this:

Pin 1 on an XLR connector is always the ground or earth connection.

Is pin 1 ground/earth or 0V? Depends what you mean by ground. The amplifier's metalwork should be earthed to the mains for safety (unless it's double insulated). That doesn't mean it has to be connected to 0V though. So what do you do with the little earth tag inside the XLR connector? It's there so you can make a link between the XLR's metalwork and pin 1 if you want to. But do you want to? If you do make the link and the amplifier's casework is connected to 0V then you're making a link between mains earth and 0V. Is that a good thing or a bad thing? Depends on how the preamp is wired. Is the preamp's 0V also connected to mains earth or is it floating?

It would be nice if balanced equipment actually did live up to its goal - that you can connect anything to anything and there'll never be a problem - but things don't always work out like that.
Having said all that, I'm not claiming that there's trouble ahead for the OP. Just wire up an RCA-XLR cable and see what happens. Most likely there won't be any problem at all.

[farflungstar]

Actually, at the risk of putting the OP right off the idea of feeding a balanced power amp from an unbalanced preamp, there is one more complication, and it's this:

Is pin 1 ground/earth or 0V? Depends what you mean by ground. The amplifier's metalwork should be earthed to the mains for safety (unless it's double insulated). That doesn't mean it has to be connected to 0V though. So what do you do with the little earth tag inside the XLR connector? It's there so you can make a link between the XLR's metalwork and pin 1 if you want to. But do you want to? If you do make the link and the amplifier's casework is connected to 0V then you're making a link between mains earth and 0V. Is that a good thing or a bad thing? Depends on how the preamp is wired. Is the preamp's 0V also connected to mains earth or is it floating?

It would be nice if balanced equipment actually did live up to its goal - that you can connect anything to anything and there'll never be a problem - but things don't always work out like that.
Having said all that, I'm not claiming that there's trouble ahead for the OP. Just wire up an RCA-XLR cable and see what happens. Most likely there won't be any problem at all.

I'd be lying if I said I wasn't worried but I've spoken wth the maker of the Truth (hes sent me 3 messages) and he assures me there won't be a problem. For extra info there is a ground lift on the Truth - there's also a second set of outputs - could these be utilised in any way?

[Spectral Morn]

Fully balanced is dual differential with separate left and right channel audio paths, basically everything doubled up, and while I personally think a suitable/matching balance pre will sound better, you are over thinking things, just buy an adapter. I use adapters for some of my single ended kit into my fully balanced pre and its fine, no issues and I use the Cardas ones, and I think they sound better..... you pays your money and makes your choice.

My gear is Balanced Audio Technology, not Audio Research.

[farflungstar]

Fully balanced is dual differential with separate left and right channel audio paths, basically everything doubled up, and while I personally think a suitable/matching balance pre will sound better, you are over thinking things, just buy an adapter. I use adapters for some of my single ended kit into my fully balanced pre and its fine, no issues and I use the Cardas ones, and I think they sound better..... you pays your money and makes your choice.

My gear is Balanced Audio Technology, not Audio Research.

Jajaja I overthink everything.

[montesquieu]

Jajaja I overthink everything.

I've used RCA-XLR adaptors with no issue in the past and I had some XLR/RCA cables at one point as well ... either way you should be fine. Personally, I'd have some cables made up (I'm sure Paul at RFC could help you there).

As well as single ended all round I have balanced outputs available on my AN DAC (4.1x fancy balanced transformer output), balanced inputs and outputs on my EAR 912, and balanced inputs on my Radford STA100. So I could in theory use balanced all round and have tried things that way. However I hear precisely no improvement from balanced wiring. I can see the point in a studio over metres and metres of distance, but not over 1m cables in a domestic setting.

Deep breath and relax.