XLR to RCA Adapters

Kirkus, yes that does sound like a pain.

I've always been a fan of bandwidth, well below 20Hz and well above 20KHz to maintain proper phase reproduction in the audio passband. Both areas can be hard for transformers (which is why I prefer to direct-couple) and is why I usually look into the loading issue if transformers are to by used; its all about out-of-band extension.

The reason you use balanced lines is lower noise and lower distortion, plus the opportunity to eliminate the sonic role that the cable has in the system. BTW, length (or shortness) of the cables has nothing to do with it!

Now if you are using a single-ended source with a balanced amplifier, you will not be able to realize this advantage. Thus comes the idea of a transformer. You would use the transformer directly at the output of the source, keeping the cables between the source and the transformer as short as possible. However the transformer (including the Jensens, which are excellent) will have a sonic artifact which is easily heard, even if properly loaded. If the transformer is kept as close to the source with the cables to it as short as possible, CMRR degradation issues will be minimized.

Now, if the main interconnect cable can be short, you are better off just making the connection with a single-ended cable. The amp, BTW, is not going to give a hoot if it has differential inputs, and the BAT does.

But if the cable is to be very long, over 20 feet, then there will be an advantage to using the transformer solution (assuming an excellent transformer), despite the artifact it introduces, because that artifact will be *less* than that of a single-ended cable being run long distances like that.

Mari555 asks about the other way 'round, where the preamp is balanced and the amp single-ended. There are several ways to do this. The most elegant is to modify the amp with a balanced input, and even though the amp is single-ended, it is possible to set it up so that the amp uses both the non-inverting and the inverting connections of the XLR.

The second method is to use an input transformer that does the conversion.

Finally, an adapter can be used to good effect, and while this technique is cheap and easy- you get what you pay for- it does not take advantage of the balanced output of the preamp and so the resulting sound will not be as good.

Just FWIW, we built the world's first balanced line preamps. We've been answering these questions for a long time.

Seakayaker, the issue with the use of a transformer is one of loading. If the transformer is not loaded, it may well be that it will express the inter-capacitive qualities of its windings rather than the turns ratio of the windings.

IOW the frequency response could go to hell. Loading of the transformer is paramount if you want to get the most out of it.

This type of application would normally use a line out transformer.

Mitch2, I appreciate that with some equipment the artifacts of the transformer will be less audible. The area I hear the most problems is in the bass- my speakers go down to 20Hz so if the bass is drying up due to low frequency phase shift its pretty audible. That is why I prefer to direct-couple.

Kirkus: just to set the record straight, the reason I advocate 600 ohms is not to improve CMRR (we have pretty good numbers there already as our gear is fully differential with very effective constant current sources) but to swamp out the inductive, resistive and capacitive effects of the interconnect cable, rendering it inaudible while the signal remains intact. I do agree and it is one of my frequent beefs that most high end audio products do not support the balanced standard and so fall right flat on their respective faces when trying to drive 600 ohms.

Uh, Victor, he was talking about an single-ended source driving a balanced amplifier...

I do think that it's highly inaccurate to characterize line output transformers, as a group, as requiring a substantial or specific load on the secondary to acheive proper transient response.

All of the line output transformers I have ever seen need some kind of load, but its not so much for transient response as for flat frequency response.

Pretty good for a bit of iron, eh?

It is indeed! Did you get a chance to check the bandwidth at 10Hz and 5 Hz also?