XLR to RCA Adapters

Just a couple of quick points here.

First - the notion that only one-half of the internal circuit will be used when supplying the single-ended signal is total nonsense. While it indeed might be true in case of some (I presume rare) products, all BAT preamps have differential inputs and internal circuits.

Two - converting the single-ended signal into balanced with a transformer most likely will be counterproductive, as the preamp itself will do that conversion just fine - see item #1.

Three... balanced circuits have other advantages besides the interface noise immunity. A very important one is the nature of interaction between the gain stages and the power supply - it is many times easier to build a **good** power supply for the balanced circuit than it is for the single-ended one.

The adapters will work great, your loss will not come from them, but from the fact that you will not be using your preamp to its fullest potential.

Regards,

Victor Khomenko

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

Chipmunk,
I have one of your VK 40 Pre Amps currently driving a VK200 amp.
I will be putting a single ended tube Amp in my system next mounth on a trial basis and will use XLR to RCA adaptors.

Do tou see any problems with this?

Thanks Gary

No problems, the only drawback would be in not utilizing the full potential of your preamp. All things being equal, you are better off preserving the balanced nature of the signal all the way to the speaker.

Victor

Sorry Atmasphere, I didn't mean to imply that CMRR was the raison d'etre for your inclusion of the termination resistor. It usually only shows a handful of dB improvement for the CMRR in practice, sometimes a little more at higher frequencies. A certain REL subwoofer input circuit comes to mind, and this is a single-opamp differntial input stage.

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. While there have certainly been vast quantities of poor-quality transformers produced over the decades, tolerance of a wide range of secondary load impedances is one of the fundamental differences between output and input transformers. On a modern line output transformer, it is in fact the tight coupling between the windings and their higher inter-winding capacitances that allow the primary to provide damping for the secondary. This of course requires that the primary be driven from a very low impedance source, as indicated on transformer datasheets.

Sonically, I feel that the best input transformers are virtually transparent, with the main audible artifacts a result of huge, measureable improvements in bandwidth control and noise rejection. For output transformers, I think I usually hear do have a very slight discernable signature, but it tends to be mainly at low frequencies, and frequently a rather welcome coloration. But one example of the astounding potential of output transformers can be found in any of the Audio Precision analog-based generators . . . maybe as the patents for this famous circuit near expiration we might see something similar in an audio product that we actually listen to.