Topic: Is There a Balanced Mono TRS to Unbalanced Mono TS Adapter or Cable?

[DavidNJ]

The Jensen and Rane sites show transformer designs and another that just leaves the ring unconnected.  However, it doesn't seem anyone actually makes one and I rather not build it myself.

Is a part that does this available? Is another option using a stereo TRS to mono TS Y-cable and leaving the TR-to-TS side disconnected?

Thanks,

David

[DSatz]

This is a recurrent question, and perhaps it ought to be handled in a "frequently asked questions" list.

Unfortunately the various methods of unbalancing a signal are all needed in various situations. There is no one general approach to unbalancing a signal that always works regardless of the output circuit that is generating the signal. The manufacturer of that equipment must always be asked. In some cases you'll need to leave one lead or the other unconnected entirely; in other cases you'll need to connect one lead or the other directly to ground; in yet other cases you'll need to connect one lead to ground via a capacitor. So that's six different adapter or wiring schemes right there--and in some cases, using the wrong approach (particularly grounding one of the leads directly) can damage the equipment from which the signal is coming, interfere with the powering scheme for a microphone, and/or cause gross distortion to occur.

An input transformer is probably the "most nearly general solution," but good audio transformers are far from cheap (as you may have noticed on the Jensen site--I use and recommend their gear), but a transformer suitable for microphone-level signals and impedances isn't usually suitable for line-level signals and impedances or vice versa, so again it always comes down to specific cases.

If you want to build or buy an adapter or adapter cable, you MUST find out the specific recommended connection scheme from the manufacturer of the equipment that is producing the signal (e.g. the microphone), and use ONLY that connection scheme with that equipment. You can't infer from "similar" equipment of another brand, or even from another model made by the same manufacturer. For example, if you connect a Neumann KM 140F to an unbalanced input the same way Neumann recommends doing it for the KM 140, you'll get nothing but crosstalk and noise--no useful signal at all. Similarly, if you connect a Schoeps CMC 5-- or 6-- microphone the way that was recommended for the CMT 5-- series, you'll very likely damage the microphone.

I have seen postings here that have recommended connection schemes that would work OK at low-to-moderate sound pressure levels, but would reduce the headroom of the microphone substantially; this is not something to determine by casual experiment or hearsay. Ultimately the information has to come from the equipment manufacturer to be reliable. Enough said, I hope?

--best regards

[DavidNJ]

It looks like it just takes a $70 transformer and and a few dollars of resistors.

Jensen JT-10KB-D Line Input Transformer 4:1 Stepdown For BalancedBridging Inputs JT-10KB-D

Line Input Transformer 4:1 Stepdown For Balanced Bridging Inputs ; Ideal passive "Pro to Consumer" level converter ; Wide bandwidth: !3 dB at 0.5 Hz and 180 kHz ; Recommended for levels up to +21 dBu at 20 Hz ; High input impedance: 40 k S ; High common-mode rejection: 120 dB at 60 Hz ; This transformer is designed for use in wideband line input stages. The secondary source impedance of only 225 S is an excellent match to ultra-low noise amplifiers. The primary is fully balanced and its leads may be reversed to invert polarity, if required. A 30 dB magnetic shield package is standard.